Re: [Qemu-devel] gcc auto-omit-frame-pointer vs msvc longjmp

[Bob Breuer]

Kai Tietz wrote:
> 2011/10/24 Bob Breuer <address@hidden>:
>> 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
> 
> Well, for 4.6.x (or older) we just can use the mingw32.h header in
> gcc/config/i386/ and define here a subtarget-macro to indicate that.
> The only incompatible point here might be for Wine using the
> linux-compiler to build Windows related code.
> 
> A possible patch for 4.6 gcc versions I attached to this mail.
> 
> Regards,
> Kai
> 
> Index: mingw32.h
> ===================================================================
> --- mingw32.h   (revision 180393)
> +++ mingw32.h   (working copy)
> @@ -239,3 +239,8 @@
>  /* We should find a way to not have to update this manually.  */
>  #define LIBGCJ_SONAME "libgcj" /*LIBGCC_EH_EXTN*/ "-12.dll"
> 
> +/* For 32-bit Windows we need valid frame-pointer for function using
> +   setjmp.  */
> +#define SUBTARGET_SETJMP_NEED_FRAME_POINTER \
> +  (!TARGET_64BIT && cfun->calls_setjmp)
> +
> Index: i386.c
> ===================================================================
> --- i386.c      (revision 180393)
> +++ i386.c      (working copy)
> @@ -8741,6 +8741,12 @@
>    if (SUBTARGET_FRAME_POINTER_REQUIRED)
>      return true;
> 
> +#ifdef SUBTARGET_SETJMP_NEED_FRAME_POINTER
> +  /* For older 32-bit runtimes setjmp requires valid frame-pointer.  */
> +  if (SUBTARGET_SETJMP_NEED_FRAME_POINTER)
> +    return true;
> +#endif
> +
>    /* 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.  */
> 

That works for me. Thanks.

Bob