Re: [PATCH] AArch64: Enable fast shifts on Neoverse N1

2020-09-14 Thread Richard Earnshaw (lists)
On 14/09/2020 13:01, Wilco Dijkstra wrote: > Enable the fast shift feature in Neoverse N1 tuning - this means additions > with > a shift left by 1-4 are as fast as addition. This improves multiply by > constant > expansions, eg. x * 25 is now emitted using shifts rather than a multiply: > > add

[PATCH] AArch64: Enable fast shifts on Neoverse N1

2020-09-14 Thread Wilco Dijkstra
Enable the fast shift feature in Neoverse N1 tuning - this means additions with a shift left by 1-4 are as fast as addition. This improves multiply by constant expansions, eg. x * 25 is now emitted using shifts rather than a multiply: add w0, w0, w0, lsl 2 add w0, w0, w0, lsl 2 Bootstrap OK,