I'm compiling the LLVM compiler infrastructure and have noticed that GCC 4.1
takes an excessively long time to compile versus GCC 4.0. In particular, one
file (albeit 2 million source lines) takes over 10 minutes (618.97 seconds) of
CPU time to compile. On the exact same source, GCC 4.0.2 takes just over 2
minutes (130.68 seconds). GCC 3.4 was even faster (from memory).
Here are the heavy-hitters (from -ftime-report) from highest to lowest:
usr sys wall mem
tree SSA incremental : 172.76 (30%) 0.61 ( 1%) 175.39 (22%) 9356kB ( 1%)
ggc
tree PHI insertion : 55.86 (10%) 0.30 ( 1%) 57.54 ( 7%) 6346kB ( 1%)
ggc
dominance frontiers : 40.15 ( 7%) 0.10 ( 0%) 40.02 ( 5%) 0kB ( 0%)
ggc
dominator optimization: 24.50 ( 4%) 0.57 ( 1%) 34.06 ( 4%) 74359kB ( 8%)
ggc
tree PTA : 19.51 ( 3%) 1.44 ( 3%) 22.90 ( 3%) 15806kB ( 2%)
ggc
PRE : 19.09 ( 3%) 6.52 (15%) 27.10 ( 3%) 1960kB ( 0%)
ggc
TOTAL : 576.55 42.42 794.94 957564 kB
Attached is a tarball that contains pre-compiled source code, and the timing
statistics for both 4.0.2 and 4.1.0 as generated by GCC.
This problem may have already been reported by or related to the following
bugs:
bug 18419, bug 17895, bug 17596.
Another thing to note. The object file for 4.1.0 is 21% larger than for 4.0.2
(1454880 vs 1759292).
Platform: (Linux FC3 with updates):
Linux 2.6.12-1.1381_FC3smp #1 SMP Fri Oct 21 04:03:26 EDT 2005 i686 i686 i386
GNU/Linux
gcc -v: (slow)
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc-4.1.0/configure --prefix=/proj/install
--enable-languages=c,c++,java --with-gnuas --with-gnuld
Thread model: posix
gcc version 4.1.0
gcc -v: (fast)
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../svn/configure --prefix=/proj/install2
--enable-languages=c,c++ --with-gnuld --with-gnuas
Thread model: posix
gcc version 4.0.2
--
Summary: Compiling LLVM now takes nearly 5x as long with 4.1 as
it did with 4.0
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rspencer at x10sys dot com
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27140
