This is the mail archive of the
mailing list for the GCC project.
Re: Some benchmarks comparing gcc-3.4.3 and 4.0.0 on PowerPC G5
- From: Steven Bosscher <stevenb at suse dot de>
- To: gcc at gcc dot gnu dot org
- Cc: Bradley Lucier <lucier at math dot purdue dot edu>
- Date: Sun, 2 Jan 2005 11:47:09 +0100
- Subject: Re: Some benchmarks comparing gcc-3.4.3 and 4.0.0 on PowerPC G5
- Organization: SUSE Labs
- References: <C09506A8-5C8F-11D9-A1A3-003065BA681E@math.purdue.edu>
On Sunday 02 January 2005 08:27, Bradley Lucier wrote:
> I've put some benchmark results comparing compile and run times for C
> code generated by the Gambit-C Scheme->C compiler at
> There are a fair number of tests where the compile times for 4.0.0 are
> > 1.5 times the corresponding compile times for 3.4.3. (Both were
> built without checking.) The run-time comparisons are more difficult
> to interpret; these tests were run as much to compare -mcpu and -mtune
> options on G5 as to compare compiler performance.
> The rest of the directory has the raw data, but I'm not sure it will
> tell you much more than the table.
1) The 4.0 compilers are probably slower because all but one of the
tree-ssa optimizations are enabled at -O1. It would be interesting
to see results for -O2. We should see about turning off some of
the expensive things in tree-ssa, such as iterating DOM, at -O1.
2) You should probably compare columns with matching flags. Comparing
"4.0.0 (no options)" with "3.4.3 -mcpu=G4 -mtune=G5" is not really
3) You say "each compiler was built without checking". Do you mean
built as in "make" instead of "make bootstrap"? I compared compile
times of GCC4 built with GCC 3.4.2 vs. GCC4 built by itself, and
of GCC4 built with GCC 3.3.5 vs. GCC4 built by itself. I found that
GCC4 optimizes itself a lot better than those older GCCs. So it is
important to know if you did a plain "make", or a "make bootstrap".