Re: inline-limit: some experimental feedback

[Gerald Pfeifer <pfeifer at dbai dot tuwien dot ac dot at>]

On Tue, 21 Aug 2001, Richard B. Kreckel wrote:
> Okay, I just learned that Gerald has set the default
> PARAM_MAX_INLINE_INSNS from 10000 down to 600 in order to remedy
> compile-time performance regressions.

Minor correction: I have *increased* the limit from 100 to 600 based on
tests, never decreased it:

   http://gcc.gnu.org/ml/gcc-patches/2001-08/msg00061.html

Neither the tree-based inliner per se, nor the switch to libstdc++-v3, nor
the decrease to 100 had been performance-tested in a suitable way; this is
why GCC 3.0 and 3.0.1 appear as bad as they do compile-time and run-time
performance-wise for many C++ sources.


However, tweaking this parameter is a band-aid in any case: Even if we
tune for maximum compile-time performance or maximum run-time performance,
the result with GCC 3.0 and 3.0.1 is *still* worse than GCC 2.95.x in both
terms (for my projects at least).

The proper fix really is to improve the inliner.

Gerald

PS: Increasing the value to 2000 would tripple compile-time for my
projects, for example, and also increase binary size quite a bit.
-- 
Gerald "Jerry" pfeifer@dbai.tuwien.ac.at http://www.dbai.tuwien.ac.at/~pfeifer/