have instcombine preserve nsw/nuw/exact when sinking
common operations through a phi.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125790 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombinePHI.cpp b/lib/Transforms/InstCombine/InstCombinePHI.cpp
index 34d7ef3..297a18c 100644
--- a/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -31,22 +31,37 @@
const Type *LHSType = LHSVal->getType();
const Type *RHSType = RHSVal->getType();
+ bool isNUW = false, isNSW = false, isExact = false;
+ if (OverflowingBinaryOperator *BO =
+ dyn_cast<OverflowingBinaryOperator>(FirstInst)) {
+ isNUW = BO->hasNoUnsignedWrap();
+ isNSW = BO->hasNoSignedWrap();
+ } else if (PossiblyExactOperator *PEO =
+ dyn_cast<PossiblyExactOperator>(FirstInst))
+ isExact = PEO->isExact();
+
// Scan to see if all operands are the same opcode, and all have one use.
for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
// Verify type of the LHS matches so we don't fold cmp's of different
- // types or GEP's with different index types.
+ // types.
I->getOperand(0)->getType() != LHSType ||
I->getOperand(1)->getType() != RHSType)
return 0;
// If they are CmpInst instructions, check their predicates
- if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
- if (cast<CmpInst>(I)->getPredicate() !=
- cast<CmpInst>(FirstInst)->getPredicate())
+ if (CmpInst *CI = dyn_cast<CmpInst>(I))
+ if (CI->getPredicate() != cast<CmpInst>(FirstInst)->getPredicate())
return 0;
+ if (isNUW)
+ isNUW = cast<OverflowingBinaryOperator>(I)->hasNoUnsignedWrap();
+ if (isNSW)
+ isNSW = cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap();
+ if (isExact)
+ isExact = cast<PossiblyExactOperator>(I)->isExact();
+
// Keep track of which operand needs a phi node.
if (I->getOperand(0) != LHSVal) LHSVal = 0;
if (I->getOperand(1) != RHSVal) RHSVal = 0;
@@ -97,11 +112,17 @@
}
}
- if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
- return BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
- CmpInst *CIOp = cast<CmpInst>(FirstInst);
- return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
- LHSVal, RHSVal);
+ if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
+ return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
+ LHSVal, RHSVal);
+
+ BinaryOperator *BinOp = cast<BinaryOperator>(FirstInst);
+ BinaryOperator *NewBinOp =
+ BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
+ if (isNUW) NewBinOp->setHasNoUnsignedWrap();
+ if (isNSW) NewBinOp->setHasNoSignedWrap();
+ if (isExact) NewBinOp->setIsExact();
+ return NewBinOp;
}
Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
@@ -373,6 +394,7 @@
// code size and simplifying code.
Constant *ConstantOp = 0;
const Type *CastSrcTy = 0;
+ bool isNUW = false, isNSW = false, isExact = false;
if (isa<CastInst>(FirstInst)) {
CastSrcTy = FirstInst->getOperand(0)->getType();
@@ -389,6 +411,14 @@
ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
if (ConstantOp == 0)
return FoldPHIArgBinOpIntoPHI(PN);
+
+ if (OverflowingBinaryOperator *BO =
+ dyn_cast<OverflowingBinaryOperator>(FirstInst)) {
+ isNUW = BO->hasNoUnsignedWrap();
+ isNSW = BO->hasNoSignedWrap();
+ } else if (PossiblyExactOperator *PEO =
+ dyn_cast<PossiblyExactOperator>(FirstInst))
+ isExact = PEO->isExact();
} else {
return 0; // Cannot fold this operation.
}
@@ -404,6 +434,13 @@
} else if (I->getOperand(1) != ConstantOp) {
return 0;
}
+
+ if (isNUW)
+ isNUW = cast<OverflowingBinaryOperator>(I)->hasNoUnsignedWrap();
+ if (isNSW)
+ isNSW = cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap();
+ if (isExact)
+ isExact = cast<PossiblyExactOperator>(I)->isExact();
}
// Okay, they are all the same operation. Create a new PHI node of the
@@ -438,8 +475,13 @@
if (CastInst *FirstCI = dyn_cast<CastInst>(FirstInst))
return CastInst::Create(FirstCI->getOpcode(), PhiVal, PN.getType());
- if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
- return BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
+ if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) {
+ BinOp = BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
+ if (isNUW) BinOp->setHasNoUnsignedWrap();
+ if (isNSW) BinOp->setHasNoSignedWrap();
+ if (isExact) BinOp->setIsExact();
+ return BinOp;
+ }
CmpInst *CIOp = cast<CmpInst>(FirstInst);
return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),