[llvm] [AMDGPU] Unroll illegal vector TRUNCATE after legalization (PR #207761)

[Matt Arsenault via llvm-commits]

Juan Manuel Martinez =?utf-8?q?Caamaño?Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/207761 at github.com>


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@@ -4738,6 +4738,14 @@ SDValue AMDGPUTargetLowering::performTruncateCombine(
     }
   }
 
+  // Unroll illegal vector truncate: This is normally done by the legalizer,
+  // however patterns introduced by the dag combiner may reintroduce the illegal
+  // pattern.
+  if (DCI.isAfterLegalizeDAG() && VT.isVector() &&
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arsenm wrote:

Should probably try to avoid creating the illegal operation in the first place 

https://github.com/llvm/llvm-project/pull/207761