[llvm] [AMDGPU][InsertWaitCnts] Refactor some helper functions, NFC (PR #161160)

[Jay Foad via llvm-commits]

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@@ -748,6 +754,18 @@ class SIInstrInfo final : public AMDGPUGenInstrInfo {
     return isLDSDMA(MI) && MI.getOpcode() != AMDGPU::BUFFER_STORE_LDS_DWORD;
   }
 
+  static bool asynchronouslyWritesSCC(unsigned Opcode) {
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jayfoad wrote:

I have a slight reservation about moving these three functions into SIInstrInfo. If they're visible outside of SIInsertWaitcnts itself then I think they need better documentation to explain exactly what they do and why, since the names are not specific enough. E.g. plenty of other instructions "read VCC".

https://github.com/llvm/llvm-project/pull/161160