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[InstCombine] simplify code for xor folds; NFCI 

This is just a cleanup step. The TODO comments show
what is wrong with the 'and' version of the fold.
Fixing this should be part of recommitting:
rL300977

llvm-svn: 341405
This commit is contained in:
Sanjay Patel 2018-09-04 21:00:13 +00:00
parent 4c08654b17
commit a89f183253
1 changed files with 22 additions and 39 deletions
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61
llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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@ -2769,46 +2769,29 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I))
return FoldedLogic;
{
Value *A, *B;
if (match(Op1, m_OneUse(m_Or(m_Value(A), m_Value(B))))) {
if (A == Op0) { // A^(A|B) == A^(B|A)
cast<BinaryOperator>(Op1)->swapOperands();
std::swap(A, B);
}
if (B == Op0) { // A^(B|A) == (B|A)^A
I.swapOperands(); // Simplified below.
std::swap(Op0, Op1);
}
} else if (match(Op1, m_OneUse(m_And(m_Value(A), m_Value(B))))) {
if (A == Op0) { // A^(A&B) -> A^(B&A)
cast<BinaryOperator>(Op1)->swapOperands();
std::swap(A, B);
}
if (B == Op0) { // A^(B&A) -> (B&A)^A
I.swapOperands(); // Simplified below.
std::swap(Op0, Op1);
}
}
}
// Y ^ (X | Y) --> X & ~Y
// Y ^ (Y | X) --> X & ~Y
if (match(Op1, m_OneUse(m_c_Or(m_Value(X), m_Specific(Op0)))))
return BinaryOperator::CreateAnd(X, Builder.CreateNot(Op0));
// (X | Y) ^ Y --> X & ~Y
// (Y | X) ^ Y --> X & ~Y
if (match(Op0, m_OneUse(m_c_Or(m_Value(X), m_Specific(Op1)))))
return BinaryOperator::CreateAnd(X, Builder.CreateNot(Op1));
{
Value *A, *B;
if (match(Op0, m_OneUse(m_Or(m_Value(A), m_Value(B))))) {
if (A == Op1) // (B|A)^B == (A|B)^B
std::swap(A, B);
if (B == Op1) // (A|B)^B == A & ~B
return BinaryOperator::CreateAnd(A, Builder.CreateNot(Op1));
} else if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B))))) {
if (A == Op1) // (A&B)^A -> (B&A)^A
std::swap(A, B);
const APInt *C;
if (B == Op1 && // (B&A)^A == ~B & A
!match(Op1, m_APInt(C))) { // Canonical form is (B&C)^C
return BinaryOperator::CreateAnd(Builder.CreateNot(A), Op1);
}
}
}
// Y ^ (X & Y) --> ~X & Y
// Y ^ (Y & X) --> ~X & Y
if (match(Op1, m_OneUse(m_c_And(m_Value(X), m_Specific(Op0)))))
return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(X));
// (X & Y) ^ Y --> ~X & Y
// (Y & X) ^ Y --> ~X & Y
// Canonical form with a non-splat constant is (X & C) ^ C; don't touch that.
// TODO: Why do we treat arbitrary vector constants differently?
// TODO: A 'not' op is better for analysis and codegen, but demanded bits must
// be fixed to prefer that (otherwise we get infinite looping).
const APInt *Unused;
if (!match(Op1, m_APInt(Unused)) &&
match(Op0, m_OneUse(m_c_And(m_Value(X), m_Specific(Op1)))))
return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(X));
{
Value *A, *B, *C, *D;