[llvm-commits] [llvm] r92467 - in /llvm/trunk/lib/Transforms/InstCombine: CMakeLists.txt InstCombine.h InstCombineCompares.cpp InstructionCombining.cpp
Chris Lattner
sabre at nondot.org
Sun Jan 3 23:37:32 PST 2010
Author: lattner
Date: Mon Jan 4 01:37:31 2010
New Revision: 92467
URL: http://llvm.org/viewvc/llvm-project?rev=92467&view=rev
Log:
split instcombine of compares (visit[FI]Cmp) out to
a new InstCombineCompares.cpp file.
Added:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
Modified:
llvm/trunk/lib/Transforms/InstCombine/CMakeLists.txt
llvm/trunk/lib/Transforms/InstCombine/InstCombine.h
llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
Modified: llvm/trunk/lib/Transforms/InstCombine/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/CMakeLists.txt?rev=92467&r1=92466&r2=92467&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/CMakeLists.txt (original)
+++ llvm/trunk/lib/Transforms/InstCombine/CMakeLists.txt Mon Jan 4 01:37:31 2010
@@ -1,5 +1,6 @@
add_llvm_library(LLVMInstCombine
InstructionCombining.cpp
+ InstCombineCompares.cpp
InstCombineSimplifyDemanded.cpp
)
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombine.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombine.h?rev=92467&r1=92466&r2=92467&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombine.h (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombine.h Mon Jan 4 01:37:31 2010
@@ -32,6 +32,20 @@
SPF_SMAX, SPF_UMAX
//SPF_ABS - TODO.
};
+
+/// getComplexity: Assign a complexity or rank value to LLVM Values...
+/// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
+static inline unsigned getComplexity(Value *V) {
+ if (isa<Instruction>(V)) {
+ if (BinaryOperator::isNeg(V) ||
+ BinaryOperator::isFNeg(V) ||
+ BinaryOperator::isNot(V))
+ return 3;
+ return 4;
+ }
+ if (isa<Argument>(V)) return 3;
+ return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
+}
/// InstCombineIRInserter - This is an IRBuilder insertion helper that works
@@ -179,6 +193,8 @@
Instruction *visitInstruction(Instruction &I) { return 0; }
private:
+ Value *dyn_castNegVal(Value *V) const;
+
Instruction *visitCallSite(CallSite CS);
bool transformConstExprCastCall(CallSite CS);
Instruction *transformCallThroughTrampoline(CallSite CS);
@@ -186,7 +202,7 @@
bool DoXform = true);
bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
DbgDeclareInst *hasOneUsePlusDeclare(Value *V);
-
+ Value *EmitGEPOffset(User *GEP);
public:
// InsertNewInstBefore - insert an instruction New before instruction Old
Added: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=92467&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (added)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Mon Jan 4 01:37:31 2010
@@ -0,0 +1,2443 @@
+//===- InstCombineCompares.cpp --------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the visitICmp and visitFCmp functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "InstCombine.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Support/ConstantRange.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/PatternMatch.h"
+using namespace llvm;
+using namespace PatternMatch;
+
+/// AddOne - Add one to a ConstantInt
+static Constant *AddOne(Constant *C) {
+ return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
+}
+/// SubOne - Subtract one from a ConstantInt
+static Constant *SubOne(ConstantInt *C) {
+ return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
+}
+
+static ConstantInt *ExtractElement(Constant *V, Constant *Idx) {
+ return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx));
+}
+
+static bool HasAddOverflow(ConstantInt *Result,
+ ConstantInt *In1, ConstantInt *In2,
+ bool IsSigned) {
+ if (IsSigned)
+ if (In2->getValue().isNegative())
+ return Result->getValue().sgt(In1->getValue());
+ else
+ return Result->getValue().slt(In1->getValue());
+ else
+ return Result->getValue().ult(In1->getValue());
+}
+
+/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
+/// overflowed for this type.
+static bool AddWithOverflow(Constant *&Result, Constant *In1,
+ Constant *In2, bool IsSigned = false) {
+ Result = ConstantExpr::getAdd(In1, In2);
+
+ if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
+ for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
+ Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
+ if (HasAddOverflow(ExtractElement(Result, Idx),
+ ExtractElement(In1, Idx),
+ ExtractElement(In2, Idx),
+ IsSigned))
+ return true;
+ }
+ return false;
+ }
+
+ return HasAddOverflow(cast<ConstantInt>(Result),
+ cast<ConstantInt>(In1), cast<ConstantInt>(In2),
+ IsSigned);
+}
+
+static bool HasSubOverflow(ConstantInt *Result,
+ ConstantInt *In1, ConstantInt *In2,
+ bool IsSigned) {
+ if (IsSigned)
+ if (In2->getValue().isNegative())
+ return Result->getValue().slt(In1->getValue());
+ else
+ return Result->getValue().sgt(In1->getValue());
+ else
+ return Result->getValue().ugt(In1->getValue());
+}
+
+/// SubWithOverflow - Compute Result = In1-In2, returning true if the result
+/// overflowed for this type.
+static bool SubWithOverflow(Constant *&Result, Constant *In1,
+ Constant *In2, bool IsSigned = false) {
+ Result = ConstantExpr::getSub(In1, In2);
+
+ if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
+ for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
+ Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
+ if (HasSubOverflow(ExtractElement(Result, Idx),
+ ExtractElement(In1, Idx),
+ ExtractElement(In2, Idx),
+ IsSigned))
+ return true;
+ }
+ return false;
+ }
+
+ return HasSubOverflow(cast<ConstantInt>(Result),
+ cast<ConstantInt>(In1), cast<ConstantInt>(In2),
+ IsSigned);
+}
+
+/// isSignBitCheck - Given an exploded icmp instruction, return true if the
+/// comparison only checks the sign bit. If it only checks the sign bit, set
+/// TrueIfSigned if the result of the comparison is true when the input value is
+/// signed.
+static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
+ bool &TrueIfSigned) {
+ switch (pred) {
+ case ICmpInst::ICMP_SLT: // True if LHS s< 0
+ TrueIfSigned = true;
+ return RHS->isZero();
+ case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
+ TrueIfSigned = true;
+ return RHS->isAllOnesValue();
+ case ICmpInst::ICMP_SGT: // True if LHS s> -1
+ TrueIfSigned = false;
+ return RHS->isAllOnesValue();
+ case ICmpInst::ICMP_UGT:
+ // True if LHS u> RHS and RHS == high-bit-mask - 1
+ TrueIfSigned = true;
+ return RHS->getValue() ==
+ APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
+ case ICmpInst::ICMP_UGE:
+ // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
+ TrueIfSigned = true;
+ return RHS->getValue().isSignBit();
+ default:
+ return false;
+ }
+}
+
+// isHighOnes - Return true if the constant is of the form 1+0+.
+// This is the same as lowones(~X).
+static bool isHighOnes(const ConstantInt *CI) {
+ return (~CI->getValue() + 1).isPowerOf2();
+}
+
+/// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
+/// set of known zero and one bits, compute the maximum and minimum values that
+/// could have the specified known zero and known one bits, returning them in
+/// min/max.
+static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero,
+ const APInt& KnownOne,
+ APInt& Min, APInt& Max) {
+ assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
+ KnownZero.getBitWidth() == Min.getBitWidth() &&
+ KnownZero.getBitWidth() == Max.getBitWidth() &&
+ "KnownZero, KnownOne and Min, Max must have equal bitwidth.");
+ APInt UnknownBits = ~(KnownZero|KnownOne);
+
+ // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
+ // bit if it is unknown.
+ Min = KnownOne;
+ Max = KnownOne|UnknownBits;
+
+ if (UnknownBits.isNegative()) { // Sign bit is unknown
+ Min.set(Min.getBitWidth()-1);
+ Max.clear(Max.getBitWidth()-1);
+ }
+}
+
+// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
+// a set of known zero and one bits, compute the maximum and minimum values that
+// could have the specified known zero and known one bits, returning them in
+// min/max.
+static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero,
+ const APInt &KnownOne,
+ APInt &Min, APInt &Max) {
+ assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
+ KnownZero.getBitWidth() == Min.getBitWidth() &&
+ KnownZero.getBitWidth() == Max.getBitWidth() &&
+ "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
+ APInt UnknownBits = ~(KnownZero|KnownOne);
+
+ // The minimum value is when the unknown bits are all zeros.
+ Min = KnownOne;
+ // The maximum value is when the unknown bits are all ones.
+ Max = KnownOne|UnknownBits;
+}
+
+
+
+/// FoldCmpLoadFromIndexedGlobal - Called we see this pattern:
+/// cmp pred (load (gep GV, ...)), cmpcst
+/// where GV is a global variable with a constant initializer. Try to simplify
+/// this into some simple computation that does not need the load. For example
+/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
+///
+/// If AndCst is non-null, then the loaded value is masked with that constant
+/// before doing the comparison. This handles cases like "A[i]&4 == 0".
+Instruction *InstCombiner::
+FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV,
+ CmpInst &ICI, ConstantInt *AndCst) {
+ ConstantArray *Init = dyn_cast<ConstantArray>(GV->getInitializer());
+ if (Init == 0 || Init->getNumOperands() > 1024) return 0;
+
+ // There are many forms of this optimization we can handle, for now, just do
+ // the simple index into a single-dimensional array.
+ //
+ // Require: GEP GV, 0, i {{, constant indices}}
+ if (GEP->getNumOperands() < 3 ||
+ !isa<ConstantInt>(GEP->getOperand(1)) ||
+ !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
+ isa<Constant>(GEP->getOperand(2)))
+ return 0;
+
+ // Check that indices after the variable are constants and in-range for the
+ // type they index. Collect the indices. This is typically for arrays of
+ // structs.
+ SmallVector<unsigned, 4> LaterIndices;
+
+ const Type *EltTy = cast<ArrayType>(Init->getType())->getElementType();
+ for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
+ ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
+ if (Idx == 0) return 0; // Variable index.
+
+ uint64_t IdxVal = Idx->getZExtValue();
+ if ((unsigned)IdxVal != IdxVal) return 0; // Too large array index.
+
+ if (const StructType *STy = dyn_cast<StructType>(EltTy))
+ EltTy = STy->getElementType(IdxVal);
+ else if (const ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
+ if (IdxVal >= ATy->getNumElements()) return 0;
+ EltTy = ATy->getElementType();
+ } else {
+ return 0; // Unknown type.
+ }
+
+ LaterIndices.push_back(IdxVal);
+ }
+
+ enum { Overdefined = -3, Undefined = -2 };
+
+ // Variables for our state machines.
+
+ // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
+ // "i == 47 | i == 87", where 47 is the first index the condition is true for,
+ // and 87 is the second (and last) index. FirstTrueElement is -2 when
+ // undefined, otherwise set to the first true element. SecondTrueElement is
+ // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
+ int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
+
+ // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
+ // form "i != 47 & i != 87". Same state transitions as for true elements.
+ int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
+
+ /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
+ /// define a state machine that triggers for ranges of values that the index
+ /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
+ /// This is -2 when undefined, -3 when overdefined, and otherwise the last
+ /// index in the range (inclusive). We use -2 for undefined here because we
+ /// use relative comparisons and don't want 0-1 to match -1.
+ int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
+
+ // MagicBitvector - This is a magic bitvector where we set a bit if the
+ // comparison is true for element 'i'. If there are 64 elements or less in
+ // the array, this will fully represent all the comparison results.
+ uint64_t MagicBitvector = 0;
+
+
+ // Scan the array and see if one of our patterns matches.
+ Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
+ for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
+ Constant *Elt = Init->getOperand(i);
+
+ // If this is indexing an array of structures, get the structure element.
+ if (!LaterIndices.empty())
+ Elt = ConstantExpr::getExtractValue(Elt, LaterIndices.data(),
+ LaterIndices.size());
+
+ // If the element is masked, handle it.
+ if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
+
+ // Find out if the comparison would be true or false for the i'th element.
+ Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt,
+ CompareRHS, TD);
+ // If the result is undef for this element, ignore it.
+ if (isa<UndefValue>(C)) {
+ // Extend range state machines to cover this element in case there is an
+ // undef in the middle of the range.
+ if (TrueRangeEnd == (int)i-1)
+ TrueRangeEnd = i;
+ if (FalseRangeEnd == (int)i-1)
+ FalseRangeEnd = i;
+ continue;
+ }
+
+ // If we can't compute the result for any of the elements, we have to give
+ // up evaluating the entire conditional.
+ if (!isa<ConstantInt>(C)) return 0;
+
+ // Otherwise, we know if the comparison is true or false for this element,
+ // update our state machines.
+ bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
+
+ // State machine for single/double/range index comparison.
+ if (IsTrueForElt) {
+ // Update the TrueElement state machine.
+ if (FirstTrueElement == Undefined)
+ FirstTrueElement = TrueRangeEnd = i; // First true element.
+ else {
+ // Update double-compare state machine.
+ if (SecondTrueElement == Undefined)
+ SecondTrueElement = i;
+ else
+ SecondTrueElement = Overdefined;
+
+ // Update range state machine.
+ if (TrueRangeEnd == (int)i-1)
+ TrueRangeEnd = i;
+ else
+ TrueRangeEnd = Overdefined;
+ }
+ } else {
+ // Update the FalseElement state machine.
+ if (FirstFalseElement == Undefined)
+ FirstFalseElement = FalseRangeEnd = i; // First false element.
+ else {
+ // Update double-compare state machine.
+ if (SecondFalseElement == Undefined)
+ SecondFalseElement = i;
+ else
+ SecondFalseElement = Overdefined;
+
+ // Update range state machine.
+ if (FalseRangeEnd == (int)i-1)
+ FalseRangeEnd = i;
+ else
+ FalseRangeEnd = Overdefined;
+ }
+ }
+
+
+ // If this element is in range, update our magic bitvector.
+ if (i < 64 && IsTrueForElt)
+ MagicBitvector |= 1ULL << i;
+
+ // If all of our states become overdefined, bail out early. Since the
+ // predicate is expensive, only check it every 8 elements. This is only
+ // really useful for really huge arrays.
+ if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
+ SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
+ FalseRangeEnd == Overdefined)
+ return 0;
+ }
+
+ // Now that we've scanned the entire array, emit our new comparison(s). We
+ // order the state machines in complexity of the generated code.
+ Value *Idx = GEP->getOperand(2);
+
+
+ // If the comparison is only true for one or two elements, emit direct
+ // comparisons.
+ if (SecondTrueElement != Overdefined) {
+ // None true -> false.
+ if (FirstTrueElement == Undefined)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(GEP->getContext()));
+
+ Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
+
+ // True for one element -> 'i == 47'.
+ if (SecondTrueElement == Undefined)
+ return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
+
+ // True for two elements -> 'i == 47 | i == 72'.
+ Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx);
+ Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
+ Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx);
+ return BinaryOperator::CreateOr(C1, C2);
+ }
+
+ // If the comparison is only false for one or two elements, emit direct
+ // comparisons.
+ if (SecondFalseElement != Overdefined) {
+ // None false -> true.
+ if (FirstFalseElement == Undefined)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(GEP->getContext()));
+
+ Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
+
+ // False for one element -> 'i != 47'.
+ if (SecondFalseElement == Undefined)
+ return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
+
+ // False for two elements -> 'i != 47 & i != 72'.
+ Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx);
+ Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
+ Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx);
+ return BinaryOperator::CreateAnd(C1, C2);
+ }
+
+ // If the comparison can be replaced with a range comparison for the elements
+ // where it is true, emit the range check.
+ if (TrueRangeEnd != Overdefined) {
+ assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare");
+
+ // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
+ if (FirstTrueElement) {
+ Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
+ Idx = Builder->CreateAdd(Idx, Offs);
+ }
+
+ Value *End = ConstantInt::get(Idx->getType(),
+ TrueRangeEnd-FirstTrueElement+1);
+ return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
+ }
+
+ // False range check.
+ if (FalseRangeEnd != Overdefined) {
+ assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare");
+ // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
+ if (FirstFalseElement) {
+ Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
+ Idx = Builder->CreateAdd(Idx, Offs);
+ }
+
+ Value *End = ConstantInt::get(Idx->getType(),
+ FalseRangeEnd-FirstFalseElement);
+ return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
+ }
+
+
+ // If a 32-bit or 64-bit magic bitvector captures the entire comparison state
+ // of this load, replace it with computation that does:
+ // ((magic_cst >> i) & 1) != 0
+ if (Init->getNumOperands() <= 32 ||
+ (TD && Init->getNumOperands() <= 64 && TD->isLegalInteger(64))) {
+ const Type *Ty;
+ if (Init->getNumOperands() <= 32)
+ Ty = Type::getInt32Ty(Init->getContext());
+ else
+ Ty = Type::getInt64Ty(Init->getContext());
+ Value *V = Builder->CreateIntCast(Idx, Ty, false);
+ V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
+ V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V);
+ return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
+ }
+
+ return 0;
+}
+
+
+/// EvaluateGEPOffsetExpression - Return a value that can be used to compare
+/// the *offset* implied by a GEP to zero. For example, if we have &A[i], we
+/// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can
+/// be complex, and scales are involved. The above expression would also be
+/// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32).
+/// This later form is less amenable to optimization though, and we are allowed
+/// to generate the first by knowing that pointer arithmetic doesn't overflow.
+///
+/// If we can't emit an optimized form for this expression, this returns null.
+///
+static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I,
+ InstCombiner &IC) {
+ TargetData &TD = *IC.getTargetData();
+ gep_type_iterator GTI = gep_type_begin(GEP);
+
+ // Check to see if this gep only has a single variable index. If so, and if
+ // any constant indices are a multiple of its scale, then we can compute this
+ // in terms of the scale of the variable index. For example, if the GEP
+ // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
+ // because the expression will cross zero at the same point.
+ unsigned i, e = GEP->getNumOperands();
+ int64_t Offset = 0;
+ for (i = 1; i != e; ++i, ++GTI) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
+ // Compute the aggregate offset of constant indices.
+ if (CI->isZero()) continue;
+
+ // Handle a struct index, which adds its field offset to the pointer.
+ if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
+ } else {
+ uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
+ Offset += Size*CI->getSExtValue();
+ }
+ } else {
+ // Found our variable index.
+ break;
+ }
+ }
+
+ // If there are no variable indices, we must have a constant offset, just
+ // evaluate it the general way.
+ if (i == e) return 0;
+
+ Value *VariableIdx = GEP->getOperand(i);
+ // Determine the scale factor of the variable element. For example, this is
+ // 4 if the variable index is into an array of i32.
+ uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType());
+
+ // Verify that there are no other variable indices. If so, emit the hard way.
+ for (++i, ++GTI; i != e; ++i, ++GTI) {
+ ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
+ if (!CI) return 0;
+
+ // Compute the aggregate offset of constant indices.
+ if (CI->isZero()) continue;
+
+ // Handle a struct index, which adds its field offset to the pointer.
+ if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
+ } else {
+ uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
+ Offset += Size*CI->getSExtValue();
+ }
+ }
+
+ // Okay, we know we have a single variable index, which must be a
+ // pointer/array/vector index. If there is no offset, life is simple, return
+ // the index.
+ unsigned IntPtrWidth = TD.getPointerSizeInBits();
+ if (Offset == 0) {
+ // Cast to intptrty in case a truncation occurs. If an extension is needed,
+ // we don't need to bother extending: the extension won't affect where the
+ // computation crosses zero.
+ if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth)
+ VariableIdx = new TruncInst(VariableIdx,
+ TD.getIntPtrType(VariableIdx->getContext()),
+ VariableIdx->getName(), &I);
+ return VariableIdx;
+ }
+
+ // Otherwise, there is an index. The computation we will do will be modulo
+ // the pointer size, so get it.
+ uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
+
+ Offset &= PtrSizeMask;
+ VariableScale &= PtrSizeMask;
+
+ // To do this transformation, any constant index must be a multiple of the
+ // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
+ // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
+ // multiple of the variable scale.
+ int64_t NewOffs = Offset / (int64_t)VariableScale;
+ if (Offset != NewOffs*(int64_t)VariableScale)
+ return 0;
+
+ // Okay, we can do this evaluation. Start by converting the index to intptr.
+ const Type *IntPtrTy = TD.getIntPtrType(VariableIdx->getContext());
+ if (VariableIdx->getType() != IntPtrTy)
+ VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy,
+ true /*SExt*/,
+ VariableIdx->getName(), &I);
+ Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
+ return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I);
+}
+
+/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
+/// else. At this point we know that the GEP is on the LHS of the comparison.
+Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
+ ICmpInst::Predicate Cond,
+ Instruction &I) {
+ // Look through bitcasts.
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS))
+ RHS = BCI->getOperand(0);
+
+ Value *PtrBase = GEPLHS->getOperand(0);
+ if (TD && PtrBase == RHS && GEPLHS->isInBounds()) {
+ // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
+ // This transformation (ignoring the base and scales) is valid because we
+ // know pointers can't overflow since the gep is inbounds. See if we can
+ // output an optimized form.
+ Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this);
+
+ // If not, synthesize the offset the hard way.
+ if (Offset == 0)
+ Offset = EmitGEPOffset(GEPLHS);
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
+ Constant::getNullValue(Offset->getType()));
+ } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
+ // If the base pointers are different, but the indices are the same, just
+ // compare the base pointer.
+ if (PtrBase != GEPRHS->getOperand(0)) {
+ bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
+ IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
+ GEPRHS->getOperand(0)->getType();
+ if (IndicesTheSame)
+ for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
+ if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
+ IndicesTheSame = false;
+ break;
+ }
+
+ // If all indices are the same, just compare the base pointers.
+ if (IndicesTheSame)
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
+ GEPLHS->getOperand(0), GEPRHS->getOperand(0));
+
+ // Otherwise, the base pointers are different and the indices are
+ // different, bail out.
+ return 0;
+ }
+
+ // If one of the GEPs has all zero indices, recurse.
+ bool AllZeros = true;
+ for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(GEPLHS->getOperand(i)) ||
+ !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
+ AllZeros = false;
+ break;
+ }
+ if (AllZeros)
+ return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
+ ICmpInst::getSwappedPredicate(Cond), I);
+
+ // If the other GEP has all zero indices, recurse.
+ AllZeros = true;
+ for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(GEPRHS->getOperand(i)) ||
+ !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
+ AllZeros = false;
+ break;
+ }
+ if (AllZeros)
+ return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
+
+ if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
+ // If the GEPs only differ by one index, compare it.
+ unsigned NumDifferences = 0; // Keep track of # differences.
+ unsigned DiffOperand = 0; // The operand that differs.
+ for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
+ if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
+ if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
+ GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
+ // Irreconcilable differences.
+ NumDifferences = 2;
+ break;
+ } else {
+ if (NumDifferences++) break;
+ DiffOperand = i;
+ }
+ }
+
+ if (NumDifferences == 0) // SAME GEP?
+ return ReplaceInstUsesWith(I, // No comparison is needed here.
+ ConstantInt::get(Type::getInt1Ty(I.getContext()),
+ ICmpInst::isTrueWhenEqual(Cond)));
+
+ else if (NumDifferences == 1) {
+ Value *LHSV = GEPLHS->getOperand(DiffOperand);
+ Value *RHSV = GEPRHS->getOperand(DiffOperand);
+ // Make sure we do a signed comparison here.
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
+ }
+ }
+
+ // Only lower this if the icmp is the only user of the GEP or if we expect
+ // the result to fold to a constant!
+ if (TD &&
+ (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
+ (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
+ // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
+ Value *L = EmitGEPOffset(GEPLHS);
+ Value *R = EmitGEPOffset(GEPRHS);
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
+ }
+ }
+ return 0;
+}
+
+/// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X".
+Instruction *InstCombiner::FoldICmpAddOpCst(ICmpInst &ICI,
+ Value *X, ConstantInt *CI,
+ ICmpInst::Predicate Pred,
+ Value *TheAdd) {
+ // If we have X+0, exit early (simplifying logic below) and let it get folded
+ // elsewhere. icmp X+0, X -> icmp X, X
+ if (CI->isZero()) {
+ bool isTrue = ICmpInst::isTrueWhenEqual(Pred);
+ return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
+ }
+
+ // (X+4) == X -> false.
+ if (Pred == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext()));
+
+ // (X+4) != X -> true.
+ if (Pred == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext()));
+
+ // If this is an instruction (as opposed to constantexpr) get NUW/NSW info.
+ bool isNUW = false, isNSW = false;
+ if (BinaryOperator *Add = dyn_cast<BinaryOperator>(TheAdd)) {
+ isNUW = Add->hasNoUnsignedWrap();
+ isNSW = Add->hasNoSignedWrap();
+ }
+
+ // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
+ // so the values can never be equal. Similiarly for all other "or equals"
+ // operators.
+
+ // (X+1) <u X --> X >u (MAXUINT-1) --> X != 255
+ // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
+ // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
+ if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
+ // If this is an NUW add, then this is always false.
+ if (isNUW)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext()));
+
+ Value *R = ConstantExpr::getSub(ConstantInt::get(CI->getType(), -1ULL), CI);
+ return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
+ }
+
+ // (X+1) >u X --> X <u (0-1) --> X != 255
+ // (X+2) >u X --> X <u (0-2) --> X <u 254
+ // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
+ if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) {
+ // If this is an NUW add, then this is always true.
+ if (isNUW)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext()));
+ return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI));
+ }
+
+ unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits();
+ ConstantInt *SMax = ConstantInt::get(X->getContext(),
+ APInt::getSignedMaxValue(BitWidth));
+
+ // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
+ // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
+ // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
+ // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
+ // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
+ // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
+ if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) {
+ // If this is an NSW add, then we have two cases: if the constant is
+ // positive, then this is always false, if negative, this is always true.
+ if (isNSW) {
+ bool isTrue = CI->getValue().isNegative();
+ return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
+ }
+
+ return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI));
+ }
+
+ // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
+ // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
+ // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
+ // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
+ // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
+ // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
+
+ // If this is an NSW add, then we have two cases: if the constant is
+ // positive, then this is always true, if negative, this is always false.
+ if (isNSW) {
+ bool isTrue = !CI->getValue().isNegative();
+ return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
+ }
+
+ assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE);
+ Constant *C = ConstantInt::get(X->getContext(), CI->getValue()-1);
+ return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C));
+}
+
+/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
+/// and CmpRHS are both known to be integer constants.
+Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
+ ConstantInt *DivRHS) {
+ ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
+ const APInt &CmpRHSV = CmpRHS->getValue();
+
+ // FIXME: If the operand types don't match the type of the divide
+ // then don't attempt this transform. The code below doesn't have the
+ // logic to deal with a signed divide and an unsigned compare (and
+ // vice versa). This is because (x /s C1) <s C2 produces different
+ // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
+ // (x /u C1) <u C2. Simply casting the operands and result won't
+ // work. :( The if statement below tests that condition and bails
+ // if it finds it.
+ bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
+ if (!ICI.isEquality() && DivIsSigned != ICI.isSigned())
+ return 0;
+ if (DivRHS->isZero())
+ return 0; // The ProdOV computation fails on divide by zero.
+ if (DivIsSigned && DivRHS->isAllOnesValue())
+ return 0; // The overflow computation also screws up here
+ if (DivRHS->isOne())
+ return 0; // Not worth bothering, and eliminates some funny cases
+ // with INT_MIN.
+
+ // Compute Prod = CI * DivRHS. We are essentially solving an equation
+ // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
+ // C2 (CI). By solving for X we can turn this into a range check
+ // instead of computing a divide.
+ Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS);
+
+ // Determine if the product overflows by seeing if the product is
+ // not equal to the divide. Make sure we do the same kind of divide
+ // as in the LHS instruction that we're folding.
+ bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
+ ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
+
+ // Get the ICmp opcode
+ ICmpInst::Predicate Pred = ICI.getPredicate();
+
+ // Figure out the interval that is being checked. For example, a comparison
+ // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
+ // Compute this interval based on the constants involved and the signedness of
+ // the compare/divide. This computes a half-open interval, keeping track of
+ // whether either value in the interval overflows. After analysis each
+ // overflow variable is set to 0 if it's corresponding bound variable is valid
+ // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
+ int LoOverflow = 0, HiOverflow = 0;
+ Constant *LoBound = 0, *HiBound = 0;
+
+ if (!DivIsSigned) { // udiv
+ // e.g. X/5 op 3 --> [15, 20)
+ LoBound = Prod;
+ HiOverflow = LoOverflow = ProdOV;
+ if (!HiOverflow)
+ HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false);
+ } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
+ if (CmpRHSV == 0) { // (X / pos) op 0
+ // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
+ LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
+ HiBound = DivRHS;
+ } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos
+ LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
+ HiOverflow = LoOverflow = ProdOV;
+ if (!HiOverflow)
+ HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true);
+ } else { // (X / pos) op neg
+ // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
+ HiBound = AddOne(Prod);
+ LoOverflow = HiOverflow = ProdOV ? -1 : 0;
+ if (!LoOverflow) {
+ ConstantInt* DivNeg =
+ cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
+ LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0;
+ }
+ }
+ } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0.
+ if (CmpRHSV == 0) { // (X / neg) op 0
+ // e.g. X/-5 op 0 --> [-4, 5)
+ LoBound = AddOne(DivRHS);
+ HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
+ if (HiBound == DivRHS) { // -INTMIN = INTMIN
+ HiOverflow = 1; // [INTMIN+1, overflow)
+ HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
+ }
+ } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos
+ // e.g. X/-5 op 3 --> [-19, -14)
+ HiBound = AddOne(Prod);
+ HiOverflow = LoOverflow = ProdOV ? -1 : 0;
+ if (!LoOverflow)
+ LoOverflow = AddWithOverflow(LoBound, HiBound, DivRHS, true) ? -1 : 0;
+ } else { // (X / neg) op neg
+ LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
+ LoOverflow = HiOverflow = ProdOV;
+ if (!HiOverflow)
+ HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, true);
+ }
+
+ // Dividing by a negative swaps the condition. LT <-> GT
+ Pred = ICmpInst::getSwappedPredicate(Pred);
+ }
+
+ Value *X = DivI->getOperand(0);
+ switch (Pred) {
+ default: llvm_unreachable("Unhandled icmp opcode!");
+ case ICmpInst::ICMP_EQ:
+ if (LoOverflow && HiOverflow)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext()));
+ else if (HiOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
+ ICmpInst::ICMP_UGE, X, LoBound);
+ else if (LoOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
+ ICmpInst::ICMP_ULT, X, HiBound);
+ else
+ return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
+ case ICmpInst::ICMP_NE:
+ if (LoOverflow && HiOverflow)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext()));
+ else if (HiOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
+ ICmpInst::ICMP_ULT, X, LoBound);
+ else if (LoOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
+ ICmpInst::ICMP_UGE, X, HiBound);
+ else
+ return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_SLT:
+ if (LoOverflow == +1) // Low bound is greater than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext()));
+ if (LoOverflow == -1) // Low bound is less than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext()));
+ return new ICmpInst(Pred, X, LoBound);
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_SGT:
+ if (HiOverflow == +1) // High bound greater than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext()));
+ else if (HiOverflow == -1) // High bound less than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext()));
+ if (Pred == ICmpInst::ICMP_UGT)
+ return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
+ else
+ return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
+ }
+}
+
+
+/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
+///
+Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
+ Instruction *LHSI,
+ ConstantInt *RHS) {
+ const APInt &RHSV = RHS->getValue();
+
+ switch (LHSI->getOpcode()) {
+ case Instruction::Trunc:
+ if (ICI.isEquality() && LHSI->hasOneUse()) {
+ // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
+ // of the high bits truncated out of x are known.
+ unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
+ SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
+ APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits));
+ APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
+ ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne);
+
+ // If all the high bits are known, we can do this xform.
+ if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
+ // Pull in the high bits from known-ones set.
+ APInt NewRHS(RHS->getValue());
+ NewRHS.zext(SrcBits);
+ NewRHS |= KnownOne;
+ return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
+ ConstantInt::get(ICI.getContext(), NewRHS));
+ }
+ }
+ break;
+
+ case Instruction::Xor: // (icmp pred (xor X, XorCST), CI)
+ if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
+ // If this is a comparison that tests the signbit (X < 0) or (x > -1),
+ // fold the xor.
+ if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
+ (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
+ Value *CompareVal = LHSI->getOperand(0);
+
+ // If the sign bit of the XorCST is not set, there is no change to
+ // the operation, just stop using the Xor.
+ if (!XorCST->getValue().isNegative()) {
+ ICI.setOperand(0, CompareVal);
+ Worklist.Add(LHSI);
+ return &ICI;
+ }
+
+ // Was the old condition true if the operand is positive?
+ bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
+
+ // If so, the new one isn't.
+ isTrueIfPositive ^= true;
+
+ if (isTrueIfPositive)
+ return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal,
+ SubOne(RHS));
+ else
+ return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal,
+ AddOne(RHS));
+ }
+
+ if (LHSI->hasOneUse()) {
+ // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
+ if (!ICI.isEquality() && XorCST->getValue().isSignBit()) {
+ const APInt &SignBit = XorCST->getValue();
+ ICmpInst::Predicate Pred = ICI.isSigned()
+ ? ICI.getUnsignedPredicate()
+ : ICI.getSignedPredicate();
+ return new ICmpInst(Pred, LHSI->getOperand(0),
+ ConstantInt::get(ICI.getContext(),
+ RHSV ^ SignBit));
+ }
+
+ // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
+ if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) {
+ const APInt &NotSignBit = XorCST->getValue();
+ ICmpInst::Predicate Pred = ICI.isSigned()
+ ? ICI.getUnsignedPredicate()
+ : ICI.getSignedPredicate();
+ Pred = ICI.getSwappedPredicate(Pred);
+ return new ICmpInst(Pred, LHSI->getOperand(0),
+ ConstantInt::get(ICI.getContext(),
+ RHSV ^ NotSignBit));
+ }
+ }
+ }
+ break;
+ case Instruction::And: // (icmp pred (and X, AndCST), RHS)
+ if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
+ LHSI->getOperand(0)->hasOneUse()) {
+ ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
+
+ // If the LHS is an AND of a truncating cast, we can widen the
+ // and/compare to be the input width without changing the value
+ // produced, eliminating a cast.
+ if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
+ // We can do this transformation if either the AND constant does not
+ // have its sign bit set or if it is an equality comparison.
+ // Extending a relational comparison when we're checking the sign
+ // bit would not work.
+ if (Cast->hasOneUse() &&
+ (ICI.isEquality() ||
+ (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) {
+ uint32_t BitWidth =
+ cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
+ APInt NewCST = AndCST->getValue();
+ NewCST.zext(BitWidth);
+ APInt NewCI = RHSV;
+ NewCI.zext(BitWidth);
+ Value *NewAnd =
+ Builder->CreateAnd(Cast->getOperand(0),
+ ConstantInt::get(ICI.getContext(), NewCST),
+ LHSI->getName());
+ return new ICmpInst(ICI.getPredicate(), NewAnd,
+ ConstantInt::get(ICI.getContext(), NewCI));
+ }
+ }
+
+ // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
+ // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
+ // happens a LOT in code produced by the C front-end, for bitfield
+ // access.
+ BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
+ if (Shift && !Shift->isShift())
+ Shift = 0;
+
+ ConstantInt *ShAmt;
+ ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
+ const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
+ const Type *AndTy = AndCST->getType(); // Type of the and.
+
+ // We can fold this as long as we can't shift unknown bits
+ // into the mask. This can only happen with signed shift
+ // rights, as they sign-extend.
+ if (ShAmt) {
+ bool CanFold = Shift->isLogicalShift();
+ if (!CanFold) {
+ // To test for the bad case of the signed shr, see if any
+ // of the bits shifted in could be tested after the mask.
+ uint32_t TyBits = Ty->getPrimitiveSizeInBits();
+ int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
+
+ uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
+ if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) &
+ AndCST->getValue()) == 0)
+ CanFold = true;
+ }
+
+ if (CanFold) {
+ Constant *NewCst;
+ if (Shift->getOpcode() == Instruction::Shl)
+ NewCst = ConstantExpr::getLShr(RHS, ShAmt);
+ else
+ NewCst = ConstantExpr::getShl(RHS, ShAmt);
+
+ // Check to see if we are shifting out any of the bits being
+ // compared.
+ if (ConstantExpr::get(Shift->getOpcode(),
+ NewCst, ShAmt) != RHS) {
+ // If we shifted bits out, the fold is not going to work out.
+ // As a special case, check to see if this means that the
+ // result is always true or false now.
+ if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(ICI,
+ ConstantInt::getFalse(ICI.getContext()));
+ if (ICI.getPredicate() == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(ICI,
+ ConstantInt::getTrue(ICI.getContext()));
+ } else {
+ ICI.setOperand(1, NewCst);
+ Constant *NewAndCST;
+ if (Shift->getOpcode() == Instruction::Shl)
+ NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
+ else
+ NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
+ LHSI->setOperand(1, NewAndCST);
+ LHSI->setOperand(0, Shift->getOperand(0));
+ Worklist.Add(Shift); // Shift is dead.
+ return &ICI;
+ }
+ }
+ }
+
+ // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
+ // preferable because it allows the C<<Y expression to be hoisted out
+ // of a loop if Y is invariant and X is not.
+ if (Shift && Shift->hasOneUse() && RHSV == 0 &&
+ ICI.isEquality() && !Shift->isArithmeticShift() &&
+ !isa<Constant>(Shift->getOperand(0))) {
+ // Compute C << Y.
+ Value *NS;
+ if (Shift->getOpcode() == Instruction::LShr) {
+ NS = Builder->CreateShl(AndCST, Shift->getOperand(1), "tmp");
+ } else {
+ // Insert a logical shift.
+ NS = Builder->CreateLShr(AndCST, Shift->getOperand(1), "tmp");
+ }
+
+ // Compute X & (C << Y).
+ Value *NewAnd =
+ Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
+
+ ICI.setOperand(0, NewAnd);
+ return &ICI;
+ }
+ }
+
+ // Try to optimize things like "A[i]&42 == 0" to index computations.
+ if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) {
+ if (GetElementPtrInst *GEP =
+ dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
+ if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
+ !LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) {
+ ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1));
+ if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C))
+ return Res;
+ }
+ }
+ break;
+
+ case Instruction::Or: {
+ if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse())
+ break;
+ Value *P, *Q;
+ if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
+ // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
+ // -> and (icmp eq P, null), (icmp eq Q, null).
+
+ Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P,
+ Constant::getNullValue(P->getType()));
+ Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q,
+ Constant::getNullValue(Q->getType()));
+ Instruction *Op;
+ if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+ Op = BinaryOperator::CreateAnd(ICIP, ICIQ);
+ else
+ Op = BinaryOperator::CreateOr(ICIP, ICIQ);
+ return Op;
+ }
+ break;
+ }
+
+ case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
+ ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!ShAmt) break;
+
+ uint32_t TypeBits = RHSV.getBitWidth();
+
+ // Check that the shift amount is in range. If not, don't perform
+ // undefined shifts. When the shift is visited it will be
+ // simplified.
+ if (ShAmt->uge(TypeBits))
+ break;
+
+ if (ICI.isEquality()) {
+ // If we are comparing against bits always shifted out, the
+ // comparison cannot succeed.
+ Constant *Comp =
+ ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt),
+ ShAmt);
+ if (Comp != RHS) {// Comparing against a bit that we know is zero.
+ bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+ Constant *Cst =
+ ConstantInt::get(Type::getInt1Ty(ICI.getContext()), IsICMP_NE);
+ return ReplaceInstUsesWith(ICI, Cst);
+ }
+
+ if (LHSI->hasOneUse()) {
+ // Otherwise strength reduce the shift into an and.
+ uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+ Constant *Mask =
+ ConstantInt::get(ICI.getContext(), APInt::getLowBitsSet(TypeBits,
+ TypeBits-ShAmtVal));
+
+ Value *And =
+ Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask");
+ return new ICmpInst(ICI.getPredicate(), And,
+ ConstantInt::get(ICI.getContext(),
+ RHSV.lshr(ShAmtVal)));
+ }
+ }
+
+ // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
+ bool TrueIfSigned = false;
+ if (LHSI->hasOneUse() &&
+ isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
+ // (X << 31) <s 0 --> (X&1) != 0
+ Constant *Mask = ConstantInt::get(ICI.getContext(), APInt(TypeBits, 1) <<
+ (TypeBits-ShAmt->getZExtValue()-1));
+ Value *And =
+ Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask");
+ return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
+ And, Constant::getNullValue(And->getType()));
+ }
+ break;
+ }
+
+ case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
+ case Instruction::AShr: {
+ // Only handle equality comparisons of shift-by-constant.
+ ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!ShAmt || !ICI.isEquality()) break;
+
+ // Check that the shift amount is in range. If not, don't perform
+ // undefined shifts. When the shift is visited it will be
+ // simplified.
+ uint32_t TypeBits = RHSV.getBitWidth();
+ if (ShAmt->uge(TypeBits))
+ break;
+
+ uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+
+ // If we are comparing against bits always shifted out, the
+ // comparison cannot succeed.
+ APInt Comp = RHSV << ShAmtVal;
+ if (LHSI->getOpcode() == Instruction::LShr)
+ Comp = Comp.lshr(ShAmtVal);
+ else
+ Comp = Comp.ashr(ShAmtVal);
+
+ if (Comp != RHSV) { // Comparing against a bit that we know is zero.
+ bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+ Constant *Cst = ConstantInt::get(Type::getInt1Ty(ICI.getContext()),
+ IsICMP_NE);
+ return ReplaceInstUsesWith(ICI, Cst);
+ }
+
+ // Otherwise, check to see if the bits shifted out are known to be zero.
+ // If so, we can compare against the unshifted value:
+ // (X & 4) >> 1 == 2 --> (X & 4) == 4.
+ if (LHSI->hasOneUse() &&
+ MaskedValueIsZero(LHSI->getOperand(0),
+ APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) {
+ return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
+ ConstantExpr::getShl(RHS, ShAmt));
+ }
+
+ if (LHSI->hasOneUse()) {
+ // Otherwise strength reduce the shift into an and.
+ APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
+ Constant *Mask = ConstantInt::get(ICI.getContext(), Val);
+
+ Value *And = Builder->CreateAnd(LHSI->getOperand(0),
+ Mask, LHSI->getName()+".mask");
+ return new ICmpInst(ICI.getPredicate(), And,
+ ConstantExpr::getShl(RHS, ShAmt));
+ }
+ break;
+ }
+
+ case Instruction::SDiv:
+ case Instruction::UDiv:
+ // Fold: icmp pred ([us]div X, C1), C2 -> range test
+ // Fold this div into the comparison, producing a range check.
+ // Determine, based on the divide type, what the range is being
+ // checked. If there is an overflow on the low or high side, remember
+ // it, otherwise compute the range [low, hi) bounding the new value.
+ // See: InsertRangeTest above for the kinds of replacements possible.
+ if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
+ if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
+ DivRHS))
+ return R;
+ break;
+
+ case Instruction::Add:
+ // Fold: icmp pred (add X, C1), C2
+ if (!ICI.isEquality()) {
+ ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!LHSC) break;
+ const APInt &LHSV = LHSC->getValue();
+
+ ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
+ .subtract(LHSV);
+
+ if (ICI.isSigned()) {
+ if (CR.getLower().isSignBit()) {
+ return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
+ ConstantInt::get(ICI.getContext(),CR.getUpper()));
+ } else if (CR.getUpper().isSignBit()) {
+ return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
+ ConstantInt::get(ICI.getContext(),CR.getLower()));
+ }
+ } else {
+ if (CR.getLower().isMinValue()) {
+ return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
+ ConstantInt::get(ICI.getContext(),CR.getUpper()));
+ } else if (CR.getUpper().isMinValue()) {
+ return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
+ ConstantInt::get(ICI.getContext(),CR.getLower()));
+ }
+ }
+ }
+ break;
+ }
+
+ // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
+ if (ICI.isEquality()) {
+ bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+
+ // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
+ // the second operand is a constant, simplify a bit.
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
+ switch (BO->getOpcode()) {
+ case Instruction::SRem:
+ // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
+ if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
+ const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
+ if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
+ Value *NewRem =
+ Builder->CreateURem(BO->getOperand(0), BO->getOperand(1),
+ BO->getName());
+ return new ICmpInst(ICI.getPredicate(), NewRem,
+ Constant::getNullValue(BO->getType()));
+ }
+ }
+ break;
+ case Instruction::Add:
+ // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
+ if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
+ if (BO->hasOneUse())
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ ConstantExpr::getSub(RHS, BOp1C));
+ } else if (RHSV == 0) {
+ // Replace ((add A, B) != 0) with (A != -B) if A or B is
+ // efficiently invertible, or if the add has just this one use.
+ Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
+
+ if (Value *NegVal = dyn_castNegVal(BOp1))
+ return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
+ else if (Value *NegVal = dyn_castNegVal(BOp0))
+ return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
+ else if (BO->hasOneUse()) {
+ Value *Neg = Builder->CreateNeg(BOp1);
+ Neg->takeName(BO);
+ return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
+ }
+ }
+ break;
+ case Instruction::Xor:
+ // For the xor case, we can xor two constants together, eliminating
+ // the explicit xor.
+ if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ ConstantExpr::getXor(RHS, BOC));
+
+ // FALLTHROUGH
+ case Instruction::Sub:
+ // Replace (([sub|xor] A, B) != 0) with (A != B)
+ if (RHSV == 0)
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ BO->getOperand(1));
+ break;
+
+ case Instruction::Or:
+ // If bits are being or'd in that are not present in the constant we
+ // are comparing against, then the comparison could never succeed!
+ if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
+ Constant *NotCI = ConstantExpr::getNot(RHS);
+ if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
+ return ReplaceInstUsesWith(ICI,
+ ConstantInt::get(Type::getInt1Ty(ICI.getContext()),
+ isICMP_NE));
+ }
+ break;
+
+ case Instruction::And:
+ if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
+ // If bits are being compared against that are and'd out, then the
+ // comparison can never succeed!
+ if ((RHSV & ~BOC->getValue()) != 0)
+ return ReplaceInstUsesWith(ICI,
+ ConstantInt::get(Type::getInt1Ty(ICI.getContext()),
+ isICMP_NE));
+
+ // If we have ((X & C) == C), turn it into ((X & C) != 0).
+ if (RHS == BOC && RHSV.isPowerOf2())
+ return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
+ ICmpInst::ICMP_NE, LHSI,
+ Constant::getNullValue(RHS->getType()));
+
+ // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
+ if (BOC->getValue().isSignBit()) {
+ Value *X = BO->getOperand(0);
+ Constant *Zero = Constant::getNullValue(X->getType());
+ ICmpInst::Predicate pred = isICMP_NE ?
+ ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
+ return new ICmpInst(pred, X, Zero);
+ }
+
+ // ((X & ~7) == 0) --> X < 8
+ if (RHSV == 0 && isHighOnes(BOC)) {
+ Value *X = BO->getOperand(0);
+ Constant *NegX = ConstantExpr::getNeg(BOC);
+ ICmpInst::Predicate pred = isICMP_NE ?
+ ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
+ return new ICmpInst(pred, X, NegX);
+ }
+ }
+ default: break;
+ }
+ } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
+ // Handle icmp {eq|ne} <intrinsic>, intcst.
+ if (II->getIntrinsicID() == Intrinsic::bswap) {
+ Worklist.Add(II);
+ ICI.setOperand(0, II->getOperand(1));
+ ICI.setOperand(1, ConstantInt::get(II->getContext(), RHSV.byteSwap()));
+ return &ICI;
+ }
+ }
+ }
+ return 0;
+}
+
+/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
+/// We only handle extending casts so far.
+///
+Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
+ const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
+ Value *LHSCIOp = LHSCI->getOperand(0);
+ const Type *SrcTy = LHSCIOp->getType();
+ const Type *DestTy = LHSCI->getType();
+ Value *RHSCIOp;
+
+ // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
+ // integer type is the same size as the pointer type.
+ if (TD && LHSCI->getOpcode() == Instruction::PtrToInt &&
+ TD->getPointerSizeInBits() ==
+ cast<IntegerType>(DestTy)->getBitWidth()) {
+ Value *RHSOp = 0;
+ if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
+ RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
+ } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
+ RHSOp = RHSC->getOperand(0);
+ // If the pointer types don't match, insert a bitcast.
+ if (LHSCIOp->getType() != RHSOp->getType())
+ RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
+ }
+
+ if (RHSOp)
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
+ }
+
+ // The code below only handles extension cast instructions, so far.
+ // Enforce this.
+ if (LHSCI->getOpcode() != Instruction::ZExt &&
+ LHSCI->getOpcode() != Instruction::SExt)
+ return 0;
+
+ bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
+ bool isSignedCmp = ICI.isSigned();
+
+ if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
+ // Not an extension from the same type?
+ RHSCIOp = CI->getOperand(0);
+ if (RHSCIOp->getType() != LHSCIOp->getType())
+ return 0;
+
+ // If the signedness of the two casts doesn't agree (i.e. one is a sext
+ // and the other is a zext), then we can't handle this.
+ if (CI->getOpcode() != LHSCI->getOpcode())
+ return 0;
+
+ // Deal with equality cases early.
+ if (ICI.isEquality())
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
+
+ // A signed comparison of sign extended values simplifies into a
+ // signed comparison.
+ if (isSignedCmp && isSignedExt)
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
+
+ // The other three cases all fold into an unsigned comparison.
+ return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
+ }
+
+ // If we aren't dealing with a constant on the RHS, exit early
+ ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
+ if (!CI)
+ return 0;
+
+ // Compute the constant that would happen if we truncated to SrcTy then
+ // reextended to DestTy.
+ Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
+ Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(),
+ Res1, DestTy);
+
+ // If the re-extended constant didn't change...
+ if (Res2 == CI) {
+ // Deal with equality cases early.
+ if (ICI.isEquality())
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
+
+ // A signed comparison of sign extended values simplifies into a
+ // signed comparison.
+ if (isSignedExt && isSignedCmp)
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
+
+ // The other three cases all fold into an unsigned comparison.
+ return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1);
+ }
+
+ // The re-extended constant changed so the constant cannot be represented
+ // in the shorter type. Consequently, we cannot emit a simple comparison.
+
+ // First, handle some easy cases. We know the result cannot be equal at this
+ // point so handle the ICI.isEquality() cases
+ if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext()));
+ if (ICI.getPredicate() == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext()));
+
+ // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
+ // should have been folded away previously and not enter in here.
+ Value *Result;
+ if (isSignedCmp) {
+ // We're performing a signed comparison.
+ if (cast<ConstantInt>(CI)->getValue().isNegative())
+ Result = ConstantInt::getFalse(ICI.getContext()); // X < (small) --> false
+ else
+ Result = ConstantInt::getTrue(ICI.getContext()); // X < (large) --> true
+ } else {
+ // We're performing an unsigned comparison.
+ if (isSignedExt) {
+ // We're performing an unsigned comp with a sign extended value.
+ // This is true if the input is >= 0. [aka >s -1]
+ Constant *NegOne = Constant::getAllOnesValue(SrcTy);
+ Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName());
+ } else {
+ // Unsigned extend & unsigned compare -> always true.
+ Result = ConstantInt::getTrue(ICI.getContext());
+ }
+ }
+
+ // Finally, return the value computed.
+ if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
+ ICI.getPredicate() == ICmpInst::ICMP_SLT)
+ return ReplaceInstUsesWith(ICI, Result);
+
+ assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
+ ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
+ "ICmp should be folded!");
+ if (Constant *CI = dyn_cast<Constant>(Result))
+ return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
+ return BinaryOperator::CreateNot(Result);
+}
+
+
+
+Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
+ bool Changed = false;
+
+ /// Orders the operands of the compare so that they are listed from most
+ /// complex to least complex. This puts constants before unary operators,
+ /// before binary operators.
+ if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
+ I.swapOperands();
+ Changed = true;
+ }
+
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, TD))
+ return ReplaceInstUsesWith(I, V);
+
+ const Type *Ty = Op0->getType();
+
+ // icmp's with boolean values can always be turned into bitwise operations
+ if (Ty == Type::getInt1Ty(I.getContext())) {
+ switch (I.getPredicate()) {
+ default: llvm_unreachable("Invalid icmp instruction!");
+ case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B)
+ Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp");
+ return BinaryOperator::CreateNot(Xor);
+ }
+ case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B
+ return BinaryOperator::CreateXor(Op0, Op1);
+
+ case ICmpInst::ICMP_UGT:
+ std::swap(Op0, Op1); // Change icmp ugt -> icmp ult
+ // FALL THROUGH
+ case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B
+ Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
+ return BinaryOperator::CreateAnd(Not, Op1);
+ }
+ case ICmpInst::ICMP_SGT:
+ std::swap(Op0, Op1); // Change icmp sgt -> icmp slt
+ // FALL THROUGH
+ case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B
+ Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
+ return BinaryOperator::CreateAnd(Not, Op0);
+ }
+ case ICmpInst::ICMP_UGE:
+ std::swap(Op0, Op1); // Change icmp uge -> icmp ule
+ // FALL THROUGH
+ case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B
+ Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
+ return BinaryOperator::CreateOr(Not, Op1);
+ }
+ case ICmpInst::ICMP_SGE:
+ std::swap(Op0, Op1); // Change icmp sge -> icmp sle
+ // FALL THROUGH
+ case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B
+ Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
+ return BinaryOperator::CreateOr(Not, Op0);
+ }
+ }
+ }
+
+ unsigned BitWidth = 0;
+ if (TD)
+ BitWidth = TD->getTypeSizeInBits(Ty->getScalarType());
+ else if (Ty->isIntOrIntVector())
+ BitWidth = Ty->getScalarSizeInBits();
+
+ bool isSignBit = false;
+
+ // See if we are doing a comparison with a constant.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ Value *A = 0, *B = 0;
+
+ // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
+ if (I.isEquality() && CI->isZero() &&
+ match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
+ // (icmp cond A B) if cond is equality
+ return new ICmpInst(I.getPredicate(), A, B);
+ }
+
+ // If we have an icmp le or icmp ge instruction, turn it into the
+ // appropriate icmp lt or icmp gt instruction. This allows us to rely on
+ // them being folded in the code below. The SimplifyICmpInst code has
+ // already handled the edge cases for us, so we just assert on them.
+ switch (I.getPredicate()) {
+ default: break;
+ case ICmpInst::ICMP_ULE:
+ assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE
+ return new ICmpInst(ICmpInst::ICMP_ULT, Op0,
+ ConstantInt::get(CI->getContext(), CI->getValue()+1));
+ case ICmpInst::ICMP_SLE:
+ assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE
+ return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
+ ConstantInt::get(CI->getContext(), CI->getValue()+1));
+ case ICmpInst::ICMP_UGE:
+ assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE
+ return new ICmpInst(ICmpInst::ICMP_UGT, Op0,
+ ConstantInt::get(CI->getContext(), CI->getValue()-1));
+ case ICmpInst::ICMP_SGE:
+ assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE
+ return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
+ ConstantInt::get(CI->getContext(), CI->getValue()-1));
+ }
+
+ // If this comparison is a normal comparison, it demands all
+ // bits, if it is a sign bit comparison, it only demands the sign bit.
+ bool UnusedBit;
+ isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
+ }
+
+ // See if we can fold the comparison based on range information we can get
+ // by checking whether bits are known to be zero or one in the input.
+ if (BitWidth != 0) {
+ APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0);
+ APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0);
+
+ if (SimplifyDemandedBits(I.getOperandUse(0),
+ isSignBit ? APInt::getSignBit(BitWidth)
+ : APInt::getAllOnesValue(BitWidth),
+ Op0KnownZero, Op0KnownOne, 0))
+ return &I;
+ if (SimplifyDemandedBits(I.getOperandUse(1),
+ APInt::getAllOnesValue(BitWidth),
+ Op1KnownZero, Op1KnownOne, 0))
+ return &I;
+
+ // Given the known and unknown bits, compute a range that the LHS could be
+ // in. Compute the Min, Max and RHS values based on the known bits. For the
+ // EQ and NE we use unsigned values.
+ APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
+ APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
+ if (I.isSigned()) {
+ ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
+ Op0Min, Op0Max);
+ ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
+ Op1Min, Op1Max);
+ } else {
+ ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
+ Op0Min, Op0Max);
+ ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
+ Op1Min, Op1Max);
+ }
+
+ // If Min and Max are known to be the same, then SimplifyDemandedBits
+ // figured out that the LHS is a constant. Just constant fold this now so
+ // that code below can assume that Min != Max.
+ if (!isa<Constant>(Op0) && Op0Min == Op0Max)
+ return new ICmpInst(I.getPredicate(),
+ ConstantInt::get(I.getContext(), Op0Min), Op1);
+ if (!isa<Constant>(Op1) && Op1Min == Op1Max)
+ return new ICmpInst(I.getPredicate(), Op0,
+ ConstantInt::get(I.getContext(), Op1Min));
+
+ // Based on the range information we know about the LHS, see if we can
+ // simplify this comparison. For example, (x&4) < 8 is always true.
+ switch (I.getPredicate()) {
+ default: llvm_unreachable("Unknown icmp opcode!");
+ case ICmpInst::ICMP_EQ:
+ if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ break;
+ case ICmpInst::ICMP_NE:
+ if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ break;
+ case ICmpInst::ICMP_ULT:
+ if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
+ ConstantInt::get(CI->getContext(), CI->getValue()-1));
+
+ // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
+ if (CI->isMinValue(true))
+ return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
+ Constant::getAllOnesValue(Op0->getType()));
+ }
+ break;
+ case ICmpInst::ICMP_UGT:
+ if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+
+ if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
+ ConstantInt::get(CI->getContext(), CI->getValue()+1));
+
+ // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
+ if (CI->isMaxValue(true))
+ return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
+ Constant::getNullValue(Op0->getType()));
+ }
+ break;
+ case ICmpInst::ICMP_SLT:
+ if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
+ ConstantInt::get(CI->getContext(), CI->getValue()-1));
+ }
+ break;
+ case ICmpInst::ICMP_SGT:
+ if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+
+ if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
+ ConstantInt::get(CI->getContext(), CI->getValue()+1));
+ }
+ break;
+ case ICmpInst::ICMP_SGE:
+ assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
+ if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ break;
+ case ICmpInst::ICMP_SLE:
+ assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
+ if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ break;
+ case ICmpInst::ICMP_UGE:
+ assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
+ if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ break;
+ case ICmpInst::ICMP_ULE:
+ assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
+ if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ break;
+ }
+
+ // Turn a signed comparison into an unsigned one if both operands
+ // are known to have the same sign.
+ if (I.isSigned() &&
+ ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) ||
+ (Op0KnownOne.isNegative() && Op1KnownOne.isNegative())))
+ return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
+ }
+
+ // Test if the ICmpInst instruction is used exclusively by a select as
+ // part of a minimum or maximum operation. If so, refrain from doing
+ // any other folding. This helps out other analyses which understand
+ // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
+ // and CodeGen. And in this case, at least one of the comparison
+ // operands has at least one user besides the compare (the select),
+ // which would often largely negate the benefit of folding anyway.
+ if (I.hasOneUse())
+ if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin()))
+ if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
+ (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
+ return 0;
+
+ // See if we are doing a comparison between a constant and an instruction that
+ // can be folded into the comparison.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ // Since the RHS is a ConstantInt (CI), if the left hand side is an
+ // instruction, see if that instruction also has constants so that the
+ // instruction can be folded into the icmp
+ if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+ if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
+ return Res;
+ }
+
+ // Handle icmp with constant (but not simple integer constant) RHS
+ if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
+ if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+ switch (LHSI->getOpcode()) {
+ case Instruction::GetElementPtr:
+ // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
+ if (RHSC->isNullValue() &&
+ cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
+ return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
+ Constant::getNullValue(LHSI->getOperand(0)->getType()));
+ break;
+ case Instruction::PHI:
+ // Only fold icmp into the PHI if the phi and icmp are in the same
+ // block. If in the same block, we're encouraging jump threading. If
+ // not, we are just pessimizing the code by making an i1 phi.
+ if (LHSI->getParent() == I.getParent())
+ if (Instruction *NV = FoldOpIntoPhi(I, true))
+ return NV;
+ break;
+ case Instruction::Select: {
+ // If either operand of the select is a constant, we can fold the
+ // comparison into the select arms, which will cause one to be
+ // constant folded and the select turned into a bitwise or.
+ Value *Op1 = 0, *Op2 = 0;
+ if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1)))
+ Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
+ if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2)))
+ Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
+
+ // We only want to perform this transformation if it will not lead to
+ // additional code. This is true if either both sides of the select
+ // fold to a constant (in which case the icmp is replaced with a select
+ // which will usually simplify) or this is the only user of the
+ // select (in which case we are trading a select+icmp for a simpler
+ // select+icmp).
+ if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) {
+ if (!Op1)
+ Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1),
+ RHSC, I.getName());
+ if (!Op2)
+ Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2),
+ RHSC, I.getName());
+ return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
+ }
+ break;
+ }
+ case Instruction::Call:
+ // If we have (malloc != null), and if the malloc has a single use, we
+ // can assume it is successful and remove the malloc.
+ if (isMalloc(LHSI) && LHSI->hasOneUse() &&
+ isa<ConstantPointerNull>(RHSC)) {
+ // Need to explicitly erase malloc call here, instead of adding it to
+ // Worklist, because it won't get DCE'd from the Worklist since
+ // isInstructionTriviallyDead() returns false for function calls.
+ // It is OK to replace LHSI/MallocCall with Undef because the
+ // instruction that uses it will be erased via Worklist.
+ if (extractMallocCall(LHSI)) {
+ LHSI->replaceAllUsesWith(UndefValue::get(LHSI->getType()));
+ EraseInstFromFunction(*LHSI);
+ return ReplaceInstUsesWith(I,
+ ConstantInt::get(Type::getInt1Ty(I.getContext()),
+ !I.isTrueWhenEqual()));
+ }
+ if (CallInst* MallocCall = extractMallocCallFromBitCast(LHSI))
+ if (MallocCall->hasOneUse()) {
+ MallocCall->replaceAllUsesWith(
+ UndefValue::get(MallocCall->getType()));
+ EraseInstFromFunction(*MallocCall);
+ Worklist.Add(LHSI); // The malloc's bitcast use.
+ return ReplaceInstUsesWith(I,
+ ConstantInt::get(Type::getInt1Ty(I.getContext()),
+ !I.isTrueWhenEqual()));
+ }
+ }
+ break;
+ case Instruction::IntToPtr:
+ // icmp pred inttoptr(X), null -> icmp pred X, 0
+ if (RHSC->isNullValue() && TD &&
+ TD->getIntPtrType(RHSC->getContext()) ==
+ LHSI->getOperand(0)->getType())
+ return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
+ Constant::getNullValue(LHSI->getOperand(0)->getType()));
+ break;
+
+ case Instruction::Load:
+ // Try to optimize things like "A[i] > 4" to index computations.
+ if (GetElementPtrInst *GEP =
+ dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
+ if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
+ !cast<LoadInst>(LHSI)->isVolatile())
+ if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
+ return Res;
+ }
+ break;
+ }
+ }
+
+ // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
+ if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
+ if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
+ return NI;
+ if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
+ if (Instruction *NI = FoldGEPICmp(GEP, Op0,
+ ICmpInst::getSwappedPredicate(I.getPredicate()), I))
+ return NI;
+
+ // Test to see if the operands of the icmp are casted versions of other
+ // values. If the ptr->ptr cast can be stripped off both arguments, we do so
+ // now.
+ if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
+ if (isa<PointerType>(Op0->getType()) &&
+ (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
+ // We keep moving the cast from the left operand over to the right
+ // operand, where it can often be eliminated completely.
+ Op0 = CI->getOperand(0);
+
+ // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
+ // so eliminate it as well.
+ if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
+ Op1 = CI2->getOperand(0);
+
+ // If Op1 is a constant, we can fold the cast into the constant.
+ if (Op0->getType() != Op1->getType()) {
+ if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+ Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
+ } else {
+ // Otherwise, cast the RHS right before the icmp
+ Op1 = Builder->CreateBitCast(Op1, Op0->getType());
+ }
+ }
+ return new ICmpInst(I.getPredicate(), Op0, Op1);
+ }
+ }
+
+ if (isa<CastInst>(Op0)) {
+ // Handle the special case of: icmp (cast bool to X), <cst>
+ // This comes up when you have code like
+ // int X = A < B;
+ // if (X) ...
+ // For generality, we handle any zero-extension of any operand comparison
+ // with a constant or another cast from the same type.
+ if (isa<Constant>(Op1) || isa<CastInst>(Op1))
+ if (Instruction *R = visitICmpInstWithCastAndCast(I))
+ return R;
+ }
+
+ // See if it's the same type of instruction on the left and right.
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+ if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
+ if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() &&
+ Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1)) {
+ switch (Op0I->getOpcode()) {
+ default: break;
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Xor:
+ if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
+ return new ICmpInst(I.getPredicate(), Op0I->getOperand(0),
+ Op1I->getOperand(0));
+ // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
+ if (CI->getValue().isSignBit()) {
+ ICmpInst::Predicate Pred = I.isSigned()
+ ? I.getUnsignedPredicate()
+ : I.getSignedPredicate();
+ return new ICmpInst(Pred, Op0I->getOperand(0),
+ Op1I->getOperand(0));
+ }
+
+ if (CI->getValue().isMaxSignedValue()) {
+ ICmpInst::Predicate Pred = I.isSigned()
+ ? I.getUnsignedPredicate()
+ : I.getSignedPredicate();
+ Pred = I.getSwappedPredicate(Pred);
+ return new ICmpInst(Pred, Op0I->getOperand(0),
+ Op1I->getOperand(0));
+ }
+ }
+ break;
+ case Instruction::Mul:
+ if (!I.isEquality())
+ break;
+
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
+ // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
+ // Mask = -1 >> count-trailing-zeros(Cst).
+ if (!CI->isZero() && !CI->isOne()) {
+ const APInt &AP = CI->getValue();
+ ConstantInt *Mask = ConstantInt::get(I.getContext(),
+ APInt::getLowBitsSet(AP.getBitWidth(),
+ AP.getBitWidth() -
+ AP.countTrailingZeros()));
+ Value *And1 = Builder->CreateAnd(Op0I->getOperand(0), Mask);
+ Value *And2 = Builder->CreateAnd(Op1I->getOperand(0), Mask);
+ return new ICmpInst(I.getPredicate(), And1, And2);
+ }
+ }
+ break;
+ }
+ }
+ }
+ }
+
+ // ~x < ~y --> y < x
+ { Value *A, *B;
+ if (match(Op0, m_Not(m_Value(A))) &&
+ match(Op1, m_Not(m_Value(B))))
+ return new ICmpInst(I.getPredicate(), B, A);
+ }
+
+ if (I.isEquality()) {
+ Value *A, *B, *C, *D;
+
+ // -x == -y --> x == y
+ if (match(Op0, m_Neg(m_Value(A))) &&
+ match(Op1, m_Neg(m_Value(B))))
+ return new ICmpInst(I.getPredicate(), A, B);
+
+ if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
+ if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
+ Value *OtherVal = A == Op1 ? B : A;
+ return new ICmpInst(I.getPredicate(), OtherVal,
+ Constant::getNullValue(A->getType()));
+ }
+
+ if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
+ // A^c1 == C^c2 --> A == C^(c1^c2)
+ ConstantInt *C1, *C2;
+ if (match(B, m_ConstantInt(C1)) &&
+ match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
+ Constant *NC = ConstantInt::get(I.getContext(),
+ C1->getValue() ^ C2->getValue());
+ Value *Xor = Builder->CreateXor(C, NC, "tmp");
+ return new ICmpInst(I.getPredicate(), A, Xor);
+ }
+
+ // A^B == A^D -> B == D
+ if (A == C) return new ICmpInst(I.getPredicate(), B, D);
+ if (A == D) return new ICmpInst(I.getPredicate(), B, C);
+ if (B == C) return new ICmpInst(I.getPredicate(), A, D);
+ if (B == D) return new ICmpInst(I.getPredicate(), A, C);
+ }
+ }
+
+ if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0)) {
+ // A == (A^B) -> B == 0
+ Value *OtherVal = A == Op0 ? B : A;
+ return new ICmpInst(I.getPredicate(), OtherVal,
+ Constant::getNullValue(A->getType()));
+ }
+
+ // (A-B) == A -> B == 0
+ if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B))))
+ return new ICmpInst(I.getPredicate(), B,
+ Constant::getNullValue(B->getType()));
+
+ // A == (A-B) -> B == 0
+ if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B))))
+ return new ICmpInst(I.getPredicate(), B,
+ Constant::getNullValue(B->getType()));
+
+ // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
+ if (Op0->hasOneUse() && Op1->hasOneUse() &&
+ match(Op0, m_And(m_Value(A), m_Value(B))) &&
+ match(Op1, m_And(m_Value(C), m_Value(D)))) {
+ Value *X = 0, *Y = 0, *Z = 0;
+
+ if (A == C) {
+ X = B; Y = D; Z = A;
+ } else if (A == D) {
+ X = B; Y = C; Z = A;
+ } else if (B == C) {
+ X = A; Y = D; Z = B;
+ } else if (B == D) {
+ X = A; Y = C; Z = B;
+ }
+
+ if (X) { // Build (X^Y) & Z
+ Op1 = Builder->CreateXor(X, Y, "tmp");
+ Op1 = Builder->CreateAnd(Op1, Z, "tmp");
+ I.setOperand(0, Op1);
+ I.setOperand(1, Constant::getNullValue(Op1->getType()));
+ return &I;
+ }
+ }
+ }
+
+ {
+ Value *X; ConstantInt *Cst;
+ // icmp X+Cst, X
+ if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X)
+ return FoldICmpAddOpCst(I, X, Cst, I.getPredicate(), Op0);
+
+ // icmp X, X+Cst
+ if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X)
+ return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate(), Op1);
+ }
+ return Changed ? &I : 0;
+}
+
+
+
+
+
+
+/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
+///
+Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
+ Instruction *LHSI,
+ Constant *RHSC) {
+ if (!isa<ConstantFP>(RHSC)) return 0;
+ const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
+
+ // Get the width of the mantissa. We don't want to hack on conversions that
+ // might lose information from the integer, e.g. "i64 -> float"
+ int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
+ if (MantissaWidth == -1) return 0; // Unknown.
+
+ // Check to see that the input is converted from an integer type that is small
+ // enough that preserves all bits. TODO: check here for "known" sign bits.
+ // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
+ unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits();
+
+ // If this is a uitofp instruction, we need an extra bit to hold the sign.
+ bool LHSUnsigned = isa<UIToFPInst>(LHSI);
+ if (LHSUnsigned)
+ ++InputSize;
+
+ // If the conversion would lose info, don't hack on this.
+ if ((int)InputSize > MantissaWidth)
+ return 0;
+
+ // Otherwise, we can potentially simplify the comparison. We know that it
+ // will always come through as an integer value and we know the constant is
+ // not a NAN (it would have been previously simplified).
+ assert(!RHS.isNaN() && "NaN comparison not already folded!");
+
+ ICmpInst::Predicate Pred;
+ switch (I.getPredicate()) {
+ default: llvm_unreachable("Unexpected predicate!");
+ case FCmpInst::FCMP_UEQ:
+ case FCmpInst::FCMP_OEQ:
+ Pred = ICmpInst::ICMP_EQ;
+ break;
+ case FCmpInst::FCMP_UGT:
+ case FCmpInst::FCMP_OGT:
+ Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
+ break;
+ case FCmpInst::FCMP_UGE:
+ case FCmpInst::FCMP_OGE:
+ Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
+ break;
+ case FCmpInst::FCMP_ULT:
+ case FCmpInst::FCMP_OLT:
+ Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
+ break;
+ case FCmpInst::FCMP_ULE:
+ case FCmpInst::FCMP_OLE:
+ Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
+ break;
+ case FCmpInst::FCMP_UNE:
+ case FCmpInst::FCMP_ONE:
+ Pred = ICmpInst::ICMP_NE;
+ break;
+ case FCmpInst::FCMP_ORD:
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ case FCmpInst::FCMP_UNO:
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ }
+
+ const IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
+
+ // Now we know that the APFloat is a normal number, zero or inf.
+
+ // See if the FP constant is too large for the integer. For example,
+ // comparing an i8 to 300.0.
+ unsigned IntWidth = IntTy->getScalarSizeInBits();
+
+ if (!LHSUnsigned) {
+ // If the RHS value is > SignedMax, fold the comparison. This handles +INF
+ // and large values.
+ APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false);
+ SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
+ APFloat::rmNearestTiesToEven);
+ if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
+ if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
+ Pred == ICmpInst::ICMP_SLE)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ }
+ } else {
+ // If the RHS value is > UnsignedMax, fold the comparison. This handles
+ // +INF and large values.
+ APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false);
+ UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
+ APFloat::rmNearestTiesToEven);
+ if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
+ if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
+ Pred == ICmpInst::ICMP_ULE)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ }
+ }
+
+ if (!LHSUnsigned) {
+ // See if the RHS value is < SignedMin.
+ APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false);
+ SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
+ APFloat::rmNearestTiesToEven);
+ if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
+ if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
+ Pred == ICmpInst::ICMP_SGE)
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ }
+ }
+
+ // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
+ // [0, UMAX], but it may still be fractional. See if it is fractional by
+ // casting the FP value to the integer value and back, checking for equality.
+ // Don't do this for zero, because -0.0 is not fractional.
+ Constant *RHSInt = LHSUnsigned
+ ? ConstantExpr::getFPToUI(RHSC, IntTy)
+ : ConstantExpr::getFPToSI(RHSC, IntTy);
+ if (!RHS.isZero()) {
+ bool Equal = LHSUnsigned
+ ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
+ : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
+ if (!Equal) {
+ // If we had a comparison against a fractional value, we have to adjust
+ // the compare predicate and sometimes the value. RHSC is rounded towards
+ // zero at this point.
+ switch (Pred) {
+ default: llvm_unreachable("Unexpected integer comparison!");
+ case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ case ICmpInst::ICMP_ULE:
+ // (float)int <= 4.4 --> int <= 4
+ // (float)int <= -4.4 --> false
+ if (RHS.isNegative())
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ break;
+ case ICmpInst::ICMP_SLE:
+ // (float)int <= 4.4 --> int <= 4
+ // (float)int <= -4.4 --> int < -4
+ if (RHS.isNegative())
+ Pred = ICmpInst::ICMP_SLT;
+ break;
+ case ICmpInst::ICMP_ULT:
+ // (float)int < -4.4 --> false
+ // (float)int < 4.4 --> int <= 4
+ if (RHS.isNegative())
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
+ Pred = ICmpInst::ICMP_ULE;
+ break;
+ case ICmpInst::ICMP_SLT:
+ // (float)int < -4.4 --> int < -4
+ // (float)int < 4.4 --> int <= 4
+ if (!RHS.isNegative())
+ Pred = ICmpInst::ICMP_SLE;
+ break;
+ case ICmpInst::ICMP_UGT:
+ // (float)int > 4.4 --> int > 4
+ // (float)int > -4.4 --> true
+ if (RHS.isNegative())
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ break;
+ case ICmpInst::ICMP_SGT:
+ // (float)int > 4.4 --> int > 4
+ // (float)int > -4.4 --> int >= -4
+ if (RHS.isNegative())
+ Pred = ICmpInst::ICMP_SGE;
+ break;
+ case ICmpInst::ICMP_UGE:
+ // (float)int >= -4.4 --> true
+ // (float)int >= 4.4 --> int > 4
+ if (!RHS.isNegative())
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
+ Pred = ICmpInst::ICMP_UGT;
+ break;
+ case ICmpInst::ICMP_SGE:
+ // (float)int >= -4.4 --> int >= -4
+ // (float)int >= 4.4 --> int > 4
+ if (!RHS.isNegative())
+ Pred = ICmpInst::ICMP_SGT;
+ break;
+ }
+ }
+ }
+
+ // Lower this FP comparison into an appropriate integer version of the
+ // comparison.
+ return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
+}
+
+Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
+ bool Changed = false;
+
+ /// Orders the operands of the compare so that they are listed from most
+ /// complex to least complex. This puts constants before unary operators,
+ /// before binary operators.
+ if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
+ I.swapOperands();
+ Changed = true;
+ }
+
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, TD))
+ return ReplaceInstUsesWith(I, V);
+
+ // Simplify 'fcmp pred X, X'
+ if (Op0 == Op1) {
+ switch (I.getPredicate()) {
+ default: llvm_unreachable("Unknown predicate!");
+ case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
+ case FCmpInst::FCMP_ULT: // True if unordered or less than
+ case FCmpInst::FCMP_UGT: // True if unordered or greater than
+ case FCmpInst::FCMP_UNE: // True if unordered or not equal
+ // Canonicalize these to be 'fcmp uno %X, 0.0'.
+ I.setPredicate(FCmpInst::FCMP_UNO);
+ I.setOperand(1, Constant::getNullValue(Op0->getType()));
+ return &I;
+
+ case FCmpInst::FCMP_ORD: // True if ordered (no nans)
+ case FCmpInst::FCMP_OEQ: // True if ordered and equal
+ case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
+ case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
+ // Canonicalize these to be 'fcmp ord %X, 0.0'.
+ I.setPredicate(FCmpInst::FCMP_ORD);
+ I.setOperand(1, Constant::getNullValue(Op0->getType()));
+ return &I;
+ }
+ }
+
+ // Handle fcmp with constant RHS
+ if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
+ if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+ switch (LHSI->getOpcode()) {
+ case Instruction::PHI:
+ // Only fold fcmp into the PHI if the phi and fcmp are in the same
+ // block. If in the same block, we're encouraging jump threading. If
+ // not, we are just pessimizing the code by making an i1 phi.
+ if (LHSI->getParent() == I.getParent())
+ if (Instruction *NV = FoldOpIntoPhi(I, true))
+ return NV;
+ break;
+ case Instruction::SIToFP:
+ case Instruction::UIToFP:
+ if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
+ return NV;
+ break;
+ case Instruction::Select: {
+ // If either operand of the select is a constant, we can fold the
+ // comparison into the select arms, which will cause one to be
+ // constant folded and the select turned into a bitwise or.
+ Value *Op1 = 0, *Op2 = 0;
+ if (LHSI->hasOneUse()) {
+ if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
+ // Fold the known value into the constant operand.
+ Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
+ // Insert a new FCmp of the other select operand.
+ Op2 = Builder->CreateFCmp(I.getPredicate(),
+ LHSI->getOperand(2), RHSC, I.getName());
+ } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
+ // Fold the known value into the constant operand.
+ Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
+ // Insert a new FCmp of the other select operand.
+ Op1 = Builder->CreateFCmp(I.getPredicate(), LHSI->getOperand(1),
+ RHSC, I.getName());
+ }
+ }
+
+ if (Op1)
+ return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
+ break;
+ }
+ case Instruction::Load:
+ if (GetElementPtrInst *GEP =
+ dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
+ if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
+ !cast<LoadInst>(LHSI)->isVolatile())
+ if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
+ return Res;
+ }
+ break;
+ }
+ }
+
+ return Changed ? &I : 0;
+}
Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=92467&r1=92466&r2=92467&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Mon Jan 4 01:37:31 2010
@@ -48,7 +48,6 @@
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Support/CallSite.h"
-#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
@@ -79,20 +78,6 @@
}
-// getComplexity: Assign a complexity or rank value to LLVM Values...
-// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
-static unsigned getComplexity(Value *V) {
- if (isa<Instruction>(V)) {
- if (BinaryOperator::isNeg(V) ||
- BinaryOperator::isFNeg(V) ||
- BinaryOperator::isNot(V))
- return 3;
- return 4;
- }
- if (isa<Argument>(V)) return 3;
- return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
-}
-
// isOnlyUse - Return true if this instruction will be deleted if we stop using
// it.
static bool isOnlyUse(Value *V) {
@@ -246,7 +231,7 @@
// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
// if the LHS is a constant zero (which is the 'negate' form).
//
-static inline Value *dyn_castNegVal(Value *V) {
+Value *InstCombiner::dyn_castNegVal(Value *V) const {
if (BinaryOperator::isNeg(V))
return BinaryOperator::getNegArgument(V);
@@ -392,13 +377,11 @@
/// AddOne - Add one to a ConstantInt
static Constant *AddOne(Constant *C) {
- return ConstantExpr::getAdd(C,
- ConstantInt::get(C->getType(), 1));
+ return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
}
/// SubOne - Subtract one from a ConstantInt
static Constant *SubOne(ConstantInt *C) {
- return ConstantExpr::getSub(C,
- ConstantInt::get(C->getType(), 1));
+ return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
}
/// MultiplyOverflows - True if the multiply can not be expressed in an int
/// this size.
@@ -424,49 +407,6 @@
}
-// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
-// set of known zero and one bits, compute the maximum and minimum values that
-// could have the specified known zero and known one bits, returning them in
-// min/max.
-static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero,
- const APInt& KnownOne,
- APInt& Min, APInt& Max) {
- assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
- KnownZero.getBitWidth() == Min.getBitWidth() &&
- KnownZero.getBitWidth() == Max.getBitWidth() &&
- "KnownZero, KnownOne and Min, Max must have equal bitwidth.");
- APInt UnknownBits = ~(KnownZero|KnownOne);
-
- // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
- // bit if it is unknown.
- Min = KnownOne;
- Max = KnownOne|UnknownBits;
-
- if (UnknownBits.isNegative()) { // Sign bit is unknown
- Min.set(Min.getBitWidth()-1);
- Max.clear(Max.getBitWidth()-1);
- }
-}
-
-// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
-// a set of known zero and one bits, compute the maximum and minimum values that
-// could have the specified known zero and known one bits, returning them in
-// min/max.
-static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero,
- const APInt &KnownOne,
- APInt &Min, APInt &Max) {
- assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
- KnownZero.getBitWidth() == Min.getBitWidth() &&
- KnownZero.getBitWidth() == Max.getBitWidth() &&
- "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
- APInt UnknownBits = ~(KnownZero|KnownOne);
-
- // The minimum value is when the unknown bits are all zeros.
- Min = KnownOne;
- // The maximum value is when the unknown bits are all ones.
- Max = KnownOne|UnknownBits;
-}
-
/// AssociativeOpt - Perform an optimization on an associative operator. This
/// function is designed to check a chain of associative operators for a
@@ -1138,8 +1078,8 @@
/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
/// code necessary to compute the offset from the base pointer (without adding
/// in the base pointer). Return the result as a signed integer of intptr size.
-static Value *EmitGEPOffset(User *GEP, InstCombiner &IC) {
- TargetData &TD = *IC.getTargetData();
+Value *InstCombiner::EmitGEPOffset(User *GEP) {
+ TargetData &TD = *getTargetData();
gep_type_iterator GTI = gep_type_begin(GEP);
const Type *IntPtrTy = TD.getIntPtrType(GEP->getContext());
Value *Result = Constant::getNullValue(IntPtrTy);
@@ -1159,9 +1099,9 @@
if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
- Result = IC.Builder->CreateAdd(Result,
- ConstantInt::get(IntPtrTy, Size),
- GEP->getName()+".offs");
+ Result = Builder->CreateAdd(Result,
+ ConstantInt::get(IntPtrTy, Size),
+ GEP->getName()+".offs");
continue;
}
@@ -1170,130 +1110,25 @@
ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
Scale = ConstantExpr::getMul(OC, Scale);
// Emit an add instruction.
- Result = IC.Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
+ Result = Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
continue;
}
// Convert to correct type.
if (Op->getType() != IntPtrTy)
- Op = IC.Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c");
+ Op = Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c");
if (Size != 1) {
Constant *Scale = ConstantInt::get(IntPtrTy, Size);
// We'll let instcombine(mul) convert this to a shl if possible.
- Op = IC.Builder->CreateMul(Op, Scale, GEP->getName()+".idx");
+ Op = Builder->CreateMul(Op, Scale, GEP->getName()+".idx");
}
// Emit an add instruction.
- Result = IC.Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
+ Result = Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
}
return Result;
}
-/// EvaluateGEPOffsetExpression - Return a value that can be used to compare
-/// the *offset* implied by a GEP to zero. For example, if we have &A[i], we
-/// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can
-/// be complex, and scales are involved. The above expression would also be
-/// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32).
-/// This later form is less amenable to optimization though, and we are allowed
-/// to generate the first by knowing that pointer arithmetic doesn't overflow.
-///
-/// If we can't emit an optimized form for this expression, this returns null.
-///
-static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I,
- InstCombiner &IC) {
- TargetData &TD = *IC.getTargetData();
- gep_type_iterator GTI = gep_type_begin(GEP);
-
- // Check to see if this gep only has a single variable index. If so, and if
- // any constant indices are a multiple of its scale, then we can compute this
- // in terms of the scale of the variable index. For example, if the GEP
- // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
- // because the expression will cross zero at the same point.
- unsigned i, e = GEP->getNumOperands();
- int64_t Offset = 0;
- for (i = 1; i != e; ++i, ++GTI) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
- // Compute the aggregate offset of constant indices.
- if (CI->isZero()) continue;
-
- // Handle a struct index, which adds its field offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
- } else {
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
- Offset += Size*CI->getSExtValue();
- }
- } else {
- // Found our variable index.
- break;
- }
- }
-
- // If there are no variable indices, we must have a constant offset, just
- // evaluate it the general way.
- if (i == e) return 0;
-
- Value *VariableIdx = GEP->getOperand(i);
- // Determine the scale factor of the variable element. For example, this is
- // 4 if the variable index is into an array of i32.
- uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType());
-
- // Verify that there are no other variable indices. If so, emit the hard way.
- for (++i, ++GTI; i != e; ++i, ++GTI) {
- ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
- if (!CI) return 0;
-
- // Compute the aggregate offset of constant indices.
- if (CI->isZero()) continue;
-
- // Handle a struct index, which adds its field offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
- } else {
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
- Offset += Size*CI->getSExtValue();
- }
- }
-
- // Okay, we know we have a single variable index, which must be a
- // pointer/array/vector index. If there is no offset, life is simple, return
- // the index.
- unsigned IntPtrWidth = TD.getPointerSizeInBits();
- if (Offset == 0) {
- // Cast to intptrty in case a truncation occurs. If an extension is needed,
- // we don't need to bother extending: the extension won't affect where the
- // computation crosses zero.
- if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth)
- VariableIdx = new TruncInst(VariableIdx,
- TD.getIntPtrType(VariableIdx->getContext()),
- VariableIdx->getName(), &I);
- return VariableIdx;
- }
-
- // Otherwise, there is an index. The computation we will do will be modulo
- // the pointer size, so get it.
- uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
-
- Offset &= PtrSizeMask;
- VariableScale &= PtrSizeMask;
-
- // To do this transformation, any constant index must be a multiple of the
- // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
- // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
- // multiple of the variable scale.
- int64_t NewOffs = Offset / (int64_t)VariableScale;
- if (Offset != NewOffs*(int64_t)VariableScale)
- return 0;
-
- // Okay, we can do this evaluation. Start by converting the index to intptr.
- const Type *IntPtrTy = TD.getIntPtrType(VariableIdx->getContext());
- if (VariableIdx->getType() != IntPtrTy)
- VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy,
- true /*SExt*/,
- VariableIdx->getName(), &I);
- Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
- return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I);
-}
/// Optimize pointer differences into the same array into a size. Consider:
@@ -1349,12 +1184,12 @@
return 0;
// Emit the offset of the GEP and an intptr_t.
- Value *Result = EmitGEPOffset(GEP, *this);
+ Value *Result = EmitGEPOffset(GEP);
// If we had a constant expression GEP on the other side offsetting the
// pointer, subtract it from the offset we have.
if (CstGEP) {
- Value *CstOffset = EmitGEPOffset(CstGEP, *this);
+ Value *CstOffset = EmitGEPOffset(CstGEP);
Result = Builder->CreateSub(Result, CstOffset);
}
@@ -1559,36 +1394,6 @@
return 0;
}
-/// isSignBitCheck - Given an exploded icmp instruction, return true if the
-/// comparison only checks the sign bit. If it only checks the sign bit, set
-/// TrueIfSigned if the result of the comparison is true when the input value is
-/// signed.
-static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
- bool &TrueIfSigned) {
- switch (pred) {
- case ICmpInst::ICMP_SLT: // True if LHS s< 0
- TrueIfSigned = true;
- return RHS->isZero();
- case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
- TrueIfSigned = true;
- return RHS->isAllOnesValue();
- case ICmpInst::ICMP_SGT: // True if LHS s> -1
- TrueIfSigned = false;
- return RHS->isAllOnesValue();
- case ICmpInst::ICMP_UGT:
- // True if LHS u> RHS and RHS == high-bit-mask - 1
- TrueIfSigned = true;
- return RHS->getValue() ==
- APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
- case ICmpInst::ICMP_UGE:
- // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
- TrueIfSigned = true;
- return RHS->getValue().isSignBit();
- default:
- return false;
- }
-}
-
Instruction *InstCombiner::visitMul(BinaryOperator &I) {
bool Changed = SimplifyCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
@@ -2242,12 +2047,6 @@
return CI->getValue().isPowerOf2();
}
-// isHighOnes - Return true if the constant is of the form 1+0+.
-// This is the same as lowones(~X).
-static bool isHighOnes(const ConstantInt *CI) {
- return (~CI->getValue() + 1).isPowerOf2();
-}
-
/// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
/// are carefully arranged to allow folding of expressions such as:
///
@@ -4186,2223 +3985,6 @@
return Changed ? &I : 0;
}
-static ConstantInt *ExtractElement(Constant *V, Constant *Idx) {
- return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx));
-}
-
-static bool HasAddOverflow(ConstantInt *Result,
- ConstantInt *In1, ConstantInt *In2,
- bool IsSigned) {
- if (IsSigned)
- if (In2->getValue().isNegative())
- return Result->getValue().sgt(In1->getValue());
- else
- return Result->getValue().slt(In1->getValue());
- else
- return Result->getValue().ult(In1->getValue());
-}
-
-/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
-/// overflowed for this type.
-static bool AddWithOverflow(Constant *&Result, Constant *In1,
- Constant *In2, bool IsSigned = false) {
- Result = ConstantExpr::getAdd(In1, In2);
-
- if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
- for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
- Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
- if (HasAddOverflow(ExtractElement(Result, Idx),
- ExtractElement(In1, Idx),
- ExtractElement(In2, Idx),
- IsSigned))
- return true;
- }
- return false;
- }
-
- return HasAddOverflow(cast<ConstantInt>(Result),
- cast<ConstantInt>(In1), cast<ConstantInt>(In2),
- IsSigned);
-}
-
-static bool HasSubOverflow(ConstantInt *Result,
- ConstantInt *In1, ConstantInt *In2,
- bool IsSigned) {
- if (IsSigned)
- if (In2->getValue().isNegative())
- return Result->getValue().slt(In1->getValue());
- else
- return Result->getValue().sgt(In1->getValue());
- else
- return Result->getValue().ugt(In1->getValue());
-}
-
-/// SubWithOverflow - Compute Result = In1-In2, returning true if the result
-/// overflowed for this type.
-static bool SubWithOverflow(Constant *&Result, Constant *In1,
- Constant *In2, bool IsSigned = false) {
- Result = ConstantExpr::getSub(In1, In2);
-
- if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
- for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
- Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
- if (HasSubOverflow(ExtractElement(Result, Idx),
- ExtractElement(In1, Idx),
- ExtractElement(In2, Idx),
- IsSigned))
- return true;
- }
- return false;
- }
-
- return HasSubOverflow(cast<ConstantInt>(Result),
- cast<ConstantInt>(In1), cast<ConstantInt>(In2),
- IsSigned);
-}
-
-
-/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
-/// else. At this point we know that the GEP is on the LHS of the comparison.
-Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
- ICmpInst::Predicate Cond,
- Instruction &I) {
- // Look through bitcasts.
- if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS))
- RHS = BCI->getOperand(0);
-
- Value *PtrBase = GEPLHS->getOperand(0);
- if (TD && PtrBase == RHS && GEPLHS->isInBounds()) {
- // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
- // This transformation (ignoring the base and scales) is valid because we
- // know pointers can't overflow since the gep is inbounds. See if we can
- // output an optimized form.
- Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this);
-
- // If not, synthesize the offset the hard way.
- if (Offset == 0)
- Offset = EmitGEPOffset(GEPLHS, *this);
- return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
- Constant::getNullValue(Offset->getType()));
- } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
- // If the base pointers are different, but the indices are the same, just
- // compare the base pointer.
- if (PtrBase != GEPRHS->getOperand(0)) {
- bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
- IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
- GEPRHS->getOperand(0)->getType();
- if (IndicesTheSame)
- for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
- if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
- IndicesTheSame = false;
- break;
- }
-
- // If all indices are the same, just compare the base pointers.
- if (IndicesTheSame)
- return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
- GEPLHS->getOperand(0), GEPRHS->getOperand(0));
-
- // Otherwise, the base pointers are different and the indices are
- // different, bail out.
- return 0;
- }
-
- // If one of the GEPs has all zero indices, recurse.
- bool AllZeros = true;
- for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
- if (!isa<Constant>(GEPLHS->getOperand(i)) ||
- !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
- AllZeros = false;
- break;
- }
- if (AllZeros)
- return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
- ICmpInst::getSwappedPredicate(Cond), I);
-
- // If the other GEP has all zero indices, recurse.
- AllZeros = true;
- for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
- if (!isa<Constant>(GEPRHS->getOperand(i)) ||
- !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
- AllZeros = false;
- break;
- }
- if (AllZeros)
- return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
-
- if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
- // If the GEPs only differ by one index, compare it.
- unsigned NumDifferences = 0; // Keep track of # differences.
- unsigned DiffOperand = 0; // The operand that differs.
- for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
- if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
- if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
- GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
- // Irreconcilable differences.
- NumDifferences = 2;
- break;
- } else {
- if (NumDifferences++) break;
- DiffOperand = i;
- }
- }
-
- if (NumDifferences == 0) // SAME GEP?
- return ReplaceInstUsesWith(I, // No comparison is needed here.
- ConstantInt::get(Type::getInt1Ty(I.getContext()),
- ICmpInst::isTrueWhenEqual(Cond)));
-
- else if (NumDifferences == 1) {
- Value *LHSV = GEPLHS->getOperand(DiffOperand);
- Value *RHSV = GEPRHS->getOperand(DiffOperand);
- // Make sure we do a signed comparison here.
- return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
- }
- }
-
- // Only lower this if the icmp is the only user of the GEP or if we expect
- // the result to fold to a constant!
- if (TD &&
- (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
- (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
- // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
- Value *L = EmitGEPOffset(GEPLHS, *this);
- Value *R = EmitGEPOffset(GEPRHS, *this);
- return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
- }
- }
- return 0;
-}
-
-/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
-///
-Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
- Instruction *LHSI,
- Constant *RHSC) {
- if (!isa<ConstantFP>(RHSC)) return 0;
- const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
-
- // Get the width of the mantissa. We don't want to hack on conversions that
- // might lose information from the integer, e.g. "i64 -> float"
- int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
- if (MantissaWidth == -1) return 0; // Unknown.
-
- // Check to see that the input is converted from an integer type that is small
- // enough that preserves all bits. TODO: check here for "known" sign bits.
- // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
- unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits();
-
- // If this is a uitofp instruction, we need an extra bit to hold the sign.
- bool LHSUnsigned = isa<UIToFPInst>(LHSI);
- if (LHSUnsigned)
- ++InputSize;
-
- // If the conversion would lose info, don't hack on this.
- if ((int)InputSize > MantissaWidth)
- return 0;
-
- // Otherwise, we can potentially simplify the comparison. We know that it
- // will always come through as an integer value and we know the constant is
- // not a NAN (it would have been previously simplified).
- assert(!RHS.isNaN() && "NaN comparison not already folded!");
-
- ICmpInst::Predicate Pred;
- switch (I.getPredicate()) {
- default: llvm_unreachable("Unexpected predicate!");
- case FCmpInst::FCMP_UEQ:
- case FCmpInst::FCMP_OEQ:
- Pred = ICmpInst::ICMP_EQ;
- break;
- case FCmpInst::FCMP_UGT:
- case FCmpInst::FCMP_OGT:
- Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
- break;
- case FCmpInst::FCMP_UGE:
- case FCmpInst::FCMP_OGE:
- Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
- break;
- case FCmpInst::FCMP_ULT:
- case FCmpInst::FCMP_OLT:
- Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
- break;
- case FCmpInst::FCMP_ULE:
- case FCmpInst::FCMP_OLE:
- Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
- break;
- case FCmpInst::FCMP_UNE:
- case FCmpInst::FCMP_ONE:
- Pred = ICmpInst::ICMP_NE;
- break;
- case FCmpInst::FCMP_ORD:
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- case FCmpInst::FCMP_UNO:
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- }
-
- const IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
-
- // Now we know that the APFloat is a normal number, zero or inf.
-
- // See if the FP constant is too large for the integer. For example,
- // comparing an i8 to 300.0.
- unsigned IntWidth = IntTy->getScalarSizeInBits();
-
- if (!LHSUnsigned) {
- // If the RHS value is > SignedMax, fold the comparison. This handles +INF
- // and large values.
- APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false);
- SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
- APFloat::rmNearestTiesToEven);
- if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
- if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
- Pred == ICmpInst::ICMP_SLE)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- }
- } else {
- // If the RHS value is > UnsignedMax, fold the comparison. This handles
- // +INF and large values.
- APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false);
- UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
- APFloat::rmNearestTiesToEven);
- if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
- if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
- Pred == ICmpInst::ICMP_ULE)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- }
- }
-
- if (!LHSUnsigned) {
- // See if the RHS value is < SignedMin.
- APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false);
- SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
- APFloat::rmNearestTiesToEven);
- if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
- if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
- Pred == ICmpInst::ICMP_SGE)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- }
- }
-
- // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
- // [0, UMAX], but it may still be fractional. See if it is fractional by
- // casting the FP value to the integer value and back, checking for equality.
- // Don't do this for zero, because -0.0 is not fractional.
- Constant *RHSInt = LHSUnsigned
- ? ConstantExpr::getFPToUI(RHSC, IntTy)
- : ConstantExpr::getFPToSI(RHSC, IntTy);
- if (!RHS.isZero()) {
- bool Equal = LHSUnsigned
- ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
- : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
- if (!Equal) {
- // If we had a comparison against a fractional value, we have to adjust
- // the compare predicate and sometimes the value. RHSC is rounded towards
- // zero at this point.
- switch (Pred) {
- default: llvm_unreachable("Unexpected integer comparison!");
- case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- case ICmpInst::ICMP_ULE:
- // (float)int <= 4.4 --> int <= 4
- // (float)int <= -4.4 --> false
- if (RHS.isNegative())
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- break;
- case ICmpInst::ICMP_SLE:
- // (float)int <= 4.4 --> int <= 4
- // (float)int <= -4.4 --> int < -4
- if (RHS.isNegative())
- Pred = ICmpInst::ICMP_SLT;
- break;
- case ICmpInst::ICMP_ULT:
- // (float)int < -4.4 --> false
- // (float)int < 4.4 --> int <= 4
- if (RHS.isNegative())
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- Pred = ICmpInst::ICMP_ULE;
- break;
- case ICmpInst::ICMP_SLT:
- // (float)int < -4.4 --> int < -4
- // (float)int < 4.4 --> int <= 4
- if (!RHS.isNegative())
- Pred = ICmpInst::ICMP_SLE;
- break;
- case ICmpInst::ICMP_UGT:
- // (float)int > 4.4 --> int > 4
- // (float)int > -4.4 --> true
- if (RHS.isNegative())
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- break;
- case ICmpInst::ICMP_SGT:
- // (float)int > 4.4 --> int > 4
- // (float)int > -4.4 --> int >= -4
- if (RHS.isNegative())
- Pred = ICmpInst::ICMP_SGE;
- break;
- case ICmpInst::ICMP_UGE:
- // (float)int >= -4.4 --> true
- // (float)int >= 4.4 --> int > 4
- if (!RHS.isNegative())
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- Pred = ICmpInst::ICMP_UGT;
- break;
- case ICmpInst::ICMP_SGE:
- // (float)int >= -4.4 --> int >= -4
- // (float)int >= 4.4 --> int > 4
- if (!RHS.isNegative())
- Pred = ICmpInst::ICMP_SGT;
- break;
- }
- }
- }
-
- // Lower this FP comparison into an appropriate integer version of the
- // comparison.
- return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
-}
-
-/// FoldCmpLoadFromIndexedGlobal - Called we see this pattern:
-/// cmp pred (load (gep GV, ...)), cmpcst
-/// where GV is a global variable with a constant initializer. Try to simplify
-/// this into some simple computation that does not need the load. For example
-/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
-///
-/// If AndCst is non-null, then the loaded value is masked with that constant
-/// before doing the comparison. This handles cases like "A[i]&4 == 0".
-Instruction *InstCombiner::
-FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV,
- CmpInst &ICI, ConstantInt *AndCst) {
- ConstantArray *Init = dyn_cast<ConstantArray>(GV->getInitializer());
- if (Init == 0 || Init->getNumOperands() > 1024) return 0;
-
- // There are many forms of this optimization we can handle, for now, just do
- // the simple index into a single-dimensional array.
- //
- // Require: GEP GV, 0, i {{, constant indices}}
- if (GEP->getNumOperands() < 3 ||
- !isa<ConstantInt>(GEP->getOperand(1)) ||
- !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
- isa<Constant>(GEP->getOperand(2)))
- return 0;
-
- // Check that indices after the variable are constants and in-range for the
- // type they index. Collect the indices. This is typically for arrays of
- // structs.
- SmallVector<unsigned, 4> LaterIndices;
-
- const Type *EltTy = cast<ArrayType>(Init->getType())->getElementType();
- for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
- ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
- if (Idx == 0) return 0; // Variable index.
-
- uint64_t IdxVal = Idx->getZExtValue();
- if ((unsigned)IdxVal != IdxVal) return 0; // Too large array index.
-
- if (const StructType *STy = dyn_cast<StructType>(EltTy))
- EltTy = STy->getElementType(IdxVal);
- else if (const ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
- if (IdxVal >= ATy->getNumElements()) return 0;
- EltTy = ATy->getElementType();
- } else {
- return 0; // Unknown type.
- }
-
- LaterIndices.push_back(IdxVal);
- }
-
- enum { Overdefined = -3, Undefined = -2 };
-
- // Variables for our state machines.
-
- // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
- // "i == 47 | i == 87", where 47 is the first index the condition is true for,
- // and 87 is the second (and last) index. FirstTrueElement is -2 when
- // undefined, otherwise set to the first true element. SecondTrueElement is
- // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
- int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
-
- // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
- // form "i != 47 & i != 87". Same state transitions as for true elements.
- int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
-
- /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
- /// define a state machine that triggers for ranges of values that the index
- /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
- /// This is -2 when undefined, -3 when overdefined, and otherwise the last
- /// index in the range (inclusive). We use -2 for undefined here because we
- /// use relative comparisons and don't want 0-1 to match -1.
- int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
-
- // MagicBitvector - This is a magic bitvector where we set a bit if the
- // comparison is true for element 'i'. If there are 64 elements or less in
- // the array, this will fully represent all the comparison results.
- uint64_t MagicBitvector = 0;
-
-
- // Scan the array and see if one of our patterns matches.
- Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
- for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
- Constant *Elt = Init->getOperand(i);
-
- // If this is indexing an array of structures, get the structure element.
- if (!LaterIndices.empty())
- Elt = ConstantExpr::getExtractValue(Elt, LaterIndices.data(),
- LaterIndices.size());
-
- // If the element is masked, handle it.
- if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
-
- // Find out if the comparison would be true or false for the i'th element.
- Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt,
- CompareRHS, TD);
- // If the result is undef for this element, ignore it.
- if (isa<UndefValue>(C)) {
- // Extend range state machines to cover this element in case there is an
- // undef in the middle of the range.
- if (TrueRangeEnd == (int)i-1)
- TrueRangeEnd = i;
- if (FalseRangeEnd == (int)i-1)
- FalseRangeEnd = i;
- continue;
- }
-
- // If we can't compute the result for any of the elements, we have to give
- // up evaluating the entire conditional.
- if (!isa<ConstantInt>(C)) return 0;
-
- // Otherwise, we know if the comparison is true or false for this element,
- // update our state machines.
- bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
-
- // State machine for single/double/range index comparison.
- if (IsTrueForElt) {
- // Update the TrueElement state machine.
- if (FirstTrueElement == Undefined)
- FirstTrueElement = TrueRangeEnd = i; // First true element.
- else {
- // Update double-compare state machine.
- if (SecondTrueElement == Undefined)
- SecondTrueElement = i;
- else
- SecondTrueElement = Overdefined;
-
- // Update range state machine.
- if (TrueRangeEnd == (int)i-1)
- TrueRangeEnd = i;
- else
- TrueRangeEnd = Overdefined;
- }
- } else {
- // Update the FalseElement state machine.
- if (FirstFalseElement == Undefined)
- FirstFalseElement = FalseRangeEnd = i; // First false element.
- else {
- // Update double-compare state machine.
- if (SecondFalseElement == Undefined)
- SecondFalseElement = i;
- else
- SecondFalseElement = Overdefined;
-
- // Update range state machine.
- if (FalseRangeEnd == (int)i-1)
- FalseRangeEnd = i;
- else
- FalseRangeEnd = Overdefined;
- }
- }
-
-
- // If this element is in range, update our magic bitvector.
- if (i < 64 && IsTrueForElt)
- MagicBitvector |= 1ULL << i;
-
- // If all of our states become overdefined, bail out early. Since the
- // predicate is expensive, only check it every 8 elements. This is only
- // really useful for really huge arrays.
- if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
- SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
- FalseRangeEnd == Overdefined)
- return 0;
- }
-
- // Now that we've scanned the entire array, emit our new comparison(s). We
- // order the state machines in complexity of the generated code.
- Value *Idx = GEP->getOperand(2);
-
-
- // If the comparison is only true for one or two elements, emit direct
- // comparisons.
- if (SecondTrueElement != Overdefined) {
- // None true -> false.
- if (FirstTrueElement == Undefined)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(GEP->getContext()));
-
- Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
-
- // True for one element -> 'i == 47'.
- if (SecondTrueElement == Undefined)
- return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
-
- // True for two elements -> 'i == 47 | i == 72'.
- Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx);
- Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
- Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx);
- return BinaryOperator::CreateOr(C1, C2);
- }
-
- // If the comparison is only false for one or two elements, emit direct
- // comparisons.
- if (SecondFalseElement != Overdefined) {
- // None false -> true.
- if (FirstFalseElement == Undefined)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(GEP->getContext()));
-
- Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
-
- // False for one element -> 'i != 47'.
- if (SecondFalseElement == Undefined)
- return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
-
- // False for two elements -> 'i != 47 & i != 72'.
- Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx);
- Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
- Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx);
- return BinaryOperator::CreateAnd(C1, C2);
- }
-
- // If the comparison can be replaced with a range comparison for the elements
- // where it is true, emit the range check.
- if (TrueRangeEnd != Overdefined) {
- assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare");
-
- // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
- if (FirstTrueElement) {
- Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
- Idx = Builder->CreateAdd(Idx, Offs);
- }
-
- Value *End = ConstantInt::get(Idx->getType(),
- TrueRangeEnd-FirstTrueElement+1);
- return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
- }
-
- // False range check.
- if (FalseRangeEnd != Overdefined) {
- assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare");
- // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
- if (FirstFalseElement) {
- Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
- Idx = Builder->CreateAdd(Idx, Offs);
- }
-
- Value *End = ConstantInt::get(Idx->getType(),
- FalseRangeEnd-FirstFalseElement);
- return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
- }
-
-
- // If a 32-bit or 64-bit magic bitvector captures the entire comparison state
- // of this load, replace it with computation that does:
- // ((magic_cst >> i) & 1) != 0
- if (Init->getNumOperands() <= 32 ||
- (TD && Init->getNumOperands() <= 64 && TD->isLegalInteger(64))) {
- const Type *Ty;
- if (Init->getNumOperands() <= 32)
- Ty = Type::getInt32Ty(Init->getContext());
- else
- Ty = Type::getInt64Ty(Init->getContext());
- Value *V = Builder->CreateIntCast(Idx, Ty, false);
- V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
- V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V);
- return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
- }
-
- return 0;
-}
-
-
-Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
- bool Changed = false;
-
- /// Orders the operands of the compare so that they are listed from most
- /// complex to least complex. This puts constants before unary operators,
- /// before binary operators.
- if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
- I.swapOperands();
- Changed = true;
- }
-
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, TD))
- return ReplaceInstUsesWith(I, V);
-
- // Simplify 'fcmp pred X, X'
- if (Op0 == Op1) {
- switch (I.getPredicate()) {
- default: llvm_unreachable("Unknown predicate!");
- case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
- case FCmpInst::FCMP_ULT: // True if unordered or less than
- case FCmpInst::FCMP_UGT: // True if unordered or greater than
- case FCmpInst::FCMP_UNE: // True if unordered or not equal
- // Canonicalize these to be 'fcmp uno %X, 0.0'.
- I.setPredicate(FCmpInst::FCMP_UNO);
- I.setOperand(1, Constant::getNullValue(Op0->getType()));
- return &I;
-
- case FCmpInst::FCMP_ORD: // True if ordered (no nans)
- case FCmpInst::FCMP_OEQ: // True if ordered and equal
- case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
- case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
- // Canonicalize these to be 'fcmp ord %X, 0.0'.
- I.setPredicate(FCmpInst::FCMP_ORD);
- I.setOperand(1, Constant::getNullValue(Op0->getType()));
- return &I;
- }
- }
-
- // Handle fcmp with constant RHS
- if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
- if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
- switch (LHSI->getOpcode()) {
- case Instruction::PHI:
- // Only fold fcmp into the PHI if the phi and fcmp are in the same
- // block. If in the same block, we're encouraging jump threading. If
- // not, we are just pessimizing the code by making an i1 phi.
- if (LHSI->getParent() == I.getParent())
- if (Instruction *NV = FoldOpIntoPhi(I, true))
- return NV;
- break;
- case Instruction::SIToFP:
- case Instruction::UIToFP:
- if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
- return NV;
- break;
- case Instruction::Select: {
- // If either operand of the select is a constant, we can fold the
- // comparison into the select arms, which will cause one to be
- // constant folded and the select turned into a bitwise or.
- Value *Op1 = 0, *Op2 = 0;
- if (LHSI->hasOneUse()) {
- if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
- // Fold the known value into the constant operand.
- Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
- // Insert a new FCmp of the other select operand.
- Op2 = Builder->CreateFCmp(I.getPredicate(),
- LHSI->getOperand(2), RHSC, I.getName());
- } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
- // Fold the known value into the constant operand.
- Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
- // Insert a new FCmp of the other select operand.
- Op1 = Builder->CreateFCmp(I.getPredicate(), LHSI->getOperand(1),
- RHSC, I.getName());
- }
- }
-
- if (Op1)
- return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
- break;
- }
- case Instruction::Load:
- if (GetElementPtrInst *GEP =
- dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
- if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
- !cast<LoadInst>(LHSI)->isVolatile())
- if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
- return Res;
- }
- break;
- }
- }
-
- return Changed ? &I : 0;
-}
-
-Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
- bool Changed = false;
-
- /// Orders the operands of the compare so that they are listed from most
- /// complex to least complex. This puts constants before unary operators,
- /// before binary operators.
- if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
- I.swapOperands();
- Changed = true;
- }
-
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, TD))
- return ReplaceInstUsesWith(I, V);
-
- const Type *Ty = Op0->getType();
-
- // icmp's with boolean values can always be turned into bitwise operations
- if (Ty == Type::getInt1Ty(I.getContext())) {
- switch (I.getPredicate()) {
- default: llvm_unreachable("Invalid icmp instruction!");
- case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B)
- Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp");
- return BinaryOperator::CreateNot(Xor);
- }
- case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B
- return BinaryOperator::CreateXor(Op0, Op1);
-
- case ICmpInst::ICMP_UGT:
- std::swap(Op0, Op1); // Change icmp ugt -> icmp ult
- // FALL THROUGH
- case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B
- Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
- return BinaryOperator::CreateAnd(Not, Op1);
- }
- case ICmpInst::ICMP_SGT:
- std::swap(Op0, Op1); // Change icmp sgt -> icmp slt
- // FALL THROUGH
- case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B
- Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
- return BinaryOperator::CreateAnd(Not, Op0);
- }
- case ICmpInst::ICMP_UGE:
- std::swap(Op0, Op1); // Change icmp uge -> icmp ule
- // FALL THROUGH
- case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B
- Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
- return BinaryOperator::CreateOr(Not, Op1);
- }
- case ICmpInst::ICMP_SGE:
- std::swap(Op0, Op1); // Change icmp sge -> icmp sle
- // FALL THROUGH
- case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B
- Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
- return BinaryOperator::CreateOr(Not, Op0);
- }
- }
- }
-
- unsigned BitWidth = 0;
- if (TD)
- BitWidth = TD->getTypeSizeInBits(Ty->getScalarType());
- else if (Ty->isIntOrIntVector())
- BitWidth = Ty->getScalarSizeInBits();
-
- bool isSignBit = false;
-
- // See if we are doing a comparison with a constant.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- Value *A = 0, *B = 0;
-
- // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
- if (I.isEquality() && CI->isZero() &&
- match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
- // (icmp cond A B) if cond is equality
- return new ICmpInst(I.getPredicate(), A, B);
- }
-
- // If we have an icmp le or icmp ge instruction, turn it into the
- // appropriate icmp lt or icmp gt instruction. This allows us to rely on
- // them being folded in the code below. The SimplifyICmpInst code has
- // already handled the edge cases for us, so we just assert on them.
- switch (I.getPredicate()) {
- default: break;
- case ICmpInst::ICMP_ULE:
- assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE
- return new ICmpInst(ICmpInst::ICMP_ULT, Op0,
- AddOne(CI));
- case ICmpInst::ICMP_SLE:
- assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE
- return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
- AddOne(CI));
- case ICmpInst::ICMP_UGE:
- assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE
- return new ICmpInst(ICmpInst::ICMP_UGT, Op0,
- SubOne(CI));
- case ICmpInst::ICMP_SGE:
- assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE
- return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
- SubOne(CI));
- }
-
- // If this comparison is a normal comparison, it demands all
- // bits, if it is a sign bit comparison, it only demands the sign bit.
- bool UnusedBit;
- isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
- }
-
- // See if we can fold the comparison based on range information we can get
- // by checking whether bits are known to be zero or one in the input.
- if (BitWidth != 0) {
- APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0);
- APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0);
-
- if (SimplifyDemandedBits(I.getOperandUse(0),
- isSignBit ? APInt::getSignBit(BitWidth)
- : APInt::getAllOnesValue(BitWidth),
- Op0KnownZero, Op0KnownOne, 0))
- return &I;
- if (SimplifyDemandedBits(I.getOperandUse(1),
- APInt::getAllOnesValue(BitWidth),
- Op1KnownZero, Op1KnownOne, 0))
- return &I;
-
- // Given the known and unknown bits, compute a range that the LHS could be
- // in. Compute the Min, Max and RHS values based on the known bits. For the
- // EQ and NE we use unsigned values.
- APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
- APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
- if (I.isSigned()) {
- ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
- Op0Min, Op0Max);
- ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
- Op1Min, Op1Max);
- } else {
- ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
- Op0Min, Op0Max);
- ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
- Op1Min, Op1Max);
- }
-
- // If Min and Max are known to be the same, then SimplifyDemandedBits
- // figured out that the LHS is a constant. Just constant fold this now so
- // that code below can assume that Min != Max.
- if (!isa<Constant>(Op0) && Op0Min == Op0Max)
- return new ICmpInst(I.getPredicate(),
- ConstantInt::get(I.getContext(), Op0Min), Op1);
- if (!isa<Constant>(Op1) && Op1Min == Op1Max)
- return new ICmpInst(I.getPredicate(), Op0,
- ConstantInt::get(I.getContext(), Op1Min));
-
- // Based on the range information we know about the LHS, see if we can
- // simplify this comparison. For example, (x&4) < 8 is always true.
- switch (I.getPredicate()) {
- default: llvm_unreachable("Unknown icmp opcode!");
- case ICmpInst::ICMP_EQ:
- if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- break;
- case ICmpInst::ICMP_NE:
- if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- break;
- case ICmpInst::ICMP_ULT:
- if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
- return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C
- return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
- SubOne(CI));
-
- // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
- if (CI->isMinValue(true))
- return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
- Constant::getAllOnesValue(Op0->getType()));
- }
- break;
- case ICmpInst::ICMP_UGT:
- if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
-
- if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
- return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C
- return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
- AddOne(CI));
-
- // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
- if (CI->isMaxValue(true))
- return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
- Constant::getNullValue(Op0->getType()));
- }
- break;
- case ICmpInst::ICMP_SLT:
- if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
- return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C
- return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
- SubOne(CI));
- }
- break;
- case ICmpInst::ICMP_SGT:
- if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
-
- if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
- return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C
- return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
- AddOne(CI));
- }
- break;
- case ICmpInst::ICMP_SGE:
- assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
- if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- break;
- case ICmpInst::ICMP_SLE:
- assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
- if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- break;
- case ICmpInst::ICMP_UGE:
- assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
- if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- break;
- case ICmpInst::ICMP_ULE:
- assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
- if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
- return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
- if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
- return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
- break;
- }
-
- // Turn a signed comparison into an unsigned one if both operands
- // are known to have the same sign.
- if (I.isSigned() &&
- ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) ||
- (Op0KnownOne.isNegative() && Op1KnownOne.isNegative())))
- return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
- }
-
- // Test if the ICmpInst instruction is used exclusively by a select as
- // part of a minimum or maximum operation. If so, refrain from doing
- // any other folding. This helps out other analyses which understand
- // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
- // and CodeGen. And in this case, at least one of the comparison
- // operands has at least one user besides the compare (the select),
- // which would often largely negate the benefit of folding anyway.
- if (I.hasOneUse())
- if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin()))
- if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
- (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
- return 0;
-
- // See if we are doing a comparison between a constant and an instruction that
- // can be folded into the comparison.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
- // Since the RHS is a ConstantInt (CI), if the left hand side is an
- // instruction, see if that instruction also has constants so that the
- // instruction can be folded into the icmp
- if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
- if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
- return Res;
- }
-
- // Handle icmp with constant (but not simple integer constant) RHS
- if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
- if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
- switch (LHSI->getOpcode()) {
- case Instruction::GetElementPtr:
- // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
- if (RHSC->isNullValue() &&
- cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
- return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
- Constant::getNullValue(LHSI->getOperand(0)->getType()));
- break;
- case Instruction::PHI:
- // Only fold icmp into the PHI if the phi and icmp are in the same
- // block. If in the same block, we're encouraging jump threading. If
- // not, we are just pessimizing the code by making an i1 phi.
- if (LHSI->getParent() == I.getParent())
- if (Instruction *NV = FoldOpIntoPhi(I, true))
- return NV;
- break;
- case Instruction::Select: {
- // If either operand of the select is a constant, we can fold the
- // comparison into the select arms, which will cause one to be
- // constant folded and the select turned into a bitwise or.
- Value *Op1 = 0, *Op2 = 0;
- if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1)))
- Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
- if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2)))
- Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
-
- // We only want to perform this transformation if it will not lead to
- // additional code. This is true if either both sides of the select
- // fold to a constant (in which case the icmp is replaced with a select
- // which will usually simplify) or this is the only user of the
- // select (in which case we are trading a select+icmp for a simpler
- // select+icmp).
- if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) {
- if (!Op1)
- Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1),
- RHSC, I.getName());
- if (!Op2)
- Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2),
- RHSC, I.getName());
- return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
- }
- break;
- }
- case Instruction::Call:
- // If we have (malloc != null), and if the malloc has a single use, we
- // can assume it is successful and remove the malloc.
- if (isMalloc(LHSI) && LHSI->hasOneUse() &&
- isa<ConstantPointerNull>(RHSC)) {
- // Need to explicitly erase malloc call here, instead of adding it to
- // Worklist, because it won't get DCE'd from the Worklist since
- // isInstructionTriviallyDead() returns false for function calls.
- // It is OK to replace LHSI/MallocCall with Undef because the
- // instruction that uses it will be erased via Worklist.
- if (extractMallocCall(LHSI)) {
- LHSI->replaceAllUsesWith(UndefValue::get(LHSI->getType()));
- EraseInstFromFunction(*LHSI);
- return ReplaceInstUsesWith(I,
- ConstantInt::get(Type::getInt1Ty(I.getContext()),
- !I.isTrueWhenEqual()));
- }
- if (CallInst* MallocCall = extractMallocCallFromBitCast(LHSI))
- if (MallocCall->hasOneUse()) {
- MallocCall->replaceAllUsesWith(
- UndefValue::get(MallocCall->getType()));
- EraseInstFromFunction(*MallocCall);
- Worklist.Add(LHSI); // The malloc's bitcast use.
- return ReplaceInstUsesWith(I,
- ConstantInt::get(Type::getInt1Ty(I.getContext()),
- !I.isTrueWhenEqual()));
- }
- }
- break;
- case Instruction::IntToPtr:
- // icmp pred inttoptr(X), null -> icmp pred X, 0
- if (RHSC->isNullValue() && TD &&
- TD->getIntPtrType(RHSC->getContext()) ==
- LHSI->getOperand(0)->getType())
- return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
- Constant::getNullValue(LHSI->getOperand(0)->getType()));
- break;
-
- case Instruction::Load:
- // Try to optimize things like "A[i] > 4" to index computations.
- if (GetElementPtrInst *GEP =
- dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
- if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
- !cast<LoadInst>(LHSI)->isVolatile())
- if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
- return Res;
- }
- break;
- }
- }
-
- // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
- if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
- return NI;
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
- if (Instruction *NI = FoldGEPICmp(GEP, Op0,
- ICmpInst::getSwappedPredicate(I.getPredicate()), I))
- return NI;
-
- // Test to see if the operands of the icmp are casted versions of other
- // values. If the ptr->ptr cast can be stripped off both arguments, we do so
- // now.
- if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
- if (isa<PointerType>(Op0->getType()) &&
- (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
- // We keep moving the cast from the left operand over to the right
- // operand, where it can often be eliminated completely.
- Op0 = CI->getOperand(0);
-
- // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
- // so eliminate it as well.
- if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
- Op1 = CI2->getOperand(0);
-
- // If Op1 is a constant, we can fold the cast into the constant.
- if (Op0->getType() != Op1->getType()) {
- if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
- Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
- } else {
- // Otherwise, cast the RHS right before the icmp
- Op1 = Builder->CreateBitCast(Op1, Op0->getType());
- }
- }
- return new ICmpInst(I.getPredicate(), Op0, Op1);
- }
- }
-
- if (isa<CastInst>(Op0)) {
- // Handle the special case of: icmp (cast bool to X), <cst>
- // This comes up when you have code like
- // int X = A < B;
- // if (X) ...
- // For generality, we handle any zero-extension of any operand comparison
- // with a constant or another cast from the same type.
- if (isa<Constant>(Op1) || isa<CastInst>(Op1))
- if (Instruction *R = visitICmpInstWithCastAndCast(I))
- return R;
- }
-
- // See if it's the same type of instruction on the left and right.
- if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
- if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
- if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() &&
- Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1)) {
- switch (Op0I->getOpcode()) {
- default: break;
- case Instruction::Add:
- case Instruction::Sub:
- case Instruction::Xor:
- if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
- return new ICmpInst(I.getPredicate(), Op0I->getOperand(0),
- Op1I->getOperand(0));
- // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
- if (CI->getValue().isSignBit()) {
- ICmpInst::Predicate Pred = I.isSigned()
- ? I.getUnsignedPredicate()
- : I.getSignedPredicate();
- return new ICmpInst(Pred, Op0I->getOperand(0),
- Op1I->getOperand(0));
- }
-
- if (CI->getValue().isMaxSignedValue()) {
- ICmpInst::Predicate Pred = I.isSigned()
- ? I.getUnsignedPredicate()
- : I.getSignedPredicate();
- Pred = I.getSwappedPredicate(Pred);
- return new ICmpInst(Pred, Op0I->getOperand(0),
- Op1I->getOperand(0));
- }
- }
- break;
- case Instruction::Mul:
- if (!I.isEquality())
- break;
-
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
- // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
- // Mask = -1 >> count-trailing-zeros(Cst).
- if (!CI->isZero() && !CI->isOne()) {
- const APInt &AP = CI->getValue();
- ConstantInt *Mask = ConstantInt::get(I.getContext(),
- APInt::getLowBitsSet(AP.getBitWidth(),
- AP.getBitWidth() -
- AP.countTrailingZeros()));
- Value *And1 = Builder->CreateAnd(Op0I->getOperand(0), Mask);
- Value *And2 = Builder->CreateAnd(Op1I->getOperand(0), Mask);
- return new ICmpInst(I.getPredicate(), And1, And2);
- }
- }
- break;
- }
- }
- }
- }
-
- // ~x < ~y --> y < x
- { Value *A, *B;
- if (match(Op0, m_Not(m_Value(A))) &&
- match(Op1, m_Not(m_Value(B))))
- return new ICmpInst(I.getPredicate(), B, A);
- }
-
- if (I.isEquality()) {
- Value *A, *B, *C, *D;
-
- // -x == -y --> x == y
- if (match(Op0, m_Neg(m_Value(A))) &&
- match(Op1, m_Neg(m_Value(B))))
- return new ICmpInst(I.getPredicate(), A, B);
-
- if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
- if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
- Value *OtherVal = A == Op1 ? B : A;
- return new ICmpInst(I.getPredicate(), OtherVal,
- Constant::getNullValue(A->getType()));
- }
-
- if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
- // A^c1 == C^c2 --> A == C^(c1^c2)
- ConstantInt *C1, *C2;
- if (match(B, m_ConstantInt(C1)) &&
- match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
- Constant *NC = ConstantInt::get(I.getContext(),
- C1->getValue() ^ C2->getValue());
- Value *Xor = Builder->CreateXor(C, NC, "tmp");
- return new ICmpInst(I.getPredicate(), A, Xor);
- }
-
- // A^B == A^D -> B == D
- if (A == C) return new ICmpInst(I.getPredicate(), B, D);
- if (A == D) return new ICmpInst(I.getPredicate(), B, C);
- if (B == C) return new ICmpInst(I.getPredicate(), A, D);
- if (B == D) return new ICmpInst(I.getPredicate(), A, C);
- }
- }
-
- if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
- (A == Op0 || B == Op0)) {
- // A == (A^B) -> B == 0
- Value *OtherVal = A == Op0 ? B : A;
- return new ICmpInst(I.getPredicate(), OtherVal,
- Constant::getNullValue(A->getType()));
- }
-
- // (A-B) == A -> B == 0
- if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B))))
- return new ICmpInst(I.getPredicate(), B,
- Constant::getNullValue(B->getType()));
-
- // A == (A-B) -> B == 0
- if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B))))
- return new ICmpInst(I.getPredicate(), B,
- Constant::getNullValue(B->getType()));
-
- // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
- if (Op0->hasOneUse() && Op1->hasOneUse() &&
- match(Op0, m_And(m_Value(A), m_Value(B))) &&
- match(Op1, m_And(m_Value(C), m_Value(D)))) {
- Value *X = 0, *Y = 0, *Z = 0;
-
- if (A == C) {
- X = B; Y = D; Z = A;
- } else if (A == D) {
- X = B; Y = C; Z = A;
- } else if (B == C) {
- X = A; Y = D; Z = B;
- } else if (B == D) {
- X = A; Y = C; Z = B;
- }
-
- if (X) { // Build (X^Y) & Z
- Op1 = Builder->CreateXor(X, Y, "tmp");
- Op1 = Builder->CreateAnd(Op1, Z, "tmp");
- I.setOperand(0, Op1);
- I.setOperand(1, Constant::getNullValue(Op1->getType()));
- return &I;
- }
- }
- }
-
- {
- Value *X; ConstantInt *Cst;
- // icmp X+Cst, X
- if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X)
- return FoldICmpAddOpCst(I, X, Cst, I.getPredicate(), Op0);
-
- // icmp X, X+Cst
- if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X)
- return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate(), Op1);
- }
- return Changed ? &I : 0;
-}
-
-/// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X".
-Instruction *InstCombiner::FoldICmpAddOpCst(ICmpInst &ICI,
- Value *X, ConstantInt *CI,
- ICmpInst::Predicate Pred,
- Value *TheAdd) {
- // If we have X+0, exit early (simplifying logic below) and let it get folded
- // elsewhere. icmp X+0, X -> icmp X, X
- if (CI->isZero()) {
- bool isTrue = ICmpInst::isTrueWhenEqual(Pred);
- return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
- }
-
- // (X+4) == X -> false.
- if (Pred == ICmpInst::ICMP_EQ)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext()));
-
- // (X+4) != X -> true.
- if (Pred == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext()));
-
- // If this is an instruction (as opposed to constantexpr) get NUW/NSW info.
- bool isNUW = false, isNSW = false;
- if (BinaryOperator *Add = dyn_cast<BinaryOperator>(TheAdd)) {
- isNUW = Add->hasNoUnsignedWrap();
- isNSW = Add->hasNoSignedWrap();
- }
-
- // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
- // so the values can never be equal. Similiarly for all other "or equals"
- // operators.
-
- // (X+1) <u X --> X >u (MAXUINT-1) --> X != 255
- // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
- // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
- if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
- // If this is an NUW add, then this is always false.
- if (isNUW)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext()));
-
- Value *R = ConstantExpr::getSub(ConstantInt::get(CI->getType(), -1ULL), CI);
- return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
- }
-
- // (X+1) >u X --> X <u (0-1) --> X != 255
- // (X+2) >u X --> X <u (0-2) --> X <u 254
- // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
- if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) {
- // If this is an NUW add, then this is always true.
- if (isNUW)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext()));
- return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI));
- }
-
- unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits();
- ConstantInt *SMax = ConstantInt::get(X->getContext(),
- APInt::getSignedMaxValue(BitWidth));
-
- // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
- // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
- // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
- // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
- // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
- // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
- if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) {
- // If this is an NSW add, then we have two cases: if the constant is
- // positive, then this is always false, if negative, this is always true.
- if (isNSW) {
- bool isTrue = CI->getValue().isNegative();
- return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
- }
-
- return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI));
- }
-
- // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
- // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
- // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
- // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
- // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
- // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
-
- // If this is an NSW add, then we have two cases: if the constant is
- // positive, then this is always true, if negative, this is always false.
- if (isNSW) {
- bool isTrue = !CI->getValue().isNegative();
- return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
- }
-
- assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE);
- Constant *C = ConstantInt::get(X->getContext(), CI->getValue()-1);
- return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C));
-}
-
-/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
-/// and CmpRHS are both known to be integer constants.
-Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
- ConstantInt *DivRHS) {
- ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
- const APInt &CmpRHSV = CmpRHS->getValue();
-
- // FIXME: If the operand types don't match the type of the divide
- // then don't attempt this transform. The code below doesn't have the
- // logic to deal with a signed divide and an unsigned compare (and
- // vice versa). This is because (x /s C1) <s C2 produces different
- // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
- // (x /u C1) <u C2. Simply casting the operands and result won't
- // work. :( The if statement below tests that condition and bails
- // if it finds it.
- bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
- if (!ICI.isEquality() && DivIsSigned != ICI.isSigned())
- return 0;
- if (DivRHS->isZero())
- return 0; // The ProdOV computation fails on divide by zero.
- if (DivIsSigned && DivRHS->isAllOnesValue())
- return 0; // The overflow computation also screws up here
- if (DivRHS->isOne())
- return 0; // Not worth bothering, and eliminates some funny cases
- // with INT_MIN.
-
- // Compute Prod = CI * DivRHS. We are essentially solving an equation
- // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
- // C2 (CI). By solving for X we can turn this into a range check
- // instead of computing a divide.
- Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS);
-
- // Determine if the product overflows by seeing if the product is
- // not equal to the divide. Make sure we do the same kind of divide
- // as in the LHS instruction that we're folding.
- bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
- ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
-
- // Get the ICmp opcode
- ICmpInst::Predicate Pred = ICI.getPredicate();
-
- // Figure out the interval that is being checked. For example, a comparison
- // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
- // Compute this interval based on the constants involved and the signedness of
- // the compare/divide. This computes a half-open interval, keeping track of
- // whether either value in the interval overflows. After analysis each
- // overflow variable is set to 0 if it's corresponding bound variable is valid
- // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
- int LoOverflow = 0, HiOverflow = 0;
- Constant *LoBound = 0, *HiBound = 0;
-
- if (!DivIsSigned) { // udiv
- // e.g. X/5 op 3 --> [15, 20)
- LoBound = Prod;
- HiOverflow = LoOverflow = ProdOV;
- if (!HiOverflow)
- HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false);
- } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
- if (CmpRHSV == 0) { // (X / pos) op 0
- // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
- LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
- HiBound = DivRHS;
- } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos
- LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
- HiOverflow = LoOverflow = ProdOV;
- if (!HiOverflow)
- HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true);
- } else { // (X / pos) op neg
- // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
- HiBound = AddOne(Prod);
- LoOverflow = HiOverflow = ProdOV ? -1 : 0;
- if (!LoOverflow) {
- ConstantInt* DivNeg =
- cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
- LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0;
- }
- }
- } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0.
- if (CmpRHSV == 0) { // (X / neg) op 0
- // e.g. X/-5 op 0 --> [-4, 5)
- LoBound = AddOne(DivRHS);
- HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
- if (HiBound == DivRHS) { // -INTMIN = INTMIN
- HiOverflow = 1; // [INTMIN+1, overflow)
- HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
- }
- } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos
- // e.g. X/-5 op 3 --> [-19, -14)
- HiBound = AddOne(Prod);
- HiOverflow = LoOverflow = ProdOV ? -1 : 0;
- if (!LoOverflow)
- LoOverflow = AddWithOverflow(LoBound, HiBound, DivRHS, true) ? -1 : 0;
- } else { // (X / neg) op neg
- LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
- LoOverflow = HiOverflow = ProdOV;
- if (!HiOverflow)
- HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, true);
- }
-
- // Dividing by a negative swaps the condition. LT <-> GT
- Pred = ICmpInst::getSwappedPredicate(Pred);
- }
-
- Value *X = DivI->getOperand(0);
- switch (Pred) {
- default: llvm_unreachable("Unhandled icmp opcode!");
- case ICmpInst::ICMP_EQ:
- if (LoOverflow && HiOverflow)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext()));
- else if (HiOverflow)
- return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
- ICmpInst::ICMP_UGE, X, LoBound);
- else if (LoOverflow)
- return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
- ICmpInst::ICMP_ULT, X, HiBound);
- else
- return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
- case ICmpInst::ICMP_NE:
- if (LoOverflow && HiOverflow)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext()));
- else if (HiOverflow)
- return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
- ICmpInst::ICMP_ULT, X, LoBound);
- else if (LoOverflow)
- return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
- ICmpInst::ICMP_UGE, X, HiBound);
- else
- return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_SLT:
- if (LoOverflow == +1) // Low bound is greater than input range.
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext()));
- if (LoOverflow == -1) // Low bound is less than input range.
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext()));
- return new ICmpInst(Pred, X, LoBound);
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_SGT:
- if (HiOverflow == +1) // High bound greater than input range.
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext()));
- else if (HiOverflow == -1) // High bound less than input range.
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext()));
- if (Pred == ICmpInst::ICMP_UGT)
- return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
- else
- return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
- }
-}
-
-
-/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
-///
-Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
- Instruction *LHSI,
- ConstantInt *RHS) {
- const APInt &RHSV = RHS->getValue();
-
- switch (LHSI->getOpcode()) {
- case Instruction::Trunc:
- if (ICI.isEquality() && LHSI->hasOneUse()) {
- // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
- // of the high bits truncated out of x are known.
- unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
- SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
- APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits));
- APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
- ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne);
-
- // If all the high bits are known, we can do this xform.
- if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
- // Pull in the high bits from known-ones set.
- APInt NewRHS(RHS->getValue());
- NewRHS.zext(SrcBits);
- NewRHS |= KnownOne;
- return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
- ConstantInt::get(ICI.getContext(), NewRHS));
- }
- }
- break;
-
- case Instruction::Xor: // (icmp pred (xor X, XorCST), CI)
- if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
- // If this is a comparison that tests the signbit (X < 0) or (x > -1),
- // fold the xor.
- if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
- (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
- Value *CompareVal = LHSI->getOperand(0);
-
- // If the sign bit of the XorCST is not set, there is no change to
- // the operation, just stop using the Xor.
- if (!XorCST->getValue().isNegative()) {
- ICI.setOperand(0, CompareVal);
- Worklist.Add(LHSI);
- return &ICI;
- }
-
- // Was the old condition true if the operand is positive?
- bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
-
- // If so, the new one isn't.
- isTrueIfPositive ^= true;
-
- if (isTrueIfPositive)
- return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal,
- SubOne(RHS));
- else
- return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal,
- AddOne(RHS));
- }
-
- if (LHSI->hasOneUse()) {
- // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
- if (!ICI.isEquality() && XorCST->getValue().isSignBit()) {
- const APInt &SignBit = XorCST->getValue();
- ICmpInst::Predicate Pred = ICI.isSigned()
- ? ICI.getUnsignedPredicate()
- : ICI.getSignedPredicate();
- return new ICmpInst(Pred, LHSI->getOperand(0),
- ConstantInt::get(ICI.getContext(),
- RHSV ^ SignBit));
- }
-
- // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
- if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) {
- const APInt &NotSignBit = XorCST->getValue();
- ICmpInst::Predicate Pred = ICI.isSigned()
- ? ICI.getUnsignedPredicate()
- : ICI.getSignedPredicate();
- Pred = ICI.getSwappedPredicate(Pred);
- return new ICmpInst(Pred, LHSI->getOperand(0),
- ConstantInt::get(ICI.getContext(),
- RHSV ^ NotSignBit));
- }
- }
- }
- break;
- case Instruction::And: // (icmp pred (and X, AndCST), RHS)
- if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
- LHSI->getOperand(0)->hasOneUse()) {
- ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
-
- // If the LHS is an AND of a truncating cast, we can widen the
- // and/compare to be the input width without changing the value
- // produced, eliminating a cast.
- if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
- // We can do this transformation if either the AND constant does not
- // have its sign bit set or if it is an equality comparison.
- // Extending a relational comparison when we're checking the sign
- // bit would not work.
- if (Cast->hasOneUse() &&
- (ICI.isEquality() ||
- (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) {
- uint32_t BitWidth =
- cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
- APInt NewCST = AndCST->getValue();
- NewCST.zext(BitWidth);
- APInt NewCI = RHSV;
- NewCI.zext(BitWidth);
- Value *NewAnd =
- Builder->CreateAnd(Cast->getOperand(0),
- ConstantInt::get(ICI.getContext(), NewCST),
- LHSI->getName());
- return new ICmpInst(ICI.getPredicate(), NewAnd,
- ConstantInt::get(ICI.getContext(), NewCI));
- }
- }
-
- // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
- // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
- // happens a LOT in code produced by the C front-end, for bitfield
- // access.
- BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
- if (Shift && !Shift->isShift())
- Shift = 0;
-
- ConstantInt *ShAmt;
- ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
- const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
- const Type *AndTy = AndCST->getType(); // Type of the and.
-
- // We can fold this as long as we can't shift unknown bits
- // into the mask. This can only happen with signed shift
- // rights, as they sign-extend.
- if (ShAmt) {
- bool CanFold = Shift->isLogicalShift();
- if (!CanFold) {
- // To test for the bad case of the signed shr, see if any
- // of the bits shifted in could be tested after the mask.
- uint32_t TyBits = Ty->getPrimitiveSizeInBits();
- int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
-
- uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
- if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) &
- AndCST->getValue()) == 0)
- CanFold = true;
- }
-
- if (CanFold) {
- Constant *NewCst;
- if (Shift->getOpcode() == Instruction::Shl)
- NewCst = ConstantExpr::getLShr(RHS, ShAmt);
- else
- NewCst = ConstantExpr::getShl(RHS, ShAmt);
-
- // Check to see if we are shifting out any of the bits being
- // compared.
- if (ConstantExpr::get(Shift->getOpcode(),
- NewCst, ShAmt) != RHS) {
- // If we shifted bits out, the fold is not going to work out.
- // As a special case, check to see if this means that the
- // result is always true or false now.
- if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
- return ReplaceInstUsesWith(ICI,
- ConstantInt::getFalse(ICI.getContext()));
- if (ICI.getPredicate() == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(ICI,
- ConstantInt::getTrue(ICI.getContext()));
- } else {
- ICI.setOperand(1, NewCst);
- Constant *NewAndCST;
- if (Shift->getOpcode() == Instruction::Shl)
- NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
- else
- NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
- LHSI->setOperand(1, NewAndCST);
- LHSI->setOperand(0, Shift->getOperand(0));
- Worklist.Add(Shift); // Shift is dead.
- return &ICI;
- }
- }
- }
-
- // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
- // preferable because it allows the C<<Y expression to be hoisted out
- // of a loop if Y is invariant and X is not.
- if (Shift && Shift->hasOneUse() && RHSV == 0 &&
- ICI.isEquality() && !Shift->isArithmeticShift() &&
- !isa<Constant>(Shift->getOperand(0))) {
- // Compute C << Y.
- Value *NS;
- if (Shift->getOpcode() == Instruction::LShr) {
- NS = Builder->CreateShl(AndCST, Shift->getOperand(1), "tmp");
- } else {
- // Insert a logical shift.
- NS = Builder->CreateLShr(AndCST, Shift->getOperand(1), "tmp");
- }
-
- // Compute X & (C << Y).
- Value *NewAnd =
- Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
-
- ICI.setOperand(0, NewAnd);
- return &ICI;
- }
- }
-
- // Try to optimize things like "A[i]&42 == 0" to index computations.
- if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) {
- if (GetElementPtrInst *GEP =
- dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
- if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
- !LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) {
- ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1));
- if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C))
- return Res;
- }
- }
- break;
-
- case Instruction::Or: {
- if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse())
- break;
- Value *P, *Q;
- if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
- // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
- // -> and (icmp eq P, null), (icmp eq Q, null).
-
- Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P,
- Constant::getNullValue(P->getType()));
- Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q,
- Constant::getNullValue(Q->getType()));
- Instruction *Op;
- if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
- Op = BinaryOperator::CreateAnd(ICIP, ICIQ);
- else
- Op = BinaryOperator::CreateOr(ICIP, ICIQ);
- return Op;
- }
- break;
- }
-
- case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
- ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
- if (!ShAmt) break;
-
- uint32_t TypeBits = RHSV.getBitWidth();
-
- // Check that the shift amount is in range. If not, don't perform
- // undefined shifts. When the shift is visited it will be
- // simplified.
- if (ShAmt->uge(TypeBits))
- break;
-
- if (ICI.isEquality()) {
- // If we are comparing against bits always shifted out, the
- // comparison cannot succeed.
- Constant *Comp =
- ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt),
- ShAmt);
- if (Comp != RHS) {// Comparing against a bit that we know is zero.
- bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
- Constant *Cst =
- ConstantInt::get(Type::getInt1Ty(ICI.getContext()), IsICMP_NE);
- return ReplaceInstUsesWith(ICI, Cst);
- }
-
- if (LHSI->hasOneUse()) {
- // Otherwise strength reduce the shift into an and.
- uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
- Constant *Mask =
- ConstantInt::get(ICI.getContext(), APInt::getLowBitsSet(TypeBits,
- TypeBits-ShAmtVal));
-
- Value *And =
- Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask");
- return new ICmpInst(ICI.getPredicate(), And,
- ConstantInt::get(ICI.getContext(),
- RHSV.lshr(ShAmtVal)));
- }
- }
-
- // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
- bool TrueIfSigned = false;
- if (LHSI->hasOneUse() &&
- isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
- // (X << 31) <s 0 --> (X&1) != 0
- Constant *Mask = ConstantInt::get(ICI.getContext(), APInt(TypeBits, 1) <<
- (TypeBits-ShAmt->getZExtValue()-1));
- Value *And =
- Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask");
- return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
- And, Constant::getNullValue(And->getType()));
- }
- break;
- }
-
- case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
- case Instruction::AShr: {
- // Only handle equality comparisons of shift-by-constant.
- ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
- if (!ShAmt || !ICI.isEquality()) break;
-
- // Check that the shift amount is in range. If not, don't perform
- // undefined shifts. When the shift is visited it will be
- // simplified.
- uint32_t TypeBits = RHSV.getBitWidth();
- if (ShAmt->uge(TypeBits))
- break;
-
- uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
-
- // If we are comparing against bits always shifted out, the
- // comparison cannot succeed.
- APInt Comp = RHSV << ShAmtVal;
- if (LHSI->getOpcode() == Instruction::LShr)
- Comp = Comp.lshr(ShAmtVal);
- else
- Comp = Comp.ashr(ShAmtVal);
-
- if (Comp != RHSV) { // Comparing against a bit that we know is zero.
- bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
- Constant *Cst = ConstantInt::get(Type::getInt1Ty(ICI.getContext()),
- IsICMP_NE);
- return ReplaceInstUsesWith(ICI, Cst);
- }
-
- // Otherwise, check to see if the bits shifted out are known to be zero.
- // If so, we can compare against the unshifted value:
- // (X & 4) >> 1 == 2 --> (X & 4) == 4.
- if (LHSI->hasOneUse() &&
- MaskedValueIsZero(LHSI->getOperand(0),
- APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) {
- return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
- ConstantExpr::getShl(RHS, ShAmt));
- }
-
- if (LHSI->hasOneUse()) {
- // Otherwise strength reduce the shift into an and.
- APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
- Constant *Mask = ConstantInt::get(ICI.getContext(), Val);
-
- Value *And = Builder->CreateAnd(LHSI->getOperand(0),
- Mask, LHSI->getName()+".mask");
- return new ICmpInst(ICI.getPredicate(), And,
- ConstantExpr::getShl(RHS, ShAmt));
- }
- break;
- }
-
- case Instruction::SDiv:
- case Instruction::UDiv:
- // Fold: icmp pred ([us]div X, C1), C2 -> range test
- // Fold this div into the comparison, producing a range check.
- // Determine, based on the divide type, what the range is being
- // checked. If there is an overflow on the low or high side, remember
- // it, otherwise compute the range [low, hi) bounding the new value.
- // See: InsertRangeTest above for the kinds of replacements possible.
- if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
- if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
- DivRHS))
- return R;
- break;
-
- case Instruction::Add:
- // Fold: icmp pred (add X, C1), C2
- if (!ICI.isEquality()) {
- ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
- if (!LHSC) break;
- const APInt &LHSV = LHSC->getValue();
-
- ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
- .subtract(LHSV);
-
- if (ICI.isSigned()) {
- if (CR.getLower().isSignBit()) {
- return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
- ConstantInt::get(ICI.getContext(),CR.getUpper()));
- } else if (CR.getUpper().isSignBit()) {
- return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
- ConstantInt::get(ICI.getContext(),CR.getLower()));
- }
- } else {
- if (CR.getLower().isMinValue()) {
- return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
- ConstantInt::get(ICI.getContext(),CR.getUpper()));
- } else if (CR.getUpper().isMinValue()) {
- return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
- ConstantInt::get(ICI.getContext(),CR.getLower()));
- }
- }
- }
- break;
- }
-
- // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
- if (ICI.isEquality()) {
- bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
-
- // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
- // the second operand is a constant, simplify a bit.
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
- switch (BO->getOpcode()) {
- case Instruction::SRem:
- // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
- if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
- const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
- if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
- Value *NewRem =
- Builder->CreateURem(BO->getOperand(0), BO->getOperand(1),
- BO->getName());
- return new ICmpInst(ICI.getPredicate(), NewRem,
- Constant::getNullValue(BO->getType()));
- }
- }
- break;
- case Instruction::Add:
- // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
- if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
- if (BO->hasOneUse())
- return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
- ConstantExpr::getSub(RHS, BOp1C));
- } else if (RHSV == 0) {
- // Replace ((add A, B) != 0) with (A != -B) if A or B is
- // efficiently invertible, or if the add has just this one use.
- Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
-
- if (Value *NegVal = dyn_castNegVal(BOp1))
- return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
- else if (Value *NegVal = dyn_castNegVal(BOp0))
- return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
- else if (BO->hasOneUse()) {
- Value *Neg = Builder->CreateNeg(BOp1);
- Neg->takeName(BO);
- return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
- }
- }
- break;
- case Instruction::Xor:
- // For the xor case, we can xor two constants together, eliminating
- // the explicit xor.
- if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
- return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
- ConstantExpr::getXor(RHS, BOC));
-
- // FALLTHROUGH
- case Instruction::Sub:
- // Replace (([sub|xor] A, B) != 0) with (A != B)
- if (RHSV == 0)
- return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
- BO->getOperand(1));
- break;
-
- case Instruction::Or:
- // If bits are being or'd in that are not present in the constant we
- // are comparing against, then the comparison could never succeed!
- if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
- Constant *NotCI = ConstantExpr::getNot(RHS);
- if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
- return ReplaceInstUsesWith(ICI,
- ConstantInt::get(Type::getInt1Ty(ICI.getContext()),
- isICMP_NE));
- }
- break;
-
- case Instruction::And:
- if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
- // If bits are being compared against that are and'd out, then the
- // comparison can never succeed!
- if ((RHSV & ~BOC->getValue()) != 0)
- return ReplaceInstUsesWith(ICI,
- ConstantInt::get(Type::getInt1Ty(ICI.getContext()),
- isICMP_NE));
-
- // If we have ((X & C) == C), turn it into ((X & C) != 0).
- if (RHS == BOC && RHSV.isPowerOf2())
- return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
- ICmpInst::ICMP_NE, LHSI,
- Constant::getNullValue(RHS->getType()));
-
- // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
- if (BOC->getValue().isSignBit()) {
- Value *X = BO->getOperand(0);
- Constant *Zero = Constant::getNullValue(X->getType());
- ICmpInst::Predicate pred = isICMP_NE ?
- ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
- return new ICmpInst(pred, X, Zero);
- }
-
- // ((X & ~7) == 0) --> X < 8
- if (RHSV == 0 && isHighOnes(BOC)) {
- Value *X = BO->getOperand(0);
- Constant *NegX = ConstantExpr::getNeg(BOC);
- ICmpInst::Predicate pred = isICMP_NE ?
- ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
- return new ICmpInst(pred, X, NegX);
- }
- }
- default: break;
- }
- } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
- // Handle icmp {eq|ne} <intrinsic>, intcst.
- if (II->getIntrinsicID() == Intrinsic::bswap) {
- Worklist.Add(II);
- ICI.setOperand(0, II->getOperand(1));
- ICI.setOperand(1, ConstantInt::get(II->getContext(), RHSV.byteSwap()));
- return &ICI;
- }
- }
- }
- return 0;
-}
-
-/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
-/// We only handle extending casts so far.
-///
-Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
- const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
- Value *LHSCIOp = LHSCI->getOperand(0);
- const Type *SrcTy = LHSCIOp->getType();
- const Type *DestTy = LHSCI->getType();
- Value *RHSCIOp;
-
- // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
- // integer type is the same size as the pointer type.
- if (TD && LHSCI->getOpcode() == Instruction::PtrToInt &&
- TD->getPointerSizeInBits() ==
- cast<IntegerType>(DestTy)->getBitWidth()) {
- Value *RHSOp = 0;
- if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
- RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
- } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
- RHSOp = RHSC->getOperand(0);
- // If the pointer types don't match, insert a bitcast.
- if (LHSCIOp->getType() != RHSOp->getType())
- RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
- }
-
- if (RHSOp)
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
- }
-
- // The code below only handles extension cast instructions, so far.
- // Enforce this.
- if (LHSCI->getOpcode() != Instruction::ZExt &&
- LHSCI->getOpcode() != Instruction::SExt)
- return 0;
-
- bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
- bool isSignedCmp = ICI.isSigned();
-
- if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
- // Not an extension from the same type?
- RHSCIOp = CI->getOperand(0);
- if (RHSCIOp->getType() != LHSCIOp->getType())
- return 0;
-
- // If the signedness of the two casts doesn't agree (i.e. one is a sext
- // and the other is a zext), then we can't handle this.
- if (CI->getOpcode() != LHSCI->getOpcode())
- return 0;
-
- // Deal with equality cases early.
- if (ICI.isEquality())
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
-
- // A signed comparison of sign extended values simplifies into a
- // signed comparison.
- if (isSignedCmp && isSignedExt)
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
-
- // The other three cases all fold into an unsigned comparison.
- return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
- }
-
- // If we aren't dealing with a constant on the RHS, exit early
- ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
- if (!CI)
- return 0;
-
- // Compute the constant that would happen if we truncated to SrcTy then
- // reextended to DestTy.
- Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
- Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(),
- Res1, DestTy);
-
- // If the re-extended constant didn't change...
- if (Res2 == CI) {
- // Deal with equality cases early.
- if (ICI.isEquality())
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
-
- // A signed comparison of sign extended values simplifies into a
- // signed comparison.
- if (isSignedExt && isSignedCmp)
- return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
-
- // The other three cases all fold into an unsigned comparison.
- return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1);
- }
-
- // The re-extended constant changed so the constant cannot be represented
- // in the shorter type. Consequently, we cannot emit a simple comparison.
-
- // First, handle some easy cases. We know the result cannot be equal at this
- // point so handle the ICI.isEquality() cases
- if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
- return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext()));
- if (ICI.getPredicate() == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext()));
-
- // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
- // should have been folded away previously and not enter in here.
- Value *Result;
- if (isSignedCmp) {
- // We're performing a signed comparison.
- if (cast<ConstantInt>(CI)->getValue().isNegative())
- Result = ConstantInt::getFalse(ICI.getContext()); // X < (small) --> false
- else
- Result = ConstantInt::getTrue(ICI.getContext()); // X < (large) --> true
- } else {
- // We're performing an unsigned comparison.
- if (isSignedExt) {
- // We're performing an unsigned comp with a sign extended value.
- // This is true if the input is >= 0. [aka >s -1]
- Constant *NegOne = Constant::getAllOnesValue(SrcTy);
- Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName());
- } else {
- // Unsigned extend & unsigned compare -> always true.
- Result = ConstantInt::getTrue(ICI.getContext());
- }
- }
-
- // Finally, return the value computed.
- if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
- ICI.getPredicate() == ICmpInst::ICMP_SLT)
- return ReplaceInstUsesWith(ICI, Result);
-
- assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
- ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
- "ICmp should be folded!");
- if (Constant *CI = dyn_cast<Constant>(Result))
- return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
- return BinaryOperator::CreateNot(Result);
-}
Instruction *InstCombiner::visitShl(BinaryOperator &I) {
return commonShiftTransforms(I);
@@ -7292,7 +4874,7 @@
if (TD && GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
if (GEP->hasAllConstantIndices()) {
// We are guaranteed to get a constant from EmitGEPOffset.
- ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP, *this));
+ ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP));
int64_t Offset = OffsetV->getSExtValue();
// Get the base pointer input of the bitcast, and the type it points to.
@@ -10874,7 +8456,7 @@
!isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) {
// Determine how much the GEP moves the pointer. We are guaranteed to get
// a constant back from EmitGEPOffset.
- ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP, *this));
+ ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP));
int64_t Offset = OffsetV->getSExtValue();
// If this GEP instruction doesn't move the pointer, just replace the GEP
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