On Tue, Jul 21, 2020 at 5:18 PM Paul Eggert <egg...@cs.ucla.edu> wrote: > > On 7/21/20 8:51 AM, Florian Weimer wrote: > > The official aligned_alloc produces pointers compatible with free. > > This module cannot do that. > > I don't see why not, at least on platforms of interest to Gnulib. On systems > that provide no native way to do an aligned allocation, we merely keep calling > malloc with suitable arguments until we get a pointer that is suitably > aligned. > We then free all the unsuitable storage we allocated along the way, and return > the good pointer. > > Of course this would not be as efficient as a native aligned_alloc would be, > but > it should be good enough for portability to nonstandard platforms, for many > applications anyway - and that is the Gnulib Way. > > Eventually I hope even Microsoft will figure out how to do aligned allocation, > and even if my hope is dashed that's OK, our code will still work.
I believe Redmond has _aligned_malloc. > There is a real advantage to using aligned_alloc instead of some nonstandard > allocate/free pair. With aligned_alloc you can hand pointers off to other code > that expects to use 'free' (and there is a lot of such code out there). Plus, I believe the compiler can track pointer alignment better. I've never been able to get GCC's __builtin_assume_aligned to work. My attempts to use it always seem to crash. Jeff Jeff
