http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51106
--- Comment #17 from rguenther at suse dot de <rguenther at suse dot de> 2012-03-27 13:50:57 UTC --- On Tue, 27 Mar 2012, abel at gcc dot gnu.org wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51106 > > --- Comment #16 from Andrey Belevantsev <abel at gcc dot gnu.org> 2012-03-27 > 13:28:03 UTC --- > So, something like the below patch, or even better -- as we want to fold all > RTL-build related pseudo passes into expand, make > pass_instantiate_virtual_regs > also the expand part (thus, until the into_cfglayout pass), and then the new > cleanup_cfg will nicely work at the end of expand. > > diff --git a/gcc/cfgrtl.c b/gcc/cfgrtl.c > index b86cc74..0c27d11 100644 > --- a/gcc/cfgrtl.c > +++ b/gcc/cfgrtl.c > @@ -2261,7 +2261,7 @@ purge_dead_edges (basic_block bb) > edge e; > rtx insn = BB_END (bb), note; > bool purged = false; > - bool found; > + bool found, fallthru; > edge_iterator ei; > > if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb)) > @@ -2433,16 +2433,22 @@ purge_dead_edges (basic_block bb) > as these are only created by conditional branches. If we find such an > edge we know that there used to be a jump here and can then safely > remove all non-fallthru edges. */ > - found = false; > + found = fallthru = false; > FOR_EACH_EDGE (e, ei, bb->succs) > - if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))) > - { > + { > + if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))) > found = true; > - break; > - } > - > + if (e->flags & (EDGE_FALLTHRU | EDGE_FAKE)) > + fallthru = true; > + } > if (!found) > return purged; > + if (!fallthru) > + { > + gcc_assert (single_succ_p (bb)); > + single_succ_edge (bb)->flags |= EDGE_FALLTHRU; > + return purged; > + } > > /* Remove all but the fake and fallthru edges. The fake edge may be > the only successor for this block in the case of noreturn > Looks reasonable. Though I think that whoever removed the fallthru edge should have adjusted the flags on the others.
