[PATCH] D132073: [CodeGen] Zero out only modified registers

[Bill Wendling via Phabricator via llvm-commits]

void added a comment.

In D132073#3765192 <https://reviews.llvm.org/D132073#3765192>, @nickdesaulniers wrote:

> In D132073#3764848 <https://reviews.llvm.org/D132073#3764848>, @void wrote:
>
>> In D132073#3764772 <https://reviews.llvm.org/D132073#3764772>, @efriedma wrote:
>>
>>> What am I looking for?  I still don't see anything obviously wrong.
>>
>> We shouldn't be zeroing out non-volatile registers that aren't modified by the function. In this case, we shouldn't be zeroing `%rdi`. Note that `%rsi` is marked as "modified" by the asm statements.
>
> `rsi` and `rdi` are not in any of the clobber lists...or is that what registers are being allocated for the inline asm inputs/outputs? Perhaps a MIR test would make that more obvious? Or an explicit clobber in these test cases?

Right, they aren't. Perhaps I should just write a testcase that uses inline asm and a clobber list instead of trying to scrape together something from the Linux sources.


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https://reviews.llvm.org/D132073