[llvm] [LLVM] Combine v_cvt_f32_f16 and v_add_f32/v_mul_f32 into v_fma_mix_f32 (PR #160151)

[Acim Maravic via llvm-commits]

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@@ -4127,6 +4127,24 @@ bool AMDGPUDAGToDAGISel::SelectVOP3PMadMixBF16Mods(SDValue In, SDValue &Src,
   return true;
 }
 
+bool AMDGPUDAGToDAGISel::SelectVOP3PMadMixModsNeg(SDValue In, SDValue &Src,
+                                                  SDValue &SrcMods) const {
+  unsigned Mods = 0;
+  SelectVOP3PMadMixModsImpl(In, Src, Mods, MVT::f16);
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Acim-Maravic wrote:

A GlobalISel equivalent for this pattern is not necessary. In SelectionDAG, DAGCombiner folds (fadd y, (fneg x)) into (fsub y, x), before the main instruction selection matching occurs. An alternative could be to modify the DAGCombiner to avoid folding fadd (fneg x) into fsub when the target has FMA support and at least one of the operands is an fpextend
?

https://github.com/llvm/llvm-project/pull/160151