[llvm] [AMDGPU][GlobalISel] Add BF16 widening to V2BF16 for packed instructions (PR #214370)

[Lukas Sommer via llvm-commits]

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@@ -1008,6 +1008,10 @@ AMDGPULegalizerInfo::AMDGPULegalizerInfo(const GCNSubtarget &ST_,
     FPOpActions.clampMaxNumElementsStrict(0, F64, 2);
   }
 
+  if (ST.hasBF16PackedInsts()) {
+    FPOpActions.customFor({BF16}).legalFor({V2BF16});
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sommerlukas wrote:

Could we use a MoreElements rule here instead of a custom action, e.g., something like `moreElementsIf`?

https://github.com/llvm/llvm-project/pull/214370