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2015-06-01 15:26 GMT+03:00 Ilya Enkovich <enkovich....@gmail.com>: > 2015-05-29 1:15 GMT+03:00 Jeff Law <l...@redhat.com>: >> >> Right, but you're blindly propagating. The right thing to do is look at >> some kind of metric to estimate when it's profitable to propagate the >> constant back in vs leave it hoisted out. > > No, the patch is not to blindly propagate but to let loop invariant to > be propagated into address. Existing propagation gain estimation > (should_replace_address) still applies. > > Thanks, > Ilya > >> >> If you look at what Kugan is doing in cprop.c, that's exactly the approach >> he's taking -- looking at rtx costing to determine when to propagate the >> constant back into the loop. It could probably be made better with some >> knowledge of register pressure and looking at whether or not all uses (vs >> just some uses) of the constant will be propagated. >> >> Jeff
