[llvm] [LiveVariables] Mark use as implicit-def if defined at instr (PR #119446)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,46 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=amdgcn --run-pass=livevars -o - %s | FileCheck %s
+---
+name:            sgpr_copy
+tracksRegLiveness: true
+body:             |
+  bb.0:
+
+    ; CHECK-LABEL: name: sgpr_copy
+    ; CHECK: %sval:sreg_32 = S_MOV_B32 0
+    ; CHECK-NEXT: $sgpr0 = COPY %sval
+    ; CHECK-NEXT: $sgpr1 = COPY %sval
+    ; CHECK-NEXT: $sgpr2 = COPY %sval
+    ; CHECK-NEXT: $sgpr3 = COPY killed %sval, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3
+    ; CHECK-NEXT: dead $sgpr30_sgpr31 = COPY killed $sgpr0_sgpr1_sgpr2_sgpr3
+    %sval:sreg_32 = S_MOV_B32 0
+
+    $sgpr0 = COPY %sval
+    $sgpr1 = COPY %sval
+    $sgpr2 = COPY %sval
+    $sgpr3 = COPY %sval
+    $sgpr30_sgpr31 = COPY $sgpr0_sgpr1_sgpr2_sgpr3
+
+...
+---
+name:            vgpr_copy
+tracksRegLiveness: true
+body:             |
+  bb.0:
+
+    ; CHECK-LABEL: name: vgpr_copy
+    ; CHECK: %vval:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
+    ; CHECK-NEXT: $vgpr0 = COPY %vval
+    ; CHECK-NEXT: $vgpr1 = COPY %vval
+    ; CHECK-NEXT: $vgpr2 = COPY %vval
+    ; CHECK-NEXT: $vgpr3 = COPY killed %vval, implicit-def $vgpr0_vgpr1_vgpr2_vgpr3
+    ; CHECK-NEXT: dead [[COPY:%[0-9]+]]:vgpr_32 = COPY killed $vgpr0_vgpr1_vgpr2_vgpr3
+    %vval:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
+
+    $vgpr0 = COPY %vval
+    $vgpr1 = COPY %vval
+    $vgpr2 = COPY %vval
+    $vgpr3 = COPY %vval
+    %0:vgpr_32 = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+
----------------
arsenm wrote:

Add some more complex cases, like a def of a different tuple in the middle (e.g. v0, v[1:2], v3). And cases where the result has undefined holes (e.g. def v0, v2, v3 leaving v1 undef) 

https://github.com/llvm/llvm-project/pull/119446