‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Monday, September 30, 2019 9:52 AM, Szabolcs Nagy <szabolcs.n...@arm.com> wrote:
> On 27/09/2019 20:23, GT wrote: > > > I am attempting to create a vector version of sincos for PPC64. > > The relevant discussion thread is on the GLIBC libc-alpha mailing list. > > Navigate it beginning at > > https://sourceware.org/ml/libc-alpha/2019-09/msg00334.html > > The intention is to reuse as much as possible from the existing GCC > > implementation of other libmvec functions. > > My questions are: Which function(s) in GCC; > > > > 1. Gather scalar function input arguments, from multiple loop iterations, > > into a single vector input argument for the vector function version? > > 2. Distribute scalar function outputs, to appropriate loop iteration > > result, from the single vector function output result? > > > > I am referring especially to vectorization of sin and cos. > > i wonder if gcc can auto-vectorize scalar sincos > calls, the vectorizer seems to want the calls to > have no side-effect, but attribute pure or const > is not appropriate for sincos (which has no return > value but takes writable pointer args) 1. Do you mean whether x86_64 already does auto-vectorize sincos? 2. Where in the code do you see the vectorizer require no side-effect? > "#pragma omp simd" on a loop seems to work but i > could not get unannotated sincos loops to vectorize. > > it seems it would be nice if we could add pure/const > somehow (maybe to the simd variant only? afaik openmp > requires no sideeffects for simd variants, but that's > probably only for explicitly marked loops?) 1. Example 1 and Example 2 at https://sourceware.org/glibc/wiki/libmvec show the 2 different ways to activate auto-vectorization. When you refer to "unannotated sincos", which of the 2 techniques do you mean? 2. Which function was auto-vectorized by "pragma omp simd" in the loop?
