[PATCH] D36335: Add ‘llvm.experimental.constrained.fma‘ Intrinsic

[Andy Kaylor via Phabricator via llvm-commits]

andrew.w.kaylor added inline comments.


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Comment at: lib/Target/X86/X86ISelDAGToDAG.cpp:2015
   default: break;
+  case ISD::FMA: {
+    SDValue ISDFMA = CurDAG->getNode(X86ISD::FMADD, SDLoc(Node),
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wdng wrote:
> andrew.w.kaylor wrote:
> > Can you explain why this was necessary?  I would have expected there to have been handling already in place for ISD::FMA.
> No it doesn't, looks like X86 doesn't handle ISD:FMA automatically unless we there is -mattr=+fma option. Without this, CodeGen/X86/fp-intrinsics.ll will fail in instruction selection.
I still don't understand.  What happens when -mattr=+fma is used?

The CodeGen/X86/fma.ll test uses that option.  This case should work in the same way.


Repository:
  rL LLVM

https://reviews.llvm.org/D36335