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* [Bug c++/97094] New: Compiling big std::unordered_map<std::string, bool> became slower
@ 2020-09-17 17:58 a.morozov at drweb dot com
2020-09-18 6:12 ` [Bug c++/97094] " rguenth at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: a.morozov at drweb dot com @ 2020-09-17 17:58 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97094
Bug ID: 97094
Summary: Compiling big std::unordered_map<std::string, bool>
became slower
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: a.morozov at drweb dot com
Target Milestone: ---
Make C++ code with big std::unordered_map<std::string, bool>:
$ cat str_map.cc
#include <string>
#include <unordered_map>
std::unordered_map<std::string, bool> m = {
#include "str.h"
};
$ find /usr/include | xargs -Iaaa echo '{"aaa", true},' >str.h
$ head -5 str.h
{"/usr/include", true},
{"/usr/include/syscall.h", true},
{"/usr/include/netash", true},
{"/usr/include/netash/ash.h", true},
{"/usr/include/lber.h", true},
$ wc -l str.h
6362 str.h
Compile it with different g++ versions:
$ time -p g++-9.3.0 -std=c++17 -c str_map.cc
real 6,35
user 5,96
sys 0,24
$ time -p g++-10.2.0 -std=c++17 -c str_map.cc
real 32,11
user 27,09
sys 2,32
10.2 is much slower than 9.3.
$ g++-9.3.0 -v
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
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)
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/97094] Compiling big std::unordered_map<std::string, bool> became slower
2020-09-17 17:58 [Bug c++/97094] New: Compiling big std::unordered_map<std::string, bool> became slower a.morozov at drweb dot com
@ 2020-09-18 6:12 ` rguenth at gcc dot gnu.org
2020-09-18 11:45 ` a.morozov at drweb dot com
2020-09-28 14:01 ` ppalka at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2020-09-18 6:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97094
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Can you try to specify an explicit -std=c++xy?
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/97094] Compiling big std::unordered_map<std::string, bool> became slower
2020-09-17 17:58 [Bug c++/97094] New: Compiling big std::unordered_map<std::string, bool> became slower a.morozov at drweb dot com
2020-09-18 6:12 ` [Bug c++/97094] " rguenth at gcc dot gnu.org
@ 2020-09-18 11:45 ` a.morozov at drweb dot com
2020-09-28 14:01 ` ppalka at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: a.morozov at drweb dot com @ 2020-09-18 11:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97094
--- Comment #2 from Alexander Morozov <a.morozov at drweb dot com> ---
$ 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)
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/97094] Compiling big std::unordered_map<std::string, bool> became slower
2020-09-17 17:58 [Bug c++/97094] New: Compiling big std::unordered_map<std::string, bool> became slower a.morozov at drweb dot com
2020-09-18 6:12 ` [Bug c++/97094] " rguenth at gcc dot gnu.org
2020-09-18 11:45 ` a.morozov at drweb dot com
@ 2020-09-28 14:01 ` ppalka at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: ppalka at gcc dot gnu.org @ 2020-09-28 14:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97094
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ppalka at gcc dot gnu.org
--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
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%)
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-09-28 14:01 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-09-17 17:58 [Bug c++/97094] New: Compiling big std::unordered_map<std::string, bool> became slower a.morozov at drweb dot com
2020-09-18 6:12 ` [Bug c++/97094] " rguenth at gcc dot gnu.org
2020-09-18 11:45 ` a.morozov at drweb dot com
2020-09-28 14:01 ` ppalka at gcc dot gnu.org
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