[llvm] [AMDGPU] Add waterfall intrinsics (PR #192409)

[Petar Avramovic via llvm-commits]

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@@ -5521,6 +5520,33 @@ AMDGPURegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
       OpdsMapping[1] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size);
       break;
     }
+    case Intrinsic::amdgcn_waterfall_begin: {
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petar-avramovic wrote:

from comment for new-reg-bank-select, can we implement in AMDGPURegBankLegalizeRules.cpp

https://github.com/llvm/llvm-project/pull/192409