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Preserve NSW information in more places. 

llvm-svn: 91656
This commit is contained in:
Dan Gohman 2009-12-18 02:09:29 +00:00
parent 3dfd04e2b7
commit b256ccfbe5
2 changed files with 20 additions and 9 deletions
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2
llvm/include/llvm/Analysis/ScalarEvolution.h
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@ -243,7 +243,7 @@ namespace llvm {
/// createNodeForGEP - Provide the special handling we need to analyze GEP
/// SCEVs.
const SCEV *createNodeForGEP(Operator *GEP);
const SCEV *createNodeForGEP(GEPOperator *GEP);
/// computeSCEVAtScope - Implementation code for getSCEVAtScope; called
/// at most once for each SCEV+Loop pair.

27
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -1460,7 +1460,9 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
AddRec->op_end());
AddRecOps[0] = getAddExpr(LIOps);
const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRec->getLoop());
const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRec->getLoop(),
AddRec->hasNoUnsignedWrap() && HasNUW,
AddRec->hasNoSignedWrap() && HasNSW);
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;
@ -1636,7 +1638,9 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
}
}
const SCEV *NewRec = getAddRecExpr(NewOps, AddRec->getLoop());
const SCEV *NewRec = getAddRecExpr(NewOps, AddRec->getLoop(),
AddRec->hasNoUnsignedWrap() && HasNUW,
AddRec->hasNoSignedWrap() && HasNSW);
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;
@ -2592,8 +2596,9 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
/// createNodeForGEP - Expand GEP instructions into add and multiply
/// operations. This allows them to be analyzed by regular SCEV code.
///
const SCEV *ScalarEvolution::createNodeForGEP(Operator *GEP) {
const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
bool InBounds = GEP->isInBounds();
const Type *IntPtrTy = getEffectiveSCEVType(GEP->getType());
Value *Base = GEP->getOperand(0);
// Don't attempt to analyze GEPs over unsized objects.
@ -2610,18 +2615,24 @@ const SCEV *ScalarEvolution::createNodeForGEP(Operator *GEP) {
// For a struct, add the member offset.
unsigned FieldNo = cast<ConstantInt>(Index)->getZExtValue();
TotalOffset = getAddExpr(TotalOffset,
getFieldOffsetExpr(STy, FieldNo));
getFieldOffsetExpr(STy, FieldNo),
/*HasNUW=*/false, /*HasNSW=*/InBounds);
} 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 = getMulExpr(LocalOffset, getAllocSizeExpr(*GTI));
TotalOffset = getAddExpr(TotalOffset, LocalOffset);
// Lower "inbounds" GEPs to NSW arithmetic.
bool HasNSW = GEP->isInBounds();
LocalOffset = getMulExpr(LocalOffset, getAllocSizeExpr(*GTI),
/*HasNUW=*/false, /*HasNSW=*/InBounds);
TotalOffset = getAddExpr(TotalOffset, LocalOffset,
/*HasNUW=*/false, /*HasNSW=*/InBounds);
}
}
return getAddExpr(getSCEV(Base), TotalOffset);
return getAddExpr(getSCEV(Base), TotalOffset,
/*HasNUW=*/false, /*HasNSW=*/InBounds);
}
/// GetMinTrailingZeros - Determine the minimum number of zero bits that S is
@ -3130,7 +3141,7 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) {
// expressions we handle are GEPs and address literals.
case Instruction::GetElementPtr:
return createNodeForGEP(U);
return createNodeForGEP(cast<GEPOperator>(U));
case Instruction::PHI:
return createNodeForPHI(cast<PHINode>(U));