Peter Alexander wrote: > On Friday, 2 November 2012 at 10:24:34 UTC, Jens Mueller wrote: > >Then I have a serious misunderstanding. > >I thought D introduced array operations to allow the compiler to > >generate efficient vector operations (in the long run), i.e. > >generate > >SIMD code. Why is this not working out? > > It works fine for large vectors. For small vectors, it is > horrendously slow. > > The syntax a[] += b[] essentially calls a function which is designed > to work for large vectors. It has to determine alignment, load > everything from memory, do the operations, then store it back. > > The SIMD extensions allow you to define variables that are > guaranteed to be aligned and will probably be in the right registers > to start with. Using them, the vectors ops don't need to determine > alignment, and often don't need to do lots of loads/stores. > > Both have their purposes.
I see. But can't the alignment problem be solved by using align. Then have the compiler emits a call that checks for alignment if none was specified else use a faster version. Jens
