[PATCH] D129073: [AMDGPU] Combine s_or_saveexec, s_xor instructions.

[Nicolai Hähnle via Phabricator via llvm-commits]

nhaehnle added a comment.

In D129073#3635744 <https://reviews.llvm.org/D129073#3635744>, @arsenm wrote:

> In D129073#3635410 <https://reviews.llvm.org/D129073#3635410>, @nhaehnle wrote:
>
>> 2. Why is this change done in SIOptimizeExecMasking instead of SIOptimizeExecMaskingPreRA? Actually, I don't remember why we have the two passes in the first place. Perhaps @rampitec remembers?
>
> The primary reason is we can't produce the terminators with output registers before register allocation in case we need to insert spills live out of the block for the save exec. RA needs to insert spills before terminators

That makes sense, thanks.


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https://reviews.llvm.org/D129073