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

[Sebastian Neubauer via Phabricator via llvm-commits]

sebastian-ne added a comment.

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.
exec=0 is a corner case, but I don’t think we can build on that.

Other than that, it surely is more efficient than the (worst case) 4 memory operations introduced by saving all lanes of the used VGPR :)


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