Hi, > On Tue, 2013-04-23 at 15:24 -0600, Jeff Law wrote: > > > Well, you have to copy the blocks, adjust the edges and rewrite the SSA > > graph. I'd use duplicate_block to help. > > > > You really want to look at tree-ssa-threadupdate.c. There's a nice big > > block comment which gives the high level view of what needs to happen > > when you copy a block for this kind of optimization. Feel free to > > ignore the implementation which has to be fairly efficient when there's > > a large number of edges to update. > > > > Jeff > > I think I understand the high level work, it is mapping that hight level > description to the low level calls that I am having trouble with.
I'd suggest looking at gimple_duplicate_sese_region in tree-cfg.c. It does not do exactly what you need, but it deals with a somewhat similar situation, Zdenek
