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

[Petar Avramovic via llvm-branch-commits]

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@@ -233,8 +222,13 @@ body: |
     ; CHECK: liveins: $vgpr0
     ; CHECK-NEXT: {{  $}}
     ; CHECK-NEXT: [[COPY:%[0-9]+]]:vgpr(s32) = COPY $vgpr0
-    ; CHECK-NEXT: [[TRUNC:%[0-9]+]]:vgpr(s1) = G_TRUNC [[COPY]](s32)
-    ; CHECK-NEXT: [[ANYEXT:%[0-9]+]]:vgpr(s16) = G_ANYEXT [[TRUNC]](s1)
+    ; CHECK-NEXT: [[C:%[0-9]+]]:vgpr(s32) = G_CONSTANT i32 1
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:vgpr(s32) = G_AND [[COPY]], [[C]]
+    ; CHECK-NEXT: [[C1:%[0-9]+]]:vgpr(s32) = G_CONSTANT i32 0
+    ; CHECK-NEXT: [[ICMP:%[0-9]+]]:vcc(s1) = G_ICMP intpred(ne), [[AND]](s32), [[C1]]
+    ; CHECK-NEXT: [[C2:%[0-9]+]]:vgpr(s16) = G_CONSTANT i16 1
+    ; CHECK-NEXT: [[C3:%[0-9]+]]:vgpr(s16) = G_CONSTANT i16 0
+    ; CHECK-NEXT: [[SELECT:%[0-9]+]]:vgpr(s16) = G_SELECT [[ICMP]](s1), [[C2]], [[C3]]
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petar-avramovic wrote:

I think there is not much we can do here. Test by itself is not appropriate for regbankselect considering our rules in legalizer.
Input like this should not reach regbankselect.
Should have been picked up by basic trunc + anyext combine from artifact combiner in legalizer:
    %0:_(s32) = COPY $vgpr0
    %2:_(s16) = G_TRUNC %0
I see no reason to try and fix this as it would require running combiner before regbanklegalize


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