[llvm] AMDGPU: fix isSafeToSink expecting exactly one predecessor (PR #89224)

[via llvm-commits]

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@@ -214,14 +214,13 @@ bool SIInstrInfo::isSafeToSink(MachineInstr &MI,
       // does not contain SuccToSinkTo and also has divergent exit condition.
       while (FromCycle && !FromCycle->contains(ToCycle)) {
         // After structurize-cfg, there should be exactly one cycle exit.
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ruiling wrote:

I just notice the old comment is still there, please help remove it. Thanks!

https://github.com/llvm/llvm-project/pull/89224