On Fri, Apr 12, 2024 at 3:54 PM Qing Zhao <qing.z...@oracle.com> wrote:
>
I have no comments here, if Siddesh is OK with this I approve.
> gcc/ChangeLog:
>
> * tree-object-size.cc (access_with_size_object_size): New function.
> (call_object_size): Call the new function.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/builtin-object-size-common.h: Add a new macro EXPECT.
> * gcc.dg/flex-array-counted-by-3.c: New test.
> * gcc.dg/flex-array-counted-by-4.c: New test.
> * gcc.dg/flex-array-counted-by-5.c: New test.
> ---
> .../gcc.dg/builtin-object-size-common.h | 11 ++
> .../gcc.dg/flex-array-counted-by-3.c | 63 +++++++
> .../gcc.dg/flex-array-counted-by-4.c | 178 ++++++++++++++++++
> .../gcc.dg/flex-array-counted-by-5.c | 48 +++++
> gcc/tree-object-size.cc | 60 ++++++
> 5 files changed, 360 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/flex-array-counted-by-3.c
> create mode 100644 gcc/testsuite/gcc.dg/flex-array-counted-by-4.c
> create mode 100644 gcc/testsuite/gcc.dg/flex-array-counted-by-5.c
>
> diff --git a/gcc/testsuite/gcc.dg/builtin-object-size-common.h
> b/gcc/testsuite/gcc.dg/builtin-object-size-common.h
> index 66ff7cdd953a..b677067c6e6b 100644
> --- a/gcc/testsuite/gcc.dg/builtin-object-size-common.h
> +++ b/gcc/testsuite/gcc.dg/builtin-object-size-common.h
> @@ -30,3 +30,14 @@ unsigned nfails = 0;
> __builtin_abort ();
> \
> return 0;
> \
> } while (0)
> +
> +#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);
> diff --git a/gcc/testsuite/gcc.dg/flex-array-counted-by-3.c
> b/gcc/testsuite/gcc.dg/flex-array-counted-by-3.c
> new file mode 100644
> index 000000000000..78f50230e891
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/flex-array-counted-by-3.c
> @@ -0,0 +1,63 @@
> +/* Test the attribute counted_by and its usage in
> + * __builtin_dynamic_object_size. */
> +/* { dg-do run } */
> +/* { dg-options "-O2" } */
> +
> +#include "builtin-object-size-common.h"
> +
> +struct flex {
> + int b;
> + int c[];
> +} *array_flex;
> +
> +struct annotated {
> + int b;
> + int c[] __attribute__ ((counted_by (b)));
> +} *array_annotated;
> +
> +struct nested_annotated {
> + struct {
> + union {
> + int b;
> + float f;
> + };
> + int n;
> + };
> + int c[] __attribute__ ((counted_by (b)));
> +} *array_nested_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;
> +
> + array_nested_annotated
> + = (struct nested_annotated *)malloc (sizeof (struct nested_annotated)
> + + attr_count * sizeof (int));
> + array_nested_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));
> + EXPECT(__builtin_dynamic_object_size(array_nested_annotated->c, 1),
> + array_nested_annotated->b * sizeof (int));
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + setup (10,10);
> + test ();
> + DONE ();
> +}
> diff --git a/gcc/testsuite/gcc.dg/flex-array-counted-by-4.c
> b/gcc/testsuite/gcc.dg/flex-array-counted-by-4.c
> new file mode 100644
> index 000000000000..20103d58ef51
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/flex-array-counted-by-4.c
> @@ -0,0 +1,178 @@
> +/* Test the attribute counted_by and its usage in
> +__builtin_dynamic_object_size: what's the correct behavior when the
> +allocation size mismatched with the value of counted_by attribute?
> +We should always use the latest value that is hold by the counted_by
> +field. */
> +/* { dg-do run } */
> +/* { dg-options "-O -fstrict-flex-arrays=3" } */
> +
> +#include "builtin-object-size-common.h"
> +
> +struct annotated {
> + size_t foo;
> + char others;
> + char array[] __attribute__((counted_by (foo)));
> +};
> +
> +#define noinline __attribute__((__noinline__))
> +#define SIZE_BUMP 10
> +#define MAX(a, b) ((a) > (b) ? (a) : (b))
> +
> +/* In general, Due to type casting, the type for the pointee of a pointer
> + does not say anything about the object it points to,
> + So, __builtin_object_size can not directly use the type of the pointee
> + to decide the size of the object the pointer points to.
> +
> + There are only two reliable ways:
> + A. observed allocations (call to the allocation functions in the routine)
> + B. observed accesses (read or write access to the location of the
> + pointer points to)
> +
> + That provide information about the type/existence of an object at
> + the corresponding address.
> +
> + For A, we use the "alloc_size" attribute for the corresponding allocation
> + functions to determine the object size;
> + (We treat counted_by attribute the same as the "alloc_size" attribute)
> +
> + For B, we use the SIZE info of the TYPE attached to the corresponding
> access.
> +
> + The only other way in C which ensures that a pointer actually points
> + to an object of the correct type is 'static':
> +
> + void foo(struct P *p[static 1]);
> +
> + See https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624814.html
> + for more details. */
> +
> +/* In the following function, malloc allocated more space than the value
> + of counted_by attribute. Then what's the correct behavior we expect
> + the __builtin_dynamic_object_size should have for each of the cases? */
> +
> +static struct annotated * noinline alloc_buf_more (size_t index)
> +{
> + struct annotated *p;
> + size_t allocated_size
> + = MAX (sizeof (struct annotated),
> + (__builtin_offsetof (struct annotated, array[0])
> + + (index + SIZE_BUMP) * sizeof (char)));
> + p = (struct annotated *) malloc (allocated_size);
> +
> + p->foo = index;
> +
> + /* When checking the observed access p->array, we have info on both
> + observered allocation and observed access,
> + A.1 from observed allocation:
> + allocated_size - offsetof (struct annotated, array[0])
> +
> + A.2 from the counted-by attribute:
> + p->foo * sizeof (char)
> +
> + We always use the latest value that is hold by the counted-by field.
> + */
> +
> + EXPECT(__builtin_dynamic_object_size(p->array, 0),
> + (p->foo) * sizeof(char));
> +
> + EXPECT(__builtin_dynamic_object_size(p->array, 1),
> + (p->foo) * sizeof(char));
> +
> + EXPECT(__builtin_dynamic_object_size(p->array, 2),
> + (p->foo) * sizeof(char));
> +
> + EXPECT(__builtin_dynamic_object_size(p->array, 3),
> + (p->foo) * sizeof(char));
> +
> + /* When checking the pointer p, we only have info on the observed
> allocation.
> + So, the object size info can only been obtained from the call to malloc.
> + For both MAXIMUM and MINIMUM: A = (index + SIZE_BUMP) * sizeof (char) */
> + EXPECT(__builtin_dynamic_object_size(p, 0), allocated_size);
> + EXPECT(__builtin_dynamic_object_size(p, 1), allocated_size);
> + EXPECT(__builtin_dynamic_object_size(p, 2), allocated_size);
> + EXPECT(__builtin_dynamic_object_size(p, 3), allocated_size);
> + return p;
> +}
> +
> +/* In the following function, malloc allocated less space than the value
> + of counted_by attribute. Then what's the correct behavior we expect
> + the __builtin_dynamic_object_size should have for each of the cases?
> + NOTE: this is an user error, GCC should issue warnings for such case.
> + This is a seperate issue we should address later. */
> +
> +static struct annotated * noinline alloc_buf_less (size_t index)
> +{
> + struct annotated *p;
> + size_t allocated_size
> + = MAX (sizeof (struct annotated),
> + (__builtin_offsetof (struct annotated, array[0])
> + + (index) * sizeof (char)));
> + p = (struct annotated *) malloc (allocated_size);
> +
> + p->foo = index + SIZE_BUMP;
> +
> + /* When checking the observed access p->array, we have info on both
> + observered allocation and observed access,
> + A.1 from observed allocation:
> + allocated_size - offsetof (struct annotated, array[0])
> + A.2 from the counted-by attribute:
> + p->foo * sizeof (char)
> +
> + We always use the latest value that is hold by the counted-by field.
> + */
> +
> + EXPECT(__builtin_dynamic_object_size(p->array, 0),
> + (p->foo) * sizeof(char));
> +
> + EXPECT(__builtin_dynamic_object_size(p->array, 1),
> + (p->foo) * sizeof(char));
> +
> + EXPECT(__builtin_dynamic_object_size(p->array, 2),
> + (p->foo) * sizeof(char));
> +
> + EXPECT(__builtin_dynamic_object_size(p->array, 3),
> + (p->foo) * sizeof(char));
> +
> + /* When checking the pointer p, we only have info on the observed
> + allocation. So, the object size info can only been obtained from
> + the call to malloc. */
> + EXPECT(__builtin_dynamic_object_size(p, 0), allocated_size);
> + EXPECT(__builtin_dynamic_object_size(p, 1), allocated_size);
> + EXPECT(__builtin_dynamic_object_size(p, 2), allocated_size);
> + EXPECT(__builtin_dynamic_object_size(p, 3), allocated_size);
> + return p;
> +}
> +
> +int main ()
> +{
> + struct annotated *p, *q;
> + p = alloc_buf_more (10);
> + q = alloc_buf_less (10);
> +
> + /* When checking the access p->array, we only have info on the counted-by
> + value. */
> + EXPECT(__builtin_dynamic_object_size(p->array, 0), p->foo * sizeof(char));
> + EXPECT(__builtin_dynamic_object_size(p->array, 1), p->foo * sizeof(char));
> + EXPECT(__builtin_dynamic_object_size(p->array, 2), p->foo * sizeof(char));
> + EXPECT(__builtin_dynamic_object_size(p->array, 3), p->foo * sizeof(char));
> + /* When checking the pointer p, we have no observed allocation nor observed
> + access, therefore, we cannot determine the size info here. */
> + EXPECT(__builtin_dynamic_object_size(p, 0), -1);
> + EXPECT(__builtin_dynamic_object_size(p, 1), -1);
> + EXPECT(__builtin_dynamic_object_size(p, 2), 0);
> + EXPECT(__builtin_dynamic_object_size(p, 3), 0);
> +
> + /* When checking the access p->array, we only have info on the counted-by
> + value. */
> + EXPECT(__builtin_dynamic_object_size(q->array, 0), q->foo * sizeof(char));
> + EXPECT(__builtin_dynamic_object_size(q->array, 1), q->foo * sizeof(char));
> + EXPECT(__builtin_dynamic_object_size(q->array, 2), q->foo * sizeof(char));
> + EXPECT(__builtin_dynamic_object_size(q->array, 3), q->foo * sizeof(char));
> + /* When checking the pointer p, we have no observed allocation nor observed
> + access, therefore, we cannot determine the size info here. */
> + EXPECT(__builtin_dynamic_object_size(q, 0), -1);
> + EXPECT(__builtin_dynamic_object_size(q, 1), -1);
> + EXPECT(__builtin_dynamic_object_size(q, 2), 0);
> + EXPECT(__builtin_dynamic_object_size(q, 3), 0);
> +
> + DONE ();
> +}
> diff --git a/gcc/testsuite/gcc.dg/flex-array-counted-by-5.c
> b/gcc/testsuite/gcc.dg/flex-array-counted-by-5.c
> new file mode 100644
> index 000000000000..68f9b0f7c8d2
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/flex-array-counted-by-5.c
> @@ -0,0 +1,48 @@
> +/* Test the attribute counted_by 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 {
> + struct {
> + union {
> + int b;
> + float f;
> + };
> + int n;
> + };
> + int c[] __attribute__ ((counted_by (b)));
> +} *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 ();
> +}
> diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc
> index 018fbc30cbb6..8de264d1dee2 100644
> --- a/gcc/tree-object-size.cc
> +++ b/gcc/tree-object-size.cc
> @@ -37,6 +37,7 @@ along with GCC; see the file COPYING3. If not see
> #include "attribs.h"
> #include "builtins.h"
> #include "gimplify-me.h"
> +#include "gimplify.h"
>
> struct object_size_info
> {
> @@ -60,6 +61,7 @@ static tree compute_object_offset (tree, const_tree);
> static bool addr_object_size (struct object_size_info *,
> const_tree, int, tree *, tree *t = NULL);
> static tree alloc_object_size (const gcall *, int);
> +static tree access_with_size_object_size (const gcall *, int);
> static tree pass_through_call (const gcall *);
> static void collect_object_sizes_for (struct object_size_info *, tree);
> static void expr_object_size (struct object_size_info *, tree, tree);
> @@ -749,6 +751,60 @@ addr_object_size (struct object_size_info *osi,
> const_tree ptr,
> return false;
> }
>
> +/* Compute __builtin_object_size for a CALL to .ACCESS_WITH_SIZE,
> + OBJECT_SIZE_TYPE is the second argument from __builtin_object_size.
> + The 2nd, 3rd, and the 4th parameters of the call determine the size of
> + the CALL:
> +
> + 2nd argument REF_TO_SIZE: The reference to the size of the object,
> + 3rd argument CLASS_OF_SIZE: The size referenced by the REF_TO_SIZE
> represents
> + 0: the number of bytes;
> + 1: the number of the elements of the object type;
> + 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
> +
> + The size of the element can be retrived from the result type of the call,
> + which is the pointer to the array type. */
> +static tree
> +access_with_size_object_size (const gcall *call, int object_size_type)
> +{
> + /* If not for dynamic object size, return. */
> + if ((object_size_type & OST_DYNAMIC) == 0)
> + return size_unknown (object_size_type);
> +
> + gcc_assert (gimple_call_internal_p (call, IFN_ACCESS_WITH_SIZE));
> + /* Result type is a pointer type to the original flexible array type. */
> + tree result_type = gimple_call_return_type (call);
> + gcc_assert (POINTER_TYPE_P (result_type));
> + tree element_size = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (result_type)));
> + tree ref_to_size = gimple_call_arg (call, 1);
> + unsigned int class_of_size = TREE_INT_CST_LOW (gimple_call_arg (call, 2));
> + tree type = TREE_TYPE (gimple_call_arg (call, 3));
> +
> + tree size = fold_build2 (MEM_REF, type, ref_to_size,
> + build_int_cst (ptr_type_node, 0));
> +
> + /* If size is negative value, treat it as zero. */
> + if (!TYPE_UNSIGNED (type))
> + {
> + tree cond_expr = fold_build2 (LT_EXPR, boolean_type_node,
> + unshare_expr (size), build_zero_cst (type));
> + size = fold_build3 (COND_EXPR, integer_type_node, cond_expr,
> + build_zero_cst (type), size);
> + }
> +
> + if (class_of_size == 1)
> + size = size_binop (MULT_EXPR,
> + fold_convert (sizetype, size),
> + fold_convert (sizetype, element_size));
> + else
> + size = fold_convert (sizetype, size);
> +
> + if (!todo)
> + todo = TODO_update_ssa_only_virtuals;
> +
> + return size;
> +}
>
> /* Compute __builtin_object_size for CALL, which is a GIMPLE_CALL.
> Handles calls to functions declared with attribute alloc_size.
> @@ -1350,8 +1406,12 @@ call_object_size (struct object_size_info *osi, tree
> ptr, gcall *call)
>
> bool is_strdup = gimple_call_builtin_p (call, BUILT_IN_STRDUP);
> bool is_strndup = gimple_call_builtin_p (call, BUILT_IN_STRNDUP);
> + bool is_access_with_size
> + = gimple_call_internal_p (call, IFN_ACCESS_WITH_SIZE);
> if (is_strdup || is_strndup)
> bytes = strdup_object_size (call, object_size_type, is_strndup);
> + else if (is_access_with_size)
> + bytes = access_with_size_object_size (call, object_size_type);
> else
> bytes = alloc_object_size (call, object_size_type);
>
> --
> 2.31.1
>
