[llvm] [DAGCombiner] Preserve debug location of original load in fold (conv (load x)) (PR #160236)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,26 @@
+; RUN: llc -mtriple=amdgcn -mcpu=gfx942 < %s | FileCheck %s
+
+; CHECK-LABEL:  test:
+; CHECK:        .loc    1 8 16 prologue_end             ; test.py:8:16
+; CHECK-NEXT:   s_load_dword
+
+define void @test(ptr addrspace(1) inreg readonly captures(none) %0, ptr addrspace(1) inreg writeonly captures(none) %1) local_unnamed_addr !dbg !4 {
+  %3 = load <1 x float>, ptr addrspace(1) %0, align 4, !dbg !8, !amdgpu.noclobber !6
+  store <1 x float> %3, ptr addrspace(1) %1, align 4, !dbg !7
----------------
arsenm wrote:

```suggestion
  %ld = load <1 x float>, ptr addrspace(1) %arg0, align 4, !dbg !8, !amdgpu.noclobber !6
  store <1 x float> %ld, ptr addrspace(1) %arg1, align 4, !dbg !7
```

https://github.com/llvm/llvm-project/pull/160236