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More PRE compile-time optimizations 

This fixes a bug in bitmap_list_view which could end up with
a NULL head->current which makes followup searches fail.  Oops.

It also further optimizes the PRE DFS walk by removing useless
stuff and special-casing bitmaps with just one element for
EXECUTE_IF_AND_IN_BITMAP which makes a quite big difference.

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

	* bitmap.c (bitmap_list_view): Restore head->current.
	* tree-ssa-pre.c (pre_expr_DFS): Elide expr_visited bitmap.
	Special-case value expression bitmaps with one element.
	(bitmap_find_leader): Likewise.
	(sorted_array_from_bitmap_set): Elide expr_visited bitmap.
This commit is contained in:
Richard Biener 2020-11-12 15:05:03 +01:00
parent cb808c583d
commit 896db49a44
2 changed files with 28 additions and 17 deletions
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5
gcc/bitmap.c
View File

@ -678,6 +678,11 @@ bitmap_list_view (bitmap head)
}
head->tree_form = false;
if (!head->current)
{
head->current = head->first;
head->indx = head->current ? head->current->indx : 0;
}
}
/* Convert bitmap HEAD from linked-list view to splay-tree view.

40
gcc/tree-ssa-pre.c
View File

@ -806,15 +806,15 @@ bitmap_set_free (bitmap_set_t set)
}
static void
pre_expr_DFS (pre_expr expr, bitmap_set_t set, bitmap expr_visited,
bitmap val_visited, vec<pre_expr> &post);
pre_expr_DFS (pre_expr expr, bitmap_set_t set, 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)
pre_expr_DFS (unsigned val, bitmap_set_t set, bitmap val_visited,
vec<pre_expr> &post)
{
unsigned int i;
bitmap_iterator bi;
@ -822,21 +822,25 @@ pre_expr_DFS (unsigned val, bitmap_set_t set, bitmap expr_visited,
/* Iterate over all leaders and DFS recurse. Borrowed from
bitmap_find_leader. */
bitmap exprset = value_expressions[val];
if (!exprset->first->next)
{
EXECUTE_IF_SET_IN_BITMAP (exprset, 0, i, bi)
if (bitmap_bit_p (&set->expressions, i))
pre_expr_DFS (expression_for_id (i), set, val_visited, post);
return;
}
EXECUTE_IF_AND_IN_BITMAP (exprset, &set->expressions, 0, i, bi)
pre_expr_DFS (expression_for_id (i),
set, expr_visited, val_visited, post);
pre_expr_DFS (expression_for_id (i), set, 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 expr_visited,
bitmap val_visited, vec<pre_expr> &post)
pre_expr_DFS (pre_expr expr, bitmap_set_t set, bitmap val_visited,
vec<pre_expr> &post)
{
if (!bitmap_set_bit (expr_visited, get_expression_id (expr)))
return;
switch (expr->kind)
{
case NARY:
@ -851,7 +855,7 @@ pre_expr_DFS (pre_expr expr, bitmap_set_t set, bitmap expr_visited,
recursed already. Avoid the costly bitmap_find_leader. */
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);
pre_expr_DFS (op_val_id, set, val_visited, post);
}
break;
}
@ -873,8 +877,7 @@ pre_expr_DFS (pre_expr expr, bitmap_set_t set, bitmap expr_visited,
unsigned op_val_id = VN_INFO (op[n])->value_id;
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);
pre_expr_DFS (op_val_id, set, val_visited, post);
}
}
break;
@ -896,13 +899,11 @@ sorted_array_from_bitmap_set (bitmap_set_t set)
/* Pre-allocate enough space for the array. */
result.create (bitmap_count_bits (&set->expressions));
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);
pre_expr_DFS (i, set, val_visited, result);
return result;
}
@ -1883,6 +1884,11 @@ bitmap_find_leader (bitmap_set_t set, unsigned int val)
bitmap_iterator bi;
bitmap exprset = value_expressions[val];
if (!exprset->first->next)
EXECUTE_IF_SET_IN_BITMAP (exprset, 0, i, bi)
if (bitmap_bit_p (&set->expressions, i))
return expression_for_id (i);
EXECUTE_IF_AND_IN_BITMAP (exprset, &set->expressions, 0, i, bi)
return expression_for_id (i);
}