https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106408
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to rguent...@suse.de from comment #3) > On Fri, 22 Jul 2022, hubicka at ucw dot cz wrote: > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106408 > > > > --- Comment #2 from Jan Hubicka <hubicka at ucw dot cz> --- > > > + /* If block is a loop that is possibly infinite we should not > > > + hoist across it. */ > > > + if (block->loop_father->header == block > > > + && !finite_loop_p (block->loop_father)) > > > + BB_MAY_NOTRETURN (block) = 1; > > > + > > Don't you just need to handle also BBs that have backedge out that is > > not a latch of loop? > > I would need to handle all blocks with an incoming backedge, > and for non-irreducible regions can use finite_loop_p, yes. > Not sure what you mean with backedge out. > > So the following would handle loops and irreducible regions correctly > I think. > > diff --git a/gcc/tree-ssa-pre.cc b/gcc/tree-ssa-pre.cc > index e029bd36da3..a2d8b52f872 100644 > --- a/gcc/tree-ssa-pre.cc > +++ b/gcc/tree-ssa-pre.cc > @@ -52,6 +52,7 @@ along with GCC; see the file COPYING3. If not see > #include "tree-cfgcleanup.h" > #include "alias.h" > #include "gimple-range.h" > +#include "tree-ssa-loop-niter.h" > > /* Even though this file is called tree-ssa-pre.cc, we actually > implement a bit more than just PRE here. All of them piggy-back > @@ -3939,6 +3940,16 @@ compute_avail (function *fun) > > BB_MAY_NOTRETURN (block) = 0; > > + /* If this block is an entry into a CFG cycle that is possibly > infinite > + we should not hoist across it. */ > + edge_iterator ei; > + edge e; > + FOR_EACH_EDGE (e, ei, block->preds) > + if ((e->flags & EDGE_DFS_BACK) > + && (block->loop_father->header != block > + || !finite_loop_p (block->loop_father))) > + BB_MAY_NOTRETURN (block) = 1; > + > /* Now compute value numbers and populate value sets with all > the expressions computed in BLOCK. */ > bool set_bb_may_notreturn = false; It regresses FAIL: gcc.dg/tree-ssa/loadpre10.c scan-tree-dump-times pre "Eliminated: 1" 1 FAIL: gcc.dg/tree-ssa/loadpre8.c scan-tree-dump-times pre "Eliminated: 1" 1 FAIL: gcc.dg/tree-ssa/pr21417.c scan-tree-dump-times thread2 "jump thread" 1
