[llvm] [clang] [AMDGPU] Emit a waitcnt instruction after each memory instruction (PR #79236)

[Pierre van Houtryve via llvm-commits]

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+; Testing the -amdgpu-precise-memory-op option
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Pierre-vh wrote:

Please generate the test using `update_llc_test_checks`, much easier to update if/when things change.

Also I think you don't need `-verify-machineinstrs`. It's expensive and runs anyway when EXPENSIVE_CHECKS is on.

https://github.com/llvm/llvm-project/pull/79236