[PATCH] D13003: [DAGCombiner] Improve FMA support for interpolation patterns

[Matt Arsenault via llvm-commits]

arsenm added a comment.

In http://reviews.llvm.org/D13003#249540, @RKSimon wrote:

> > There aren't any tests stressing the FMAD path. AMDGPU seems to be only target using it still, and the one test change is in the expansion of an intrinsic which should be removed. If you can add some of those that would be good, otherwise I can try to do it after you commit
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> Thanks Matt, I can add some FMAD tests for v_mad_f32 - is that the only instruction I should be testing for?


Yes. The fneg should be folded in as a source modifier that looks something like v_mad_f32 v0, v1, v2, -v3. Sometimes v_mac_f32 is used, although in these cases that shouldn't happen

> Most of your comments about the preamble are just as relevant for the other FMA pattern combines (visitFADDForFMACombine, visitFSUBForFMACombine); given that I copied+pasted most of it from them should they be updated as well?


Yes, probably


Repository:
  rL LLVM

http://reviews.llvm.org/D13003