[Bug target/114978] [14/15 regression] 548.exchange2_r 14%-28% regressions on Loongarch64 after gcc 14 snapshot 20240317

["chz0808 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114978

--- Comment #7 from Chen Chen <chz0808 at gmail dot com> ---
(In reply to Richard Biener from comment #6)
> https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=471.407.0
> 
> shows a recent improvement that then regressed again, maybe you have a
> similar artifact with the choosing of the snapshots.  Try a snapshot from
> february for comparison for example.

Thanks for the nice graph!

We did more tests on AMD Zen4 CPU R9 7940HS (system: Debian 12) and used
similar parameters as yours. The results are following:

with parameters "-m64 -g -Ofast -march=native":
13.2.0:    30.0 (87.2s) [gcc 13.2 release]
20240121:  29.8 (88.0s) [gcc 14 snapshot]
20240218:  29.8 (88.0s) [gcc 14 snapshot]
20240303:  29.2 (89.8s) [gcc 14 snapshot]
20240310:  31.7 (82.6s) [gcc 14 snapshot]
20240317:  31.7 (82.7s) [gcc 14 snapshot]
20240324:  28.3 (92.5s) [gcc 14 snapshot]
20240430:  28.4 (92.3s) [gcc 14 snapshot, 14.1.0-RC]
14.1.0:    28.4 (92.4s) [gcc 14.1 release]

with parameters "-m64 -g -Ofast -march=native -flto":
13.2.0:    30.5 (85.8s) [gcc 13.2 release]
20240121:  30.5 (85.9s) [gcc 14 snapshot]
20240218:  29.5 (88.7s) [gcc 14 snapshot]
20240303:  30.5 (86.0s) [gcc 14 snapshot]
20240310:  31.6 (82.8s) [gcc 14 snapshot]
20240317:  31.7 (82.7s) [gcc 14 snapshot]
20240324:  28.6 (91.6s) [gcc 14 snapshot]
20240430:  29.1 (89.9s) [gcc 14 snapshot, 14.1.0-RC]
14.1.0:    29.1 (90.1s) [gcc 14.1 release]

The scores with gcc 14.1 release are 8.2-10.4% lower than those with gcc 14
snapshot 20240317, and 4.6-5.3% lower than those with gcc 13.2 release.