[llvm] [VPlan] Propagate FastMathFlags from phis to blends (PR #180226)

[Luke Lau via llvm-commits]

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@@ -578,6 +578,9 @@ Value *VPInstruction::generate(VPTransformState &State) {
                   OnlyFirstLaneUsed || vputils::isSingleScalar(getOperand(0)));
     Value *Op1 = State.get(getOperand(1), OnlyFirstLaneUsed);
     Value *Op2 = State.get(getOperand(2), OnlyFirstLaneUsed);
+    IRBuilderBase::FastMathFlagGuard FMFG(Builder);
+    if (hasFastMathFlags())
+      Builder.setFastMathFlags(getFastMathFlags());
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lukel97 wrote:

Thanks, done in f937e5cab499. Btw I don't think we want to pass the underlying value anymore right? The VPIRFlags should be used explicitly in case e.g. they get dropped in VPlanTransforms::dropPoisonGeneratingRecipes

https://github.com/llvm/llvm-project/pull/180226