https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66948
Bug ID: 66948 Summary: Performance regression in bit manipulation code Product: gcc Version: unknown 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 36017 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36017&action=edit Testcase The attached test code requires significantly more CPU time when compiled with current trunk, compared to gcc 4.8.4 and the gcc 5 branch. gcc 4.8.4: martin@marvin ~/lsnew $ gcc -std=c99 -O3 testcase.c martin@marvin ~/lsnew $ time ./a.out real 0m4.039s user 0m4.041s sys 0m0.000s gcc 5 branch: martin@marvin ~/lsnew $ gcc -std=c99 -O3 testcase.c martin@marvin ~/lsnew $ time ./a.out real 0m3.820s user 0m3.822s sys 0m0.000s trunk: martin@marvin ~/lsnew $ gcc -std=c99 -O3 testcase.c martin@marvin ~/lsnew $ time ./a.out real 0m4.492s user 0m4.493s sys 0m0.004s