[PATCH] D61622: [FastISel][X86] If selectFNeg fails, fall back to SelectionDAG not treating it as an fsub.

[Cameron McInally via Phabricator via llvm-commits]

cameron.mcinally added inline comments.


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Comment at: llvm/test/CodeGen/X86/fast-isel-fneg.ll:68
 ; SSE2-NEXT:    movsd {{.*#+}} xmm0 = mem[0],zero
-; SSE2-NEXT:    subsd (%ecx), %xmm0
+; SSE2-NEXT:    xorps {{\.LCPI.*}}, %xmm0
 ; SSE2-NEXT:    movsd %xmm0, (%eax)
----------------
The general idea is good, but I'm failing to see how this instruction changed from subsd to xorps. Am I missing something subtle?


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  https://reviews.llvm.org/D61622/new/

https://reviews.llvm.org/D61622