https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114978
Bug ID: 114978
Summary: 548.exchange2_r 14%-28% regressions on Loongarch64
after gcc 14 snapshot 20240317
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: chz0808 at gmail dot com
Target Milestone: ---
We tested Loongarch64 CPU Loongson 3A6000 with "LA664" architecture in Linux
operating system AOSC OS 11.4.0 (default gcc version is 13.2.0). And we found
the 548.exchange2_r benchmark from SPEC 2017 INTrate suite suffered significant
regressions from 14% to 28% with various compiling options.
The rate-1 results are following:
after snapshot 20240317 score 14.3-19.3% lower with parameters "-g -Ofast
-march=native":
13.2.0: 11.7 (223s) [gcc 13.2.0, system default]
20240317: 11.0 (237s) [gcc 14 snapshot 20240317]
20240324: 8.88 (295s) [gcc 14 snapshot 20240324]
20240430: 9.03 (290s) [gcc 14 snapshot 20240430, 14.1.0-RC]
14.1.0: 9.43 (278s) [gcc 14.1.0 release]
after snapshot 20240317 score 16.5-20.8% lower with parameters "-g -Ofast
-march=native -flto":
13.2.0: 12.0 (218s)
20240317: 10.6 (248s)
20240324: 8.40 (312s)
20240430: 8.48 (309s)
14.1.0: 8.85 (296s)
after snapshot 20240317 score 18-23.1% lower with parameters "-g -Ofast
-march=la664":
13.2.0: "-march=la664" flag is not supported
20240317: 11.5 (227s)
20240324: 8.84 (296s)
20240430: 9.43 (278s)
14.1.0: 9.42 (278s)
after snapshot 20240317 score 20.3-21.2% lower with parameters "-g -Ofast
-march=la664 -flto":
13.2.0: "-march=la664" flag is not supported
20240317: 11.1 (236s)
20240324: 8.75 (299s)
20240430: 8.85 (296s)
14.1.0: 8.85 (296s)
after snapshot 20240317 score 26.3-26.6% lower with parameters "-g -Ofast
-march=la464":
13.2.0: 8.76 (299s)
20240317: 12.8 (205s)
20240324: 9.39 (279s)
20240430: 9.43 (278s)
14.1.0: 9.43 (278s)
after snapshot 20240317 score 26.6-28% lower with parameters "-g -Ofast
-march=la464 -flto":
13.2.0: 8.52 (307s)
20240317: 12.8 (204s)
20240324: 9.22 (284s)
20240430: 9.37 (280s)
14.1.0: 9.40 (279s)
The gcc 14 snapshots and gcc 14.1.0 are compiled with the following parameters:
--enable-shared --enable-threads=posix --with-system-zlib
--enable-gnu-indirect-function --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch
--disable-libssp --enable-gnu-unique-object --enable-linker-build-id
--enable-lto --enable-plugin --enable-install-libiberty --disable-multilib
--disable-werror --enable-pie --enable-checking=release
--enable-libstdcxx-dual-abi --with-default-libstdcxx-abi=new
--enable-default-pie --enable-default-ssp --enable-bootstrap
--enable-languages=c,c++,fortran,lto --with-abi=lp64d --with-arch=loongarch64
--with-tune=la664 --build=loongarch64-aosc-linux-gnu
The regression may be found on other types of CPUs as well. We did a quick test
on AMD Zen4 CPU R9 7940HS and found similar but smaller regression:
The rate-1 results on x86_64 (AMD R9 7940HS) with operating system Debian 12:
after snapshot 20240317 score 8.6-9.6% lower with parameters "-m64 -g -Ofast
-march=znver3":
12.2.0: 30.1 (87.0s) [gcc 12.2.0, system default]
13.2.0: 30.6 (85.7s) [gcc 13.2 release]
20240317: 31.4 (83.3s) [gcc 14 snapshot]
20240324: 28.7 (91.2s) [gcc 14 snapshot]
20240430: 28.4 (92.2s) [gcc 14 snapshot, 14.1.0-RC]
after snapshot 20240317 score 10% lower with parameters "-m64 -g -Ofast
-march=znver3 -flto":
12.2.0: 29.0 (90.3s)
13.2.0: 30.9 (84.9s)
20240317: 32.0 (81.8s)
20240324: 28.8 (90.9s)
20240430: 28.8 (91.1s)
gcc13 and gcc14 are compiled with the following parameters:
--enable-shared --enable-threads=posix --with-system-zlib
--enable-gnu-indirect-function --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch
--disable-libssp --enable-gnu-unique-object --enable-linker-build-id
--enable-lto --enable-plugin --enable-install-libiberty --disable-multilib
--disable-werror --enable-pie --enable-checking=release
--enable-libstdcxx-dual-abi --with-default-libstdcxx-abi=new
--enable-default-pie --enable-default-ssp --enable-bootstrap
--enable-languages=c,c++,fortran,lto --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
