[Bug c++/86091] [fold expression] Slow compile time and high memory usage compared to initializer_list folds

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86091

Jonathan Wakely  changed:

   What|Removed |Added

 Resolution|FIXED   |WORKSFORME

--- Comment #3 from Jonathan Wakely  ---
(In reply to Vasili Burdo from comment #0)
> I tried multiple GCC versions starting from 5.3 to 8.0.0 on Ubuntu and
> Windows (MINGW) all of them have the same problem.

How did you test it with 5.3 when it doesn't even support fold expressions?

I can't reproduce the slowness with any version of GCC at all.

tmp$ time ~/gcc/6.1.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc -DBUG

real0m0.284s
user0m0.234s
sys 0m0.048s
tmp$ time ~/gcc/6.1.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc 

real0m0.267s
user0m0.235s
sys 0m0.028s
tmp$ time ~/gcc/6.2.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc -DBUG

real0m1.231s
user0m0.271s
sys 0m0.081s
tmp$ time ~/gcc/6.2.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc 

real0m0.298s
user0m0.225s
sys 0m0.037s
tmp$ time ~/gcc/6.3.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc -DBUG

real0m1.260s
user0m0.287s
sys 0m0.075s
tmp$ time ~/gcc/6.3.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc 

real0m0.317s
user0m0.230s
sys 0m0.034s
tmp$ time ~/gcc/6.4.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc -DBUG

real0m0.280s
user0m0.239s
sys 0m0.038s
tmp$ time ~/gcc/6.4.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc 

real0m0.264s
user0m0.226s
sys 0m0.035s
tmp$ time ~/gcc/7.1.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc -DBUG

real0m0.313s
user0m0.254s
sys 0m0.056s
tmp$ time ~/gcc/7.1.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc 

real0m0.304s
user0m0.266s
sys 0m0.036s
tmp$ time ~/gcc/7.2.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc -DBUG

real0m0.299s
user0m0.247s
sys 0m0.050s
tmp$ time ~/gcc/7.2.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc 

real0m0.281s
user0m0.245s
sys 0m0.034s
tmp$ time ~/gcc/7.3.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc -DBUG

real0m0.574s
user0m0.534s
sys 0m0.036s
tmp$ time ~/gcc/7.3.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc 

real0m0.632s
user0m0.592s
sys 0m0.037s
tmp$ time ~/gcc/8.1.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc -DBUG

real0m0.334s
user0m0.305s
sys 0m0.027s
tmp$ time ~/gcc/8.1.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc 

real0m0.652s
user0m0.610s
sys 0m0.040s
tmp$ time ~/gcc/8.2.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc -DBUG

real0m0.169s
user0m0.140s
sys 0m0.026s
tmp$ time ~/gcc/8.2.0/bin/g++  -std=gnu++1z -Wall -Wextra 86091.cc 

real0m0.296s
user0m0.249s
sys 0m0.043s

[Bug c++/86091] [fold expression] Slow compile time and high memory usage compared to initializer_list folds

[vasili.burdo at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86091

Vasili Burdo  changed:

   What|Removed |Added

 Status|UNCONFIRMED |RESOLVED
 Resolution|--- |FIXED

--- Comment #2 from Vasili Burdo  ---
Confirmed.

As of current git (master 571ee70a6d4), fold expression compliation is fast.

[Bug c++/86091] [fold expression] Slow compile time and high memory usage compared to initializer_list folds

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86091

--- Comment #1 from Richard Biener  ---
I can't reproduce the slowness.

> /usr/bin/time g++-8 t.C  -std=gnu++1z  -Wall -Wextra 
0.23user 0.04system 0:00.27elapsed 99%CPU (0avgtext+0avgdata 44028maxresident)k
0inputs+1568outputs (0major+14354minor)pagefaults 0swaps
> /usr/bin/time g++-8 t.C  -std=gnu++1z  -Wall -Wextra -DBUG
0.18user 0.03system 0:00.22elapsed 100%CPU (0avgtext+0avgdata
30476maxresident)k
0inputs+1408outputs (0major+10204minor)pagefaults 0swaps