PATCH: Also check for `movl %esp, %ebp' for x32
Mark Kettenis
mark.kettenis@xs4all.nl
Thu May 3 21:50:00 GMT 2012
> >> I did have a look at it, but still have some questions.
> >>
> >>> Hi,
> >>>
> >>> X32 may use `movl %esp, %ebp' in prologue. Â This patch checks it for
> >>> x32. Â Tested on Linux/x86-64. Â OK for trunk?
> >>
> >> But the prologues generated by various compilers are expected to be
> >> otherwise the same for both the x32 ABI and the normal 64-bit ABI? Â I
> >> guess x32 has to use "pushq %rbp" as "pushl %ebp" isn't available.
> >> And I guess you want to keep the stack 16-byte aligned anyway. Â I
> >> suppose that "movq %rsp, %rbp" is still ok for x32, but "movl %esp,
> >> %ebp" can be encoded in less bytes, so it might be a bit more
> >> efficient for x32.
> >
> > That is correct.
>
> Is my patch OK to install?
Sorry, no. I'm really unhappy with that multi-line if clause. It
really is hard to parse. I'm trying to come up with a suggestion to
make this better, but so far haven't succeeded.
Does GCC ever generate the `mov %rsp,%rsp' instruction for x32?
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