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tree-optimization/97806 - fix PRE expression post order 

This fixes the postorder compute for the case of multiple
expression leaders for a value.

2020-11-12  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/97806
	* tree-ssa-pre.c (pre_expr_DFS): New overload for visiting
	values, visiting all leaders for a value.  Use a bitmap
	for visited values.
	(sorted_array_from_bitmap_set): Walk over values and adjust.

	* gcc.dg/pr97806.c: New testcase.
This commit is contained in:
Richard Biener 2020-11-12 09:10:51 +01:00
parent fc531c2ed3
commit 64326bb428
2 changed files with 55 additions and 29 deletions
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16
gcc/testsuite/gcc.dg/pr97806.c Normal file
View File

@ -0,0 +1,16 @@
/* { dg-do compile } */
/* { dg-options "-O2" } */
int b;
long c;
int g();
void h(long *);
void i(long *);
void d() {
int e, f = b - e;
if (g())
h(&c + f);
else
i(&c + f);
__builtin_memset(0, 0, f * 8);
}

68
gcc/tree-ssa-pre.c
View File

@ -805,16 +805,36 @@ bitmap_set_free (bitmap_set_t set)
bitmap_clear (&set->values);
}
static void
pre_expr_DFS (pre_expr expr, bitmap_set_t set, bitmap expr_visited,
bitmap val_visited, vec<pre_expr> &post);
/* DFS walk leaders of VAL to their operands with leaders in SET, collecting
expressions in SET in postorder into POST. */
static void
pre_expr_DFS (unsigned val, bitmap_set_t set, bitmap expr_visited,
bitmap val_visited, vec<pre_expr> &post)
{
unsigned int i;
bitmap_iterator bi;
/* Iterate over all leaders and DFS recurse. Borrowed from
bitmap_find_leader. */
bitmap exprset = value_expressions[val];
EXECUTE_IF_AND_IN_BITMAP (exprset, &set->expressions, 0, i, bi)
pre_expr_DFS (expression_for_id (i),
set, expr_visited, val_visited, post);
}
/* DFS walk EXPR to its operands with leaders in SET, collecting
expressions in SET in postorder into POST. */
static void
pre_expr_DFS (pre_expr expr, bitmap_set_t set, bitmap visited,
hash_set<int_hash<unsigned int, 0> > &leader_set,
vec<pre_expr> &post)
pre_expr_DFS (pre_expr expr, bitmap_set_t set, bitmap expr_visited,
bitmap val_visited, vec<pre_expr> &post)
{
if (!bitmap_set_bit (visited, get_expression_id (expr)))
if (!bitmap_set_bit (expr_visited, get_expression_id (expr)))
return;
switch (expr->kind)
@ -829,12 +849,9 @@ pre_expr_DFS (pre_expr expr, bitmap_set_t set, bitmap visited,
unsigned int op_val_id = VN_INFO (nary->op[i])->value_id;
/* If we already found a leader for the value we've
recursed already. Avoid the costly bitmap_find_leader. */
if (!leader_set.add (op_val_id))
{
pre_expr leader = bitmap_find_leader (set, op_val_id);
if (leader)
pre_expr_DFS (leader, set, visited, leader_set, post);
}
if (bitmap_bit_p (&set->values, op_val_id)
&& bitmap_set_bit (val_visited, op_val_id))
pre_expr_DFS (op_val_id, set, expr_visited, val_visited, post);
}
break;
}
@ -854,12 +871,10 @@ pre_expr_DFS (pre_expr expr, bitmap_set_t set, bitmap visited,
if (!op[n] || TREE_CODE (op[n]) != SSA_NAME)
continue;
unsigned op_val_id = VN_INFO (op[n])->value_id;
if (!leader_set.add (op_val_id))
{
pre_expr leader = bitmap_find_leader (set, op_val_id);
if (leader)
pre_expr_DFS (leader, set, visited, leader_set, post);
}
if (bitmap_bit_p (&set->values, op_val_id)
&& bitmap_set_bit (val_visited, op_val_id))
pre_expr_DFS (op_val_id,
set, expr_visited, val_visited, post);
}
}
break;
@ -879,20 +894,15 @@ sorted_array_from_bitmap_set (bitmap_set_t set)
vec<pre_expr> result;
/* Pre-allocate enough space for the array. */
size_t len = bitmap_count_bits (&set->expressions);
result.create (len);
hash_set<int_hash<unsigned int, 0> > leader_set (2*len);
result.create (bitmap_count_bits (&set->expressions));
auto_bitmap visited (&grand_bitmap_obstack);
bitmap_tree_view (visited);
FOR_EACH_EXPR_ID_IN_SET (set, i, bi)
{
pre_expr expr = expression_for_id (i);
/* Hoist insertion calls us with a value-set we have to and with,
do so. */
if (bitmap_set_contains_value (set, get_expr_value_id (expr)))
pre_expr_DFS (expr, set, visited, leader_set, result);
}
auto_bitmap expr_visited (&grand_bitmap_obstack);
auto_bitmap val_visited (&grand_bitmap_obstack);
bitmap_tree_view (expr_visited);
bitmap_tree_view (val_visited);
FOR_EACH_VALUE_ID_IN_SET (set, i, bi)
if (bitmap_set_bit (val_visited, i))
pre_expr_DFS (i, set, expr_visited, val_visited, result);
return result;
}