[PATCH] D96980: [amdgpu] Revert agnostic SGPR spill.

[Ruiling, Song via Phabricator via llvm-commits]

ruiling added a comment.

In D96980#2574913 <https://reviews.llvm.org/D96980#2574913>, @sebastian-ne wrote:

> I think this approach fails when exec is zero.
> The v_mov for the save will be a noop, the v_readfirstline for the restore will read lane 0, which contains some unknown value.

For exec == 0 when reloading, I think the basic block that contains v_readfirstlane will be jumped over, see `SIInsertSkips.cpp` and `hasUnwantedEffectsWhenEXECEmpty()`


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