[llvm] [AMDGPU] Fix debug line table for MSG_DEALLOC_VGPRS optimization (PR #88924)

[Emma Pilkington via llvm-commits]

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@@ -0,0 +1,40 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn -mcpu=gfx1100 -run-pass=si-insert-waitcnts -o - %s | FileCheck %s
+
+# Verify that si-insert-waitcnts copies debug locations from the s_endpgm to the
+# "dealloc vgprs" s_sendmsg. If these are not present, the debugger will be
+# unable to break at the end of the shader.
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epilk wrote:

Sure, I'll add more context to the commit. I just asked @lancesix about this, its not just that the VGPRs are unavailable, the problem is also that deallocating VGPRs makes it impossible to do a context save, which GDB needs to report a breakpoint. See: https://github.com/ROCm/ROCdbgapi/blob/7e22c4d4a8852e1950aea7f9d3e49899e4929fb6/include/amd-dbgapi.h.in#L358-L361

https://github.com/llvm/llvm-project/pull/88924