[Patch, _eh, dawin, Version2] Allow targets to suppress epilogues in _eh frames.

[IainS]

On 16 Aug 2010, at 05:15, Jack Howarth wrote:

>>   I am also seeing the failure...
>>
>> FAIL: gfortran.dg/g77/980701-0.f  -Os  execution test

Hm.  This test does not contain any (overt) exception handling, I  
guess we must be seeing an interaction with the fortran runtime
(or some aspect of the optimize for smallest code which is unexpected  
--- note that m32 forces frame pointers on for optimize_size).

The salient difference between trunk and the patched version is that  
there are no unwind frames emitted for the patched version.
Un-patched trunk sets -fasynchronous-unwind-tables.

The test passes if   either

-fno-omit-frame-pointers

or

-funwind-tables

is given.

this can be replicated on un-patched trunk by passing '-fno- 
asynchronous-frame-tables'.

Given that -fno-asynchronous-frame-tables does not sit well with  
dawin...
I could arrange either to default to  "-funwind-tables" on m64 (at  
least for fortran) but please note the following:

======
apple_local 4.2.1 (5646) gcc/config/i386/i386.c:

   if (TARGET_64BIT)
     {
       /* Mach-O doesn't support omitting the frame pointer for now.  */
       if (flag_omit_frame_pointer == 2)
	flag_omit_frame_pointer = (TARGET_MACHO ? 0 : 1);

but we have recently changed trunk to this:

   if (TARGET_64BIT)
     {
       if (flag_zee == 2)
         flag_zee = 1;
       if (flag_omit_frame_pointer == 2)
	flag_omit_frame_pointer = 1;


------

If you know that the "does not support" is no longer true for Darwin10  
- then, fine, we can arrange the target over-rides to switch it off  
for Darwin10.

Otherwise, I'm not sure how we can justify omitting frame pointers by  
default for m64 OSX
Mike?

cheers,
Iain