On Tue, Jun 13, 2017 at 10:43:05AM +0100, Wilco Dijkstra wrote:
> Richard Earnshaw (lists) wrote:
> >
> > Why 1 and not 2? Many processors have 2 fp pipes and forcing this down
> > to a sequential stream is not obviously the right thing.
>
> 1 was faster than 2. Like I said, the reassociation is
Richard Earnshaw (lists) wrote:
>
> Why 1 and not 2? Many processors have 2 fp pipes and forcing this down
> to a sequential stream is not obviously the right thing.
1 was faster than 2. Like I said, the reassociation is too aggressive and even
splits multiply-add rather than keeping them. Until
On 12/06/17 11:50, Wilco Dijkstra wrote:
> Currently the FP reassociation width is set to 4 on AArch64. On recent
> GCCs this has become more aggressive in splitting expressions. This means
> many FMAs are split into FMUL and FADD. The reassociation increases register
> pressure, in some benchma
