Hi!
On the following testcase, starting with r221675 aka PR65177 fix
we get ICE, because FSM discovery finds a path that includes the same blocks
multiple times, like:
Registering FSM jump thread: (9, 4) incoming edge; (4, 5) (5, 12) (12, 14)
(14, 5) (5, 12) nocopy; (5, 12)
All these bbs belong to the same loop, with bb14 being the header and bb12
the latch. And the copy_bbs/duplicate_thread_path don't seem to be really
prepared to duplicate the same basic block more than once.
fsm_find_control_statement_thread_paths has guard against recursion, but it
adds to the hash_set the PHI nodes. On the testcase, bb5 is added to the
path first through one of the PHIs:
# c_3 = PHI <c_39(4), b_17(14)>
# b_33 = PHI <b_32(4), b_17(14)>
and the second time through the other PHI.
The following patch fixes that by adding to the has_set the basic blocks
containing the PHIs instead of the PHIs.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2015-04-11 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/65735
* tree-ssa-threadedge.c (fsm_find_control_statement_thread_paths):
Remove visited_phis argument, add visited_bbs, avoid recursing into the
same bb rather than just into the same phi node.
(thread_through_normal_block): Adjust caller.
* gcc.c-torture/compile/pr65735.c: New test.
--- gcc/tree-ssa-threadedge.c.jj 2015-02-16 22:18:34.000000000 +0100
+++ gcc/tree-ssa-threadedge.c 2015-04-11 16:13:51.906916300 +0200
@@ -1015,7 +1015,7 @@ static int max_threaded_paths;
static void
fsm_find_control_statement_thread_paths (tree expr,
- hash_set<gimple> *visited_phis,
+ hash_set<basic_block> *visited_bbs,
vec<basic_block, va_gc> *&path,
bool seen_loop_phi)
{
@@ -1034,7 +1034,7 @@ fsm_find_control_statement_thread_paths
return;
/* Avoid infinite recursion. */
- if (visited_phis->add (def_stmt))
+ if (visited_bbs->add (var_bb))
return;
gphi *phi = as_a <gphi *> (def_stmt);
@@ -1109,7 +1109,7 @@ fsm_find_control_statement_thread_paths
{
vec_safe_push (path, bbi);
/* Recursively follow SSA_NAMEs looking for a constant definition. */
- fsm_find_control_statement_thread_paths (arg, visited_phis, path,
+ fsm_find_control_statement_thread_paths (arg, visited_bbs, path,
seen_loop_phi);
path->pop ();
@@ -1391,13 +1391,13 @@ thread_through_normal_block (edge e,
vec<basic_block, va_gc> *bb_path;
vec_alloc (bb_path, n_basic_blocks_for_fn (cfun));
vec_safe_push (bb_path, e->dest);
- hash_set<gimple> *visited_phis = new hash_set<gimple>;
+ hash_set<basic_block> *visited_bbs = new hash_set<basic_block>;
max_threaded_paths = PARAM_VALUE (PARAM_MAX_FSM_THREAD_PATHS);
- fsm_find_control_statement_thread_paths (cond, visited_phis, bb_path,
+ fsm_find_control_statement_thread_paths (cond, visited_bbs, bb_path,
false);
- delete visited_phis;
+ delete visited_bbs;
vec_free (bb_path);
}
return 0;
--- gcc/testsuite/gcc.c-torture/compile/pr65735.c.jj 2015-04-11
16:14:33.173263982 +0200
+++ gcc/testsuite/gcc.c-torture/compile/pr65735.c 2015-04-11
16:14:06.000000000 +0200
@@ -0,0 +1,21 @@
+/* PR tree-optimization/65735 */
+
+int foo (void);
+
+void
+bar (int a, int b, int c)
+{
+ while (!a)
+ {
+ c = foo ();
+ if (c == 7)
+ c = b;
+ switch (c)
+ {
+ case 1:
+ a = b++;
+ if (b)
+ b = 1;
+ }
+ }
+}
Jakub
