The same issue that arises in PR100934 can happen in the backward
threader now (Aldy?) - we eventually run into mark_irreducible_loops
for non-FSM thread paths checking for paths crossing irreducible
region boundaries.
The following thus initializes irreducible regions and makes
irreducible region discovery handle multiple latches.
Bootstrap & regtest pending.
2021-06-14 Richard Biener <rguent...@suse.de>
* cfgloopanal.c (mark_irreducible_loops): Use a dominance
check to identify loop latches.
* cfgloop.c (verify_loop_structure): Likewise.
* loop-init.c (apply_loop_flags): Allow marked irreducible
regions even with multiple latches.
* predict.c (rebuild_frequencies): Simplify.
* tree-ssa-threadbackward.c (pass_thread_jumps::execute):
Mark irreducible regions.
(pass_early_thread_jumps::execute): Likewise.
* tree-ssa-threadupdate.c
(jump_thread_path_registry::mark_threaded_blocks): Assert
we have irreducible regions marked.
---
gcc/cfgloop.c | 14 ++++++++++----
gcc/cfgloopanal.c | 2 +-
gcc/loop-init.c | 3 ++-
gcc/predict.c | 3 +--
gcc/tree-ssa-threadbackward.c | 6 ++++--
gcc/tree-ssa-threadupdate.c | 2 ++
6 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c
index 4e227cd0891..f094538b9ff 100644
--- a/gcc/cfgloop.c
+++ b/gcc/cfgloop.c
@@ -1555,11 +1555,17 @@ verify_loop_structure (void)
error ("loop %d%'s header does not belong directly to it", i);
err = 1;
}
- if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
- && (loop_latch_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP))
+ if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS))
{
- error ("loop %d%'s latch is marked as part of irreducible region", i);
- err = 1;
+ edge_iterator ei;
+ FOR_EACH_EDGE (e, ei, loop->header->preds)
+ if (dominated_by_p (CDI_DOMINATORS, e->src, loop->header)
+ && e->flags & EDGE_IRREDUCIBLE_LOOP)
+ {
+ error ("loop %d%'s latch is marked as part of irreducible"
+ " region", i);
+ err = 1;
+ }
}
}
diff --git a/gcc/cfgloopanal.c b/gcc/cfgloopanal.c
index d0eade3dd34..54426b54881 100644
--- a/gcc/cfgloopanal.c
+++ b/gcc/cfgloopanal.c
@@ -113,7 +113,7 @@ mark_irreducible_loops (void)
/* Ignore latch edges. */
if (e->dest->loop_father->header == e->dest
- && e->dest->loop_father->latch == act)
+ && dominated_by_p (CDI_DOMINATORS, act, e->dest))
continue;
/* Edges inside a single loop should be left where they are. Edges
diff --git a/gcc/loop-init.c b/gcc/loop-init.c
index 17f14075f62..1fde0ede441 100644
--- a/gcc/loop-init.c
+++ b/gcc/loop-init.c
@@ -48,7 +48,8 @@ apply_loop_flags (unsigned flags)
not work). However, we avoid modifying cfg, which some
passes may want. */
gcc_assert ((flags & ~(LOOPS_MAY_HAVE_MULTIPLE_LATCHES
- | LOOPS_HAVE_RECORDED_EXITS)) == 0);
+ | LOOPS_HAVE_RECORDED_EXITS
+ | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)) == 0);
loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES);
}
else
diff --git a/gcc/predict.c b/gcc/predict.c
index 5d0cae5c4a4..d751e6cecce 100644
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -4287,8 +4287,7 @@ rebuild_frequencies (void)
if (profile_status_for_fn (cfun) == PROFILE_GUESSED)
{
- loop_optimizer_init (0);
- mark_irreducible_loops ();
+ loop_optimizer_init (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS);
connect_infinite_loops_to_exit ();
estimate_bb_frequencies (true);
remove_fake_exit_edges ();
diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c
index 7dd8594e3d4..1a5deafc463 100644
--- a/gcc/tree-ssa-threadbackward.c
+++ b/gcc/tree-ssa-threadbackward.c
@@ -887,7 +887,8 @@ pass_thread_jumps::gate (function *fun ATTRIBUTE_UNUSED)
unsigned int
pass_thread_jumps::execute (function *fun)
{
- loop_optimizer_init (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES);
+ loop_optimizer_init (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES
+ | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS);
/* Try to thread each block with more than one successor. */
thread_jumps threader;
@@ -948,7 +949,8 @@ pass_early_thread_jumps::gate (function *fun
ATTRIBUTE_UNUSED)
unsigned int
pass_early_thread_jumps::execute (function *fun)
{
- loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
+ loop_optimizer_init (AVOID_CFG_MODIFICATIONS
+ | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS);
/* Try to thread each block with more than one successor. */
thread_jumps threader (/*speed_p=*/false);
diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c
index a86302be18e..387994fd882 100644
--- a/gcc/tree-ssa-threadupdate.c
+++ b/gcc/tree-ssa-threadupdate.c
@@ -1917,6 +1917,8 @@ jump_thread_path_registry::mark_threaded_blocks (bitmap
threaded_blocks)
edge e;
edge_iterator ei;
+ gcc_assert (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS));
+
/* It is possible to have jump threads in which one is a subpath
of the other. ie, (A, B), (B, C), (C, D) where B is a joiner
block and (B, C), (C, D) where no joiner block exists.
--
2.26.2
