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Provide InstCombines for the following 3 cases:

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A * (1 - (uitofp i1 C)) -> select C, 0, A
B * (uitofp i1 C) -> select C, B, 0
select C, 0, A + select C, B, 0 -> select C, B, A

These come up in code that has been hand-optimized from a select to a linear blend, 
on platforms where that may have mattered. We want to undo such changes 
with the following transform:
A*(1 - uitofp i1 C) + B*(uitofp i1 C) -> select C, A, B



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181216 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jean-Luc Duprat
2013-05-06 16:55:50 +00:00
parent 4c8850cd1c
commit c5cf6e5365
4 changed files with 93 additions and 0 deletions
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28
lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
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@ -524,6 +524,34 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
}
}
// B * (uitofp i1 C) -> select C, B, 0
if(I.hasNoNaNs() && I.hasNoInfs() && I.hasNoSignedZeros()) {
Value *LHS=Op0, *RHS=Op1;
Value *B, *C;
if (!match(RHS, m_UIToFp(m_Value(C))))
std::swap(LHS, RHS);
if (match(RHS, m_UIToFp(m_Value(C)))) {
B=LHS;
Value *Zero = ConstantFP::getNegativeZero(B->getType());
return SelectInst::Create(C, B, Zero);
}
}
// A * (1 - uitofp i1 C) -> select C, 0, A
if(I.hasNoNaNs() && I.hasNoInfs() && I.hasNoSignedZeros()) {
Value *LHS=Op0, *RHS=Op1;
Value *A, *C;
if (!match(RHS, m_FSub(m_FPOne(), m_UIToFp(m_Value(C)))))
std::swap(LHS, RHS);
if (match(RHS, m_FSub(m_FPOne(), m_UIToFp(m_Value(C))))) {
A=LHS;
Value *Zero = ConstantFP::getNegativeZero(A->getType());
return SelectInst::Create(C, Zero, A);
}
}
if (!isa<Constant>(Op1))
std::swap(Opnd0, Opnd1);
else