Hi Richard,
In this change:
https://gcc.gnu.org/ml/gcc-patches/2014-06/msg01278.html
where substitute_and_fold() was changed to use a dom walker, the calls
to purge dead EH edges during the walk can alter the dom-tree, and have
chaotic results; the testcase in PR 61554 has some blocks traversed
twice during the walk, causing the segfault during CCP.
The patch records the to-be-purged-for-dead-EH blocks in a similar
manner like stmts_to_remove, and processes it after the walk. (another
possible method would be using a bitmap to record the BBs + calling
gimple_purge_all_dead_eh_edges...)
Bootstrapped and tested on x86_64-linux, is this okay for trunk?
Thanks,
Chung-Lin
2014-06-23 Chung-Lin Tang <clt...@codesourcery.com>
PR tree-optimization/61554
* tree-ssa-propagate.c (substitute_and_fold_dom_walker):
Add 'vec<basic_block> bbs_to_purge_dead_eh_edges' member,
properly update constructor/destructor.
(substitute_and_fold_dom_walker::before_dom_children):
Remove call to gimple_purge_dead_eh_edges, add bb to
bbs_to_purge_dead_eh_edges instead.
(substitute_and_fold): Call gimple_purge_dead_eh_edges for
bbs recorded in bbs_to_purge_dead_eh_edges.
Index: tree-ssa-propagate.c
===================================================================
--- tree-ssa-propagate.c (revision 211874)
+++ tree-ssa-propagate.c (working copy)
@@ -1031,8 +1031,13 @@ class substitute_and_fold_dom_walker : public dom_
fold_fn (fold_fn_), do_dce (do_dce_), something_changed (false)
{
stmts_to_remove.create (0);
+ bbs_to_purge_dead_eh_edges.create (0);
}
- ~substitute_and_fold_dom_walker () { stmts_to_remove.release (); }
+ ~substitute_and_fold_dom_walker ()
+ {
+ stmts_to_remove.release ();
+ bbs_to_purge_dead_eh_edges.release ();
+ }
virtual void before_dom_children (basic_block);
virtual void after_dom_children (basic_block) {}
@@ -1042,6 +1047,7 @@ class substitute_and_fold_dom_walker : public dom_
bool do_dce;
bool something_changed;
vec<gimple> stmts_to_remove;
+ vec<basic_block> bbs_to_purge_dead_eh_edges;
};
void
@@ -1144,7 +1150,7 @@ substitute_and_fold_dom_walker::before_dom_childre
/* If we cleaned up EH information from the statement,
remove EH edges. */
if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
- gimple_purge_dead_eh_edges (bb);
+ bbs_to_purge_dead_eh_edges.safe_push (bb);
if (is_gimple_assign (stmt)
&& (get_gimple_rhs_class (gimple_assign_rhs_code (stmt))
@@ -1235,6 +1241,14 @@ substitute_and_fold (ssa_prop_get_value_fn get_val
}
}
+ while (!walker.bbs_to_purge_dead_eh_edges.is_empty ())
+ {
+ basic_block bb = walker.bbs_to_purge_dead_eh_edges.pop ();
+ gimple_purge_dead_eh_edges (bb);
+ if (dump_file && dump_flags & TDF_DETAILS)
+ fprintf (dump_file, "Purge dead EH edges from bb %d\n", bb->index);
+ }
+
statistics_counter_event (cfun, "Constants propagated",
prop_stats.num_const_prop);
statistics_counter_event (cfun, "Copies propagated",
