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fold things like a^b != c^a -> b != c. This implements InstCombine/xor.ll:test27

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32893 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-01-05 03:04:57 +00:00
parent 297a22b97d
commit 4f0e33d145
1 changed files with 33 additions and 12 deletions
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45
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -5173,30 +5173,51 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
}
if (I.isEquality()) {
Value *A, *B;
if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
(A == Op1 || B == Op1)) {
// (A^B) == A -> B == 0
Value *OtherVal = A == Op1 ? B : A;
return new ICmpInst(I.getPredicate(), OtherVal,
Constant::getNullValue(A->getType()));
} else if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
(A == Op0 || B == Op0)) {
Value *A, *B, *C, *D;
if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
Value *OtherVal = A == Op1 ? B : A;
return new ICmpInst(I.getPredicate(), OtherVal,
Constant::getNullValue(A->getType()));
}
if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
// A^c1 == C^c2 --> A == C^(c1^c2)
if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
if (ConstantInt *C2 = dyn_cast<ConstantInt>(D))
if (Op1->hasOneUse()) {
Constant *NC = ConstantExpr::getXor(C1, C2);
Instruction *Xor = BinaryOperator::createXor(C, NC, "tmp");
return new ICmpInst(I.getPredicate(), A,
InsertNewInstBefore(Xor, I));
}
// A^B == A^D -> B == D
if (A == C) return new ICmpInst(I.getPredicate(), B, D);
if (A == D) return new ICmpInst(I.getPredicate(), B, C);
if (B == C) return new ICmpInst(I.getPredicate(), A, D);
if (B == D) return new ICmpInst(I.getPredicate(), A, C);
}
}
if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
(A == Op0 || B == Op0)) {
// A == (A^B) -> B == 0
Value *OtherVal = A == Op0 ? B : A;
return new ICmpInst(I.getPredicate(), OtherVal,
Constant::getNullValue(A->getType()));
} else if (match(Op0, m_Sub(m_Value(A), m_Value(B))) && A == Op1) {
}
if (match(Op0, m_Sub(m_Value(A), m_Value(B))) && A == Op1) {
// (A-B) == A -> B == 0
return new ICmpInst(I.getPredicate(), B,
Constant::getNullValue(B->getType()));
} else if (match(Op1, m_Sub(m_Value(A), m_Value(B))) && A == Op0) {
}
if (match(Op1, m_Sub(m_Value(A), m_Value(B))) && A == Op0) {
// A == (A-B) -> B == 0
return new ICmpInst(I.getPredicate(), B,
Constant::getNullValue(B->getType()));
}
Value *C, *D;
// (X&Z) == (Y&Z) -> (X^Y) & Z == 0
if (Op0->hasOneUse() && Op1->hasOneUse() &&
match(Op0, m_And(m_Value(A), m_Value(B))) &&