[llvm] Split vgpr regalloc pipeline (PR #93526)

[Christudasan Devadasan via llvm-commits]

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@@ -1555,6 +1555,17 @@ void SIFrameLowering::determinePrologEpilogSGPRSaves(
   }
 }
 
+// Mark all WWM VGPRs as BB LiveIns.
+static void addWwmRegBBLiveIn(MachineFunction &MF) {
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cdevadas wrote:

We shift back the wwm-regs to the lowest range at this point. They aren't explicitly marked reserved. I'll do that by calling MRI.reserveReg() on these new regs. With that, I can stop adding them to BBLiveIns.

https://github.com/llvm/llvm-project/pull/93526