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[ValueTracking] add check inversion for x and xor x, -1 #96425

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[ValueTracking] add check inversion for x and xor x, -1 #96425

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5 changes: 5 additions & 0 deletions llvm/lib/Analysis/ValueTracking.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8180,6 +8180,11 @@ bool llvm::isKnownNegation(const Value *X, const Value *Y, bool NeedNSW,
}

bool llvm::isKnownInversion(const Value *X, const Value *Y) {

// Handle X = xor Y, -1 or Y = xor X, -1
if (match(X, m_Not(m_Specific(Y))) || match(Y, m_Not(m_Specific(X))))
return true;

// Handle X = icmp pred A, B, Y = icmp pred A, C.
Value *A, *B, *C;
ICmpInst::Predicate Pred1, Pred2;
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22 changes: 7 additions & 15 deletions llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1840,14 +1840,6 @@ static Instruction *foldOrToXor(BinaryOperator &I,
match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
return BinaryOperator::CreateNot(Builder.CreateAnd(A, B));

// (A & ~B) | (~A & B) --> A ^ B
// (A & ~B) | (B & ~A) --> A ^ B
// (~B & A) | (~A & B) --> A ^ B
// (~B & A) | (B & ~A) --> A ^ B
if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) &&
match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B))))
return BinaryOperator::CreateXor(A, B);

return nullptr;
}

Expand Down Expand Up @@ -3426,16 +3418,16 @@ static Value *foldOrOfInversions(BinaryOperator &I,
assert(I.getOpcode() == Instruction::Or &&
"Simplification only supports or at the moment.");

Value *Cmp1, *Cmp2, *Cmp3, *Cmp4;
if (!match(I.getOperand(0), m_And(m_Value(Cmp1), m_Value(Cmp2))) ||
!match(I.getOperand(1), m_And(m_Value(Cmp3), m_Value(Cmp4))))
Value *A, *B, *C, *D;
if (!match(I.getOperand(0), m_And(m_Value(A), m_Value(B))) ||
!match(I.getOperand(1), m_And(m_Value(C), m_Value(D))))
return nullptr;

// Check if any two pairs of the and operations are inversions of each other.
if (isKnownInversion(Cmp1, Cmp3) && isKnownInversion(Cmp2, Cmp4))
return Builder.CreateXor(Cmp1, Cmp4);
if (isKnownInversion(Cmp1, Cmp4) && isKnownInversion(Cmp2, Cmp3))
return Builder.CreateXor(Cmp1, Cmp3);
if (isKnownInversion(A, C) && isKnownInversion(B, D))
return Builder.CreateXor(A, D);
if (isKnownInversion(A, D) && isKnownInversion(B, C))
return Builder.CreateXor(A, C);

return nullptr;
}
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4 changes: 2 additions & 2 deletions llvm/test/Transforms/InstCombine/and-or-not.ll
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Expand Up @@ -200,7 +200,7 @@ define i32 @or_to_xor3(float %fa, float %fb) {
; CHECK-LABEL: @or_to_xor3(
; CHECK-NEXT: [[A:%.*]] = fptosi float [[FA:%.*]] to i32
; CHECK-NEXT: [[B:%.*]] = fptosi float [[FB:%.*]] to i32
; CHECK-NEXT: [[OR:%.*]] = xor i32 [[B]], [[A]]
; CHECK-NEXT: [[OR:%.*]] = xor i32 [[A]], [[B]]
; CHECK-NEXT: ret i32 [[OR]]
;
%a = fptosi float %fa to i32
Expand All @@ -219,7 +219,7 @@ define i32 @or_to_xor4(float %fa, float %fb) {
; CHECK-LABEL: @or_to_xor4(
; CHECK-NEXT: [[A:%.*]] = fptosi float [[FA:%.*]] to i32
; CHECK-NEXT: [[B:%.*]] = fptosi float [[FB:%.*]] to i32
; CHECK-NEXT: [[OR:%.*]] = xor i32 [[B]], [[A]]
; CHECK-NEXT: [[OR:%.*]] = xor i32 [[A]], [[B]]
; CHECK-NEXT: ret i32 [[OR]]
;
%a = fptosi float %fa to i32
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