https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85416
Bug ID: 85416
Summary: Massive performance regression when switching on
"-march=native"
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: mar...@mpa-garching.mpg.de
Target Milestone: ---
Created attachment 43945
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43945&action=edit
Test case
When compiling the attached test case with
g++ -O3 -std=c++14 testcase.cc
and measuring the runtime via
time ./a.out
I get a CPU time of roughly 1.3 seconds
Recompiling with
g++ -O3 -std=c++14 -march=native testcase.cc
increases run time to over 8 seconds.
CPU: Intel Core i5-5300U
This was measured on trunk (gcc version 8.0.1 20180411), but I see similar
performance degradations already in gcc 5.4.
