On Thu, Sep 17, 2015 at 09:18:42AM -0500, Bill Schmidt wrote: > On Thu, 2015-09-17 at 09:39 +0200, Richard Biener wrote: > > So just to clarify - you need to reduce the vector with max to a scalar > > but want the (same) result in all vector elements? > > Yes. Alan Hayward's cond-reduction patch is set up to perform a > reduction to scalar, followed by a scalar broadcast to get the value > into all positions. It happens that our most efficient expansion to > reduce to scalar will naturally produce the value in all positions.
It also is many insns after expand, so relying on combine to combine all that plus the following splat (as Richard suggests below) is not really going to work. If there also are targets where the _scal version is cheaper, maybe we should keep both, and have expand expand to whatever the target supports? Segher
