On Wed, Apr 18, 2012 at 5:25 PM, Richard Guenther <richard.guent...@gmail.com> wrote: > On Wed, Apr 18, 2012 at 8:53 AM, Bin.Cheng <amker.ch...@gmail.com> wrote:
> > I don't understand method 2. I'd do > > start at the single predecessor of the sink-to block > > foreach stmt from the end to the beginning of that block > if the stmt has a VDEF or the same VUSE as the stmt we sink, break > > (continue searching for VDEFs in predecessors - that now gets more expensive, > I suppose limiting sinking to the cases where the above finds sth > would be easiest, > even limiting sinking to never sink across any stores) > > walk the vuse -> vdef chain, using refs_anti_dependent_p to see whether > the load is clobbered. > > But I'd suggest limiting the sinking to never sink across stores - the alias > memory model we have in GCC seriously limits these anyway. How would > the numbers change if you do that? Interesting, maybe method 1 I implemented is too conservative. I implemented as you described, and the numbers are: 1) 766, If the stop condition is "stmt_may_clobber_ref_p" 2) 719, if the stop condition is "gimple_vdef || stmt_may_clobber_ref_p" Also, I past make check on x86 for 1). Is it good? I am not sure about it since bootstrapping builds gcc 2 times and libraries 3 times. Thanks -- Best Regards.
