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Re: [wip] Delete prev_func_name and ecs->stop_func_name
On Wed, Apr 16, 2003 at 10:28:42AM -0400, Andrew Cagney wrote:
> >On Wed, Apr 16, 2003 at 12:29:25AM -0400, Andrew Cagney wrote:
> >
> >>Running the i386 testsuite with gcov on an existing GDB reveals:
> >>
> >> int
> >> find_pc_sect_partial_function
> >> 10133 {
> >> 10133 struct partial_symtab *pst;
> >> struct symbol *f;
> >> struct minimal_symbol *msymbol;
> >> struct partial_symbol *psb;
> >> struct obj_section *osect;
> >> int i;
> >> CORE_ADDR mapped_pc;
> >>
> >> 10133 mapped_pc = overlay_mapped_address (pc, section);
> >>
> >> 10133 if (mapped_pc >= cache_pc_function_low
> >> && mapped_pc < cache_pc_function_high
> >> && section == cache_pc_function_section)
> >> 3565 goto return_cached_value;
> >>
> >> 3565 if (SIGTRAMP_START_P () && ...
> >>
> >>that is, 10133 calls to find_pc_sect_partial_function, 3565 of which
> >>missed in the cache. Modifying infrun.c so that it doesn't cache the
> >>name turns up:
> >>
> >> int
> >> find_pc_sect_partial_function
> >> 12087 {
> >> 12087 struct partial_symtab *pst;
> >> struct symbol *f;
> >> struct minimal_symbol *msymbol;
> >> struct partial_symbol *psb;
> >> struct obj_section *osect;
> >> int i;
> >> CORE_ADDR mapped_pc;
> >>
> >> 12087 mapped_pc = overlay_mapped_address (pc, section);
> >>
> >> 12087 if (mapped_pc >= cache_pc_function_low
> >> && mapped_pc < cache_pc_function_high
> >> && section == cache_pc_function_section)
> >> 3569 goto return_cached_value;
> >
> >
> >What're the following lines for both of these? There's some
> >optimization at work here, or these numbers show the exact opposite of
> >what you want. That's 3569 _hits_ to the cache.
>
> No.
>
> > But matching the
> >execution count for the line after the goto is suspicious.
>
> It's gcov playing tricks, the goto is being counted in the false path.
> The first analysis illustrates this:
>
> >>> 3565 goto return_cached_value;
> >>>
> >>> 3565 if (SIGTRAMP_START_P () && ...
>
> and the second is identical.
In that case, go for it!
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer