Re: [PATCH] Allow FP to be used as a call-saved registe

[Jeff Law <law at redhat dot com>]

On 09/05/2016 08:59 AM, Tamar Christina wrote:
> Hi All,
>
> This patch allows the FP register to be used as a call-saved
> register when -fomit-frame-pointer is used.
>
> The change is done in such a way that the defaults do not change.
> To use the FP register both -fomit-frame-pointer and
> -fcall-saved-<hard_fp_reg> need to be used.
>
> Regression ran on aarch64-none-linux-gnu and no regressions.
> Bootstrapped and ran regressions on `x86_64` and no regressions.
>
> A new test fp_free_1 was added to test functionality.
>
> Ok for trunk?
>
> Thanks,
> Tamar
>
> PS. I don't have commit rights so if OK can someone apply the patch for me.
>
> gcc/
> 2016-09-01  Tamar Christina  <tamar.christina@arm.com>
>
> 	* gcc/reginfo.c (fix_register): Allow FP to be set if
> 	-fomit-frame-pointer.
I'm a little surprised you need this.  Most ports allow use of FP as a 
call-saved register with -fomit-frame-pointer.

Also note the documentation explicitly forbids using -fcall-saved for 
the stack or frame pointer.


Jeff