Date: Sun, 15 Dec 2019 13:06:29 -0500 From: Jeffrey Walton <noloader@...il.com> To: musl@...ts.openwall.com Subject: Re: max_align_t mess on i386 On Sat, Dec 14, 2019 at 10:19 AM Rich Felker <dalias@...c.org> wrote: > > In reserching how much memory could be saved, and how practical it > would be, for the new malloc to align only to 8-byte boundaries > instead of 16-byte on archs where alignof(max_align_t) is 8 (pretty > much all 32-bit archs), I discovered that GCC quietly changed its > idead of i386 max_align_t to 16-byte alignment in GCC 7, to better > accommodate the new _Float128 access via SSE. Presumably (I haven't > checked) the change is reflected with changes in the psABI document to > make it "official". Be careful with policy changes like this. The malloc (3) man page says: The malloc() and calloc() functions return a pointer to the allocated memory that is suitably aligned for any kind of variable. I expect to be able to use a pointer returned by malloc (and friends) in MMX, SSE and AVX functions. Jeff
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