Re: [PATCH] x86: Properly check register CFA offset

[Uros Bizjak <ubizjak at gmail dot com>]

On Wed, Jul 26, 2017 at 6:14 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>
> X86 epilogue saves register at CFA offset.  Since its location on stack
> is computed as CFA - its CFA_OFFSET, CFA_OFFSET points the end of the
> saved register location on stack.  This patch updates sp_valid_at and
> fp_valid_at to properly check register CFA offset.
>
> Tested on x86-64.  OK for trunk if there are no regressions on i686?
>
> Thanks.
>
> H.J.
> --
> gcc/
>
>         PR target/81563
>         * config/i386/i386.c (sp_valid_at): Properly check CFA offset.
>         (fp_valid_at): Likewise.
>
> gcc/testsuite/
>
>         PR target/81563
>         * gcc.target/i386/pr81563.c: New test

OK.

Thanks,
Uros.

> ---
>  gcc/config/i386/i386.c                  | 10 ++++++----
>  gcc/testsuite/gcc.target/i386/pr81563.c | 14 ++++++++++++++
>  2 files changed, 20 insertions(+), 4 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr81563.c
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 084b4a6a0db..f1486ff3750 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -13102,24 +13102,26 @@ choose_baseaddr_len (unsigned int regno, HOST_WIDE_INT offset)
>    return len;
>  }
>
> -/* Determine if the stack pointer is valid for accessing the cfa_offset.  */
> +/* Determine if the stack pointer is valid for accessing the cfa_offset.
> +   The register is saved at CFA - CFA_OFFSET.  */
>
>  static inline bool
>  sp_valid_at (HOST_WIDE_INT cfa_offset)
>  {
>    const struct machine_frame_state &fs = cfun->machine->fs;
>    return fs.sp_valid && !(fs.sp_realigned
> -                         && cfa_offset < fs.sp_realigned_offset);
> +                         && cfa_offset <= fs.sp_realigned_offset);
>  }
>
> -/* Determine if the frame pointer is valid for accessing the cfa_offset.  */
> +/* Determine if the frame pointer is valid for accessing the cfa_offset.
> +   The register is saved at CFA - CFA_OFFSET.  */
>
>  static inline bool
>  fp_valid_at (HOST_WIDE_INT cfa_offset)
>  {
>    const struct machine_frame_state &fs = cfun->machine->fs;
>    return fs.fp_valid && !(fs.sp_valid && fs.sp_realigned
> -                         && cfa_offset >= fs.sp_realigned_offset);
> +                         && cfa_offset > fs.sp_realigned_offset);
>  }
>
>  /* Choose a base register based upon alignment requested, speed and/or
> diff --git a/gcc/testsuite/gcc.target/i386/pr81563.c b/gcc/testsuite/gcc.target/i386/pr81563.c
> new file mode 100644
> index 00000000000..ebfd583daf5
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr81563.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile { target ia32 } } */
> +/* { dg-options "-O2 -maccumulate-outgoing-args -mincoming-stack-boundary=2 -mpreferred-stack-boundary=3 -mregparm=3 -mtune-ctrl=epilogue_using_move" } */
> +
> +extern void bar (long long int, int);
> +
> +long long int
> +fn1 (long long int x)
> +{
> +  bar (x, 1);
> +  return x;
> +}
> +
> +/* { dg-final { scan-assembler-times "movl\[\\t \]*-8\\(%ebp\\),\[\\t \]*%esi" 1 } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]*-4\\(%ebp\\),\[\\t \]*%edi" 1 } } */
> --
> 2.13.3
>