Re: [PATCH 01/11] Remove unused and unsafe call to __builtin_frame_address

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Mar 19 13:45, Peter Foley wrote:
> initial_sp has been unused since commit fbf23e3 back in 2000.
> Keep the value, so as to avoid changing the offset of magic_biscuit.
> 
> winsup/cygwin/lib/_cygwin_crt0_common.cc:140:52:
> error: calling 'void* __builtin_frame_address(unsigned int)' with a
> nonzero argument is unsafe [-Werror=frame-address]
>    u->initial_sp = (char *) __builtin_frame_address (1);
> 
> winsup/cygwin/ChangeLog
> lib/_cygwin_crt0_common.cc (_cygwin_crt0_common): Initialize initial_sp
> with nullptr.
> 
> Signed-off-by: Peter Foley <pefoley2@pefoley.com>
> ---
>  winsup/cygwin/lib/_cygwin_crt0_common.cc | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/winsup/cygwin/lib/_cygwin_crt0_common.cc b/winsup/cygwin/lib/_cygwin_crt0_common.cc
> index 718ce94..96ebeee 100644
> --- a/winsup/cygwin/lib/_cygwin_crt0_common.cc
> +++ b/winsup/cygwin/lib/_cygwin_crt0_common.cc
> @@ -135,9 +135,8 @@ _cygwin_crt0_common (MainFunc f, per_process *u)
>    u->premain[3] = cygwin_premain3;
>    u->fmode_ptr = &_fmode;
>  
> -  /* This is used to record what the initial sp was.  The value is needed
> -     when copying the parent's stack to the child during a fork.  */
> -  u->initial_sp = (char *) __builtin_frame_address (1);
> +  /* Unused */
> +  u->initial_sp = nullptr;

We're not building in C++11 mode yet.  I fixed that locally to use
NULL instead, which I'd prefer anyway.  Patch applied.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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