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

[Kai Tietz]

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.  */