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Differential D145772 Diff 504052 llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

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llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

Show First 20 Lines • Show All 1,692 Lines • ▼ Show 20 Lines ConstantRange R = ConstantRange::makeExactICmpRegion(CPred, *CmpC)
.binaryOp(BO->getOpcode(), *BinOpC); .binaryOp(BO->getOpcode(), *BinOpC);
if (R == *C) { if (R == *C) {
BO->dropPoisonGeneratingFlags(); BO->dropPoisonGeneratingFlags();
return BO; return BO;
} }
return nullptr; return nullptr;
} }
/// canonicalize all variants of strong order compare to (a > b) - (a < b)
static Instruction *
canonicalizeStrongOrderCmp(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
InstCombiner::BuilderTy &Builder) {
if (!isa<Constant>(TrueVal))
return nullptr;
Type *Ty = TrueVal->getType();
ICmpInst::Predicate Pred = ICI->getPredicate();
Value *CmpLHS = ICI->getOperand(0);
Value *CmpRHS = ICI->getOperand(1);
Value *ICI2;
ICmpInst::Predicate Pred2;
Constant *InnerTC, *InnerFC;
auto SwapICmp = [&Builder, CmpLHS, CmpRHS](ICmpInst::Predicate Pred) {
return Builder.CreateICmp(ICmpInst::getSwappedPredicate(Pred), CmpLHS,
CmpRHS);
};
if (FalseVal->hasOneUse() &&
match(FalseVal, m_Select(m_Value(ICI2), m_ImmConstant(InnerTC),
m_ImmConstant(InnerFC))) &&
match(ICI2, m_ICmp(Pred2, m_Specific(CmpLHS), m_Specific(CmpRHS)))) {
if (Pred == ICmpInst::ICMP_EQ && match(TrueVal, m_Zero()) &&
ICI->hasOneUse()) {
// A == B ? 0 : (A < B ? -1 : 1) --> (a > b) - (a < b)
if (match(InnerTC, m_AllOnes()) && match(InnerFC, m_One()) &&
(Pred2 == ICmpInst::ICMP_SLT || Pred2 == ICmpInst::ICMP_ULT)) {
Value *ZExt = Builder.CreateZExt(SwapICmp(Pred2), Ty);
Value *SExt = Builder.CreateSExt(ICI2, Ty);
return BinaryOperator::CreateAdd(ZExt, SExt);
}
// A == B ? 0 : (A > B ? 1 : -1) --> (a > b) - (a < b)
if (match(InnerTC, m_One()) && match(InnerFC, m_AllOnes()) &&
(Pred2 == ICmpInst::ICMP_SGT || Pred2 == ICmpInst::ICMP_UGT)) {
Value *ZExt = Builder.CreateZExt(ICI2, Ty);
Value *SExt = Builder.CreateSExt(SwapICmp(Pred2), Ty);
return BinaryOperator::CreateAdd(ZExt, SExt);
}
}
}
if (match(TrueVal, m_AllOnes()) && match(FalseVal, m_ZExt(m_Value(ICI2))) &&
match(ICI2, m_ICmp(Pred2, m_Specific(CmpLHS), m_Specific(CmpRHS))) &&
(Pred2 != ICmpInst::ICMP_NE ||
(FalseVal->hasOneUse() && ICI2->hasOneUse()))) {
// A < B ? -1 : zext (A > B) --> (a > b) - (a < b)
// A < B ? -1 : zext (A != B) --> (a > b) - (a < b)
if ((Pred == ICmpInst::ICMP_SLT &&
(Pred2 == ICmpInst::ICMP_NE || Pred2 == ICmpInst::ICMP_SGT)) ||
(Pred == ICmpInst::ICMP_ULT &&
(Pred2 == ICmpInst::ICMP_NE || Pred2 == ICmpInst::ICMP_UGT))) {
Value *ZExt = FalseVal;
if (Pred2 == ICmpInst::ICMP_NE)
ZExt = Builder.CreateZExt(SwapICmp(Pred), Ty);
Value *SExt = Builder.CreateSExt(ICI, Ty);
return BinaryOperator::CreateAdd(ZExt, SExt);
}
}
if (match(TrueVal, m_One()) && match(FalseVal, m_SExt(m_Value(ICI2))) &&
match(ICI2, m_ICmp(Pred2, m_Specific(CmpLHS), m_Specific(CmpRHS))) &&
(Pred2 != ICmpInst::ICMP_NE ||
(FalseVal->hasOneUse() && ICI2->hasOneUse()))) {
// A > B ? 1 : sext (A < B) --> (a > b) - (a < b)
// A > B ? 1 : sext (A != B) --> (a > b) - (a < b)
if ((Pred == ICmpInst::ICMP_SGT &&
(Pred2 == ICmpInst::ICMP_NE || Pred2 == ICmpInst::ICMP_SLT)) ||
(Pred == ICmpInst::ICMP_UGT &&
(Pred2 == ICmpInst::ICMP_NE || Pred2 == ICmpInst::ICMP_ULT))) {
Value *ZExt = Builder.CreateZExt(ICI, Ty);
Value *SExt = FalseVal;
if (Pred2 == ICmpInst::ICMP_NE)
SExt = Builder.CreateSExt(SwapICmp(Pred), Ty);
return BinaryOperator::CreateAdd(ZExt, SExt);
}
}
return nullptr;
}
/// Visit a SelectInst that has an ICmpInst as its first operand. /// Visit a SelectInst that has an ICmpInst as its first operand.
Instruction *InstCombinerImpl::foldSelectInstWithICmp(SelectInst &SI, Instruction *InstCombinerImpl::foldSelectInstWithICmp(SelectInst &SI,
ICmpInst *ICI) { ICmpInst *ICI) {
if (Instruction *NewSel = foldSelectValueEquivalence(SI, *ICI)) if (Instruction *NewSel = foldSelectValueEquivalence(SI, *ICI))
return NewSel; return NewSel;
if (Instruction *NewSPF = canonicalizeSPF(SI, *ICI, *this)) if (Instruction *NewSPF = canonicalizeSPF(SI, *ICI, *this))
return NewSPF; return NewSPF;
Show All 26 Lines if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
Changed = true; Changed = true;
} else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) { } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
// Transform (X != C) ? Y : X -> (X != C) ? Y : C // Transform (X != C) ? Y : X -> (X != C) ? Y : C
SI.setOperand(2, CmpRHS); SI.setOperand(2, CmpRHS);
Changed = true; Changed = true;
} }
} }
if (Instruction *V =
canonicalizeStrongOrderCmp(ICI, TrueVal, FalseVal, Builder))
return V;
// Canonicalize a signbit condition to use zero constant by swapping: // Canonicalize a signbit condition to use zero constant by swapping:
// (CmpLHS > -1) ? TV : FV --> (CmpLHS < 0) ? FV : TV // (CmpLHS > -1) ? TV : FV --> (CmpLHS < 0) ? FV : TV
// To avoid conflicts (infinite loops) with other canonicalizations, this is // To avoid conflicts (infinite loops) with other canonicalizations, this is
// not applied with any constant select arm. // not applied with any constant select arm.
if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes()) && if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes()) &&
!match(TrueVal, m_Constant()) && !match(FalseVal, m_Constant()) && !match(TrueVal, m_Constant()) && !match(FalseVal, m_Constant()) &&
ICI->hasOneUse()) { ICI->hasOneUse()) {
InstCombiner::BuilderTy::InsertPointGuard Guard(Builder); InstCombiner::BuilderTy::InsertPointGuard Guard(Builder);
▲ Show 20 Lines • Show All 1,844 Lines • Show Last 20 Lines