http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58999
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
--enable-checking=release makes quite a big difference
$ time ~/gcc/4.x/bin/g++ -std=c++11 -c t.cc -ftime-report
Execution times (seconds)
phase setup : 0.00 ( 0%) usr 0.01 ( 2%) sys 0.05 ( 0%) wall
1323 kB ( 0%) ggc
phase parsing : 12.84 (100%) usr 0.44 (96%) sys 13.31 (99%) wall
1422475 kB (100%) ggc
phase opt and generate : 0.00 ( 0%) usr 0.01 ( 2%) sys 0.09 ( 1%) wall
42 kB ( 0%) ggc
phase last asm : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
0 kB ( 0%) ggc
|overload resolution : 0.03 ( 0%) usr 0.01 ( 2%) sys 0.03 ( 0%) wall
1153 kB ( 0%) ggc
garbage collection : 0.19 ( 1%) usr 0.00 ( 0%) sys 0.19 ( 1%) wall
0 kB ( 0%) ggc
parser function body : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
1 kB ( 0%) ggc
template instantiation : 12.65 (99%) usr 0.44 (96%) sys 13.11 (97%) wall
1422149 kB (100%) ggc
tree gimplify : 0.00 ( 0%) usr 0.01 ( 2%) sys 0.00 ( 0%) wall
0 kB ( 0%) ggc
tree STMT verifier : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
0 kB ( 0%) ggc
expand : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall
1 kB ( 0%) ggc
LRA non-specific : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
0 kB ( 0%) ggc
shorten branches : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall
0 kB ( 0%) ggc
symout : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
0 kB ( 0%) ggc
rest of compilation : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.03 ( 0%) wall
2 kB ( 0%) ggc
TOTAL : 12.84 0.46 13.50
1423858 kB
Extra diagnostic checks enabled; compiler may run slowly.
Configure with --enable-checking=release to disable checks.
real 0m14.014s
user 0m12.853s
sys 0m0.528s
$ time ~/gcc/4.x-release/bin/g++ -std=c++11 -c t.cc -ftime-report
Execution times (seconds)
phase setup : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.05 ( 1%) wall
1374 kB ( 0%) ggc
phase parsing : 7.40 (100%) usr 0.28 (100%) sys 7.71 (98%)
wall 1422475 kB (100%) ggc
phase opt and generate : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.05 ( 1%) wall
42 kB ( 0%) ggc
phase last asm : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
0 kB ( 0%) ggc
|overload resolution : 0.06 ( 1%) usr 0.01 ( 4%) sys 0.07 ( 1%) wall
1153 kB ( 0%) ggc
garbage collection : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
0 kB ( 0%) ggc
parser (global) : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall
309 kB ( 0%) ggc
template instantiation : 7.39 (100%) usr 0.28 (100%) sys 7.68 (98%)
wall 1422149 kB (100%) ggc
expand : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
1 kB ( 0%) ggc
integrated RA : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
24 kB ( 0%) ggc
shorten branches : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
0 kB ( 0%) ggc
symout : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall
0 kB ( 0%) ggc
rest of compilation : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall
2 kB ( 0%) ggc
TOTAL : 7.41 0.28 7.83
1423909 kB
real 0m8.237s
user 0m7.420s
sys 0m0.328s
But it's still orders of magnitude slower than clang
