https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81614
Uroš Bizjak <ubizjak at gmail dot com> changed:
What |Removed |Added
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CC| |hjl.tools at gmail dot com
--- Comment #1 from Uroš Bizjak <ubizjak at gmail dot com> ---
This transformation is handled by -mtune-ctrl=partial_reg_stall tune flag (and
more specifically, -mtune-ctrl=^promote_qimode flag).
Partial register stalls were discussed many times in the past, but apparently
the compiler still produces fastest code when partial register stalls are
enabled on latest target processors (e.g. -mtune=intel).
BTW, there are quite some flags in x86-tune.def under:
/*****************************************************************************/
/* Historical relics: tuning flags that helps a specific old CPU designs */
/*****************************************************************************/
where nobody bothered to change defaults for new processors.
Also, it is hard to confirm tuning PRs without hard benchmark data.
Adding CC.
