On Tue, May 14, 2019 at 01:13:34PM -0600, Jeff Law wrote: > Trying to guess what the target is going to do, then changing the > structure of the loops in gimple based on that guess -- is that really a > good idea. It's fairly counter to many of the design goals around gimple.
That is exactly what ivopts does in the first place? It tries to find what ivs result in cheaper code, and it looks at a lot of target-specific stuff for that (like available addressing modes and the cost to use those). I think doloops fit perfectly well in that scheme. This patch is not radically changing anything. Segher
