[llvm] [CodeGen] Register-coalescer remat fix subreg liveness (PR #165662)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,58 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 6
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx950 -run-pass=register-coalescer -verify-coalescing -o - %s | FileCheck %s
+
+# This test is to check fix for failure with "Bad machine code: Defining instruction does not modify register" due to corrupt lane mask.
+
+---
+name:            reg_coalescer_subreg_liveness
+tracksRegLiveness: true
+liveins:
+body:             |
+  ; CHECK-LABEL: name: reg_coalescer_subreg_liveness
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT:   liveins: $sgpr4_sgpr5
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:sgpr_64 = COPY $sgpr4_sgpr5
+  ; CHECK-NEXT:   undef [[S_LOAD_DWORD_IMM:%[0-9]+]].sub2:sgpr_128 = S_LOAD_DWORD_IMM [[COPY]], 0, 0 :: (dereferenceable invariant load (s32), align 16, addrspace 4)
+  ; CHECK-NEXT:   [[S_LOAD_DWORD_IMM:%[0-9]+]].sub1:sgpr_128 = S_LOAD_DWORD_IMM [[COPY]], 24, 0 :: (dereferenceable invariant load (s32), align 8, addrspace 4)
+  ; CHECK-NEXT:   [[S_LOAD_DWORD_IMM:%[0-9]+]].sub0:sgpr_128 = S_MOV_B32 1
+  ; CHECK-NEXT:   undef [[S_MOV_B32_:%[0-9]+]].sub0:sgpr_256 = S_MOV_B32 0
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   successors: %bb.2(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   S_NOP 0, implicit [[S_LOAD_DWORD_IMM]], implicit [[S_MOV_B32_]]
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arsenm wrote:

The S_NOP disappeared in the latest version of the patch? Did refineSubRanges fix this? 

https://github.com/llvm/llvm-project/pull/165662