https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67435
--- Comment #9 from Markus Trippelsdorf <trippels at gcc dot gnu.org> --- (In reply to Yann Collet from comment #8) > However, for some reason, in the table provided, both Sandy Bridge and > Haswell get a default loop alignment value of 16. not 32. > > Is there a reason for that choice ? These values are normally strait out of the Vendors manuals. And there are also drawbacks to high alignment values. > Less precise but still great, having the ability to set this optimization > parameter for a function or a section code would be great. But my experiment > seem to show that using #pragma or __attribute__ with align-loops does not > work, as if the optimization setting was simply ignored. Well, there already is an aligned attribute for functions, variables and fields, see: http://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes
