[llvm-branch-commits] [llvm] AMDGPU/GlobalISel: add RegBankLegalize rules for extends and trunc (PR #132383)

[Nicolai Hähnle via llvm-branch-commits]

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@@ -160,8 +154,7 @@ body: |
     ; CHECK-NEXT: [[C:%[0-9]+]]:vgpr(s32) = G_CONSTANT i32 1
     ; CHECK-NEXT: [[C1:%[0-9]+]]:vgpr(s32) = G_CONSTANT i32 0
     ; CHECK-NEXT: [[SELECT:%[0-9]+]]:vgpr(s32) = G_SELECT [[ICMP]](s1), [[C]], [[C1]]
-    ; CHECK-NEXT: [[DEF:%[0-9]+]]:vgpr(s32) = G_IMPLICIT_DEF
-    ; CHECK-NEXT: [[MV:%[0-9]+]]:vgpr(s64) = G_MERGE_VALUES [[SELECT]](s32), [[DEF]](s32)
+    ; CHECK-NEXT: [[MV:%[0-9]+]]:vgpr(s64) = G_MERGE_VALUES [[SELECT]](s32), [[C1]](s32)
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nhaehnle wrote:

This change is a code quality regression: the input has `G_ANYEXT`, so the high half can be undefined.

https://github.com/llvm/llvm-project/pull/132383