[Bug c/67435] Large performance drop on apparently unrelated changes (probable cause : strange inlining side-effect)

[yann.collet.73 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67435

--- Comment #5 from Yann Collet <yann.collet.73 at gmail dot com> ---
Complementary information :

-Winline : does not output anything (is that normal ?)

-fdump-ipa-inline : produce several large files, the interesting one being 1.5
MB long. That's a huge dump to analyze.

Nonetheless, I had a deeper look directly at the function which speed is
affected.
Looking at both slow and fast versions, I could spot *no difference* regarding
inline decisions. From what I can tell, the dump file seems strictly identical.

(note : there could be some differences somewhere else that I did not spotted).


Since then, I've also been suggested that maybe this effect could related to
something else, instruction cache line alignment.