2023-05-17 Qing Zhao <qing.z...@oracle.com>
gcc/ChangeLog:
PR C/108896
* tree-object-size.cc (addr_object_size): Use the element_count
attribute info.
* tree.cc (component_ref_has_element_count_p): New function.
(component_ref_get_element_count): New function.
* tree.h (component_ref_has_element_count_p): New prototype.
(component_ref_get_element_count): New prototype.
gcc/testsuite/ChangeLog:
PR C/108896
* gcc.dg/flex-array-element-count-2.c: New test.
---
.../gcc.dg/flex-array-element-count-2.c | 56 +++++++++++
gcc/tree-object-size.cc | 37 ++++++--
gcc/tree.cc | 93 +++++++++++++++++++
gcc/tree.h | 10 ++
4 files changed, 189 insertions(+), 7 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/flex-array-element-count-2.c
diff --git a/gcc/testsuite/gcc.dg/flex-array-element-count-2.c
b/gcc/testsuite/gcc.dg/flex-array-element-count-2.c
new file mode 100644
index 00000000000..5a280e8c731
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/flex-array-element-count-2.c
@@ -0,0 +1,56 @@
+/* test the attribute element_count and its usage in
+ * __builtin_dynamic_object_size. */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+#include "builtin-object-size-common.h"
+
+#define expect(p, _v) do { \
+ size_t v = _v; \
+ if (p == v) \
+ __builtin_printf ("ok: %s == %zd\n", #p, p); \
+ else \
+ { \
+ __builtin_printf ("WAT: %s == %zd (expected %zd)\n", #p, p, v); \
+ FAIL (); \
+ } \
+} while (0);
+
+struct flex {
+ int b;
+ int c[];
+} *array_flex;
+
+struct annotated {
+ int b;
+ int c[] __attribute__ ((element_count ("b")));
+} *array_annotated;
+
+void __attribute__((__noinline__)) setup (int normal_count, int attr_count)
+{
+ array_flex
+ = (struct flex *)malloc (sizeof (struct flex)
+ + normal_count * sizeof (int));
+ array_flex->b = normal_count;
+
+ array_annotated
+ = (struct annotated *)malloc (sizeof (struct annotated)
+ + attr_count * sizeof (int));
+ array_annotated->b = attr_count;
+
+ return;
+}
+
+void __attribute__((__noinline__)) test ()
+{
+ expect(__builtin_dynamic_object_size(array_flex->c, 1), -1);
+ expect(__builtin_dynamic_object_size(array_annotated->c, 1),
+ array_annotated->b * sizeof (int));
+}
+
+int main(int argc, char *argv[])
+{
+ setup (10,10);
+ test ();
+ DONE ();
+}
diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc
index 9a936a91983..f9aadd59054 100644
--- a/gcc/tree-object-size.cc
+++ b/gcc/tree-object-size.cc
@@ -585,6 +585,7 @@ addr_object_size (struct object_size_info *osi, const_tree
ptr,
if (pt_var != TREE_OPERAND (ptr, 0))
{
tree var;
+ tree element_count_ref = NULL_TREE;
if (object_size_type & OST_SUBOBJECT)
{
@@ -600,11 +601,12 @@ addr_object_size (struct object_size_info *osi,
const_tree ptr,
var = TREE_OPERAND (var, 0);
if (var != pt_var && TREE_CODE (var) == ARRAY_REF)
var = TREE_OPERAND (var, 0);
- if (! TYPE_SIZE_UNIT (TREE_TYPE (var))
+ if (! component_ref_has_element_count_p (var)
+ && ((! TYPE_SIZE_UNIT (TREE_TYPE (var))
|| ! tree_fits_uhwi_p (TYPE_SIZE_UNIT (TREE_TYPE (var)))
|| (pt_var_size && TREE_CODE (pt_var_size) == INTEGER_CST
&& tree_int_cst_lt (pt_var_size,
- TYPE_SIZE_UNIT (TREE_TYPE (var)))))
+ TYPE_SIZE_UNIT (TREE_TYPE (var)))))))
var = pt_var;
else if (var != pt_var && TREE_CODE (pt_var) == MEM_REF)
{
@@ -612,6 +614,7 @@ addr_object_size (struct object_size_info *osi, const_tree
ptr,
/* For &X->fld, compute object size if fld isn't a flexible array
member. */
bool is_flexible_array_mem_ref = false;
+
while (v && v != pt_var)
switch (TREE_CODE (v))
{
@@ -639,6 +642,8 @@ addr_object_size (struct object_size_info *osi, const_tree
ptr,
break;
}
is_flexible_array_mem_ref = array_ref_flexible_size_p (v);
+ element_count_ref = component_ref_get_element_count (v);
+
while (v != pt_var && TREE_CODE (v) == COMPONENT_REF)
if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
!= UNION_TYPE
@@ -652,8 +657,11 @@ addr_object_size (struct object_size_info *osi, const_tree
ptr,
== RECORD_TYPE)
{
/* compute object size only if v is not a
- flexible array member. */
- if (!is_flexible_array_mem_ref)
+ flexible array member or the flexible array member
+ has a known element count indicated by the user
+ through attribute element_count. */
+ if (!is_flexible_array_mem_ref
+ || element_count_ref)
{
v = NULL_TREE;
break;
@@ -686,9 +694,24 @@ addr_object_size (struct object_size_info *osi, const_tree
ptr,
if (var != pt_var)
{
- var_size = TYPE_SIZE_UNIT (TREE_TYPE (var));
- if (!TREE_CONSTANT (var_size))
- var_size = get_or_create_ssa_default_def (cfun, var_size);
+ if (!element_count_ref)
+ {
+ var_size = TYPE_SIZE_UNIT (TREE_TYPE (var));
+ if (!TREE_CONSTANT (var_size))
+ var_size = get_or_create_ssa_default_def (cfun, var_size);
+ }
+ else
+ {
+ gcc_assert (TREE_CODE (var) == COMPONENT_REF
+ && TREE_CODE (TREE_TYPE (var)) == ARRAY_TYPE);
+ tree element_size = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (var)));
+ var_size
+ = size_binop (MULT_EXPR,
+ fold_convert (sizetype, element_count_ref),
+ fold_convert (sizetype, element_size));
+ if (!todo)
+ todo = TODO_update_ssa_only_virtuals;
+ }
if (!var_size)
return false;
}
diff --git a/gcc/tree.cc b/gcc/tree.cc
index 7e6de288886..48753b94f2c 100644
--- a/gcc/tree.cc
+++ b/gcc/tree.cc
@@ -12745,6 +12745,99 @@ array_ref_element_size (tree exp)
return SUBSTITUTE_PLACEHOLDER_IN_EXPR (TYPE_SIZE_UNIT (elmt_type), exp);
}
+/* For a component_ref that has an array type ARRAY_REF, return TRUE when
+ an element_count attribute attached to the corresponding FIELD_DECL.
+ return FALSE otherwise. */
+bool
+component_ref_has_element_count_p (tree array_ref)
+{
+ if (TREE_CODE (array_ref) != COMPONENT_REF)
+ return false;
+
+ if (TREE_CODE (TREE_TYPE (array_ref)) != ARRAY_TYPE)
+ return false;
+
+ tree struct_object = TREE_OPERAND (array_ref, 0);
+ tree struct_type = TREE_TYPE (struct_object);
+
+ if (!RECORD_OR_UNION_TYPE_P (struct_type))
+ return false;
+ tree field_decl = TREE_OPERAND (array_ref, 1);
+ tree attr_element_count = lookup_attribute ("element_count",
+ DECL_ATTRIBUTES (field_decl));
+
+ if (!attr_element_count)
+ return false;
+ return true;
+}
+
+
+/* For a component_ref that has an array type ARRAY_REF, get the object that
+ represents its element_count per the attribute element_count attached to
+ the corresponding FIELD_DECL. return NULL_TREE when cannot find such
+ object.
+ For example, if:
+
+ struct P {
+ int k;
+ int x[] __attribute__ ((element_count ("k")));
+ } *p;
+
+ for the following reference:
+
+ p->x[b]
+
+ the object that represents its element count will be:
+
+ p->k
+
+ So, when component_ref_get_element_count (p->x[b]) is called, p->k should
be
+ returned.
+*/
+
+tree
+component_ref_get_element_count (tree array_ref)
+{
+ if (! component_ref_has_element_count_p (array_ref))
+ return NULL_TREE;
+
+ tree struct_object = TREE_OPERAND (array_ref, 0);
+ tree struct_type = TREE_TYPE (struct_object);
+ tree field_decl = TREE_OPERAND (array_ref, 1);
+ tree attr_element_count = lookup_attribute ("element_count",
+ DECL_ATTRIBUTES (field_decl));
+ gcc_assert (attr_element_count);
+
+ /* If there is an element_count attribute attached to the field,
+ get the field that maps to the element_count. */
+
+ const char *fieldname
+ = TREE_STRING_POINTER (TREE_VALUE (TREE_VALUE (attr_element_count)));
+
+ tree element_count_field = NULL_TREE;
+ for (tree field = TYPE_FIELDS (struct_type); field;
+ field = DECL_CHAIN (field))
+ if (TREE_CODE (field) == FIELD_DECL
+ && DECL_NAME (field) != NULL
+ && strcmp (IDENTIFIER_POINTER (DECL_NAME (field)), fieldname) == 0)
+ {
+ element_count_field = field;
+ break;
+ }
+
+ gcc_assert (element_count_field);
+
+ /* generate the tree node that represent the element_count of this array
+ ref. This is a COMPONENT_REF to the element_count_field of the
+ containing structure. */
+
+ tree element_count_ref = build3 (COMPONENT_REF,
+ TREE_TYPE (element_count_field),
+ struct_object, element_count_field,
+ NULL_TREE);
+ return element_count_ref;
+}
+
/* Return a tree representing the lower bound of the array mentioned in
EXP, an ARRAY_REF or an ARRAY_RANGE_REF. */
diff --git a/gcc/tree.h b/gcc/tree.h
index 0b72663e6a1..8f36370a02d 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -5582,6 +5582,16 @@ extern tree get_base_address (tree t);
of EXP, an ARRAY_REF or an ARRAY_RANGE_REF. */
extern tree array_ref_element_size (tree);
+/* Give a component_ref that has an array type, return true when an
+ attribute element_count attached to the corresponding FIELD_DECL. */
+extern bool component_ref_has_element_count_p (tree);
+
+/* Give a component_ref that has an array type, return the object that
+ represents its element_count per the attribute element_count attached to
+ the corresponding FIELD_DECL. return NULL_TREE when cannot find such
+ object. */
+extern tree component_ref_get_element_count (tree);
+
/* Return a typenode for the "standard" C type with a given name. */
extern tree get_typenode_from_name (const char *);
--
2.31.1
