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Re: [PATCH] i386: Replace PREINIT_FUNCTION@PLT with *%eax in call
- From: Christian Brauner <christian at brauner dot io>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Mon, 14 May 2018 17:46:49 +0200
- Subject: Re: [PATCH] i386: Replace PREINIT_FUNCTION@PLT with *%eax in call
- References: <20180512133145.GA30506@gmail.com>
On Sat, May 12, 2018 at 06:31:45AM -0700, H.J. Lu wrote:
> Since we have loaded address of PREINIT_FUNCTION into %eax, we can
> avoid extra branch to PLT slot.
>
> Any comments?
>
> H.J.
> ---
> * sysdeps/i386/crti.S (_init): Replace PREINIT_FUNCTION@PLT
> with *%eax in call.
> ---
> sysdeps/i386/crti.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sysdeps/i386/crti.S b/sysdeps/i386/crti.S
> index c0422f9ce3..065460b813 100644
> --- a/sysdeps/i386/crti.S
> +++ b/sysdeps/i386/crti.S
> @@ -68,7 +68,7 @@ _init:
> movl PREINIT_FUNCTION@GOT(%ebx), %eax
> testl %eax, %eax
> je .Lno_weak_fn
> - call PREINIT_FUNCTION@PLT
The PREINIT_FUNCTION macro is essentially just __gmon_start__, right? So
unless this was somehow introduced specifically for profiling purposes
this seems legit.
Acked-by: Christian Brauner (Ubuntu) <christian@brauner.io>
> + call *%eax
> .Lno_weak_fn:
> #else
> call PREINIT_FUNCTION
> --
> 2.17.0
>