[PATCH] D73939: [AMDGPU] Fix infinite loop with fma combines

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


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Comment at: llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp:742
+  switch (Op.getOpcode()) {
+    case ISD::FMA: {
+      // Negating a fma is not free if it has users without source mods.
----------------
kerbowa wrote:
> arsenm wrote:
> > This is incomplete and FMAD will have the same problem at minimum
> The hang at least doesn't effect FMAD. The combine that triggers this wont happen.
Where is the combine? It's also suspicious if an fneg combine triggered for FMA but not FMAD. 


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Comment at: llvm/test/CodeGen/AMDGPU/fma-combine.ll:699
+}
+
 attributes #0 = { nounwind readnone }
----------------
should also have an fmad case


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D73939/new/

https://reviews.llvm.org/D73939