https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79390
--- Comment #22 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to rguent...@suse.de from comment #21) > On April 7, 2017 6:57:13 PM GMT+02:00, "jakub at gcc dot gnu.org" > <gcc-bugzi...@gcc.gnu.org> wrote: > >https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79390 > > > >--- Comment #20 from Jakub Jelinek <jakub at gcc dot gnu.org> --- > >So, Richard, any thoughts on what can be done split paths to avoid > >this? > > Invent some new heuristic that avoids splitting this case... Index: gcc/gimple-ssa-split-paths.c =================================================================== --- gcc/gimple-ssa-split-paths.c (revision 246803) +++ gcc/gimple-ssa-split-paths.c (working copy) @@ -249,13 +249,17 @@ is_feasible_trace (basic_block bb) imm_use_iterator iter2; FOR_EACH_IMM_USE_FAST (use2_p, iter2, gimple_phi_result (stmt)) { - if (is_gimple_debug (USE_STMT (use2_p))) + gimple *use_stmt = USE_STMT (use2_p); + if (is_gimple_debug (use_stmt)) continue; - basic_block use_bb = gimple_bb (USE_STMT (use2_p)); + basic_block use_bb = gimple_bb (use_stmt); if (use_bb != bb && dominated_by_p (CDI_DOMINATORS, bb, use_bb)) { - found_useful_phi = true; + if (gcond *cond = dyn_cast <gcond *> (use_stmt)) + if (gimple_cond_code (cond) == EQ_EXPR + || gimple_cond_code (cond) == NE_EXPR) + found_useful_phi = true; break; } } avoids the splitting at at least passes tree-ssa.exp testing. Throwing it on full testing (there are some path splitting testcases randomly placed IIRC).
