+2006-01-16 Richard Guenther <rguenther@suse.de>
+
+ * tree-ssa-alias.c (struct used_part): Add write_only field.
+ (get_or_create_used_part_for): Initialize it to true.
+ (create_overlap_variables_for): Don't create structure variables
+ for structures that only are written to.
+ (find_used_portions): Handle MODIFY_EXPR to track whether a
+ structure is only written to.
+
2006-01-16 Kazu Hirata <kazu@codesourcery.com>
* bb-reorder.c (partition_hot_cold_basic_blocks): Make it
return 0;
}
-/* The V_MUST_DEF comes from the initial assignment; the V_MAY_DEF
- comes from the asm. */
-/* { dg-final { scan-tree-dump-times "V_MUST_DEF" 1 "alias1" } } */
-/* { dg-final { scan-tree-dump-times "V_MAY_DEF" 1 "alias1" } } */
+/* The V_*_DEF comes from the initial assignment and the asm. */
+/* { dg-final { scan-tree-dump-times "_DEF" 2 "alias1" } } */
/* { dg-final { cleanup-tree-dump "alias1" } } */
variable. Implicit uses occur when we can't tell what part we
are referencing, and have to make conservative assumptions. */
bool implicit_uses;
+ /* True if the structure is only written to or taken its address. */
+ bool write_only;
} *used_part_t;
/* An array of used_part structures, indexed by variable uid. */
up->maxused = 0;
up->explicit_uses = false;
up->implicit_uses = false;
+ up->write_only = true;
}
return up;
used_part_t up;
size_t uid = DECL_UID (var);
- if (!up_lookup (uid))
+ up = up_lookup (uid);
+ if (!up
+ || up->write_only)
return;
- up = up_lookup (uid);
push_fields_onto_fieldstack (TREE_TYPE (var), &fieldstack, 0, NULL);
if (VEC_length (fieldoff_s, fieldstack) != 0)
{
entire structure. */
static tree
-find_used_portions (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
+find_used_portions (tree *tp, int *walk_subtrees, void *lhs_p)
{
switch (TREE_CODE (*tp))
{
+ case MODIFY_EXPR:
+ /* Recurse manually here to track whether the use is in the
+ LHS of an assignment. */
+ find_used_portions (&TREE_OPERAND (*tp, 0), walk_subtrees, tp);
+ return find_used_portions (&TREE_OPERAND (*tp, 1), walk_subtrees, NULL);
case REALPART_EXPR:
case IMAGPART_EXPR:
case COMPONENT_REF:
up->explicit_uses = true;
else
up->implicit_uses = true;
+ if (!lhs_p)
+ up->write_only = false;
up_insert (uid, up);
*walk_subtrees = 0;