[Bug inline-asm/39078] Registers in on clober list are cloberred when compiled with optimization (x86_64) ?

["ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

------- Comment #3 from ubizjak at gmail dot com  2009-02-06 11:51 -------
> > r11 is saved by the caller so this is the generated code is valid. 
> > Since nothing else uses r11 in the inline-asm, the code is correct.
> The problem is not that r11 not saved at stack, but that saved on the stack
> value of r15 ALWAYS will be overwritten - by the 'call my_syscall' instruction
> and saved on the stack values of rbx, r12, r13 and r14 MAY BE overritten if
> my_syscall function wrote something to the stack

These values have been saved into red-zone area. Since gcc does not know that
you have a call in the asm it thinks that func_1 is a leaf function where
redzone area can be used for temporary storage.

You can use -mno-red-zone to disable red-zone, but in reality, you should not
call other functions from inside asm.


-- 

ubizjak at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39078