Provide InstCombines for the following 3 cases:
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
diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index df73906..0ac0ca2 100644
--- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -524,6 +524,34 @@
}
}
+ // 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