[llvm] [AMDGPU] Save/Restore SCC bit across waterfall loop. (PR #68363)

[Sirish Pande via llvm-commits]

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@@ -5094,6 +5094,39 @@ unsigned SIInstrInfo::getVALUOp(const MachineInstr &MI) const {
       "Unexpected scalar opcode without corresponding vector one!");
 }
 
+bool SIInstrInfo::isSCCDefinedBefore(MachineBasicBlock &MBB,
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srpande wrote:

We could change computeRegisterLiveness to change to do the following:
1. Default as is right now.
2. Just do backward scan to defs
3. Just do forward scan to uses.

https://github.com/llvm/llvm-project/pull/68363