Re: Strange code in dwarf2cfi.c:cfi_pop_frame()

[Michal Ludvig <mludvig at suse dot cz>]

Mark Kettenis wrote:
> The following bit of code surprises me a bit:
>
> /* Restore the machine to the state it had before the current frame
>    was created.  */
> void
> cfi_pop_frame (struct frame_info *fi)
> {
>   char regbuf[MAX_REGISTER_RAW_SIZE];
>   int regnum;
>
>   fi = get_current_frame ();
>
>   ...
>
> }
>
> Why does it override FI with the current frame?
Because it is expected, that fi will contain a valid frame info when 
this function returns. But you're right, that line doesn't need to be 
there, because cfi_pop_frame() is called from:
[blockframe.c]
void
generic_pop_current_frame (void (*popper) (struct frame_info * frame))
{
  struct frame_info *frame = get_current_frame ();

  if (PC_IN_CALL_DUMMY (frame->pc, frame->frame, frame->frame))
    generic_pop_dummy_frame ();
  else
    (*popper) (frame);  // <==== here
}

and so get_current_frame() is called twice. First from 
generic_pop_current_frame() and then immediately from cfi_pop_frame(). 
I'll test if it's safe to remove the second call and eventually send a 
patch.

Michal Ludvig
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