Re: Precompiled headers (or other speed ups)

["Zack Weinberg" <zackw@Stanford.EDU>]

On Wed, Jan 10, 2001 at 09:53:18PM +0000, Neil Booth wrote:
> Zack Weinberg wrote:-
> 
> > The tokenizer is, in my tests, consistently faster than the analogue
> > in GCC 2.95.  Macro expansion can still be a bottleneck under some
> > conditions.
> 
> That's interesting.  Are these tests you've done recently?  i.e. is it
> since I moved us to the forwards-looking, almost-no-step-back lexer?
> It's good news if it is.

I haven't done a rigorous head-to-head test recently, but we are
measurably faster than we were in July, and that wasn't much slower
than 2.95.  This is C at -O0, so no major backend or parser
regressions to confuse the issue.

Most of the win is probably from not tokenizing twice.

> Stand-alone CPP is dog slow on token output (50%-70% of run-time!),
> because of GLIBC.  But we know that, and decided we don't care too
> much for the moment since for the common case we're now integrated.

*nod*

> If you like, I can work on the function-like macro expansion as a
> "performance enhancement" during the GCC 3.0 branch for release.  I
> think we can speed up nested function-like macros a lot (and have an
> old patch on my drive to do so, but it would need dusting off a
> little).

I think that'd be a good idea.

zw