[llvm] [AMDGPU][SIInsertWaitcnts] Track SCC. Insert KM_CNT waits for SCC writes. (PR #157843)

[Jay Foad via llvm-commits]

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@@ -586,6 +591,7 @@ class SIInsertWaitcnts {
                              WaitcntBrackets &ScoreBrackets);
   bool insertWaitcntInBlock(MachineFunction &MF, MachineBasicBlock &Block,
                             WaitcntBrackets &ScoreBrackets);
+  bool asynchronouslyWritesSCC(unsigned Opcode) const;
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jayfoad wrote:

We have future patches where this method will depend on properties of the subtarget. But yes it could be `static` to begin with.

https://github.com/llvm/llvm-project/pull/157843