[llvm] [AMDGPU] Generate waterfall for calls with SGPR(inreg) argument (PR #146997)

[Shilei Tian via llvm-commits]

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@@ -1333,6 +1343,10 @@ class SIInstrInfo final : public AMDGPUGenInstrInfo {
   void moveToVALUImpl(SIInstrWorklist &Worklist, MachineDominatorTree *MDT,
                       MachineInstr &Inst) const;
 
+  void createWaterFall(MachineInstr *MI, MachineDominatorTree *MDT,
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shiltian wrote:

Can you add document to this function?

https://github.com/llvm/llvm-project/pull/146997