On March 13, 2014 5:00:53 PM CET, Paulo Matos <pma...@broadcom.com> wrote: >> -----Original Message----- >> From: Richard Biener [mailto:richard.guent...@gmail.com] >> Sent: 13 March 2014 13:24 >> To: Paulo Matos >> Cc: gcc@gcc.gnu.org >> Subject: Re: dom requires PROP_loops >> >> >> Probably RTL cfgcleaup needs the same treatment as GIMPLE cfgcleanup >> then - allow removal if loop properties allows it. >> > >In both cfgcleanup.c and tree-cfgcleanup.c I can see code that protects >loop latches, but I see no code that allows removal of latch if >property allows it. >From what you say I would expect this would already be implemented in >tree-cfgcleanup.c, however what actually happens is that since >current_loops is non-null (PROP_loops is not destroyed in tree >loopdone), tree-cfgcleanup call chain ends up calling >cleanup_tree_cfg_bb on the bb loop latch and tree_forwarder_block_p >returns false for bb because of the following code thereby not removing >the latch: > if (current_loops) > { > basic_block dest; > /* Protect loop latches, headers and preheaders. */ > if (bb->loop_father->header == bb) > return false; > dest = EDGE_SUCC (bb, 0)->dest; > > if (dest->loop_father->header == dest) > return false; > } > >Why do we need to protect the latch?
You are looking at old sources. Richard. >Paulo Matos > >> Richard. >>
