Re: _Unwind_FindEnclosingFunction vs darwin

[Andrew Haley <aph at redhat dot com>]

Jack Howarth wrote:
> On Sat, Dec 19, 2009 at 10:50:53AM +0000, Andrew Haley wrote:
>> Jack Howarth wrote:
>>> On Fri, Dec 18, 2009 at 03:01:08PM +0000, Andrew Haley wrote:
>>>> _Unwind_Find_FDE is a standard function.  Does Darwin support that?
>>>>
>>> Andrew,
>>>     I believe we do have _Unwind_Find_FDE on darwin10 but it
>>> is only functional if compact unwind information isn't used.
>>> This is currently the case in gcc trunk since I disabled
>>> the darwin10 linker's default of using compact unwind info
>>> to avoid issues with the new epilog unwind info on the
>>> darwin10 linker.
>>>      Shouldn't we be able to add something like...
>>>
>>>  void *
>>>  darwin10_Unwind_FindEnclosingFunction (void *pc)
>>>  {
>>>    struct dwarf_eh_bases bases;
>>>    const struct dwarf_fde *fde = _Unwind_Find_FDE (pc-1, &bases);
>>>    if (fde)
>>>      return bases.func;
>>>    else
>>>      return NULL;
>>>  }
>>>
>>> and use...
>>>
>>> #undefine _Unwind_FindEnclosingFunction(PC) 
>>> #define _Unwind_FindEnclosingFunction(PC) darwin10_Unwind_FindEnclosingFunction(PC)
>>>
>>> to avoid the system _Unwind_FindEnclosingFunction() on darwin10?
>> Sure.
>>
>>> I assume that darwin10_Unwind_FindEnclosingFunction code would have to go into
>>> libjava/darwin.cc. However, I am unclear where to place...
>>>
>>> #undefine _Unwind_FindEnclosingFunction(PC) 
>>> #define _Unwind_FindEnclosingFunction(PC) darwin10_Unwind_FindEnclosingFunction(PC)
>> It can either go in include/config.h if it's autoconf'd or perhaps in
>> one of the libgcj include files.
>>
>> The easiest thing would be to add
>>
>> #ifdef USING_DARWIN_CRT
>> #undefine _Unwind_FindEnclosingFunction(PC)
>> #define _Unwind_FindEnclosingFunction(PC) darwin10_Unwind_FindEnclosingFunction(PC)
>> #endif
>>
>> to include/posix.h.
>>
>> Please make sure that darwin10_Unwind_FindEnclosingFunction is not exported from
>> anywhere.  I'd just declare it static inline in include/posix.h.
>>
>> Andrew.
> 
> Andrew,
>    The bigger question is were do we put the actual code for darwin10_Unwind_FindEnclosingFunction()
> such that libgcj can access it.

Define it static inline in libjava/include/posix.h..

Andrew.