__builtin_frame_address vs %esp in pt-machine.h

[Ulrich Drepper]

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Roland McGrath wrote:
> What was the reason for this change in linuxthreads?
> 
>      2001-04-12  Ulrich Drepper  <drepper@redhat.com>
> 
> 	     * sysdeps/i386/Makefile: Make sure gcc uses a frame pointer for
> 	     all the files which use CURRENT_STACK_FRAME.
> 	     * sysdeps/i386/pt-machine.h (CURRENT_STACK_FRAME): Define using
> 	     __builtin_frame_address.
> 	     * sysdeps/i386/i686/pt-machine.h: Likewise.
> 
> The -fomit-frame-pointer build is broken for !FLOATING_STACKS because we
> failed to keep the sysdeps/i386/Makefile up to date with every source file
> that uses THREAD_*MEM (probably my fault). 

The problem is the ptlongjmp.c code.  For its use of CURRENT_STACK_FRAME
the value must be as accurate as possible since otherwise the detection
of frames which have to be handled might be wrong.

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