diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-11.c | 1 | ||||
| -rw-r--r-- | gcc/tree-ssa-threadupdate.c | 33 |
4 files changed, 33 insertions, 12 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 3613a68..6a7d988 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2015-11-02 Jeff Law <jeff@redhat.com> + + * tree-ssa-threadupdate.c (valid_jump_thread_path): Also detect + cases where the loop latch edge is in the middle of an FSM + path. + 2015-11-03 Tom de Vries <tom@codesourcery.com> * tree-ssa-structalias.c (make_restrict_var_constraints): Rename to ... diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index a86920a..3dc4edc 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2015-11-02 Jeff Law <law@redhat.com> + + * gcc.dg/tree-ssa/ssa-thread-11.c: Verify that we do not have + irreducible loops in the CFG. + 2015-11-02 Alan Lawrence <alan.lawrence@arm.com> Revert: diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-11.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-11.c index 6a076e1..a729f56 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-11.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-11.c @@ -1,5 +1,6 @@ /* { dg-do compile { target { ! { logical_op_short_circuit || { m68k*-*-* mep*-*-* bfin*-*-* v850*-*-* moxie*-*-* m32c*-*-* fr30*-*-* mcore*-*-* frv-*-* h8300-*-* m32r-*-* mn10300-*-* msp430-*-* pdp11-*-* rl78-*-* rx-*-* vax-*-*} } } } } */ /* { dg-options "-O2 -fdump-tree-vrp2-details" } */ +/* { dg-final { scan-tree-dump-not "IRREDUCIBLE_LOOP" "vrp2" } } */ /* { dg-final { scan-tree-dump "FSM" "vrp2" } } */ void abort (void); diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c index 511433a..68650e5 100644 --- a/gcc/tree-ssa-threadupdate.c +++ b/gcc/tree-ssa-threadupdate.c @@ -2547,29 +2547,38 @@ valid_jump_thread_path (vec<jump_thread_edge *> *path) { unsigned len = path->length (); bool multiway_branch = false; + bool threaded_through_latch = false; /* Check that the path is connected and see if there's a multi-way branch on the path. */ for (unsigned int j = 0; j < len - 1; j++) { - if ((*path)[j]->e->dest != (*path)[j+1]->e->src) + edge e = (*path)[j]->e; + struct loop *loop = e->dest->loop_father; + + if (e->dest != (*path)[j+1]->e->src) return false; - gimple *last = last_stmt ((*path)[j]->e->dest); + + /* If we're threading through the loop latch back into the + same loop and the destination does not dominate the loop + latch, then this thread would create an irreducible loop. */ + if (loop->latch + && loop_latch_edge (loop) == e + && loop == path->last()->e->dest->loop_father + && (determine_bb_domination_status (loop, path->last ()->e->dest) + == DOMST_NONDOMINATING)) + threaded_through_latch = true; + + gimple *last = last_stmt (e->dest); multiway_branch |= (last && gimple_code (last) == GIMPLE_SWITCH); } - /* If we are trying to thread the loop latch to a block that does - not dominate the loop latch, then that will create an irreducible - loop. We avoid that unless the jump thread has a multi-way + /* If we are trying to thread through the loop latch to a block in the + loop that does not dominate the loop latch, then that will create an + irreducible loop. We avoid that unless the jump thread has a multi-way branch, in which case we have deemed it worth losing other loop optimizations later if we can eliminate the multi-way branch. */ - edge e = (*path)[0]->e; - struct loop *loop = e->dest->loop_father; - if (!multiway_branch - && loop->latch - && loop_latch_edge (loop) == e - && (determine_bb_domination_status (loop, path->last ()->e->dest) - == DOMST_NONDOMINATING)) + if (!multiway_branch && threaded_through_latch) return false; return true; |