[llvm] [WIP][AMDGPU][SIInsertWaitcnts] Do not add s_waitcnt when the counters are known to be 0 already (PR #65735)

[Jay Foad via llvm-commits]

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@@ -364,7 +371,6 @@ class SIInsertWaitcnts : public MachineFunctionPass {
   const MachineRegisterInfo *MRI = nullptr;
   AMDGPU::IsaVersion IV;
 
-  DenseSet<MachineInstr *> TrackedWaitcntSet;
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jayfoad wrote:

Is my understanding correct? Previously we used TrackedWaitcntSet to distinguish pre-existing waitcnts from waitcnts inserted by this pass. Now we don't need that, all we need it to know the difference between hard and soft waitcnts?

https://github.com/llvm/llvm-project/pull/65735