Re: GCC 3.0 Status Report

[Daniel Berlin <dberlin@redhat.com>]

Geoff Keating <geoffk@geoffk.org> writes:

> Mark Mitchell <mark@codesourcery.com> writes:
> 
> >   In the short term, we will focus on compile-time performance, 
> >   especially in C++.  At that point, application testing will 
> >   become the major focus.  Performance of the generated code
> >   will be a greater focus of the 3.1 release.
> 
> Hi Mark,
> 
> I have some news for you, which might be good or might be bad, your
> choice :-).
> 
> Jason Merrill took over the PCH stuff from where I left it, and
> finished the C++ support.  Based on the numbers I had for C, I
> expected a 2x or 3x speed improvement, which is nice but not
> earth-shattering.  However, we have some new numbers from Daniel
> Berlin which indicates that the speed improvement is more on the order
> of 20x, when compiling KDE; I guess I just didn't realize how huge C++
> headers were.

Just to give you some idea of the largeness of C++ headers, I took a
random KDE app, khotkeys, took all of the headers it includes that
aren't specific to itself (IE those in qt2/include and kde2/include
only), through them in a file, and -save-temps'd it, and removed
blank lines, to see how much code it was:

bash-2.04# cat test.cc
#include "test.h"
bash-2.04# cat test.h
#include <kapp.h>
#include <klineedit.h>
#include <kwin.h>
#include <krun.h>
#include <kdesktopfile.h>
#include <ksimpleconfig.h>
#include <kurifilter.h>
#include <kstddirs.h>
#include <kdebug.h>
#include <kuniqueapp.h>
#include <qtimer.h>
#include <dcopobject.h>
#include <kurifilter.h>
#include <kglobalaccel.h>
bash-2.04# remblanklines test.ii
bash-2.04# wc test.ii
   8780   38085  300160 noblanks
This isn't uncommon, and is the very low end (khotkeys is three C++
files, total). 

--Dan