[llvm-commits] [llvm] r75511 - in /llvm/trunk: include/llvm/Analysis/ScalarEvolution.h lib/Analysis/ScalarEvolution.cpp test/Transforms/IndVarSimplify/iv-sext.ll
Dan Gohman
gohman at apple.com
Mon Jul 13 14:35:55 PDT 2009
Author: djg
Date: Mon Jul 13 16:35:55 2009
New Revision: 75511
URL: http://llvm.org/viewvc/llvm-project?rev=75511&view=rev
Log:
Reapply 75252, with a fix to avoid the infinite recursion case. The
check for avoiding re-analyzing a widening cast needed to happen
earlier, as getSCEV itself may result in a isLoopGuardedByCond query.
Modified:
llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
llvm/trunk/lib/Analysis/ScalarEvolution.cpp
llvm/trunk/test/Transforms/IndVarSimplify/iv-sext.ll
Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=75511&r1=75510&r2=75511&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Mon Jul 13 16:35:55 2009
@@ -26,6 +26,7 @@
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/Allocator.h"
+#include "llvm/Support/ConstantRange.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/DenseMap.h"
#include <iosfwd>
@@ -330,12 +331,20 @@
/// found.
BasicBlock* getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
- /// isNecessaryCond - Test whether the given CondValue value is a condition
- /// which is at least as strict as the one described by Pred, LHS, and RHS.
+ /// isNecessaryCond - Test whether the condition described by Pred, LHS,
+ /// and RHS is a necessary condition for the given Cond value to evaluate
+ /// to true.
bool isNecessaryCond(Value *Cond, ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
bool Inverse);
+ /// isNecessaryCondOperands - Test whether the condition described by Pred,
+ /// LHS, and RHS is a necessary condition for the condition described by
+ /// Pred, FoundLHS, and FoundRHS to evaluate to true.
+ bool isNecessaryCondOperands(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS,
+ const SCEV *FoundLHS, const SCEV *FoundRHS);
+
/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
/// in the header of its containing loop, we know the loop executes a
/// constant number of times, and the PHI node is just a recurrence
@@ -495,10 +504,16 @@
/// isLoopGuardedByCond - Test whether entry to the loop is protected by
/// a conditional between LHS and RHS. This is used to help avoid max
- /// expressions in loop trip counts.
+ /// expressions in loop trip counts, and to eliminate casts.
bool isLoopGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS);
+ /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
+ /// protected by a conditional between LHS and RHS. This is used to
+ /// to eliminate casts.
+ bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS);
+
/// getBackedgeTakenCount - If the specified loop has a predictable
/// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
/// object. The backedge-taken count is the number of times the loop header
@@ -534,13 +549,42 @@
/// bitwidth of S.
uint32_t GetMinTrailingZeros(const SCEV *S);
- /// GetMinLeadingZeros - Determine the minimum number of zero bits that S is
- /// guaranteed to begin with (at every loop iteration).
- uint32_t GetMinLeadingZeros(const SCEV *S);
-
- /// GetMinSignBits - Determine the minimum number of sign bits that S is
- /// guaranteed to begin with.
- uint32_t GetMinSignBits(const SCEV *S);
+ /// getUnsignedRange - Determine the unsigned range for a particular SCEV.
+ ///
+ ConstantRange getUnsignedRange(const SCEV *S);
+
+ /// getSignedRange - Determine the signed range for a particular SCEV.
+ ///
+ ConstantRange getSignedRange(const SCEV *S);
+
+ /// isKnownNegative - Test if the given expression is known to be negative.
+ ///
+ bool isKnownNegative(const SCEV *S);
+
+ /// isKnownPositive - Test if the given expression is known to be positive.
+ ///
+ bool isKnownPositive(const SCEV *S);
+
+ /// isKnownNonNegative - Test if the given expression is known to be
+ /// non-negative.
+ ///
+ bool isKnownNonNegative(const SCEV *S);
+
+ /// isKnownNonPositive - Test if the given expression is known to be
+ /// non-positive.
+ ///
+ bool isKnownNonPositive(const SCEV *S);
+
+ /// isKnownNonZero - Test if the given expression is known to be
+ /// non-zero.
+ ///
+ bool isKnownNonZero(const SCEV *S);
+
+ /// isKnownNonZero - Test if the given expression is known to satisfy
+ /// the condition described by Pred, LHS, and RHS.
+ ///
+ bool isKnownPredicate(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS);
virtual bool runOnFunction(Function &F);
virtual void releaseMemory();
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=75511&r1=75510&r2=75511&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Mon Jul 13 16:35:55 2009
@@ -787,6 +787,11 @@
// this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
if (AR->isAffine()) {
+ const SCEV *Start = AR->getStart();
+ const SCEV *Step = AR->getStepRecurrence(*this);
+ unsigned BitWidth = getTypeSizeInBits(AR->getType());
+ const Loop *L = AR->getLoop();
+
// Check whether the backedge-taken count is SCEVCouldNotCompute.
// Note that this serves two purposes: It filters out loops that are
// simply not analyzable, and it covers the case where this code is
@@ -795,12 +800,10 @@
// in infinite recursion. In the later case, the analysis code will
// cope with a conservative value, and it will take care to purge
// that value once it has finished.
- const SCEV *MaxBECount = getMaxBackedgeTakenCount(AR->getLoop());
+ const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
// Manually compute the final value for AR, checking for
// overflow.
- const SCEV *Start = AR->getStart();
- const SCEV *Step = AR->getStepRecurrence(*this);
// Check whether the backedge-taken count can be losslessly casted to
// the addrec's type. The count is always unsigned.
@@ -809,8 +812,7 @@
const SCEV *RecastedMaxBECount =
getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
if (MaxBECount == RecastedMaxBECount) {
- const Type *WideTy =
- IntegerType::get(getTypeSizeInBits(Start->getType()) * 2);
+ const Type *WideTy = IntegerType::get(BitWidth * 2);
// Check whether Start+Step*MaxBECount has no unsigned overflow.
const SCEV *ZMul =
getMulExpr(CastedMaxBECount,
@@ -824,7 +826,7 @@
// Return the expression with the addrec on the outside.
return getAddRecExpr(getZeroExtendExpr(Start, Ty),
getZeroExtendExpr(Step, Ty),
- AR->getLoop());
+ L);
// Similar to above, only this time treat the step value as signed.
// This covers loops that count down.
@@ -840,7 +842,35 @@
// Return the expression with the addrec on the outside.
return getAddRecExpr(getZeroExtendExpr(Start, Ty),
getSignExtendExpr(Step, Ty),
- AR->getLoop());
+ L);
+ }
+
+ // If the backedge is guarded by a comparison with the pre-inc value
+ // the addrec is safe. Also, if the entry is guarded by a comparison
+ // with the start value and the backedge is guarded by a comparison
+ // with the post-inc value, the addrec is safe.
+ if (isKnownPositive(Step)) {
+ const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
+ getUnsignedRange(Step).getUnsignedMax());
+ if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
+ (isLoopGuardedByCond(L, ICmpInst::ICMP_ULT, Start, N) &&
+ isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT,
+ AR->getPostIncExpr(*this), N)))
+ // Return the expression with the addrec on the outside.
+ return getAddRecExpr(getZeroExtendExpr(Start, Ty),
+ getZeroExtendExpr(Step, Ty),
+ L);
+ } else if (isKnownNegative(Step)) {
+ const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
+ getSignedRange(Step).getSignedMin());
+ if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) &&
+ (isLoopGuardedByCond(L, ICmpInst::ICMP_UGT, Start, N) ||
+ isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT,
+ AR->getPostIncExpr(*this), N)))
+ // Return the expression with the addrec on the outside.
+ return getAddRecExpr(getZeroExtendExpr(Start, Ty),
+ getSignExtendExpr(Step, Ty),
+ L);
}
}
}
@@ -889,6 +919,11 @@
// this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
if (AR->isAffine()) {
+ const SCEV *Start = AR->getStart();
+ const SCEV *Step = AR->getStepRecurrence(*this);
+ unsigned BitWidth = getTypeSizeInBits(AR->getType());
+ const Loop *L = AR->getLoop();
+
// Check whether the backedge-taken count is SCEVCouldNotCompute.
// Note that this serves two purposes: It filters out loops that are
// simply not analyzable, and it covers the case where this code is
@@ -897,12 +932,10 @@
// in infinite recursion. In the later case, the analysis code will
// cope with a conservative value, and it will take care to purge
// that value once it has finished.
- const SCEV *MaxBECount = getMaxBackedgeTakenCount(AR->getLoop());
+ const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
// Manually compute the final value for AR, checking for
// overflow.
- const SCEV *Start = AR->getStart();
- const SCEV *Step = AR->getStepRecurrence(*this);
// Check whether the backedge-taken count can be losslessly casted to
// the addrec's type. The count is always unsigned.
@@ -911,8 +944,7 @@
const SCEV *RecastedMaxBECount =
getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
if (MaxBECount == RecastedMaxBECount) {
- const Type *WideTy =
- IntegerType::get(getTypeSizeInBits(Start->getType()) * 2);
+ const Type *WideTy = IntegerType::get(BitWidth * 2);
// Check whether Start+Step*MaxBECount has no signed overflow.
const SCEV *SMul =
getMulExpr(CastedMaxBECount,
@@ -926,7 +958,35 @@
// Return the expression with the addrec on the outside.
return getAddRecExpr(getSignExtendExpr(Start, Ty),
getSignExtendExpr(Step, Ty),
- AR->getLoop());
+ L);
+ }
+
+ // If the backedge is guarded by a comparison with the pre-inc value
+ // the addrec is safe. Also, if the entry is guarded by a comparison
+ // with the start value and the backedge is guarded by a comparison
+ // with the post-inc value, the addrec is safe.
+ if (isKnownPositive(Step)) {
+ const SCEV *N = getConstant(APInt::getSignedMinValue(BitWidth) -
+ getSignedRange(Step).getSignedMax());
+ if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SLT, AR, N) ||
+ (isLoopGuardedByCond(L, ICmpInst::ICMP_SLT, Start, N) &&
+ isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SLT,
+ AR->getPostIncExpr(*this), N)))
+ // Return the expression with the addrec on the outside.
+ return getAddRecExpr(getSignExtendExpr(Start, Ty),
+ getSignExtendExpr(Step, Ty),
+ L);
+ } else if (isKnownNegative(Step)) {
+ const SCEV *N = getConstant(APInt::getSignedMaxValue(BitWidth) -
+ getSignedRange(Step).getSignedMin());
+ if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SGT, AR, N) ||
+ (isLoopGuardedByCond(L, ICmpInst::ICMP_SGT, Start, N) &&
+ isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SGT,
+ AR->getPostIncExpr(*this), N)))
+ // Return the expression with the addrec on the outside.
+ return getAddRecExpr(getSignExtendExpr(Start, Ty),
+ getSignExtendExpr(Step, Ty),
+ L);
}
}
}
@@ -2368,19 +2428,16 @@
const StructLayout &SL = *TD->getStructLayout(STy);
unsigned FieldNo = cast<ConstantInt>(Index)->getZExtValue();
uint64_t Offset = SL.getElementOffset(FieldNo);
- TotalOffset = getAddExpr(TotalOffset,
- getIntegerSCEV(Offset, IntPtrTy));
+ TotalOffset = getAddExpr(TotalOffset, getIntegerSCEV(Offset, IntPtrTy));
} else {
// For an array, add the element offset, explicitly scaled.
const SCEV *LocalOffset = getSCEV(Index);
if (!isa<PointerType>(LocalOffset->getType()))
// Getelementptr indicies are signed.
- LocalOffset = getTruncateOrSignExtend(LocalOffset,
- IntPtrTy);
+ LocalOffset = getTruncateOrSignExtend(LocalOffset, IntPtrTy);
LocalOffset =
getMulExpr(LocalOffset,
- getIntegerSCEV(TD->getTypeAllocSize(*GTI),
- IntPtrTy));
+ getIntegerSCEV(TD->getTypeAllocSize(*GTI), IntPtrTy));
TotalOffset = getAddExpr(TotalOffset, LocalOffset);
}
}
@@ -2468,18 +2525,95 @@
return 0;
}
-uint32_t
-ScalarEvolution::GetMinLeadingZeros(const SCEV *S) {
- // TODO: Handle other SCEV expression types here.
+/// getUnsignedRange - Determine the unsigned range for a particular SCEV.
+///
+ConstantRange
+ScalarEvolution::getUnsignedRange(const SCEV *S) {
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
- return C->getValue()->getValue().countLeadingZeros();
+ return ConstantRange(C->getValue()->getValue());
+
+ if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
+ ConstantRange X = getUnsignedRange(Add->getOperand(0));
+ for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
+ X = X.add(getUnsignedRange(Add->getOperand(i)));
+ return X;
+ }
+
+ if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
+ ConstantRange X = getUnsignedRange(Mul->getOperand(0));
+ for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
+ X = X.multiply(getUnsignedRange(Mul->getOperand(i)));
+ return X;
+ }
+
+ if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
+ ConstantRange X = getUnsignedRange(SMax->getOperand(0));
+ for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
+ X = X.smax(getUnsignedRange(SMax->getOperand(i)));
+ return X;
+ }
+
+ if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
+ ConstantRange X = getUnsignedRange(UMax->getOperand(0));
+ for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
+ X = X.umax(getUnsignedRange(UMax->getOperand(i)));
+ return X;
+ }
+
+ if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
+ ConstantRange X = getUnsignedRange(UDiv->getLHS());
+ ConstantRange Y = getUnsignedRange(UDiv->getRHS());
+ return X.udiv(Y);
+ }
+
+ if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
+ ConstantRange X = getUnsignedRange(ZExt->getOperand());
+ return X.zeroExtend(cast<IntegerType>(ZExt->getType())->getBitWidth());
+ }
+
+ if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
+ ConstantRange X = getUnsignedRange(SExt->getOperand());
+ return X.signExtend(cast<IntegerType>(SExt->getType())->getBitWidth());
+ }
+
+ if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
+ ConstantRange X = getUnsignedRange(Trunc->getOperand());
+ return X.truncate(cast<IntegerType>(Trunc->getType())->getBitWidth());
+ }
+
+ ConstantRange FullSet(getTypeSizeInBits(S->getType()), true);
- if (const SCEVZeroExtendExpr *C = dyn_cast<SCEVZeroExtendExpr>(S)) {
- // A zero-extension cast adds zero bits.
- return GetMinLeadingZeros(C->getOperand()) +
- (getTypeSizeInBits(C->getType()) -
- getTypeSizeInBits(C->getOperand()->getType()));
+ if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
+ const SCEV *T = getBackedgeTakenCount(AddRec->getLoop());
+ const SCEVConstant *Trip = dyn_cast<SCEVConstant>(T);
+ if (!Trip) return FullSet;
+
+ // TODO: non-affine addrec
+ if (AddRec->isAffine()) {
+ const Type *Ty = AddRec->getType();
+ const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
+ if (getTypeSizeInBits(MaxBECount->getType()) <= getTypeSizeInBits(Ty)) {
+ MaxBECount = getNoopOrZeroExtend(MaxBECount, Ty);
+
+ const SCEV *Start = AddRec->getStart();
+ const SCEV *End = AddRec->evaluateAtIteration(MaxBECount, *this);
+
+ // Check for overflow.
+ if (!isKnownPredicate(ICmpInst::ICMP_ULE, Start, End))
+ return FullSet;
+
+ ConstantRange StartRange = getUnsignedRange(Start);
+ ConstantRange EndRange = getUnsignedRange(End);
+ APInt Min = APIntOps::umin(StartRange.getUnsignedMin(),
+ EndRange.getUnsignedMin());
+ APInt Max = APIntOps::umax(StartRange.getUnsignedMax(),
+ EndRange.getUnsignedMax());
+ if (Min.isMinValue() && Max.isMaxValue())
+ return ConstantRange(Min.getBitWidth(), /*isFullSet=*/true);
+ return ConstantRange(Min, Max+1);
+ }
+ }
}
if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
@@ -2488,67 +2622,119 @@
APInt Mask = APInt::getAllOnesValue(BitWidth);
APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
ComputeMaskedBits(U->getValue(), Mask, Zeros, Ones, TD);
- return Zeros.countLeadingOnes();
+ return ConstantRange(Ones, ~Zeros);
}
- return 1;
+ return FullSet;
}
-uint32_t
-ScalarEvolution::GetMinSignBits(const SCEV *S) {
- // TODO: Handle other SCEV expression types here.
+/// getSignedRange - Determine the signed range for a particular SCEV.
+///
+ConstantRange
+ScalarEvolution::getSignedRange(const SCEV *S) {
+
+ if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
+ return ConstantRange(C->getValue()->getValue());
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
- const APInt &A = C->getValue()->getValue();
- return A.isNegative() ? A.countLeadingOnes() :
- A.countLeadingZeros();
+ if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
+ ConstantRange X = getSignedRange(Add->getOperand(0));
+ for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
+ X = X.add(getSignedRange(Add->getOperand(i)));
+ return X;
}
- if (const SCEVSignExtendExpr *C = dyn_cast<SCEVSignExtendExpr>(S)) {
- // A sign-extension cast adds sign bits.
- return GetMinSignBits(C->getOperand()) +
- (getTypeSizeInBits(C->getType()) -
- getTypeSizeInBits(C->getOperand()->getType()));
+ if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
+ ConstantRange X = getSignedRange(Mul->getOperand(0));
+ for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
+ X = X.multiply(getSignedRange(Mul->getOperand(i)));
+ return X;
}
- if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
- unsigned BitWidth = getTypeSizeInBits(A->getType());
+ if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
+ ConstantRange X = getSignedRange(SMax->getOperand(0));
+ for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
+ X = X.smax(getSignedRange(SMax->getOperand(i)));
+ return X;
+ }
- // Special case decrementing a value (ADD X, -1):
- if (const SCEVConstant *CRHS = dyn_cast<SCEVConstant>(A->getOperand(0)))
- if (CRHS->isAllOnesValue()) {
- SmallVector<const SCEV *, 4> OtherOps(A->op_begin() + 1, A->op_end());
- const SCEV *OtherOpsAdd = getAddExpr(OtherOps);
- unsigned LZ = GetMinLeadingZeros(OtherOpsAdd);
-
- // If the input is known to be 0 or 1, the output is 0/-1, which is all
- // sign bits set.
- if (LZ == BitWidth - 1)
- return BitWidth;
-
- // If we are subtracting one from a positive number, there is no carry
- // out of the result.
- if (LZ > 0)
- return GetMinSignBits(OtherOpsAdd);
- }
-
- // Add can have at most one carry bit. Thus we know that the output
- // is, at worst, one more bit than the inputs.
- unsigned Min = BitWidth;
- for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
- unsigned N = GetMinSignBits(A->getOperand(i));
- Min = std::min(Min, N) - 1;
- if (Min == 0) return 1;
+ if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
+ ConstantRange X = getSignedRange(UMax->getOperand(0));
+ for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
+ X = X.umax(getSignedRange(UMax->getOperand(i)));
+ return X;
+ }
+
+ if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
+ ConstantRange X = getSignedRange(UDiv->getLHS());
+ ConstantRange Y = getSignedRange(UDiv->getRHS());
+ return X.udiv(Y);
+ }
+
+ if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
+ ConstantRange X = getSignedRange(ZExt->getOperand());
+ return X.zeroExtend(cast<IntegerType>(ZExt->getType())->getBitWidth());
+ }
+
+ if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
+ ConstantRange X = getSignedRange(SExt->getOperand());
+ return X.signExtend(cast<IntegerType>(SExt->getType())->getBitWidth());
+ }
+
+ if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
+ ConstantRange X = getSignedRange(Trunc->getOperand());
+ return X.truncate(cast<IntegerType>(Trunc->getType())->getBitWidth());
+ }
+
+ ConstantRange FullSet(getTypeSizeInBits(S->getType()), true);
+
+ if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
+ const SCEV *T = getBackedgeTakenCount(AddRec->getLoop());
+ const SCEVConstant *Trip = dyn_cast<SCEVConstant>(T);
+ if (!Trip) return FullSet;
+
+ // TODO: non-affine addrec
+ if (AddRec->isAffine()) {
+ const Type *Ty = AddRec->getType();
+ const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
+ if (getTypeSizeInBits(MaxBECount->getType()) <= getTypeSizeInBits(Ty)) {
+ MaxBECount = getNoopOrZeroExtend(MaxBECount, Ty);
+
+ const SCEV *Start = AddRec->getStart();
+ const SCEV *Step = AddRec->getStepRecurrence(*this);
+ const SCEV *End = AddRec->evaluateAtIteration(MaxBECount, *this);
+
+ // Check for overflow.
+ if (!(isKnownPositive(Step) &&
+ isKnownPredicate(ICmpInst::ICMP_SLT, Start, End)) &&
+ !(isKnownNegative(Step) &&
+ isKnownPredicate(ICmpInst::ICMP_SGT, Start, End)))
+ return FullSet;
+
+ ConstantRange StartRange = getSignedRange(Start);
+ ConstantRange EndRange = getSignedRange(End);
+ APInt Min = APIntOps::smin(StartRange.getSignedMin(),
+ EndRange.getSignedMin());
+ APInt Max = APIntOps::smax(StartRange.getSignedMax(),
+ EndRange.getSignedMax());
+ if (Min.isMinSignedValue() && Max.isMaxSignedValue())
+ return ConstantRange(Min.getBitWidth(), /*isFullSet=*/true);
+ return ConstantRange(Min, Max+1);
+ }
}
- return 1;
}
if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
// For a SCEVUnknown, ask ValueTracking.
- return ComputeNumSignBits(U->getValue(), TD);
+ unsigned BitWidth = getTypeSizeInBits(U->getType());
+ unsigned NS = ComputeNumSignBits(U->getValue(), TD);
+ if (NS == 1)
+ return FullSet;
+ return
+ ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
+ APInt::getSignedMaxValue(BitWidth).ashr(NS - 1)+1);
}
- return 1;
+ return FullSet;
}
/// createSCEV - We know that there is no SCEV for the specified value.
@@ -3628,7 +3814,7 @@
if (!isSCEVable(Op->getType()))
return V;
- const SCEV *OpV = getSCEVAtScope(getSCEV(Op), L);
+ const SCEV* OpV = getSCEVAtScope(Op, L);
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(OpV)) {
Constant *C = SC->getValue();
if (C->getType() != Op->getType())
@@ -4029,12 +4215,176 @@
return false;
}
-/// isLoopGuardedByCond - Test whether entry to the loop is protected by
-/// a conditional between LHS and RHS. This is used to help avoid max
-/// expressions in loop trip counts.
-bool ScalarEvolution::isLoopGuardedByCond(const Loop *L,
- ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS) {
+bool ScalarEvolution::isKnownNegative(const SCEV *S) {
+ return getSignedRange(S).getSignedMax().isNegative();
+}
+
+bool ScalarEvolution::isKnownPositive(const SCEV *S) {
+ return getSignedRange(S).getSignedMin().isStrictlyPositive();
+}
+
+bool ScalarEvolution::isKnownNonNegative(const SCEV *S) {
+ return !getSignedRange(S).getSignedMin().isNegative();
+}
+
+bool ScalarEvolution::isKnownNonPositive(const SCEV *S) {
+ return !getSignedRange(S).getSignedMax().isStrictlyPositive();
+}
+
+bool ScalarEvolution::isKnownNonZero(const SCEV *S) {
+ return isKnownNegative(S) || isKnownPositive(S);
+}
+
+bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS) {
+
+ if (HasSameValue(LHS, RHS))
+ return ICmpInst::isTrueWhenEqual(Pred);
+
+ switch (Pred) {
+ default:
+ assert(0 && "Unexpected ICmpInst::Predicate value!");
+ break;
+ case ICmpInst::ICMP_SGT:
+ Pred = ICmpInst::ICMP_SLT;
+ std::swap(LHS, RHS);
+ case ICmpInst::ICMP_SLT: {
+ ConstantRange LHSRange = getSignedRange(LHS);
+ ConstantRange RHSRange = getSignedRange(RHS);
+ if (LHSRange.getSignedMax().slt(RHSRange.getSignedMin()))
+ return true;
+ if (LHSRange.getSignedMin().sge(RHSRange.getSignedMax()))
+ return false;
+
+ const SCEV *Diff = getMinusSCEV(LHS, RHS);
+ ConstantRange DiffRange = getUnsignedRange(Diff);
+ if (isKnownNegative(Diff)) {
+ if (DiffRange.getUnsignedMax().ult(LHSRange.getUnsignedMin()))
+ return true;
+ if (DiffRange.getUnsignedMin().uge(LHSRange.getUnsignedMax()))
+ return false;
+ } else if (isKnownPositive(Diff)) {
+ if (LHSRange.getUnsignedMax().ult(DiffRange.getUnsignedMin()))
+ return true;
+ if (LHSRange.getUnsignedMin().uge(DiffRange.getUnsignedMax()))
+ return false;
+ }
+ break;
+ }
+ case ICmpInst::ICMP_SGE:
+ Pred = ICmpInst::ICMP_SLE;
+ std::swap(LHS, RHS);
+ case ICmpInst::ICMP_SLE: {
+ ConstantRange LHSRange = getSignedRange(LHS);
+ ConstantRange RHSRange = getSignedRange(RHS);
+ if (LHSRange.getSignedMax().sle(RHSRange.getSignedMin()))
+ return true;
+ if (LHSRange.getSignedMin().sgt(RHSRange.getSignedMax()))
+ return false;
+
+ const SCEV *Diff = getMinusSCEV(LHS, RHS);
+ ConstantRange DiffRange = getUnsignedRange(Diff);
+ if (isKnownNonPositive(Diff)) {
+ if (DiffRange.getUnsignedMax().ule(LHSRange.getUnsignedMin()))
+ return true;
+ if (DiffRange.getUnsignedMin().ugt(LHSRange.getUnsignedMax()))
+ return false;
+ } else if (isKnownNonNegative(Diff)) {
+ if (LHSRange.getUnsignedMax().ule(DiffRange.getUnsignedMin()))
+ return true;
+ if (LHSRange.getUnsignedMin().ugt(DiffRange.getUnsignedMax()))
+ return false;
+ }
+ break;
+ }
+ case ICmpInst::ICMP_UGT:
+ Pred = ICmpInst::ICMP_ULT;
+ std::swap(LHS, RHS);
+ case ICmpInst::ICMP_ULT: {
+ ConstantRange LHSRange = getUnsignedRange(LHS);
+ ConstantRange RHSRange = getUnsignedRange(RHS);
+ if (LHSRange.getUnsignedMax().ult(RHSRange.getUnsignedMin()))
+ return true;
+ if (LHSRange.getUnsignedMin().uge(RHSRange.getUnsignedMax()))
+ return false;
+
+ const SCEV *Diff = getMinusSCEV(LHS, RHS);
+ ConstantRange DiffRange = getUnsignedRange(Diff);
+ if (LHSRange.getUnsignedMax().ult(DiffRange.getUnsignedMin()))
+ return true;
+ if (LHSRange.getUnsignedMin().uge(DiffRange.getUnsignedMax()))
+ return false;
+ break;
+ }
+ case ICmpInst::ICMP_UGE:
+ Pred = ICmpInst::ICMP_ULE;
+ std::swap(LHS, RHS);
+ case ICmpInst::ICMP_ULE: {
+ ConstantRange LHSRange = getUnsignedRange(LHS);
+ ConstantRange RHSRange = getUnsignedRange(RHS);
+ if (LHSRange.getUnsignedMax().ule(RHSRange.getUnsignedMin()))
+ return true;
+ if (LHSRange.getUnsignedMin().ugt(RHSRange.getUnsignedMax()))
+ return false;
+
+ const SCEV *Diff = getMinusSCEV(LHS, RHS);
+ ConstantRange DiffRange = getUnsignedRange(Diff);
+ if (LHSRange.getUnsignedMax().ule(DiffRange.getUnsignedMin()))
+ return true;
+ if (LHSRange.getUnsignedMin().ugt(DiffRange.getUnsignedMax()))
+ return false;
+ break;
+ }
+ case ICmpInst::ICMP_NE: {
+ if (getUnsignedRange(LHS).intersectWith(getUnsignedRange(RHS)).isEmptySet())
+ return true;
+ if (getSignedRange(LHS).intersectWith(getSignedRange(RHS)).isEmptySet())
+ return true;
+
+ const SCEV *Diff = getMinusSCEV(LHS, RHS);
+ if (isKnownNonZero(Diff))
+ return true;
+ break;
+ }
+ case ICmpInst::ICMP_EQ:
+ break;
+ }
+ return false;
+}
+
+/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
+/// protected by a conditional between LHS and RHS. This is used to
+/// to eliminate casts.
+bool
+ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L,
+ ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS) {
+ // Interpret a null as meaning no loop, where there is obviously no guard
+ // (interprocedural conditions notwithstanding).
+ if (!L) return true;
+
+ BasicBlock *Latch = L->getLoopLatch();
+ if (!Latch)
+ return false;
+
+ BranchInst *LoopContinuePredicate =
+ dyn_cast<BranchInst>(Latch->getTerminator());
+ if (!LoopContinuePredicate ||
+ LoopContinuePredicate->isUnconditional())
+ return false;
+
+ return
+ isNecessaryCond(LoopContinuePredicate->getCondition(), Pred, LHS, RHS,
+ LoopContinuePredicate->getSuccessor(0) != L->getHeader());
+}
+
+/// isLoopGuardedByCond - Test whether entry to the loop is protected
+/// by a conditional between LHS and RHS. This is used to help avoid max
+/// expressions in loop trip counts, and to eliminate casts.
+bool
+ScalarEvolution::isLoopGuardedByCond(const Loop *L,
+ ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS) {
// Interpret a null as meaning no loop, where there is obviously no guard
// (interprocedural conditions notwithstanding).
if (!L) return false;
@@ -4063,8 +4413,9 @@
return false;
}
-/// isNecessaryCond - Test whether the given CondValue value is a condition
-/// which is at least as strict as the one described by Pred, LHS, and RHS.
+/// isNecessaryCond - Test whether the condition described by Pred, LHS,
+/// and RHS is a necessary condition for the given Cond value to evaluate
+/// to true.
bool ScalarEvolution::isNecessaryCond(Value *CondValue,
ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
@@ -4089,30 +4440,35 @@
// see if it is the comparison we are looking for.
Value *PreCondLHS = ICI->getOperand(0);
Value *PreCondRHS = ICI->getOperand(1);
- ICmpInst::Predicate Cond;
+ ICmpInst::Predicate FoundPred;
if (Inverse)
- Cond = ICI->getInversePredicate();
+ FoundPred = ICI->getInversePredicate();
else
- Cond = ICI->getPredicate();
+ FoundPred = ICI->getPredicate();
- if (Cond == Pred)
+ if (FoundPred == Pred)
; // An exact match.
- else if (!ICmpInst::isTrueWhenEqual(Cond) && Pred == ICmpInst::ICMP_NE)
- ; // The actual condition is beyond sufficient.
- else
+ else if (!ICmpInst::isTrueWhenEqual(FoundPred) && Pred == ICmpInst::ICMP_NE) {
+ // The actual condition is beyond sufficient.
+ FoundPred = ICmpInst::ICMP_NE;
+ // NE is symmetric but the original comparison may not be. Swap
+ // the operands if necessary so that they match below.
+ if (isa<SCEVConstant>(LHS))
+ std::swap(PreCondLHS, PreCondRHS);
+ } else
// Check a few special cases.
- switch (Cond) {
+ switch (FoundPred) {
case ICmpInst::ICMP_UGT:
if (Pred == ICmpInst::ICMP_ULT) {
std::swap(PreCondLHS, PreCondRHS);
- Cond = ICmpInst::ICMP_ULT;
+ FoundPred = ICmpInst::ICMP_ULT;
break;
}
return false;
case ICmpInst::ICMP_SGT:
if (Pred == ICmpInst::ICMP_SLT) {
std::swap(PreCondLHS, PreCondRHS);
- Cond = ICmpInst::ICMP_SLT;
+ FoundPred = ICmpInst::ICMP_SLT;
break;
}
return false;
@@ -4121,8 +4477,8 @@
// so check for this case by checking if the NE is comparing against
// a minimum or maximum constant.
if (!ICmpInst::isTrueWhenEqual(Pred))
- if (ConstantInt *CI = dyn_cast<ConstantInt>(PreCondRHS)) {
- const APInt &A = CI->getValue();
+ if (const SCEVConstant *C = dyn_cast<SCEVConstant>(RHS)) {
+ const APInt &A = C->getValue()->getValue();
switch (Pred) {
case ICmpInst::ICMP_SLT:
if (A.isMaxSignedValue()) break;
@@ -4139,7 +4495,7 @@
default:
return false;
}
- Cond = ICmpInst::ICMP_NE;
+ FoundPred = Pred;
// NE is symmetric but the original comparison may not be. Swap
// the operands if necessary so that they match below.
if (isa<SCEVConstant>(LHS))
@@ -4152,14 +4508,73 @@
return false;
}
- if (!PreCondLHS->getType()->isInteger()) return false;
+ assert(Pred == FoundPred && "Conditions were not reconciled!");
+
+ // Bail if the ICmp's operands' types are wider than the needed type
+ // before attempting to call getSCEV on them. This avoids infinite
+ // recursion, since the analysis of widening casts can require loop
+ // exit condition information for overflow checking, which would
+ // lead back here.
+ if (getTypeSizeInBits(LHS->getType()) <
+ getTypeSizeInBits(PreCondLHS->getType()))
+ return false;
+
+ const SCEV *FoundLHS = getSCEV(PreCondLHS);
+ const SCEV *FoundRHS = getSCEV(PreCondRHS);
+
+ // Balance the types. The case where FoundLHS' type is wider than
+ // LHS' type is checked for above.
+ if (getTypeSizeInBits(LHS->getType()) >
+ getTypeSizeInBits(FoundLHS->getType())) {
+ if (CmpInst::isSigned(Pred)) {
+ FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType());
+ FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType());
+ } else {
+ FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType());
+ FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType());
+ }
+ }
+
+ return isNecessaryCondOperands(Pred, LHS, RHS,
+ FoundLHS, FoundRHS) ||
+ // ~x < ~y --> x > y
+ isNecessaryCondOperands(Pred, LHS, RHS,
+ getNotSCEV(FoundRHS), getNotSCEV(FoundLHS));
+}
+
+/// isNecessaryCondOperands - Test whether the condition described by Pred,
+/// LHS, and RHS is a necessary condition for the condition described by
+/// Pred, FoundLHS, and FoundRHS to evaluate to true.
+bool
+ScalarEvolution::isNecessaryCondOperands(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS,
+ const SCEV *FoundLHS,
+ const SCEV *FoundRHS) {
+ switch (Pred) {
+ default: break;
+ case ICmpInst::ICMP_SLT:
+ if (isKnownPredicate(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
+ isKnownPredicate(ICmpInst::ICMP_SGE, RHS, FoundRHS))
+ return true;
+ break;
+ case ICmpInst::ICMP_SGT:
+ if (isKnownPredicate(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
+ isKnownPredicate(ICmpInst::ICMP_SLE, RHS, FoundRHS))
+ return true;
+ break;
+ case ICmpInst::ICMP_ULT:
+ if (isKnownPredicate(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
+ isKnownPredicate(ICmpInst::ICMP_UGE, RHS, FoundRHS))
+ return true;
+ break;
+ case ICmpInst::ICMP_UGT:
+ if (isKnownPredicate(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
+ isKnownPredicate(ICmpInst::ICMP_ULE, RHS, FoundRHS))
+ return true;
+ break;
+ }
- const SCEV *PreCondLHSSCEV = getSCEV(PreCondLHS);
- const SCEV *PreCondRHSSCEV = getSCEV(PreCondRHS);
- return (HasSameValue(LHS, PreCondLHSSCEV) &&
- HasSameValue(RHS, PreCondRHSSCEV)) ||
- (HasSameValue(LHS, getNotSCEV(PreCondRHSSCEV)) &&
- HasSameValue(RHS, getNotSCEV(PreCondLHSSCEV)));
+ return false;
}
/// getBECount - Subtract the end and start values and divide by the step,
@@ -4180,9 +4595,9 @@
// Check Add for unsigned overflow.
// TODO: More sophisticated things could be done here.
const Type *WideTy = Context->getIntegerType(getTypeSizeInBits(Ty) + 1);
- const SCEV *OperandExtendedAdd =
- getAddExpr(getZeroExtendExpr(Diff, WideTy),
- getZeroExtendExpr(RoundUp, WideTy));
+ const SCEV *EDiff = getZeroExtendExpr(Diff, WideTy);
+ const SCEV *ERoundUp = getZeroExtendExpr(RoundUp, WideTy);
+ const SCEV *OperandExtendedAdd = getAddExpr(EDiff, ERoundUp);
if (getZeroExtendExpr(Add, WideTy) != OperandExtendedAdd)
return getCouldNotCompute();
@@ -4244,9 +4659,9 @@
const SCEV *Start = AddRec->getOperand(0);
// Determine the minimum constant start value.
- const SCEV *MinStart = isa<SCEVConstant>(Start) ? Start :
- getConstant(isSigned ? APInt::getSignedMinValue(BitWidth) :
- APInt::getMinValue(BitWidth));
+ const SCEV *MinStart = getConstant(isSigned ?
+ getSignedRange(Start).getSignedMin() :
+ getUnsignedRange(Start).getUnsignedMin());
// If we know that the condition is true in order to enter the loop,
// then we know that it will run exactly (m-n)/s times. Otherwise, we
@@ -4254,18 +4669,16 @@
// the division must round up.
const SCEV *End = RHS;
if (!isLoopGuardedByCond(L,
- isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
+ isSigned ? ICmpInst::ICMP_SLT :
+ ICmpInst::ICMP_ULT,
getMinusSCEV(Start, Step), RHS))
End = isSigned ? getSMaxExpr(RHS, Start)
: getUMaxExpr(RHS, Start);
// Determine the maximum constant end value.
- const SCEV *MaxEnd =
- isa<SCEVConstant>(End) ? End :
- getConstant(isSigned ? APInt::getSignedMaxValue(BitWidth)
- .ashr(GetMinSignBits(End) - 1) :
- APInt::getMaxValue(BitWidth)
- .lshr(GetMinLeadingZeros(End)));
+ const SCEV *MaxEnd = getConstant(isSigned ?
+ getSignedRange(End).getSignedMax() :
+ getUnsignedRange(End).getUnsignedMax());
// Finally, we subtract these two values and divide, rounding up, to get
// the number of times the backedge is executed.
Modified: llvm/trunk/test/Transforms/IndVarSimplify/iv-sext.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/iv-sext.ll?rev=75511&r1=75510&r2=75511&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/iv-sext.ll (original)
+++ llvm/trunk/test/Transforms/IndVarSimplify/iv-sext.ll Mon Jul 13 16:35:55 2009
@@ -1,7 +1,6 @@
; RUN: llvm-as < %s | opt -indvars | llvm-dis > %t
; RUN: grep {= sext} %t | count 4
; RUN: grep {phi i64} %t | count 2
-; XFAIL: *
; Indvars should be able to promote the hiPart induction variable in the
; inner loop to i64.
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