Contributed by Ben Elliston <bje@redhat.com>
and Andrew MacLeod <amacleod@redhat.com>
Adapted to use control dependence by Steven Bosscher, SUSE Labs.
-
+
This file is part of GCC.
-
+
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.
-
+
GCC is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
-
+
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
static bitmap visited = NULL;
static unsigned int longest_chain = 0;
static unsigned int total_chain = 0;
+static unsigned int nr_walks = 0;
static bool chain_ovfl = false;
/* Worker for the walker that marks reaching definitions of REF,
which is based on a non-aliased decl, necessary. It returns
true whenever the defining statement of the current VDEF is
a kill for REF, as no dominating may-defs are necessary for REF
- anymore. DATA points to cached get_ref_base_and_extent data for REF. */
+ anymore. DATA points to the basic-block that contains the
+ stmt that refers to REF. */
static bool
-mark_aliased_reaching_defs_necessary_1 (ao_ref *ref, tree vdef,
- void *data ATTRIBUTE_UNUSED)
+mark_aliased_reaching_defs_necessary_1 (ao_ref *ref, tree vdef, void *data)
{
gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
}
/* Or they need to be exactly the same. */
else if (ref->ref
+ /* Make sure there is no induction variable involved
+ in the references (gcc.c-torture/execute/pr42142.c).
+ The simplest way is to check if the kill dominates
+ the use. */
+ && dominated_by_p (CDI_DOMINATORS, (basic_block) data,
+ gimple_bb (def_stmt))
&& operand_equal_p (ref->ref, lhs, 0))
return true;
}
ao_ref_init (&refd, ref);
chain = walk_aliased_vdefs (&refd, gimple_vuse (stmt),
mark_aliased_reaching_defs_necessary_1,
- NULL, NULL);
+ gimple_bb (stmt), NULL);
if (chain > longest_chain)
longest_chain = chain;
total_chain += chain;
+ nr_walks++;
}
/* Worker for the walker that marks reaching definitions of REF, which
/* Propagate necessity using the operands of necessary statements.
Process the uses on each statement in the worklist, and add all
feeding statements which contribute to the calculation of this
- value to the worklist.
+ value to the worklist.
In conservative mode, EL is NULL. */
propagate_necessity (struct edge_list *el)
{
gimple stmt;
- bool aggressive = (el ? true : false);
+ bool aggressive = (el ? true : false);
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "\nProcessing worklist:\n");
else
{
/* Propagate through the operands. Examine all the USE, VUSE and
- VDEF operands in this statement. Mark all the statements
+ VDEF operands in this statement. Mark all the statements
which feed this statement's uses as necessary. */
ssa_op_iter iter;
tree use;
gcc_unreachable ();
/* If we over-used our alias oracle budget drop to simple
- mode. The cost metric allows quadratic behavior up to
- a constant maximal chain and after that falls back to
+ mode. The cost metric allows quadratic behavior
+ (number of uses times number of may-defs queries) up to
+ a constant maximal number of queries and after that falls back to
super-linear complexity. */
- if (longest_chain > 256
- && total_chain > 256 * longest_chain)
+ if (/* Constant but quadratic for small functions. */
+ total_chain > 128 * 128
+ /* Linear in the number of may-defs. */
+ && total_chain > 32 * longest_chain
+ /* Linear in the number of uses. */
+ && total_chain > nr_walks * 32)
{
chain_ovfl = true;
if (visited)
}
unlink_stmt_vdef (stmt);
- gsi_remove (i, true);
- release_defs (stmt);
+ gsi_remove (i, true);
+ release_defs (stmt);
}
/* Eliminate unnecessary statements. Any instruction not marked as necessary
/* If GSI is not necessary then remove it. */
if (!gimple_plf (stmt, STMT_NECESSARY))
{
+ if (!is_gimple_debug (stmt))
+ something_changed = true;
remove_dead_stmt (&gsi, bb);
- something_changed = true;
}
else if (is_gimple_call (stmt))
{
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
fprintf (dump_file, "\n");
}
-
+
gimple_call_set_lhs (stmt, NULL_TREE);
maybe_clean_or_replace_eh_stmt (stmt, stmt);
update_stmt (stmt);
longest_chain = 0;
total_chain = 0;
+ nr_walks = 0;
chain_ovfl = false;
+ visited = BITMAP_ALLOC (NULL);
propagate_necessity (el);
BITMAP_FREE (visited);
free_edge_list (el);
if (something_changed)
- return (TODO_update_ssa | TODO_cleanup_cfg | TODO_ggc_collect
+ return (TODO_update_ssa | TODO_cleanup_cfg | TODO_ggc_collect
| TODO_remove_unused_locals);
else
return 0;
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