https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79966
Bug ID: 79966
Summary: [6/7 Regression] run time more than twice slower when
using -fipa-cp-clone
Product: gcc
Version: 7.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: dominiq at lps dot ens.fr
Target Milestone: ---
Created attachment 40927
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40927&action=edit
reduced test from pr79930
This PR is a sequel of pr79930. On gcc6 and trunk (7.0) the run time is more
than twice slower when the attached test is compiled with -fipa-cp-clone in
addition to -O2 -fpeel-loops -finline-functions:
% gfca sum_xy.f90 -O2 -fpeel-loops -finline-functions
% ./a.out
Using SUM, time: 9.28960443E-02
sum = -19609.087488337318
% gfca sum_xy.f90 -O2 -fpeel-loops -fipa-cp-clone -finline-functions
% ./a.out
Using SUM, time: 0.264802039
sum = -56108.398701889098
% gfc6 sum_xy.f90 -O2 -fpeel-loops -finline-functions
% ./a.out
Using SUM, time: 9.48660374E-02
sum = -27582.388828175150
% gfc6 sum_xy.f90 -O2 -fpeel-loops -fipa-cp-clone -finline-functions
% ./a.out
Using SUM, time: 0.279235005
sum = -37131.668569316826
% gfc5 sum_xy.f90 -O2 -fpeel-loops -finline-functions
% ./a.out
Using SUM, time: 0.106678963
sum = 6552.5940282615447
% gfc5 sum_xy.f90 -O2 -fpeel-loops -fipa-cp-clone -finline-functions
% ./a.out
Using SUM, time: 0.104918003
sum = 28692.268429922191
gfca is trunk at r245974, gfc6 is 6.3.1 at r245745, and gfc5 is 5.4.1 at
r245752.
Looking at my archives it seems that the regression appeared un gcc5 before
branching, but has been reverted since, while always being in the gcc6 branch.
