[Bug middle-end/102294] structure assignment slower than memberwise initialization

pinskia at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Sun Sep 12 22:17:38 GMT 2021


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102294

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note the Linux kernel compiles with -mno-sse where the results are hugely
difference than what can be done in the usespace where SSE can provide a speed
boost.

The easiest way to test this is to use -m32 -mno-sse

GCC:

bio_init1 Elapsed time: 2.427399 s
bio_init2 Elapsed time: 1.757616 s
bio_init3 Elapsed time: 1.959703 s

clang:
bio_init1 Elapsed time: 1.409902 s
bio_init2 Elapsed time: 1.796531 s
bio_init3 Elapsed time: 2.016957 s


So I think this might be wash for the kernel.


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