[llvm] [AMDGPU] Fix machine verification failure from INIT_EXEC lowering (PR #98333)

[Jay Foad via llvm-commits]

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@@ -1676,6 +1676,8 @@ bool SIWholeQuadMode::runOnMachineFunction(MachineFunction &MF) {
   if (!(GlobalFlags & (StateWQM | StateStrict)) && LowerToCopyInstrs.empty() &&
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jayfoad wrote:

The only thing I can see that we _might_ be able to skip over in some cases is the two `for (auto BII : Blocks)` loops below.

https://github.com/llvm/llvm-project/pull/98333