Variable tracking (location lists support) - part 1

[Vladimir Makarov]

law@redhat.com wrote:

>In message <Pine.LNX.4.58.0401291957130.23288@digraph.polyomino.org.uk>, "Josep
>h S. Myers" writes:
> >On Thu, 29 Jan 2004, Josef Zlomek wrote:
> >
> >> Without location lists, GDB printed some wierd values when debugging
> >> optimized code.  GDB with support of location lists (GDB 6.0.1 and newer)
> >> shows correct values of variables even when debugging optimized code
> >> even with -fomit-frame-pointer (when !frame_pointer_needed a special locati
> >on
> >> list for describing the changes of stack pointer is emitted).
> >
> >Does this mean that some targets that didn't previously should now have
> >-fomit-frame-pointer enabled at -O?  (The documentation saying
> >"@option{-O} also turns on @option{-fomit-frame-pointer} on machines where
> >doing so does not interfere with debugging.".)
>That would be a significant step forward -- being able to turn on FP
>elimination for ia32 is probably the easiest way to get a measureable
>performance improvement I can think of :-)
>  
>

>Yes, that is true.  As I remember the improvement was 1.5-2% for pentium4 on SPECINT2000.
>  
>
Vlad

>  
>