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

[Petar Avramovic via llvm-commits]

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@@ -217,10 +217,20 @@ bool SIInstrInfo::isSafeToSink(MachineInstr &MI,
         SmallVector<MachineBasicBlock *, 1> ExitBlocks;
         FromCycle->getExitBlocks(ExitBlocks);
         assert(ExitBlocks.size() == 1);
-        assert(ExitBlocks[0]->getSinglePredecessor());
-
+        // After structurize-cfg, cycle exit block should have exactly one
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petar-avramovic wrote:

Your proposal without asserts would return something even if input was not "structurized-cfg". Do we want to return something even when CFG is something we don't handle?

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