On 2025-06-16 18:08, Qing Zhao wrote:
gcc/ChangeLog:
* tree-object-size.cc (access_with_size_object_size): Handle pointers
with counted_by.
This should probably just say "Update comment for .ACCESS_WITH_SIZE.".
(collect_object_sizes_for): Likewise.
gcc/testsuite/ChangeLog:
* gcc.dg/pointer-counted-by-4.c: New test.
* gcc.dg/pointer-counted-by-5.c: New test.
* gcc.dg/pointer-counted-by-6.c: New test.
* gcc.dg/pointer-counted-by-7.c: New test.
---
I can't approve, but here's a review. In summary, I've suggested some
modifications to the tests, the tree-object-size change itself looks
fine to me.
gcc/testsuite/gcc.dg/pointer-counted-by-4.c | 63 +++++++++++++++++++++
gcc/testsuite/gcc.dg/pointer-counted-by-5.c | 48 ++++++++++++++++
gcc/testsuite/gcc.dg/pointer-counted-by-6.c | 47 +++++++++++++++
gcc/testsuite/gcc.dg/pointer-counted-by-7.c | 30 ++++++++++
gcc/tree-object-size.cc | 12 +++-
5 files changed, 197 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pointer-counted-by-4.c
create mode 100644 gcc/testsuite/gcc.dg/pointer-counted-by-5.c
create mode 100644 gcc/testsuite/gcc.dg/pointer-counted-by-6.c
create mode 100644 gcc/testsuite/gcc.dg/pointer-counted-by-7.c
diff --git a/gcc/testsuite/gcc.dg/pointer-counted-by-4.c
b/gcc/testsuite/gcc.dg/pointer-counted-by-4.c
new file mode 100644
index 00000000000..11e9421c819
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pointer-counted-by-4.c
@@ -0,0 +1,63 @@
+/* Test the attribute counted_by for pointer field and its usage in
+ * __builtin_dynamic_object_size. */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+#include "builtin-object-size-common.h"
+
+struct pointer_array {
+ int b;
+ int *c;
+} *p_array;
+
+struct annotated {
+ int *c __attribute__ ((counted_by (b)));
+ int b;
+} *p_array_annotated;
+
+struct nested_annotated {
+ int *c __attribute__ ((counted_by (b)));
+ struct {
+ union {
+ int b;
+ float f;
+ };
+ int n;
+ };
+} *p_array_nested_annotated;
+
+void __attribute__((__noinline__)) setup (int normal_count, int attr_count)
+{
+ p_array
+ = (struct pointer_array *) malloc (sizeof (struct pointer_array));
+ p_array->c = (int *) malloc (sizeof (int) * normal_count);
+ p_array->b = normal_count;
+
+ p_array_annotated
+ = (struct annotated *) malloc (sizeof (struct annotated));
+ p_array_annotated->c = (int *) malloc (sizeof (int) * attr_count);
+ p_array_annotated->b = attr_count;
+
+ p_array_nested_annotated
+ = (struct nested_annotated *) malloc (sizeof (struct nested_annotated));
+ p_array_nested_annotated->c = (int *) malloc (sizeof (int) * attr_count);
+ p_array_nested_annotated->b = attr_count;
+
+ return;
+}
+
+void __attribute__((__noinline__)) test ()
+{
+ EXPECT(__builtin_dynamic_object_size(p_array->c, 1), -1);
+ EXPECT(__builtin_dynamic_object_size(p_array_annotated->c, 1),
+ p_array_annotated->b * sizeof (int));
+ EXPECT(__builtin_dynamic_object_size(p_array_nested_annotated->c, 1),
+ p_array_nested_annotated->b * sizeof (int));
+}
Suggest extending this test for at least char so that you verify
scaling. e.g. you could have this in pointer-counted-by-4.c:
```
#ifndef PTR_TYPE
#define PTR_TYPE int
#endif
struct pointer_array {
int b;
PTR_TYPE *c;
} *p_array;
struct annotated {
PTR_TYPE *c __attribute__ ((counted_by (b)));
int b;
} *p_array_annotated;
struct nested_annotated {
PTR_TYPE *c __attribute__ ((counted_by (b)));
struct {
union {
int b;
float f;
};
int n;
};
} *p_array_nested_annotated;
```
and then have another test pointer-counted-by-4-char.c that simply
includes this test:
```
#define PTR_TYPE char
#include "pointer-counted-by-4.c"
```
+
+int main(int argc, char *argv[])
+{
+ setup (10,10);
+ test ();
+ DONE ();
+}
diff --git a/gcc/testsuite/gcc.dg/pointer-counted-by-5.c
b/gcc/testsuite/gcc.dg/pointer-counted-by-5.c
new file mode 100644
index 00000000000..45918c3e654
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pointer-counted-by-5.c
@@ -0,0 +1,48 @@
+/* Test the attribute counted_by for pointer fields and its usage in
+ * __builtin_dynamic_object_size: when the counted_by field is negative. */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+#include "builtin-object-size-common.h"
+
+struct annotated {
+ int b;
+ int *c __attribute__ ((counted_by (b)));
+} *array_annotated;
+
+struct nested_annotated {
+ int *c __attribute__ ((counted_by (b)));
+ struct {
+ union {
+ int b;
+ float f;
+ };
+ int n;
+ };
+} *array_nested_annotated;
+
+void __attribute__((__noinline__)) setup (int attr_count)
+{
+ array_annotated
+ = (struct annotated *)malloc (sizeof (struct annotated));
+ array_annotated->b = attr_count;
+
+ array_nested_annotated
+ = (struct nested_annotated *)malloc (sizeof (struct nested_annotated));
+ array_nested_annotated->b = attr_count - 1;
+
+ return;
+}
+
+void __attribute__((__noinline__)) test ()
+{
+ EXPECT(__builtin_dynamic_object_size(array_annotated->c, 1), 0);
+ EXPECT(__builtin_dynamic_object_size(array_nested_annotated->c, 1), 0);
+}
+
+int main(int argc, char *argv[])
+{
+ setup (-10);
+ test ();
+ DONE ();
+}
OK.
diff --git a/gcc/testsuite/gcc.dg/pointer-counted-by-6.c
b/gcc/testsuite/gcc.dg/pointer-counted-by-6.c
new file mode 100644
index 00000000000..4a1baa41d9a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pointer-counted-by-6.c
@@ -0,0 +1,47 @@
+/* Test the attribute counted_by for pointer fields and its usage in
+ * __builtin_dynamic_object_size: when the type of the pointer
+ * is casting to another type. */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+#include "builtin-object-size-common.h"
+
+typedef unsigned short u16;
+
+struct info {
+ u16 data_len;
+ char *data __attribute__((counted_by(data_len)));
+};
+
+struct foo {
+ int a;
+ int b;
+};
+
+static __attribute__((__noinline__))
+struct info *setup ()
+{
+ struct info *p;
+ size_t bytes = 3 * sizeof(struct foo);
+
+ p = (struct info *) malloc (sizeof (struct info));
+ p->data = (char *) malloc (bytes);
+ p->data_len = bytes;
+
+ return p;
+}
+
+static void
+__attribute__((__noinline__)) report (struct info *p)
+{
+ struct foo *bar = (struct foo *)p->data;
+ EXPECT(__builtin_dynamic_object_size((char *)(bar + 1), 1), 16);
+ EXPECT(__builtin_dynamic_object_size((char *)(bar + 2), 1), 8);
How about this instead; it eliminates the magic constants and also
preserves the intent of the test in a more general (i.e. integer size
agnostic) sense:
EXPECT(__builtin_dynamic_object_size((char *)(bar + 1), 1),
sizeof (struct foo) * 2);
EXPECT(__builtin_dynamic_object_size((char *)(bar + 2), 1),
sizeof (struct foo));
+}
+
+int main(int argc, char *argv[])
+{
+ struct info *p = setup();
+ report(p);
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/pointer-counted-by-7.c
b/gcc/testsuite/gcc.dg/pointer-counted-by-7.c
new file mode 100644
index 00000000000..01addbb857d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pointer-counted-by-7.c
@@ -0,0 +1,30 @@
+/* Additional test of the attribute counted_by for pointer field and its usage
+ in __builtin_dynamic_object_size. */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+#include "builtin-object-size-common.h"
+
+struct annotated {
+ int b;
+ int *c __attribute__ ((counted_by (b)));
+};
+
+struct annotated __attribute__((__noinline__)) setup (int attr_count)
+{
+ struct annotated p_array_annotated;
+ p_array_annotated.c = (int *) malloc (sizeof (int) * attr_count);
+ p_array_annotated.b = attr_count;
+
+ return p_array_annotated;
+}
+
+int main(int argc, char *argv[])
+{
+ struct annotated x = setup (10);
+ int *p = x.c;
+ x = setup (20);
+ EXPECT(__builtin_dynamic_object_size (p, 1), 10 * sizeof (int));
+ EXPECT(__builtin_dynamic_object_size (x.c, 1), 20 * sizeof (int));
+ DONE ();
+}
OK. One note: all of the tests leak memory, but it's not an unbounded
leak, so it's probably OK to ignore.
diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc
index f348673ae75..170f1197c8d 100644
--- a/gcc/tree-object-size.cc
+++ b/gcc/tree-object-size.cc
@@ -773,10 +773,12 @@ addr_object_size (struct object_size_info *osi,
const_tree ptr,
4th argument TYPE_OF_SIZE: A constant 0 with its TYPE being the same as
the TYPE
of the object referenced by REF_TO_SIZE
6th argument: A constant 0 with the pointer TYPE to the original flexible
- array type.
+ array type or pointer field type.
The size of the element can be retrived from the TYPE of the 6th argument
- of the call, which is the pointer to the array type. */
+ of the call, which is the pointer to the original flexible array type or
+ the type of the original pointer field. */
+
static tree
access_with_size_object_size (const gcall *call, int object_size_type)
{
@@ -786,7 +788,7 @@ access_with_size_object_size (const gcall *call, int
object_size_type)
gcc_assert (gimple_call_internal_p (call, IFN_ACCESS_WITH_SIZE));
/* The type of the 6th argument type is the pointer TYPE to the original
- flexible array type. */
+ flexible array type or to the original pointer type. */
tree pointer_to_array_type = TREE_TYPE (gimple_call_arg (call, 5));
gcc_assert (POINTER_TYPE_P (pointer_to_array_type));
tree element_type = TREE_TYPE (TREE_TYPE (pointer_to_array_type));
Only a comment update to indicate the scope change for
.ACCESS_WITH_SIZE. OK.
@@ -1854,6 +1856,10 @@ collect_object_sizes_for (struct object_size_info *osi,
tree var)
if (TREE_CODE (rhs) == SSA_NAME
&& POINTER_TYPE_P (TREE_TYPE (rhs)))
reexamine = merge_object_sizes (osi, var, rhs);
+ else if (TREE_CODE (rhs) == MEM_REF
+ && POINTER_TYPE_P (TREE_TYPE (rhs))
+ && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
+ reexamine = merge_object_sizes (osi, var, TREE_OPERAND (rhs, 0));
else
expr_object_size (osi, var, rhs);
}
Interesting, looks like this would improve coverage for more than just
this specific case of pointers within structs. Nice! Is this what
pointer-counted-by-7.c covers?
Thanks,
Sid
