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From: Bob Breuer <breuerr@mc.net>
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Subject: Re: [Qemu-devel] gcc auto-omit-frame-pointer vs msvc longjmp
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To: Kai Tietz <ktietz70@googlemail.com>
Cc: xunxun <xunxun1982@gmail.com>, Richard Henderson <rth@twiddle.net>, qemu-devel <qemu-devel@nongnu.org>, Mark Cave-Ayland <mark.cave-ayland@siriusit.co.uk>, "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>

Kai Tietz wrote:
> Hi,
> 
> For trunk-version I have a tentative patch for this issue.  On 4.6.x
> and older branches this doesn't work, as here we can't differenciate
> that easy between ms- and sysv-abi.
> 
> But could somebody give this patch a try?
> 
> Regards,
> Kai
> 
> ChangeLog
> 
>         * config/i386/i386.c (ix86_frame_pointer_required): Enforce use of
>         frame-pointer for 32-bit ms-abi, if setjmp is used.
> 
> Index: i386.c
> ===================================================================
> --- i386.c      (revision 180099)
> +++ i386.c      (working copy)
> @@ -8391,6 +8391,10 @@
>    if (SUBTARGET_FRAME_POINTER_REQUIRED)
>      return true;
> 
> +  /* For older 32-bit runtimes setjmp requires valid frame-pointer.  */
> +  if (TARGET_32BIT_MS_ABI && cfun->calls_setjmp)
> +    return true;
> +
>    /* In ix86_option_override_internal, TARGET_OMIT_LEAF_FRAME_POINTER
>       turns off the frame pointer by default.  Turn it back on now if
>       we've not got a leaf function.  */
> 

For a gcc 4.7 snapshot, this does fix the longjmp problem that I
encountered.  So aside from specifying -fno-omit-frame-pointer for
affected files, what can be done for 4.6?

Bob