On Sat, Mar 22, 2008 at 12:01 PM, James Philbin <[EMAIL PROTECTED]> wrote:
> > gcc keeps advancing autovectorization. Is manual vectorization worth > the > > trouble? > > Well, the way that the ufuncs are written at the moment, > -ftree-vectorize will never kick in due to the non-constant strides. > To get this to work, one has to special case out unary strides. Even > with constant strides -ftree-vectorize often produces sub-optimal code > as it has to make very conservative assumptions about the content of > variables (it can do better if -fstrict-aliasing is used, but I think Numpy would die with strict-aliasing because it relies on casting char pointers to various types. It might be possible to use void pointers, but that would be a major do over and it isn't clear what the strides and offsets, currently in char units, would become. Chuck
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