[PATCH] D118644: [x86] invert a vector select IR canonicalization with a binop identity constant

[Sanjay Patel via Phabricator via llvm-commits]

spatel marked an inline comment as done.
spatel added inline comments.


================
Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:48984-48987
+      case ISD::FADD: // X + -0.0 --> X
+        return C->isZero() && C->isNegative();
+      case ISD::FSUB: // X - 0.0 --> X
+        return C->isZero() && !C->isNegative();
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pengfei wrote:
> Do we need to consider the nsz case?
In IR, it looks like we still create the -0.0 constant even with nsz, but yes, I suspect we will want to handle both forms of zero if we have NSZ. 

We'll need more test coverage. I'll add another TODO for now.


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https://reviews.llvm.org/D118644