[PATCH] D43968: [X86] Handle EAX being live when calling chkstk for x86_64

[Reid Kleckner via Phabricator via llvm-commits]

rnk added a comment.

I see, shrink-wrapping makes it so that EAX may be live into the prologue.

I don't like that the CFI becomes imprecise, though. The user won't be able to break on `__chkstk` and take a backtrace. Does that work today when shrink wrapping isn't in use? If not, then let's just do this. If it does work, we should consider emitting an 8 byte .seh_stackalloc for the push or RAX and a smaller update after `__chkstk`.

This needs a test case. I think this might be a good time to use an MIR test case.


Repository:
  rL LLVM

https://reviews.llvm.org/D43968