https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65076
--- Comment #63 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
I think we can close this bug. gcc-6 now compiles faster than gcc-5
and the resulting binary also runs slightly faster.
CXXFLAGS="-std=c++14 -w -Ofast" for all compilers
gcc-4.9: 24.199 compile time
gcc-5 : 27.311 compile time
Performance counter stats for './a.out --cartvis 1.0 0.0 --rhomin 1e-8 -n 20'
(5 runs):
3200.800294 task-clock (msec) # 1.000 CPUs utilized
( +- 0.05% ) (99.99%)
7 context-switches # 0.002 K/sec
( +- 25.56% ) (99.99%)
0 cpu-migrations # 0.000 K/sec
(99.99%)
17,310 page-faults # 0.005 M/sec
( +- 0.01% ) (99.99%)
10,252,877,203 cycles # 3.203 GHz
( +- 0.05% ) (66.63%)
185,288,587 stalled-cycles-frontend # 1.81% frontend cycles
idle ( +- 0.51% ) (66.65%)
6,775,673,735 stalled-cycles-backend # 66.09% backend cycles
idle ( +- 0.07% ) (66.68%)
8,661,344,185 instructions # 0.84 insns per cycle
# 0.78 stalled cycles per
insn ( +- 0.10% ) (66.72%)
660,295,960 branches # 206.291 M/sec
( +- 0.45% ) (66.75%)
10,126,045 branch-misses # 1.53% of all branches
( +- 0.35% ) (66.68%)
3.201031138 seconds time elapsed
( +- 0.05% )
gcc-6 : 26.258 compile time
Performance counter stats for './a.out --cartvis 1.0 0.0 --rhomin 1e-8 -n 20'
(5 runs):
3134.574551 task-clock (msec) # 1.000 CPUs utilized
( +- 0.13% ) (99.99%)
111 context-switches # 0.035 K/sec
( +- 58.99% ) (99.99%)
0 cpu-migrations # 0.000 K/sec
(99.99%)
17,308 page-faults # 0.006 M/sec
( +- 0.00% ) (99.99%)
10,035,141,160 cycles # 3.201 GHz
( +- 0.12% ) (66.65%)
173,085,246 stalled-cycles-frontend # 1.72% frontend cycles
idle ( +- 2.71% ) (66.65%)
6,752,556,601 stalled-cycles-backend # 67.29% backend cycles
idle ( +- 0.15% ) (66.66%)
8,195,763,733 instructions # 0.82 insns per cycle
# 0.82 stalled cycles per
insn ( +- 0.19% ) (66.74%)
635,509,854 branches # 202.742 M/sec
( +- 0.46% ) (66.75%)
9,900,182 branch-misses # 1.56% of all branches
( +- 0.69% ) (66.67%)
3.135833601 seconds time elapsed
( +- 0.15% )
clang: 39.317 compile time
Performance counter stats for './a.out --cartvis 1.0 0.0 --rhomin 1e-8 -n 20'
(5 runs):
6026.232154 task-clock (msec) # 1.000 CPUs utilized
( +- 0.03% ) (99.99%)
129 context-switches # 0.021 K/sec
( +- 91.87% ) (99.99%)
0 cpu-migrations # 0.000 K/sec
( +-100.00% ) (99.99%)
17,314 page-faults # 0.003 M/sec
( +- 0.00% ) (99.99%)
19,304,680,254 cycles # 3.203 GHz
( +- 0.04% ) (66.64%)
190,735,168 stalled-cycles-frontend # 0.99% frontend cycles
idle ( +- 3.62% ) (66.64%)
10,488,375,287 stalled-cycles-backend # 54.33% backend cycles
idle ( +- 0.08% ) (66.69%)
19,895,781,820 instructions # 1.03 insns per cycle
# 0.53 stalled cycles per
insn ( +- 0.08% ) (66.70%)
945,624,800 branches # 156.918 M/sec
( +- 0.37% ) (66.69%)
13,241,690 branch-misses # 1.40% of all branches
( +- 0.42% ) (66.67%)
6.027538343 seconds time elapsed
( +- 0.04% )
