[llvm] [AMDGPU] Verify dominance when rewriting spills to registers (PR #167347)

[Jay Foad via llvm-commits]

================
@@ -0,0 +1,2084 @@
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx950 -O3 -o - %s | FileCheck %s
----------------
jayfoad wrote:

This test passes even without your patch! What was the failure mode supposed to be?

https://github.com/llvm/llvm-project/pull/167347