Hi,
This is the 2nd version of the patch, per our discussion based on the
review comments for the 1st version, the major changes in this version
are:
1. change the name "element_count" to "counted_by";
2. change the parameter for the attribute from a STRING to an
Identifier;
3. Add logic and testing cases to handle anonymous structure/unions;
4. Clarify documentation to permit the situation when the allocation
size is larger than what's specified by "counted_by", at the same time,
it's user's error if allocation size is smaller than what's specified by
"counted_by";
5. Add a complete testing case for using counted_by attribute in
__builtin_dynamic_object_size when there is mismatch between the
allocation size and the value of "counted_by", the expecting behavior
for each case and the explanation on why in the comments.
As discussed, I plan to add two more separate patch sets after this initial
patch set is approved and committed.
set 1. A new warning option and a new sanitizer option for the user error
when the allocation size is smaller than the value of "counted_by".
set 2. An improvement to __builtin_dynamic_object_size for the following
case:
struct A
{
size_t foo;
int array[] __attribute__((counted_by (foo)));
};
extern struct fix * alloc_buf ();
int main ()
{
struct fix *p = alloc_buf ();
__builtin_object_size(p->array, 0) == sizeof(struct A) + p->foo * sizeof(int);
/* with the current algorithm, it’s UNKNOWN */
__builtin_object_size(p->array, 2) == sizeof(struct A) + p->foo * sizeof(int);
/* with the current algorithm, it’s UNKNOWN */
}
Bootstrapped and regression tested on both aarch64 and X86, no issue.
Please see more details on the description of this work on:
https://gcc.gnu.org/pipermail/gcc-patches/2023-May/619708.html
Okay for committing?
thanks.
Qing
Qing Zhao (3):
Provide counted_by attribute to flexible array member field (PR108896)
Use the counted_by atribute info in builtin object size [PR108896]
Use the counted_by attribute information in bound sanitizer[PR108896]
gcc/c-family/c-attribs.cc | 54 ++++-
gcc/c-family/c-common.cc | 13 ++
gcc/c-family/c-common.h | 1 +
gcc/c-family/c-ubsan.cc | 16 ++
gcc/c/c-decl.cc | 79 +++++--
gcc/doc/extend.texi | 73 +++++++
.../gcc.dg/flex-array-counted-by-2.c | 74 +++++++
.../gcc.dg/flex-array-counted-by-3.c | 197 ++++++++++++++++++
gcc/testsuite/gcc.dg/flex-array-counted-by.c | 40 ++++
.../ubsan/flex-array-counted-by-bounds-2.c | 27 +++
.../ubsan/flex-array-counted-by-bounds.c | 46 ++++
gcc/tree-object-size.cc | 37 +++-
gcc/tree.cc | 133 ++++++++++++
gcc/tree.h | 15 ++
14 files changed, 780 insertions(+), 25 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/flex-array-counted-by-2.c
create mode 100644 gcc/testsuite/gcc.dg/flex-array-counted-by-3.c
create mode 100644 gcc/testsuite/gcc.dg/flex-array-counted-by.c
create mode 100644 gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds-2.c
create mode 100644 gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds.c
--
2.31.1
