[llvm] GlobalISel: Fix defined register of invariant.start (PR #125664)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,24 @@
+; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=amdgcn -mcpu=gfx90a -O0 -global-isel=true --stop-after=irtranslator -o - %s | FileCheck %s
+target datalayout = "A5"
+
+declare ptr @llvm.invariant.start.p5(i64 immarg, ptr addrspace(5) nocapture)
+declare void @llvm.invariant.end.p5(ptr, i64 immarg, ptr addrspace(5) nocapture)
+
+define amdgpu_kernel void @use_invariant_promotable_lds(ptr addrspace(5) %arg, i32 %i) {
+  ; CHECK-LABEL: name: use_invariant_promotable_lds
+  ; CHECK: bb.1.bb:
+  ; CHECK-NEXT:   liveins: $sgpr4_sgpr5
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:_(p4) = COPY $sgpr4_sgpr5
+  ; CHECK-NEXT:   [[INT:%[0-9]+]]:_(p4) = G_INTRINSIC intrinsic(@llvm.amdgcn.kernarg.segment.ptr)
+  ; CHECK-NEXT:   [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 36
+  ; CHECK-NEXT:   %13:_(p4) = nuw nusw G_PTR_ADD [[INT]], [[C]](s64)
+  ; CHECK-NEXT:   [[LOAD:%[0-9]+]]:_(p5) = G_LOAD %13(p4) :: (dereferenceable invariant load (p5) from %ir.arg.kernarg.offset, addrspace 4)
+  ; CHECK-NEXT:   [[DEF:%[0-9]+]]:_(p0) = G_IMPLICIT_DEF
+  ; CHECK-NEXT:   S_ENDPGM 0
+bb:
+  %tmp = call ptr @llvm.invariant.start.p5(i64 4, ptr addrspace(5) %arg)
----------------
arsenm wrote:

```suggestion
  %tmp = call ptr @llvm.invariant.start.p5(i64 4, ptr addrspace(5) %arg)
  store i32 0, ptr %tmp
```

I see the verifier error with any other use only?

https://github.com/llvm/llvm-project/pull/125664