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[InstCombine] more clean up of foldICmpXorConstant(); NFCI 

Use m_APInt for the xor constant, but this is all still guarded by the initial
ConstantInt check, so no vector types should make it in here.

llvm-svn: 278957
This commit is contained in:
Sanjay Patel 2016-08-17 19:45:18 +00:00
parent fd0fb204a0
commit daffec91ef
1 changed files with 21 additions and 27 deletions
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44
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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@ -1577,21 +1577,21 @@ Instruction *InstCombiner::foldICmpXorConstant(ICmpInst &Cmp, Instruction *Xor,
if (!RHS)
return nullptr;
auto *XorCst = dyn_cast<ConstantInt>(Xor->getOperand(1));
if (!XorCst)
const APInt *XorC;
if (!match(Xor->getOperand(1), m_APInt(XorC)))
return nullptr;
// If this is a comparison that tests the signbit (X < 0) or (x > -1),
// fold the xor.
Value *X = Xor->getOperand(0);
ICmpInst::Predicate Pred = Cmp.getPredicate();
if ((Pred == ICmpInst::ICMP_SLT && *C == 0) ||
(Pred == ICmpInst::ICMP_SGT && C->isAllOnesValue())) {
Value *CompareVal = Xor->getOperand(0);
// If the sign bit of the XorCst is not set, there is no change to
// the operation, just stop using the Xor.
if (!XorCst->isNegative()) {
Cmp.setOperand(0, CompareVal);
if (!XorC->isNegative()) {
Cmp.setOperand(0, X);
Worklist.Add(Xor);
return &Cmp;
}
@ -1603,43 +1603,37 @@ Instruction *InstCombiner::foldICmpXorConstant(ICmpInst &Cmp, Instruction *Xor,
isTrueIfPositive ^= true;
if (isTrueIfPositive)
return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, SubOne(RHS));
return new ICmpInst(ICmpInst::ICMP_SGT, X, SubOne(RHS));
else
return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, AddOne(RHS));
return new ICmpInst(ICmpInst::ICMP_SLT, X, AddOne(RHS));
}
if (Xor->hasOneUse()) {
// (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
if (!Cmp.isEquality() && XorCst->getValue().isSignBit()) {
const APInt &SignBit = XorCst->getValue();
ICmpInst::Predicate Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
// (icmp u/s (xor X SignBit), C) -> (icmp s/u X, (xor C SignBit))
if (!Cmp.isEquality() && XorC->isSignBit()) {
Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
: Cmp.getSignedPredicate();
return new ICmpInst(Pred, Xor->getOperand(0),
Builder->getInt(*C ^ SignBit));
return new ICmpInst(Pred, X, Builder->getInt(*C ^ *XorC));
}
// (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
if (!Cmp.isEquality() && XorCst->isMaxValue(true)) {
const APInt &NotSignBit = XorCst->getValue();
ICmpInst::Predicate Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
// (icmp u/s (xor X ~SignBit), C) -> (icmp s/u X, (xor C ~SignBit))
if (!Cmp.isEquality() && XorC->isMaxSignedValue()) {
Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
: Cmp.getSignedPredicate();
Pred = Cmp.getSwappedPredicate(Pred);
return new ICmpInst(Pred, Xor->getOperand(0),
Builder->getInt(*C ^ NotSignBit));
return new ICmpInst(Pred, X, Builder->getInt(*C ^ *XorC));
}
}
// (icmp ugt (xor X, C), ~C) -> (icmp ult X, C)
// iff -C is a power of 2
if (Pred == ICmpInst::ICMP_UGT && XorCst->getValue() == ~(*C) &&
(*C + 1).isPowerOf2())
return new ICmpInst(ICmpInst::ICMP_ULT, Xor->getOperand(0), XorCst);
if (Pred == ICmpInst::ICMP_UGT && *XorC == ~(*C) && (*C + 1).isPowerOf2())
return new ICmpInst(ICmpInst::ICMP_ULT, X, Xor->getOperand(1));
// (icmp ult (xor X, C), -C) -> (icmp uge X, C)
// iff -C is a power of 2
if (Pred == ICmpInst::ICMP_ULT && XorCst->getValue() == -(*C) &&
C->isPowerOf2())
return new ICmpInst(ICmpInst::ICMP_UGE, Xor->getOperand(0), XorCst);
if (Pred == ICmpInst::ICMP_ULT && *XorC == -(*C) && C->isPowerOf2())
return new ICmpInst(ICmpInst::ICMP_UGE, X, Xor->getOperand(1));
return nullptr;
}