[llvm] [AMDGPU][GISel] Add RegBankLegalize support for G_SI_CALL (PR #165747)

[Petar Avramovic via llvm-commits]

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@@ -59,6 +59,7 @@ bool RegBankLegalizeHelper::findRuleAndApplyMapping(MachineInstr &MI) {
   }
 
   SmallSet<Register, 4> WaterfallSgprs;
+  std::optional<iterator_range<MachineBasicBlock::iterator>> WaterfallRange;
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petar-avramovic wrote:

Think it would be best to have one struct argument that would have three fields
SmallSet<Register, 4> WaterfallSgprs;
const MachineInstr *RangeStart
const MachineInstr *RangeEnd

or whatever is appropriate, to have easier time dealing with initialization
also Sgpr32_WF case should have initialized Range with make_range(MI.getIterator(), std::next(MI.getIterator())); 

https://github.com/llvm/llvm-project/pull/165747