On Tue, Oct 23, 2018 at 2:49 PM Anton Youdkevitch <anton.youdkevi...@bell-sw.com> wrote: > > Looking at the examples for gcc SLP reduction I see > that the reduction variable is defined outside the > loop. It's OK to have this as an example, I thought. > However, looking at the actual implementation I found > out that this is the ONLY SLP reduction gcc does. > > /* Detect SLP reduction of the form: > > #a1 = phi <a5, a0> > a2 = operation (a1) > a3 = operation (a2) > a4 = operation (a3) > a5 = operation (a4) > > #a = phi <a5> > > PHI is the reduction phi node (#a1 = phi <a5, a0> above) > FIRST_STMT is the first reduction stmt in the chain > (a2 = operation (a1)). > > Return TRUE if a reduction chain was detected. */ > > Is there any reasoning behind this other than that > the loop-aware one is generally more profitable?
The only reasoning is lack of a implementation ... (read: time). IIRC I tried to support the case of vector constructors as additional sink but even that turned out to be non-trivial (read: more than a few hours of work) Richard. > -- > Thanks, > Anton
