[llvm] AMDGPU/GFX12: Insert waitcnts before stores with scope_sys (PR #82996)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,16 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+; RUN: llc -march=amdgcn -mcpu=gfx1200 -verify-machineinstrs < %s | FileCheck -check-prefix=GFX12 %s
----------------
arsenm wrote:

-global-isel=0

https://github.com/llvm/llvm-project/pull/82996