[llvm-commits] [llvm] r92704 - in /llvm/trunk/lib/Transforms/InstCombine: CMakeLists.txt InstCombineAddSub.cpp InstructionCombining.cpp
Chris Lattner
sabre at nondot.org
Mon Jan 4 23:18:46 PST 2010
Author: lattner
Date: Tue Jan 5 01:18:46 2010
New Revision: 92704
URL: http://llvm.org/viewvc/llvm-project?rev=92704&view=rev
Log:
split add/sub out to its own file. Eliminate use of
dyn_castNotVal in the X+~X transform. dyn_castNotVal is
dramatic overkill for what the xform needed.
Added:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
Modified:
llvm/trunk/lib/Transforms/InstCombine/CMakeLists.txt
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=92704&r1=92703&r2=92704&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/CMakeLists.txt (original)
+++ llvm/trunk/lib/Transforms/InstCombine/CMakeLists.txt Tue Jan 5 01:18:46 2010
@@ -1,5 +1,6 @@
add_llvm_library(LLVMInstCombine
InstructionCombining.cpp
+ InstCombineAddSub.cpp
InstCombineCasts.cpp
InstCombineCompares.cpp
InstCombineLoadStoreAlloca.cpp
Added: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=92704&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp (added)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Tue Jan 5 01:18:46 2010
@@ -0,0 +1,748 @@
+//===- InstCombineAddSub.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 visit functions for add, fadd, sub, and fsub.
+//
+//===----------------------------------------------------------------------===//
+
+#include "InstCombine.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Target/TargetData.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 ConstantInt::get(C->getContext(), C->getValue()-1);
+}
+
+
+// dyn_castFoldableMul - If this value is a multiply that can be folded into
+// other computations (because it has a constant operand), return the
+// non-constant operand of the multiply, and set CST to point to the multiplier.
+// Otherwise, return null.
+//
+static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
+ if (V->hasOneUse() && V->getType()->isInteger())
+ if (Instruction *I = dyn_cast<Instruction>(V)) {
+ if (I->getOpcode() == Instruction::Mul)
+ if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
+ return I->getOperand(0);
+ if (I->getOpcode() == Instruction::Shl)
+ if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
+ // The multiplier is really 1 << CST.
+ uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
+ uint32_t CSTVal = CST->getLimitedValue(BitWidth);
+ CST = ConstantInt::get(V->getType()->getContext(),
+ APInt(BitWidth, 1).shl(CSTVal));
+ return I->getOperand(0);
+ }
+ }
+ return 0;
+}
+
+
+/// WillNotOverflowSignedAdd - Return true if we can prove that:
+/// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS))
+/// This basically requires proving that the add in the original type would not
+/// overflow to change the sign bit or have a carry out.
+bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
+ // There are different heuristics we can use for this. Here are some simple
+ // ones.
+
+ // Add has the property that adding any two 2's complement numbers can only
+ // have one carry bit which can change a sign. As such, if LHS and RHS each
+ // have at least two sign bits, we know that the addition of the two values
+ // will sign extend fine.
+ if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
+ return true;
+
+
+ // If one of the operands only has one non-zero bit, and if the other operand
+ // has a known-zero bit in a more significant place than it (not including the
+ // sign bit) the ripple may go up to and fill the zero, but won't change the
+ // sign. For example, (X & ~4) + 1.
+
+ // TODO: Implement.
+
+ return false;
+}
+
+Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+
+ if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
+ I.hasNoUnsignedWrap(), TD))
+ return ReplaceInstUsesWith(I, V);
+
+
+ if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
+ // X + (signbit) --> X ^ signbit
+ const APInt& Val = CI->getValue();
+ uint32_t BitWidth = Val.getBitWidth();
+ if (Val == APInt::getSignBit(BitWidth))
+ return BinaryOperator::CreateXor(LHS, RHS);
+
+ // See if SimplifyDemandedBits can simplify this. This handles stuff like
+ // (X & 254)+1 -> (X&254)|1
+ if (SimplifyDemandedInstructionBits(I))
+ return &I;
+
+ // zext(bool) + C -> bool ? C + 1 : C
+ if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
+ if (ZI->getSrcTy() == Type::getInt1Ty(I.getContext()))
+ return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI);
+ }
+
+ if (isa<PHINode>(LHS))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+
+ ConstantInt *XorRHS = 0;
+ Value *XorLHS = 0;
+ if (isa<ConstantInt>(RHSC) &&
+ match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
+ uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
+ const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
+
+ uint32_t Size = TySizeBits / 2;
+ APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
+ APInt CFF80Val(-C0080Val);
+ do {
+ if (TySizeBits > Size) {
+ // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
+ // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
+ if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
+ (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
+ // This is a sign extend if the top bits are known zero.
+ if (!MaskedValueIsZero(XorLHS,
+ APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
+ Size = 0; // Not a sign ext, but can't be any others either.
+ break;
+ }
+ }
+ Size >>= 1;
+ C0080Val = APIntOps::lshr(C0080Val, Size);
+ CFF80Val = APIntOps::ashr(CFF80Val, Size);
+ } while (Size >= 1);
+
+ // FIXME: This shouldn't be necessary. When the backends can handle types
+ // with funny bit widths then this switch statement should be removed. It
+ // is just here to get the size of the "middle" type back up to something
+ // that the back ends can handle.
+ const Type *MiddleType = 0;
+ switch (Size) {
+ default: break;
+ case 32:
+ case 16:
+ case 8: MiddleType = IntegerType::get(I.getContext(), Size); break;
+ }
+ if (MiddleType) {
+ Value *NewTrunc = Builder->CreateTrunc(XorLHS, MiddleType, "sext");
+ return new SExtInst(NewTrunc, I.getType(), I.getName());
+ }
+ }
+ }
+
+ if (I.getType() == Type::getInt1Ty(I.getContext()))
+ return BinaryOperator::CreateXor(LHS, RHS);
+
+ if (I.getType()->isInteger()) {
+ // X + X --> X << 1
+ if (LHS == RHS)
+ return BinaryOperator::CreateShl(LHS, ConstantInt::get(I.getType(), 1));
+
+ if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
+ if (RHSI->getOpcode() == Instruction::Sub)
+ if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
+ return ReplaceInstUsesWith(I, RHSI->getOperand(0));
+ }
+ if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
+ if (LHSI->getOpcode() == Instruction::Sub)
+ if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
+ return ReplaceInstUsesWith(I, LHSI->getOperand(0));
+ }
+ }
+
+ // -A + B --> B - A
+ // -A + -B --> -(A + B)
+ if (Value *LHSV = dyn_castNegVal(LHS)) {
+ if (LHS->getType()->isIntOrIntVector()) {
+ if (Value *RHSV = dyn_castNegVal(RHS)) {
+ Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
+ return BinaryOperator::CreateNeg(NewAdd);
+ }
+ }
+
+ return BinaryOperator::CreateSub(RHS, LHSV);
+ }
+
+ // A + -B --> A - B
+ if (!isa<Constant>(RHS))
+ if (Value *V = dyn_castNegVal(RHS))
+ return BinaryOperator::CreateSub(LHS, V);
+
+
+ ConstantInt *C2;
+ if (Value *X = dyn_castFoldableMul(LHS, C2)) {
+ if (X == RHS) // X*C + X --> X * (C+1)
+ return BinaryOperator::CreateMul(RHS, AddOne(C2));
+
+ // X*C1 + X*C2 --> X * (C1+C2)
+ ConstantInt *C1;
+ if (X == dyn_castFoldableMul(RHS, C1))
+ return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2));
+ }
+
+ // X + X*C --> X * (C+1)
+ if (dyn_castFoldableMul(RHS, C2) == LHS)
+ return BinaryOperator::CreateMul(LHS, AddOne(C2));
+
+ // X + ~X --> -1 since ~X = -X-1
+ if (match(LHS, m_Not(m_Specific(RHS))) ||
+ match(RHS, m_Not(m_Specific(LHS))))
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+ // A+B --> A|B iff A and B have no bits set in common.
+ if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
+ APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
+ APInt LHSKnownOne(IT->getBitWidth(), 0);
+ APInt LHSKnownZero(IT->getBitWidth(), 0);
+ ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
+ if (LHSKnownZero != 0) {
+ APInt RHSKnownOne(IT->getBitWidth(), 0);
+ APInt RHSKnownZero(IT->getBitWidth(), 0);
+ ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
+
+ // No bits in common -> bitwise or.
+ if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
+ return BinaryOperator::CreateOr(LHS, RHS);
+ }
+ }
+
+ // W*X + Y*Z --> W * (X+Z) iff W == Y
+ if (I.getType()->isIntOrIntVector()) {
+ Value *W, *X, *Y, *Z;
+ if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
+ match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
+ if (W != Y) {
+ if (W == Z) {
+ std::swap(Y, Z);
+ } else if (Y == X) {
+ std::swap(W, X);
+ } else if (X == Z) {
+ std::swap(Y, Z);
+ std::swap(W, X);
+ }
+ }
+
+ if (W == Y) {
+ Value *NewAdd = Builder->CreateAdd(X, Z, LHS->getName());
+ return BinaryOperator::CreateMul(W, NewAdd);
+ }
+ }
+ }
+
+ if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
+ Value *X = 0;
+ if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
+ return BinaryOperator::CreateSub(SubOne(CRHS), X);
+
+ // (X & FF00) + xx00 -> (X+xx00) & FF00
+ if (LHS->hasOneUse() &&
+ match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
+ Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
+ if (Anded == CRHS) {
+ // See if all bits from the first bit set in the Add RHS up are included
+ // in the mask. First, get the rightmost bit.
+ const APInt &AddRHSV = CRHS->getValue();
+
+ // Form a mask of all bits from the lowest bit added through the top.
+ APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
+
+ // See if the and mask includes all of these bits.
+ APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
+
+ if (AddRHSHighBits == AddRHSHighBitsAnd) {
+ // Okay, the xform is safe. Insert the new add pronto.
+ Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName());
+ return BinaryOperator::CreateAnd(NewAdd, C2);
+ }
+ }
+ }
+
+ // Try to fold constant add into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
+ if (Instruction *R = FoldOpIntoSelect(I, SI))
+ return R;
+ }
+
+ // add (select X 0 (sub n A)) A --> select X A n
+ {
+ SelectInst *SI = dyn_cast<SelectInst>(LHS);
+ Value *A = RHS;
+ if (!SI) {
+ SI = dyn_cast<SelectInst>(RHS);
+ A = LHS;
+ }
+ if (SI && SI->hasOneUse()) {
+ Value *TV = SI->getTrueValue();
+ Value *FV = SI->getFalseValue();
+ Value *N;
+
+ // Can we fold the add into the argument of the select?
+ // We check both true and false select arguments for a matching subtract.
+ if (match(FV, m_Zero()) &&
+ match(TV, m_Sub(m_Value(N), m_Specific(A))))
+ // Fold the add into the true select value.
+ return SelectInst::Create(SI->getCondition(), N, A);
+ if (match(TV, m_Zero()) &&
+ match(FV, m_Sub(m_Value(N), m_Specific(A))))
+ // Fold the add into the false select value.
+ return SelectInst::Create(SI->getCondition(), A, N);
+ }
+ }
+
+ // Check for (add (sext x), y), see if we can merge this into an
+ // integer add followed by a sext.
+ if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
+ // (add (sext x), cst) --> (sext (add x, cst'))
+ if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
+ Constant *CI =
+ ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
+ if (LHSConv->hasOneUse() &&
+ ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
+ WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
+ // Insert the new, smaller add.
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ CI, "addconv");
+ return new SExtInst(NewAdd, I.getType());
+ }
+ }
+
+ // (add (sext x), (sext y)) --> (sext (add int x, y))
+ if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
+ // Only do this if x/y have the same type, if at last one of them has a
+ // single use (so we don't increase the number of sexts), and if the
+ // integer add will not overflow.
+ if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
+ (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
+ WillNotOverflowSignedAdd(LHSConv->getOperand(0),
+ RHSConv->getOperand(0))) {
+ // Insert the new integer add.
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ RHSConv->getOperand(0), "addconv");
+ return new SExtInst(NewAdd, I.getType());
+ }
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+
+ if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+ // X + 0 --> X
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
+ if (CFP->isExactlyValue(ConstantFP::getNegativeZero
+ (I.getType())->getValueAPF()))
+ return ReplaceInstUsesWith(I, LHS);
+ }
+
+ if (isa<PHINode>(LHS))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ // -A + B --> B - A
+ // -A + -B --> -(A + B)
+ if (Value *LHSV = dyn_castFNegVal(LHS))
+ return BinaryOperator::CreateFSub(RHS, LHSV);
+
+ // A + -B --> A - B
+ if (!isa<Constant>(RHS))
+ if (Value *V = dyn_castFNegVal(RHS))
+ return BinaryOperator::CreateFSub(LHS, V);
+
+ // Check for X+0.0. Simplify it to X if we know X is not -0.0.
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
+ if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS))
+ return ReplaceInstUsesWith(I, LHS);
+
+ // Check for (add double (sitofp x), y), see if we can merge this into an
+ // integer add followed by a promotion.
+ if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
+ // (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
+ // ... if the constant fits in the integer value. This is useful for things
+ // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
+ // requires a constant pool load, and generally allows the add to be better
+ // instcombined.
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
+ Constant *CI =
+ ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
+ if (LHSConv->hasOneUse() &&
+ ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
+ WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
+ // Insert the new integer add.
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ CI, "addconv");
+ return new SIToFPInst(NewAdd, I.getType());
+ }
+ }
+
+ // (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
+ if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
+ // Only do this if x/y have the same type, if at last one of them has a
+ // single use (so we don't increase the number of int->fp conversions),
+ // and if the integer add will not overflow.
+ if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
+ (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
+ WillNotOverflowSignedAdd(LHSConv->getOperand(0),
+ RHSConv->getOperand(0))) {
+ // Insert the new integer add.
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ RHSConv->getOperand(0),"addconv");
+ return new SIToFPInst(NewAdd, I.getType());
+ }
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+
+/// 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.
+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);
+
+ // Build a mask for high order bits.
+ unsigned IntPtrWidth = TD.getPointerSizeInBits();
+ uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
+
+ for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
+ ++i, ++GTI) {
+ Value *Op = *i;
+ uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
+ if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
+ if (OpC->isZero()) continue;
+
+ // Handle a struct index, which adds its field offset to the pointer.
+ if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
+
+ Result = Builder->CreateAdd(Result,
+ ConstantInt::get(IntPtrTy, Size),
+ GEP->getName()+".offs");
+ continue;
+ }
+
+ Constant *Scale = ConstantInt::get(IntPtrTy, Size);
+ Constant *OC =
+ ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
+ Scale = ConstantExpr::getMul(OC, Scale);
+ // Emit an add instruction.
+ Result = Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
+ continue;
+ }
+ // Convert to correct type.
+ if (Op->getType() != IntPtrTy)
+ 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 = Builder->CreateMul(Op, Scale, GEP->getName()+".idx");
+ }
+
+ // Emit an add instruction.
+ Result = Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
+ }
+ return Result;
+}
+
+
+
+
+/// Optimize pointer differences into the same array into a size. Consider:
+/// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer
+/// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
+///
+Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS,
+ const Type *Ty) {
+ assert(TD && "Must have target data info for this");
+
+ // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
+ // this.
+ bool Swapped = false;
+ GetElementPtrInst *GEP = 0;
+ ConstantExpr *CstGEP = 0;
+
+ // TODO: Could also optimize &A[i] - &A[j] -> "i-j", and "&A.foo[i] - &A.foo".
+ // For now we require one side to be the base pointer "A" or a constant
+ // expression derived from it.
+ if (GetElementPtrInst *LHSGEP = dyn_cast<GetElementPtrInst>(LHS)) {
+ // (gep X, ...) - X
+ if (LHSGEP->getOperand(0) == RHS) {
+ GEP = LHSGEP;
+ Swapped = false;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(RHS)) {
+ // (gep X, ...) - (ce_gep X, ...)
+ if (CE->getOpcode() == Instruction::GetElementPtr &&
+ LHSGEP->getOperand(0) == CE->getOperand(0)) {
+ CstGEP = CE;
+ GEP = LHSGEP;
+ Swapped = false;
+ }
+ }
+ }
+
+ if (GetElementPtrInst *RHSGEP = dyn_cast<GetElementPtrInst>(RHS)) {
+ // X - (gep X, ...)
+ if (RHSGEP->getOperand(0) == LHS) {
+ GEP = RHSGEP;
+ Swapped = true;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(LHS)) {
+ // (ce_gep X, ...) - (gep X, ...)
+ if (CE->getOpcode() == Instruction::GetElementPtr &&
+ RHSGEP->getOperand(0) == CE->getOperand(0)) {
+ CstGEP = CE;
+ GEP = RHSGEP;
+ Swapped = true;
+ }
+ }
+ }
+
+ if (GEP == 0)
+ return 0;
+
+ // Emit the offset of the GEP and an intptr_t.
+ 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);
+ Result = Builder->CreateSub(Result, CstOffset);
+ }
+
+
+ // If we have p - gep(p, ...) then we have to negate the result.
+ if (Swapped)
+ Result = Builder->CreateNeg(Result, "diff.neg");
+
+ return Builder->CreateIntCast(Result, Ty, true);
+}
+
+
+Instruction *InstCombiner::visitSub(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Op0 == Op1) // sub X, X -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // If this is a 'B = x-(-A)', change to B = x+A. This preserves NSW/NUW.
+ if (Value *V = dyn_castNegVal(Op1)) {
+ BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V);
+ Res->setHasNoSignedWrap(I.hasNoSignedWrap());
+ Res->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
+ return Res;
+ }
+
+ if (isa<UndefValue>(Op0))
+ return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
+ if (isa<UndefValue>(Op1))
+ return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
+ if (I.getType() == Type::getInt1Ty(I.getContext()))
+ return BinaryOperator::CreateXor(Op0, Op1);
+
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
+ // Replace (-1 - A) with (~A).
+ if (C->isAllOnesValue())
+ return BinaryOperator::CreateNot(Op1);
+
+ // C - ~X == X + (1+C)
+ Value *X = 0;
+ if (match(Op1, m_Not(m_Value(X))))
+ return BinaryOperator::CreateAdd(X, AddOne(C));
+
+ // -(X >>u 31) -> (X >>s 31)
+ // -(X >>s 31) -> (X >>u 31)
+ if (C->isZero()) {
+ if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) {
+ if (SI->getOpcode() == Instruction::LShr) {
+ if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
+ // Check to see if we are shifting out everything but the sign bit.
+ if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
+ SI->getType()->getPrimitiveSizeInBits()-1) {
+ // Ok, the transformation is safe. Insert AShr.
+ return BinaryOperator::Create(Instruction::AShr,
+ SI->getOperand(0), CU, SI->getName());
+ }
+ }
+ } else if (SI->getOpcode() == Instruction::AShr) {
+ if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
+ // Check to see if we are shifting out everything but the sign bit.
+ if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
+ SI->getType()->getPrimitiveSizeInBits()-1) {
+ // Ok, the transformation is safe. Insert LShr.
+ return BinaryOperator::CreateLShr(
+ SI->getOperand(0), CU, SI->getName());
+ }
+ }
+ }
+ }
+ }
+
+ // Try to fold constant sub into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+ if (Instruction *R = FoldOpIntoSelect(I, SI))
+ return R;
+
+ // C - zext(bool) -> bool ? C - 1 : C
+ if (ZExtInst *ZI = dyn_cast<ZExtInst>(Op1))
+ if (ZI->getSrcTy() == Type::getInt1Ty(I.getContext()))
+ return SelectInst::Create(ZI->getOperand(0), SubOne(C), C);
+ }
+
+ if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
+ if (Op1I->getOpcode() == Instruction::Add) {
+ if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
+ return BinaryOperator::CreateNeg(Op1I->getOperand(1),
+ I.getName());
+ else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
+ return BinaryOperator::CreateNeg(Op1I->getOperand(0),
+ I.getName());
+ else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
+ if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
+ // C1-(X+C2) --> (C1-C2)-X
+ return BinaryOperator::CreateSub(
+ ConstantExpr::getSub(CI1, CI2), Op1I->getOperand(0));
+ }
+ }
+
+ if (Op1I->hasOneUse()) {
+ // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
+ // is not used by anyone else...
+ //
+ if (Op1I->getOpcode() == Instruction::Sub) {
+ // Swap the two operands of the subexpr...
+ Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
+ Op1I->setOperand(0, IIOp1);
+ Op1I->setOperand(1, IIOp0);
+
+ // Create the new top level add instruction...
+ return BinaryOperator::CreateAdd(Op0, Op1);
+ }
+
+ // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
+ //
+ if (Op1I->getOpcode() == Instruction::And &&
+ (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
+ Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
+
+ Value *NewNot = Builder->CreateNot(OtherOp, "B.not");
+ return BinaryOperator::CreateAnd(Op0, NewNot);
+ }
+
+ // 0 - (X sdiv C) -> (X sdiv -C)
+ if (Op1I->getOpcode() == Instruction::SDiv)
+ if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
+ if (CSI->isZero())
+ if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
+ return BinaryOperator::CreateSDiv(Op1I->getOperand(0),
+ ConstantExpr::getNeg(DivRHS));
+
+ // X - X*C --> X * (1-C)
+ ConstantInt *C2 = 0;
+ if (dyn_castFoldableMul(Op1I, C2) == Op0) {
+ Constant *CP1 =
+ ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
+ C2);
+ return BinaryOperator::CreateMul(Op0, CP1);
+ }
+ }
+ }
+
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+ if (Op0I->getOpcode() == Instruction::Add) {
+ if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
+ return ReplaceInstUsesWith(I, Op0I->getOperand(1));
+ else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
+ return ReplaceInstUsesWith(I, Op0I->getOperand(0));
+ } else if (Op0I->getOpcode() == Instruction::Sub) {
+ if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
+ return BinaryOperator::CreateNeg(Op0I->getOperand(1),
+ I.getName());
+ }
+ }
+
+ ConstantInt *C1;
+ if (Value *X = dyn_castFoldableMul(Op0, C1)) {
+ if (X == Op1) // X*C - X --> X * (C-1)
+ return BinaryOperator::CreateMul(Op1, SubOne(C1));
+
+ ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
+ if (X == dyn_castFoldableMul(Op1, C2))
+ return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
+ }
+
+ // Optimize pointer differences into the same array into a size. Consider:
+ // &A[10] - &A[0]: we should compile this to "10".
+ if (TD) {
+ Value *LHSOp, *RHSOp;
+ if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
+ match(Op1, m_PtrToInt(m_Value(RHSOp))))
+ if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
+ return ReplaceInstUsesWith(I, Res);
+
+ // trunc(p)-trunc(q) -> trunc(p-q)
+ if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
+ match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
+ if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
+ return ReplaceInstUsesWith(I, Res);
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // If this is a 'B = x-(-A)', change to B = x+A...
+ if (Value *V = dyn_castFNegVal(Op1))
+ return BinaryOperator::CreateFAdd(Op0, V);
+
+ if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
+ if (Op1I->getOpcode() == Instruction::FAdd) {
+ if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
+ return BinaryOperator::CreateFNeg(Op1I->getOperand(1),
+ I.getName());
+ else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
+ return BinaryOperator::CreateFNeg(Op1I->getOperand(0),
+ I.getName());
+ }
+ }
+
+ return 0;
+}
Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=92704&r1=92703&r2=92704&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Tue Jan 5 01:18:46 2010
@@ -464,701 +464,6 @@
}
-/// WillNotOverflowSignedAdd - Return true if we can prove that:
-/// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS))
-/// This basically requires proving that the add in the original type would not
-/// overflow to change the sign bit or have a carry out.
-bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
- // There are different heuristics we can use for this. Here are some simple
- // ones.
-
- // Add has the property that adding any two 2's complement numbers can only
- // have one carry bit which can change a sign. As such, if LHS and RHS each
- // have at least two sign bits, we know that the addition of the two values
- // will sign extend fine.
- if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
- return true;
-
-
- // If one of the operands only has one non-zero bit, and if the other operand
- // has a known-zero bit in a more significant place than it (not including the
- // sign bit) the ripple may go up to and fill the zero, but won't change the
- // sign. For example, (X & ~4) + 1.
-
- // TODO: Implement.
-
- return false;
-}
-
-
-Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
- bool Changed = SimplifyCommutative(I);
- Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
-
- if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
- I.hasNoUnsignedWrap(), TD))
- return ReplaceInstUsesWith(I, V);
-
-
- if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
- // X + (signbit) --> X ^ signbit
- const APInt& Val = CI->getValue();
- uint32_t BitWidth = Val.getBitWidth();
- if (Val == APInt::getSignBit(BitWidth))
- return BinaryOperator::CreateXor(LHS, RHS);
-
- // See if SimplifyDemandedBits can simplify this. This handles stuff like
- // (X & 254)+1 -> (X&254)|1
- if (SimplifyDemandedInstructionBits(I))
- return &I;
-
- // zext(bool) + C -> bool ? C + 1 : C
- if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
- if (ZI->getSrcTy() == Type::getInt1Ty(I.getContext()))
- return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI);
- }
-
- if (isa<PHINode>(LHS))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
-
- ConstantInt *XorRHS = 0;
- Value *XorLHS = 0;
- if (isa<ConstantInt>(RHSC) &&
- match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
- uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
- const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
-
- uint32_t Size = TySizeBits / 2;
- APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
- APInt CFF80Val(-C0080Val);
- do {
- if (TySizeBits > Size) {
- // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
- // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
- if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
- (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
- // This is a sign extend if the top bits are known zero.
- if (!MaskedValueIsZero(XorLHS,
- APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
- Size = 0; // Not a sign ext, but can't be any others either.
- break;
- }
- }
- Size >>= 1;
- C0080Val = APIntOps::lshr(C0080Val, Size);
- CFF80Val = APIntOps::ashr(CFF80Val, Size);
- } while (Size >= 1);
-
- // FIXME: This shouldn't be necessary. When the backends can handle types
- // with funny bit widths then this switch statement should be removed. It
- // is just here to get the size of the "middle" type back up to something
- // that the back ends can handle.
- const Type *MiddleType = 0;
- switch (Size) {
- default: break;
- case 32:
- case 16:
- case 8: MiddleType = IntegerType::get(I.getContext(), Size); break;
- }
- if (MiddleType) {
- Value *NewTrunc = Builder->CreateTrunc(XorLHS, MiddleType, "sext");
- return new SExtInst(NewTrunc, I.getType(), I.getName());
- }
- }
- }
-
- if (I.getType() == Type::getInt1Ty(I.getContext()))
- return BinaryOperator::CreateXor(LHS, RHS);
-
- if (I.getType()->isInteger()) {
- // X + X --> X << 1
- if (LHS == RHS)
- return BinaryOperator::CreateShl(LHS, ConstantInt::get(I.getType(), 1));
-
- if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
- if (RHSI->getOpcode() == Instruction::Sub)
- if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
- return ReplaceInstUsesWith(I, RHSI->getOperand(0));
- }
- if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
- if (LHSI->getOpcode() == Instruction::Sub)
- if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
- return ReplaceInstUsesWith(I, LHSI->getOperand(0));
- }
- }
-
- // -A + B --> B - A
- // -A + -B --> -(A + B)
- if (Value *LHSV = dyn_castNegVal(LHS)) {
- if (LHS->getType()->isIntOrIntVector()) {
- if (Value *RHSV = dyn_castNegVal(RHS)) {
- Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
- return BinaryOperator::CreateNeg(NewAdd);
- }
- }
-
- return BinaryOperator::CreateSub(RHS, LHSV);
- }
-
- // A + -B --> A - B
- if (!isa<Constant>(RHS))
- if (Value *V = dyn_castNegVal(RHS))
- return BinaryOperator::CreateSub(LHS, V);
-
-
- ConstantInt *C2;
- if (Value *X = dyn_castFoldableMul(LHS, C2)) {
- if (X == RHS) // X*C + X --> X * (C+1)
- return BinaryOperator::CreateMul(RHS, AddOne(C2));
-
- // X*C1 + X*C2 --> X * (C1+C2)
- ConstantInt *C1;
- if (X == dyn_castFoldableMul(RHS, C1))
- return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2));
- }
-
- // X + X*C --> X * (C+1)
- if (dyn_castFoldableMul(RHS, C2) == LHS)
- return BinaryOperator::CreateMul(LHS, AddOne(C2));
-
- // X + ~X --> -1 since ~X = -X-1
- if (dyn_castNotVal(LHS) == RHS ||
- dyn_castNotVal(RHS) == LHS)
- return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
-
-
- // A+B --> A|B iff A and B have no bits set in common.
- if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
- APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
- APInt LHSKnownOne(IT->getBitWidth(), 0);
- APInt LHSKnownZero(IT->getBitWidth(), 0);
- ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
- if (LHSKnownZero != 0) {
- APInt RHSKnownOne(IT->getBitWidth(), 0);
- APInt RHSKnownZero(IT->getBitWidth(), 0);
- ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
-
- // No bits in common -> bitwise or.
- if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
- return BinaryOperator::CreateOr(LHS, RHS);
- }
- }
-
- // W*X + Y*Z --> W * (X+Z) iff W == Y
- if (I.getType()->isIntOrIntVector()) {
- Value *W, *X, *Y, *Z;
- if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
- match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
- if (W != Y) {
- if (W == Z) {
- std::swap(Y, Z);
- } else if (Y == X) {
- std::swap(W, X);
- } else if (X == Z) {
- std::swap(Y, Z);
- std::swap(W, X);
- }
- }
-
- if (W == Y) {
- Value *NewAdd = Builder->CreateAdd(X, Z, LHS->getName());
- return BinaryOperator::CreateMul(W, NewAdd);
- }
- }
- }
-
- if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
- Value *X = 0;
- if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
- return BinaryOperator::CreateSub(SubOne(CRHS), X);
-
- // (X & FF00) + xx00 -> (X+xx00) & FF00
- if (LHS->hasOneUse() &&
- match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
- Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
- if (Anded == CRHS) {
- // See if all bits from the first bit set in the Add RHS up are included
- // in the mask. First, get the rightmost bit.
- const APInt &AddRHSV = CRHS->getValue();
-
- // Form a mask of all bits from the lowest bit added through the top.
- APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
-
- // See if the and mask includes all of these bits.
- APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
-
- if (AddRHSHighBits == AddRHSHighBitsAnd) {
- // Okay, the xform is safe. Insert the new add pronto.
- Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName());
- return BinaryOperator::CreateAnd(NewAdd, C2);
- }
- }
- }
-
- // Try to fold constant add into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
- if (Instruction *R = FoldOpIntoSelect(I, SI))
- return R;
- }
-
- // add (select X 0 (sub n A)) A --> select X A n
- {
- SelectInst *SI = dyn_cast<SelectInst>(LHS);
- Value *A = RHS;
- if (!SI) {
- SI = dyn_cast<SelectInst>(RHS);
- A = LHS;
- }
- if (SI && SI->hasOneUse()) {
- Value *TV = SI->getTrueValue();
- Value *FV = SI->getFalseValue();
- Value *N;
-
- // Can we fold the add into the argument of the select?
- // We check both true and false select arguments for a matching subtract.
- if (match(FV, m_Zero()) &&
- match(TV, m_Sub(m_Value(N), m_Specific(A))))
- // Fold the add into the true select value.
- return SelectInst::Create(SI->getCondition(), N, A);
- if (match(TV, m_Zero()) &&
- match(FV, m_Sub(m_Value(N), m_Specific(A))))
- // Fold the add into the false select value.
- return SelectInst::Create(SI->getCondition(), A, N);
- }
- }
-
- // Check for (add (sext x), y), see if we can merge this into an
- // integer add followed by a sext.
- if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
- // (add (sext x), cst) --> (sext (add x, cst'))
- if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
- Constant *CI =
- ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
- if (LHSConv->hasOneUse() &&
- ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
- WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
- // Insert the new, smaller add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
- CI, "addconv");
- return new SExtInst(NewAdd, I.getType());
- }
- }
-
- // (add (sext x), (sext y)) --> (sext (add int x, y))
- if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
- // Only do this if x/y have the same type, if at last one of them has a
- // single use (so we don't increase the number of sexts), and if the
- // integer add will not overflow.
- if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
- (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
- WillNotOverflowSignedAdd(LHSConv->getOperand(0),
- RHSConv->getOperand(0))) {
- // Insert the new integer add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
- RHSConv->getOperand(0), "addconv");
- return new SExtInst(NewAdd, I.getType());
- }
- }
- }
-
- return Changed ? &I : 0;
-}
-
-Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
- bool Changed = SimplifyCommutative(I);
- Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
-
- if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
- // X + 0 --> X
- if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
- if (CFP->isExactlyValue(ConstantFP::getNegativeZero
- (I.getType())->getValueAPF()))
- return ReplaceInstUsesWith(I, LHS);
- }
-
- if (isa<PHINode>(LHS))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
-
- // -A + B --> B - A
- // -A + -B --> -(A + B)
- if (Value *LHSV = dyn_castFNegVal(LHS))
- return BinaryOperator::CreateFSub(RHS, LHSV);
-
- // A + -B --> A - B
- if (!isa<Constant>(RHS))
- if (Value *V = dyn_castFNegVal(RHS))
- return BinaryOperator::CreateFSub(LHS, V);
-
- // Check for X+0.0. Simplify it to X if we know X is not -0.0.
- if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
- if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS))
- return ReplaceInstUsesWith(I, LHS);
-
- // Check for (add double (sitofp x), y), see if we can merge this into an
- // integer add followed by a promotion.
- if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
- // (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
- // ... if the constant fits in the integer value. This is useful for things
- // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
- // requires a constant pool load, and generally allows the add to be better
- // instcombined.
- if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
- Constant *CI =
- ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
- if (LHSConv->hasOneUse() &&
- ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
- WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
- // Insert the new integer add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
- CI, "addconv");
- return new SIToFPInst(NewAdd, I.getType());
- }
- }
-
- // (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
- if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
- // Only do this if x/y have the same type, if at last one of them has a
- // single use (so we don't increase the number of int->fp conversions),
- // and if the integer add will not overflow.
- if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
- (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
- WillNotOverflowSignedAdd(LHSConv->getOperand(0),
- RHSConv->getOperand(0))) {
- // Insert the new integer add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
- RHSConv->getOperand(0),"addconv");
- return new SIToFPInst(NewAdd, I.getType());
- }
- }
- }
-
- return Changed ? &I : 0;
-}
-
-
-/// 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.
-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);
-
- // Build a mask for high order bits.
- unsigned IntPtrWidth = TD.getPointerSizeInBits();
- uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
-
- for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
- ++i, ++GTI) {
- Value *Op = *i;
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
- if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
- if (OpC->isZero()) continue;
-
- // Handle a struct index, which adds its field offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
-
- Result = Builder->CreateAdd(Result,
- ConstantInt::get(IntPtrTy, Size),
- GEP->getName()+".offs");
- continue;
- }
-
- Constant *Scale = ConstantInt::get(IntPtrTy, Size);
- Constant *OC =
- ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
- Scale = ConstantExpr::getMul(OC, Scale);
- // Emit an add instruction.
- Result = Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
- continue;
- }
- // Convert to correct type.
- if (Op->getType() != IntPtrTy)
- 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 = Builder->CreateMul(Op, Scale, GEP->getName()+".idx");
- }
-
- // Emit an add instruction.
- Result = Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
- }
- return Result;
-}
-
-
-
-
-/// Optimize pointer differences into the same array into a size. Consider:
-/// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer
-/// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
-///
-Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS,
- const Type *Ty) {
- assert(TD && "Must have target data info for this");
-
- // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
- // this.
- bool Swapped = false;
- GetElementPtrInst *GEP = 0;
- ConstantExpr *CstGEP = 0;
-
- // TODO: Could also optimize &A[i] - &A[j] -> "i-j", and "&A.foo[i] - &A.foo".
- // For now we require one side to be the base pointer "A" or a constant
- // expression derived from it.
- if (GetElementPtrInst *LHSGEP = dyn_cast<GetElementPtrInst>(LHS)) {
- // (gep X, ...) - X
- if (LHSGEP->getOperand(0) == RHS) {
- GEP = LHSGEP;
- Swapped = false;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(RHS)) {
- // (gep X, ...) - (ce_gep X, ...)
- if (CE->getOpcode() == Instruction::GetElementPtr &&
- LHSGEP->getOperand(0) == CE->getOperand(0)) {
- CstGEP = CE;
- GEP = LHSGEP;
- Swapped = false;
- }
- }
- }
-
- if (GetElementPtrInst *RHSGEP = dyn_cast<GetElementPtrInst>(RHS)) {
- // X - (gep X, ...)
- if (RHSGEP->getOperand(0) == LHS) {
- GEP = RHSGEP;
- Swapped = true;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(LHS)) {
- // (ce_gep X, ...) - (gep X, ...)
- if (CE->getOpcode() == Instruction::GetElementPtr &&
- RHSGEP->getOperand(0) == CE->getOperand(0)) {
- CstGEP = CE;
- GEP = RHSGEP;
- Swapped = true;
- }
- }
- }
-
- if (GEP == 0)
- return 0;
-
- // Emit the offset of the GEP and an intptr_t.
- 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);
- Result = Builder->CreateSub(Result, CstOffset);
- }
-
-
- // If we have p - gep(p, ...) then we have to negate the result.
- if (Swapped)
- Result = Builder->CreateNeg(Result, "diff.neg");
-
- return Builder->CreateIntCast(Result, Ty, true);
-}
-
-
-Instruction *InstCombiner::visitSub(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- if (Op0 == Op1) // sub X, X -> 0
- return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
-
- // If this is a 'B = x-(-A)', change to B = x+A. This preserves NSW/NUW.
- if (Value *V = dyn_castNegVal(Op1)) {
- BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V);
- Res->setHasNoSignedWrap(I.hasNoSignedWrap());
- Res->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
- return Res;
- }
-
- if (isa<UndefValue>(Op0))
- return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
- if (isa<UndefValue>(Op1))
- return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
- if (I.getType() == Type::getInt1Ty(I.getContext()))
- return BinaryOperator::CreateXor(Op0, Op1);
-
- if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
- // Replace (-1 - A) with (~A).
- if (C->isAllOnesValue())
- return BinaryOperator::CreateNot(Op1);
-
- // C - ~X == X + (1+C)
- Value *X = 0;
- if (match(Op1, m_Not(m_Value(X))))
- return BinaryOperator::CreateAdd(X, AddOne(C));
-
- // -(X >>u 31) -> (X >>s 31)
- // -(X >>s 31) -> (X >>u 31)
- if (C->isZero()) {
- if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) {
- if (SI->getOpcode() == Instruction::LShr) {
- if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
- // Check to see if we are shifting out everything but the sign bit.
- if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
- SI->getType()->getPrimitiveSizeInBits()-1) {
- // Ok, the transformation is safe. Insert AShr.
- return BinaryOperator::Create(Instruction::AShr,
- SI->getOperand(0), CU, SI->getName());
- }
- }
- } else if (SI->getOpcode() == Instruction::AShr) {
- if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
- // Check to see if we are shifting out everything but the sign bit.
- if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
- SI->getType()->getPrimitiveSizeInBits()-1) {
- // Ok, the transformation is safe. Insert LShr.
- return BinaryOperator::CreateLShr(
- SI->getOperand(0), CU, SI->getName());
- }
- }
- }
- }
- }
-
- // Try to fold constant sub into select arguments.
- if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
- if (Instruction *R = FoldOpIntoSelect(I, SI))
- return R;
-
- // C - zext(bool) -> bool ? C - 1 : C
- if (ZExtInst *ZI = dyn_cast<ZExtInst>(Op1))
- if (ZI->getSrcTy() == Type::getInt1Ty(I.getContext()))
- return SelectInst::Create(ZI->getOperand(0), SubOne(C), C);
- }
-
- if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
- if (Op1I->getOpcode() == Instruction::Add) {
- if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
- return BinaryOperator::CreateNeg(Op1I->getOperand(1),
- I.getName());
- else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
- return BinaryOperator::CreateNeg(Op1I->getOperand(0),
- I.getName());
- else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
- if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
- // C1-(X+C2) --> (C1-C2)-X
- return BinaryOperator::CreateSub(
- ConstantExpr::getSub(CI1, CI2), Op1I->getOperand(0));
- }
- }
-
- if (Op1I->hasOneUse()) {
- // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
- // is not used by anyone else...
- //
- if (Op1I->getOpcode() == Instruction::Sub) {
- // Swap the two operands of the subexpr...
- Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
- Op1I->setOperand(0, IIOp1);
- Op1I->setOperand(1, IIOp0);
-
- // Create the new top level add instruction...
- return BinaryOperator::CreateAdd(Op0, Op1);
- }
-
- // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
- //
- if (Op1I->getOpcode() == Instruction::And &&
- (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
- Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
-
- Value *NewNot = Builder->CreateNot(OtherOp, "B.not");
- return BinaryOperator::CreateAnd(Op0, NewNot);
- }
-
- // 0 - (X sdiv C) -> (X sdiv -C)
- if (Op1I->getOpcode() == Instruction::SDiv)
- if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
- if (CSI->isZero())
- if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
- return BinaryOperator::CreateSDiv(Op1I->getOperand(0),
- ConstantExpr::getNeg(DivRHS));
-
- // X - X*C --> X * (1-C)
- ConstantInt *C2 = 0;
- if (dyn_castFoldableMul(Op1I, C2) == Op0) {
- Constant *CP1 =
- ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
- C2);
- return BinaryOperator::CreateMul(Op0, CP1);
- }
- }
- }
-
- if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
- if (Op0I->getOpcode() == Instruction::Add) {
- if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
- return ReplaceInstUsesWith(I, Op0I->getOperand(1));
- else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
- return ReplaceInstUsesWith(I, Op0I->getOperand(0));
- } else if (Op0I->getOpcode() == Instruction::Sub) {
- if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
- return BinaryOperator::CreateNeg(Op0I->getOperand(1),
- I.getName());
- }
- }
-
- ConstantInt *C1;
- if (Value *X = dyn_castFoldableMul(Op0, C1)) {
- if (X == Op1) // X*C - X --> X * (C-1)
- return BinaryOperator::CreateMul(Op1, SubOne(C1));
-
- ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
- if (X == dyn_castFoldableMul(Op1, C2))
- return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
- }
-
- // Optimize pointer differences into the same array into a size. Consider:
- // &A[10] - &A[0]: we should compile this to "10".
- if (TD) {
- Value *LHSOp, *RHSOp;
- if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
- match(Op1, m_PtrToInt(m_Value(RHSOp))))
- if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
- return ReplaceInstUsesWith(I, Res);
-
- // trunc(p)-trunc(q) -> trunc(p-q)
- if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
- match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
- if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
- return ReplaceInstUsesWith(I, Res);
- }
-
- return 0;
-}
-
-Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
- // If this is a 'B = x-(-A)', change to B = x+A...
- if (Value *V = dyn_castFNegVal(Op1))
- return BinaryOperator::CreateFAdd(Op0, V);
-
- if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
- if (Op1I->getOpcode() == Instruction::FAdd) {
- if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
- return BinaryOperator::CreateFNeg(Op1I->getOperand(1),
- I.getName());
- else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
- return BinaryOperator::CreateFNeg(Op1I->getOperand(0),
- I.getName());
- }
- }
-
- return 0;
-}
-
/// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
/// are carefully arranged to allow folding of expressions such as:
///
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