Re: [PATCH] x86: Properly find the maximum stack slot alignment

[Uros Bizjak]

On Wed, Feb 12, 2025 at 6:25 AM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> Don't assume that stack slots can only be accessed by stack or frame
> registers.  We first find all registers defined by stack or frame
> registers.  Then check memory accesses by such registers, including
> stack and frame registers.

I wonder if this approach will also handle cases like e.g.:

    lea    64(%rsp), %rbx
    ...
    movaps    16(%rbx, %rcx), %xmm0

and:

    movq    %rsp, %rax
    ...
    lea    64(%rax), %rbx
    ...
    movaps    16(%rbx), %xmm0

?

Thanks,
uros.


>
> gcc/
>
> PR target/109780
> PR target/109093
> * config/i386/i386.cc (ix86_update_stack_alignment): New.
> (ix86_find_all_reg_use): Likewise.
> (ix86_find_max_used_stack_alignment): Also check memory accesses
> from registers defined by stack or frame registers.
>
> gcc/testsuite/
>
> PR target/109780
> PR target/109093
> * g++.target/i386/pr109780-1.C: New test.
> * gcc.target/i386/pr109093-1.c: Likewise.
> * gcc.target/i386/pr109780-1.c: Likewise.
> * gcc.target/i386/pr109780-2.c: Likewise.
>
> --
> H.J.