[llvm] [RegAlloc] Fix use-after-free in `RegAllocBase::cleanupFailedVReg` (PR #151435)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,15 @@
+; RUN: not llc -mcpu=gfx1100 -mtriple=amdgcn-amd-amdhsa -stress-regalloc=4 %s 2>&1 | FileCheck %s
+
+; CHECK: ran out of registers during register allocation in function 'f'
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arsenm wrote:

Include the error prefix, and can you add an implicit check not to cover other errors? Want to be sure the machine verifier doesn't fire 

https://github.com/llvm/llvm-project/pull/151435