[llvm] [AMDGPU] Change control flow intrinsic lowering making the wave to re… (PR #86805)

[Matt Arsenault via llvm-commits]

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@@ -15619,6 +15619,91 @@ void SITargetLowering::finalizeLowering(MachineFunction &MF) const {
     }
   }
 
+  // ISel inserts copy to regs for the successor PHIs
+  // at the BB end. We need to move the SI_WAVE_RECONVERGE right before the branch.
+  // Even we don't have to move SI_WAVE_RECONVERGE we need to take care of the
+  // S_CBRANCH_SCC0/1 as SI_WAVE_RECONVERGE overwrites SCC
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arsenm wrote:

This should have been emitted as a copy pair to a temp vreg? 

https://github.com/llvm/llvm-project/pull/86805