================
@@ -6380,7 +6380,71 @@ Instruction
*InstCombinerImpl::foldICmpUsingBoolRange(ICmpInst &I) {
Y->getType()->isIntOrIntVectorTy(1) && Pred == ICmpInst::ICMP_ULE)
return BinaryOperator::CreateOr(Builder.CreateIsNull(X), Y);
+ // icmp eq/ne X, (zext/sext (icmp eq/ne X, C))
+ ICmpInst::Predicate Pred1, Pred2;
const APInt *C;
+ Instruction *ExtI;
+ if (match(&I, m_c_ICmp(Pred1, m_Value(X),
+ m_CombineAnd(m_Instruction(ExtI),
+ m_ZExtOrSExt(m_ICmp(Pred2, m_Deferred(X),
+ m_APInt(C))))))) {
+ bool IsSExt = ExtI->getOpcode() == Instruction::SExt;
+ bool HasOneUse = ExtI->hasOneUse() && ExtI->getOperand(0)->hasOneUse();
+ auto CreateRangeCheck = [&] {
+ Value *CmpV1 =
+ Builder.CreateICmp(Pred1, X, Constant::getNullValue(X->getType()));
+ Value *CmpV2 = Builder.CreateICmp(
+ Pred1, X, ConstantInt::get(X->getType(), IsSExt ? -1 : 1));
+ return BinaryOperator::Create(
+ Pred1 == ICmpInst::ICMP_EQ ? Instruction::Or : Instruction::And,
+ CmpV1, CmpV2);
+ };
+ if (C->isZero()) {
+ if (Pred2 == ICmpInst::ICMP_EQ) {
+ // icmp eq X, (zext/sext (icmp eq X, 0)) --> false
+ // icmp ne X, (zext/sext (icmp eq X, 0)) --> true
+ return replaceInstUsesWith(
+ I, ConstantInt::getBool(I.getType(), Pred1 == ICmpInst::ICMP_NE));
+ } else if (!IsSExt || HasOneUse) {
+ // icmp eq X, (zext (icmp ne X, 0)) --> X == 0 || X == 1
+ // icmp ne X, (zext (icmp ne X, 0)) --> X != 0 && X != 1
+ // icmp eq X, (sext (icmp ne X, 0)) --> X == 0 || X == -1
+ // icmp ne X, (sext (icmp ne X, 0)) --> X != 0 && X == -1
+ return CreateRangeCheck();
+ }
+ } else if (IsSExt ? C->isAllOnes() : C->isOne()) {
+ if (Pred2 == ICmpInst::ICMP_NE) {
+ // icmp eq X, (zext (icmp ne X, 1)) --> false
+ // icmp ne X, (zext (icmp ne X, 1)) --> true
+ // icmp eq X, (sext (icmp ne X, -1)) --> false
+ // icmp ne X, (sext (icmp ne X, -1)) --> true
+ return replaceInstUsesWith(
+ I, ConstantInt::getBool(I.getType(), Pred1 == ICmpInst::ICMP_NE));
+ } else if (!IsSExt || HasOneUse) {
+ // icmp eq X, (zext (icmp eq X, 1)) --> X == 0 || X == 1
+ // icmp ne X, (zext (icmp eq X, 1)) --> X != 0 && X != 1
+ // icmp eq X, (sext (icmp eq X, -1)) --> X == 0 || X == -1
+ // icmp ne X, (sext (icmp eq X, -1)) --> X != 0 && X == -1
+ return CreateRangeCheck();
+ }
+ } else {
+ // when C != 0 && C != 1:
+ // icmp eq X, (zext (icmp eq X, C)) --> icmp eq X, 0
+ // icmp eq X, (zext (icmp ne X, C)) --> icmp eq X, 1
+ // icmp ne X, (zext (icmp eq X, C)) --> icmp ne X, 0
+ // icmp ne X, (zext (icmp ne X, C)) --> icmp ne X, 1
+ // when C != 0 && C != -1:
+ // icmp eq X, (sext (icmp eq X, C)) --> icmp eq X, 0
+ // icmp eq X, (sext (icmp ne X, C)) --> icmp eq X, -1
+ // icmp ne X, (sext (icmp eq X, C)) --> icmp ne X, 0
+ // icmp ne X, (sext (icmp ne X, C)) --> icmp ne X, -1
+ return ICmpInst::Create(
+ Instruction::ICmp, Pred1, X,
+ ConstantInt::get(X->getType(),
+ Pred2 == ICmpInst::ICMP_NE ? (IsSExt ? -1 : 1) :
0));
----------------
nikic wrote:
This looks like something that will break with 128 bit integers.
https://github.com/llvm/llvm-project/pull/65852
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