[Bug c++/97094] Compiling big std::unordered_map became slower

[ppalka at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97094

Patrick Palka  changed:

   What|Removed |Added

 CC||ppalka at gcc dot gnu.org

--- Comment #3 from Patrick Palka  ---
With GCC 10/11, according to -ftime-report most of the time/memory usage is
from


tree eh:   1.10 ( 40%)   0.18 ( 31%)   1.29 ( 38%) 
642338 kB ( 84%)

[Bug c++/97094] Compiling big std::unordered_map became slower

[a.morozov at drweb dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97094

--- Comment #2 from Alexander Morozov  ---
$ g++-9.3.0 -v -std=c++17
Using built-in specs.
COLLECT_GCC=g++-9.3.0
COLLECT_LTO_WRAPPER=/srv/projects/gcc/gcc-9.3.0-build/libexec/gcc/x86_64-pc-linux-gnu/9.3.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ./configure --enable-languages=c,c++
--prefix=/srv/projects/gcc/gcc-9.3.0-build
Thread model: posix
gcc version 9.3.0 (GCC)
$ g++-10.2.0 -v -std=c++17
Using built-in specs.
COLLECT_GCC=g++-10.2.0
COLLECT_LTO_WRAPPER=/srv/projects/gcc/gcc-10.2.0-build/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ./configure --enable-languages=c,c++
--prefix=/srv/projects/gcc/gcc-10.2.0-build
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.2.0 (GCC)

Also tried 11.0.0 20200913. The result does not look better:
$ time -p g++-9.3.0 -std=c++17 -c str_map.cc
real 6,64
user 6,06
sys 0,22
$ time -p g++-11 -std=c++17 -c str_map.cc
real 68,83
user 62,11
sys 2,76

$ g++-11 -v -std=c++17
Using built-in specs.
COLLECT_GCC=g++-11
COLLECT_LTO_WRAPPER=/srv/projects/gcc/gcc-11-20200913-build/libexec/gcc/x86_64-pc-linux-gnu/11.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ./configure --enable-languages=c,c++
--prefix=/srv/projects/gcc/gcc-11-20200913-build
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 11.0.0 20200913 (experimental) (GCC)

[Bug c++/97094] Compiling big std::unordered_map became slower

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97094

--- Comment #1 from Richard Biener  ---
Can you try to specify an explicit -std=c++xy?