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[InstCombine] Simplify the pattern a ne/eq (zext/sext (a ne/eq c)) #65852

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Oct 6, 2023
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[InstCombine] Simplify the pattern a ne/eq (zext/sext (a ne/eq c)) #65852

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d9d8bcb
[InstCombine] Simplify the pattern `a ne/eq (zext (a ne/eq c))`
dtcxzyw Sep 9, 2023
0c0166c
Merge branch 'main' into fold-icmp-eq-zext-eq-self
dtcxzyw Sep 18, 2023
bf79e86
fixup! [InstCombine] Simplify the pattern `a ne/eq (zext (a ne/eq c))`
dtcxzyw Sep 18, 2023
ba475e3
fixup! [InstCombine] Simplify the pattern `a ne/eq (zext (a ne/eq c))`
dtcxzyw Sep 18, 2023
9c9ad18
Merge branch 'main' into fold-icmp-eq-zext-eq-self
dtcxzyw Sep 18, 2023
70a70fb
fixup! [InstCombine] Simplify the pattern `a ne/eq (zext (a ne/eq c))`
dtcxzyw Sep 18, 2023
17b18e0
Merge branch 'main' into fold-icmp-eq-zext-eq-self
dtcxzyw Sep 18, 2023
418562d
fixup! [InstCombine] Simplify the pattern `a ne/eq (zext (a ne/eq c))`
dtcxzyw Sep 18, 2023
b7565cc
[InstCombine] Fix comments `zext` -> `sext`. NFC.
dtcxzyw Sep 19, 2023
5b50524
fixup! [InstCombine] Simplify the pattern `a ne/eq (zext (a ne/eq c))`
dtcxzyw Sep 24, 2023
55d52b1
fixup! [InstCombine] Simplify the pattern `a ne/eq (zext (a ne/eq c))`
dtcxzyw Sep 24, 2023
c0d8f81
fixup! [InstCombine] Simplify the pattern `a ne/eq (zext (a ne/eq c))`
dtcxzyw Oct 1, 2023
2e5fe7b
Merge branch 'main' into fold-icmp-eq-zext-eq-self
dtcxzyw Oct 1, 2023
2285a2c
fixup! [InstCombine] Simplify the pattern `a ne/eq (zext (a ne/eq c))`
dtcxzyw Oct 6, 2023
7e81e63
Merge branch 'main' into fold-icmp-eq-zext-eq-self
dtcxzyw Oct 6, 2023
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67 changes: 67 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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Expand Up @@ -6380,7 +6380,74 @@ 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))))))) {
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bool IsSExt = ExtI->getOpcode() == Instruction::SExt;
bool HasOneUse = ExtI->hasOneUse() && ExtI->getOperand(0)->hasOneUse();
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)) --> icmp ult X, 2
// icmp ne X, (zext (icmp ne X, 0)) --> icmp ugt X, 1
// icmp eq X, (sext (icmp ne X, 0)) --> icmp ult (X + 1), 2
// icmp ne X, (sext (icmp ne X, 0)) --> icmp ugt (X + 1), 1
return ICmpInst::Create(
Instruction::ICmp,
Pred1 == ICmpInst::ICMP_NE ? ICmpInst::ICMP_UGT
: ICmpInst::ICMP_ULT,
IsSExt ? Builder.CreateAdd(X, ConstantInt::get(X->getType(), 1))
: X,
ConstantInt::get(X->getType(), Pred1 == ICmpInst::ICMP_NE ? 1 : 2));
}
} 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)) --> icmp ult X, 2
// icmp ne X, (zext (icmp eq X, 1)) --> icmp ugt X, 1
// icmp eq X, (sext (icmp eq X, -1)) --> icmp ult (X + 1), 2
// icmp ne X, (sext (icmp eq X, -1)) --> icmp ugt (X + 1), 1
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return ICmpInst::Create(
Instruction::ICmp,
Pred1 == ICmpInst::ICMP_NE ? ICmpInst::ICMP_UGT
: ICmpInst::ICMP_ULT,
IsSExt ? Builder.CreateAdd(X, ConstantInt::get(X->getType(), 1))
: X,
ConstantInt::get(X->getType(), Pred1 == ICmpInst::ICMP_NE ? 1 : 2));
}
} 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, (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
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return ICmpInst::Create(
Instruction::ICmp, Pred1, X,
ConstantInt::get(X->getType(),
Pred2 == ICmpInst::ICMP_NE ? (IsSExt ? -1 : 1) : 0));
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}
}

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if (match(I.getOperand(0), m_c_Add(m_ZExt(m_Value(X)), m_SExt(m_Value(Y)))) &&
match(I.getOperand(1), m_APInt(C)) &&
X->getType()->isIntOrIntVectorTy(1) &&
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17 changes: 4 additions & 13 deletions llvm/test/Transforms/InstCombine/and-or-icmps.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -366,19 +366,10 @@ define void @simplify_before_foldAndOfICmps(ptr %p) {
; CHECK-LABEL: @simplify_before_foldAndOfICmps(
; CHECK-NEXT: [[A8:%.*]] = alloca i16, align 2
; CHECK-NEXT: [[L7:%.*]] = load i16, ptr [[A8]], align 2
; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i16 [[L7]], -1
; CHECK-NEXT: [[B11:%.*]] = zext i1 [[TMP1]] to i16
; CHECK-NEXT: [[C10:%.*]] = icmp ugt i16 [[L7]], [[B11]]
; CHECK-NEXT: [[C5:%.*]] = icmp slt i16 [[L7]], 1
; CHECK-NEXT: [[C7:%.*]] = icmp slt i16 [[L7]], 0
; CHECK-NEXT: [[B15:%.*]] = xor i1 [[C7]], [[C10]]
; CHECK-NEXT: [[C6:%.*]] = xor i1 [[B15]], true
; CHECK-NEXT: [[TMP2:%.*]] = and i1 [[C5]], [[C6]]
; CHECK-NEXT: [[C3:%.*]] = and i1 [[TMP2]], [[C10]]
; CHECK-NEXT: [[TMP3:%.*]] = xor i1 [[C10]], true
; CHECK-NEXT: [[C18:%.*]] = or i1 [[C7]], [[TMP3]]
; CHECK-NEXT: [[TMP4:%.*]] = sext i1 [[C3]] to i64
; CHECK-NEXT: [[G26:%.*]] = getelementptr i1, ptr null, i64 [[TMP4]]
; CHECK-NEXT: [[C18:%.*]] = icmp slt i16 [[L7]], 1
; CHECK-NEXT: [[L7_LOBIT:%.*]] = ashr i16 [[L7]], 15
; CHECK-NEXT: [[TMP1:%.*]] = sext i16 [[L7_LOBIT]] to i64
; CHECK-NEXT: [[G26:%.*]] = getelementptr i1, ptr null, i64 [[TMP1]]
; CHECK-NEXT: store i16 [[L7]], ptr [[P:%.*]], align 2
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; CHECK-NEXT: store i1 [[C18]], ptr [[P]], align 1
; CHECK-NEXT: store ptr [[G26]], ptr [[P]], align 8
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