On Jul 6, 2012, at 2:31 PM, Eli Friedman wrote: > On Fri, Jul 6, 2012 at 2:31 PM, Chad Rosier <[email protected]> wrote: >> >> On Jul 6, 2012, at 1:45 PM, Eli Friedman wrote: >> >>> On Fri, Jul 6, 2012 at 1:14 PM, Chad Rosier <[email protected]> wrote: >>>> All, >>>> Attached is a patch that enables a per target max vector alignment field >>>> (e.g., 32-byte alignment for x86 due to AVX). Currently, if no aligned >>>> attribute is specified the alignment of a vector is inferred from its >>>> size. Thus, very large vectors will be over-aligned with no benefit. >>>> With this patch in place the alignment will be the lesser of the size of >>>> the vector and the target max alignment unless an aligned attribute is >>>> used. >>> >>> It doesn't seem likely that x86 itself will go beyond 32-byte vectors, >>> but this sort of thing is hard to predict; a few years ago, it wasn't >>> obvious that x86 was going to introduce vectors with 32-byte >>> alignment. >> >> Ok. Do you have opinion for or against the patch or were you just making a >> general comment? > > I'm not entirely sure whether that's an argument for or against this > patch, just that we should be careful here; it's not uncommon for > architectures to introduce new vector types, and they usually want to > be natively aligned.
Understandable; my assumption was that if such a case occurs (i.e., a new vector type is introduced with a size larger then the current target max), then we would increase the max target alignment once the vector extensions are added. > -Eli _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
