================
@@ -2280,6 +2290,127 @@ Value
*InstCombinerImpl::SimplifyDemandedUseFPClass(Value *V,
Known = KnownLHS | KnownRHS;
break;
}
+ case Instruction::FMul: {
+ KnownFPClass KnownLHS, KnownRHS;
+
+ Value *X = I->getOperand(0);
+ Value *Y = I->getOperand(1);
+
+ FPClassTest SrcDemandedMask =
+ DemandedMask & (fcNan | fcZero | fcSubnormal | fcNormal);
+
+ if (DemandedMask & fcInf) {
+ // mul x, inf = inf
+ // mul large_x, large_y = inf
+ SrcDemandedMask |= fcSubnormal | fcNormal | fcInf;
+ }
+
+ if (DemandedMask & fcNan) {
+ // mul +/-inf, 0 => nan
+ SrcDemandedMask |= fcZero | fcInf;
+
+ // TODO: Mode check
+ // mul +/-inf, sub => nan if daz
+ SrcDemandedMask |= fcSubnormal;
+ }
+
+ if (X == Y) {
+ if (SimplifyDemandedFPClass(I, 0, SrcDemandedMask, KnownLHS, Depth + 1))
+ return I;
----------------
arsenm wrote:
I think this is kind of broken. It works out in these tests since the only
select simplifications performed can support multiple uses. Really this needs
to be broken up into single and multiple use versions like SimpilfyDemandedBits
is
https://github.com/llvm/llvm-project/pull/173872
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