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What to do about compile time slowdowns for 4.1?
- From: Steven Bosscher <stevenb at suse dot de>
- To: gcc at gcc dot gnu dot org
- Date: Tue, 30 Aug 2005 00:20:11 +0200
- Subject: What to do about compile time slowdowns for 4.1?
Hi,
We're supposed to be getting closer to a 4.1 release branch, but just
like in the past so-many releases we have succeeded again in slowing
down GCC, and we've slowed it down a _lot_ compared even to GCC 4.0.
Taking SPECint and CSiBE as examples:
http://www.suse.de/~aj/SPEC/amd64/CINT/sandbox-britten/Total-time_big.png
http://www.inf.u-szeged.hu/csibe/draw-diag.php?draw=sum-ot&basephp=s-i686-linux
So for compiling all of SPECint with "-O2 -march=k8" on AMD64, we have
slowed down from ~210s for GCC 4.0 to >250s for CVS HEAD.
Another example: the cc1-i files of "4.0.0 20041202 (experimental)" on
AMD64, all compilers checked out from CVS and bootstrapped with checking
disabled, and compiling those 569 files with "cc1 -O2 -quiet":
3.3 user 4m10.053s
3.4 user 4m9.642s
4.0 user 4m25.517s
HEAD user 4m53.167s
So GCC 4.1 right now is a small compile time disaster. Are there any
ideas for what can be done about it before releasing it?
Gr.
Steven