I've found a major performance regression in gcc 4.0.0's optimization of the
BYTEmark numsort benchmark. I've boiled it down to a testcase that I think will
suit you... it outputs a single number representing the number of iterations run
(higher is better). On my machine I get 900ish under 4.0.0 and around 1530 on
3.4.3.
Both were compiled and run in a Gentoo test partition, if that makes a
difference:
3.4.3: gcc version 3.4.3-20050110 (Gentoo Linux 3.4.3.20050110-r2,
ssp-3.4.3.20050110-0, pie-8.7.7)
4.0.0: gcc version 4.0.0 (Gentoo Linux 4.0.0)
--
Summary: BYTEmark numsort: performance regression 3.4.3 -> 4.0.0
with -O3 optimization
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jbucata at tulsaconnect dot com
CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21485
