This is the mail archive of the mailing list for the glibc project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH 06/25] Add struct scratch_buffer and its internal helper functions

On Mon, 23 Mar 2015, Paul Eggert wrote:

> Florian Weimer wrote:
> > I would rather go with intmax_t because it's not
> > clear to me if __alignof__ (max_align_t) increases to 64 if AVX-512 is
> > enabled on x86_64.
> That would be a bug in the C compiler, right?
> Since C allows platforms where pointers and/or floating-point values have
> alignments stricter than intmax_t, I suggest using 'max (__alignof__
> (intmax_t), __alignof__ (max_align_t))' along with a comment explaining why
> you don't trust max_align_t here.

max_align_t was added to stddef.h in GCC 4.7, so we can't rely on it in 
glibc without appropriate conditionals.  However, I see no need to allow 
for it being wrong (in code that isn't used outside of glibc).

It may well be more-aligned than intmax_t, on platforms where long double 
has 16-byte size and alignment and intmax_t has 8-byte size and alignment 
- so that does need allowing for in glibc.

Joseph S. Myers

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]