[llvm] [AArch64][GlobalISel] Combine G_CONCAT_VECTORS with Illegal Form (PR #85047)

[David Green via llvm-commits]

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@@ -359,6 +359,108 @@ class LegalizationArtifactCombiner {
     return false;
   }
 
+  // Try to combine illegal G_CONCAT_VECTORS instructions
+  // Combine if the G_CONCAT_VECTORS instruction is illegal and
+  // Source Registers are:
+  //  - Previously defined by a G_BITCAST instruction
+  //  - Defined by G_IMPLICIT_DEF with look through
+  // ===============
+  //
+  // %0(s32) = G_LOAD %ptr
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davemgreen wrote:

The G_LOAD can be removed, as it could be any instruction and it helps simplify the comment a little.

https://github.com/llvm/llvm-project/pull/85047