https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111332
Bug ID: 111332 Summary: Using GCC7.3.0 and GCC10.3.0 to compile the same test case, assembler file instructions are different and performance fallback is obvious. Product: gcc Version: 10.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: d_vampile at 163 dot com Target Milestone: --- Created attachment 55850 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55850&action=edit test case Created Attachment Test platform: x86_64 Compiler Options: gcc main.c -g -o main -O2 -msse4.2 -mavx2 -fno-inline Runtime with gcc7.3.0: $ time ./main_gcc7.3 2000 start to run 2000. end to run 2000. real 6m30.461s user 6m26.587s sys 0m0.814s Runtime with gcc10.3.0: $ time ./main_gcc10.3 2000 start to run 2000. end to run 2000. real 7m18.696s user 7m13.912s sys 0m1.098s Programs compiled with gcc10.3.0 run significantly longer than gcc7.3.0