On Tue, May 28, 2024 at 11:10 PM Qing Zhao <qing.z...@oracle.com> wrote:
>
>
>
> > On May 28, 2024, at 03:43, Richard Biener <richard.guent...@gmail.com>
> > wrote:
> >
> > On Fri, Apr 12, 2024 at 3:55 PM Qing Zhao <qing.z...@oracle.com> wrote:
> >>
> >> to carry the TYPE of the flexible array.
> >>
> >> Such information is needed during tree-object-size.cc.
> >>
> >> We cannot use the result type or the type of the 1st argument
> >> of the routine .ACCESS_WITH_SIZE to decide the element type
> >> of the original array due to possible type casting in the
> >> source code.
> >
> > OK. I guess technically an empty CONSTRUCTOR of the array type
> > would work as well (as aggregate it's fine to have it in the call) but a
> > constant zero pointer might be cheaper to have as it's shared across
> > multiple calls.
>
> So, I consider this as an approval? -:)
yes
> thanks.
>
> Qing
> >
> > Richard.
> >
> >> gcc/c/ChangeLog:
> >>
> >> * c-typeck.cc (build_access_with_size_for_counted_by): Add the 6th
> >> argument to .ACCESS_WITH_SIZE.
> >>
> >> gcc/ChangeLog:
> >>
> >> * tree-object-size.cc (access_with_size_object_size): Use the type
> >> of the 6th argument for the type of the element.
> >>
> >> gcc/testsuite/ChangeLog:
> >>
> >> * gcc.dg/flex-array-counted-by-6.c: New test.
> >> ---
> >> gcc/c/c-typeck.cc | 11 +++--
> >> gcc/internal-fn.cc | 2 +
> >> .../gcc.dg/flex-array-counted-by-6.c | 46 +++++++++++++++++++
> >> gcc/tree-object-size.cc | 16 ++++---
> >> 4 files changed, 66 insertions(+), 9 deletions(-)
> >> create mode 100644 gcc/testsuite/gcc.dg/flex-array-counted-by-6.c
> >>
> >> diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
> >> index ff6685c6c4ba..0ea3b75355a4 100644
> >> --- a/gcc/c/c-typeck.cc
> >> +++ b/gcc/c/c-typeck.cc
> >> @@ -2640,7 +2640,8 @@ build_counted_by_ref (tree datum, tree subdatum,
> >> tree *counted_by_type)
> >>
> >> to:
> >>
> >> - (*.ACCESS_WITH_SIZE (REF, COUNTED_BY_REF, 1, (TYPE_OF_SIZE)0, -1))
> >> + (*.ACCESS_WITH_SIZE (REF, COUNTED_BY_REF, 1, (TYPE_OF_SIZE)0, -1,
> >> + (TYPE_OF_ARRAY *)0))
> >>
> >> NOTE: The return type of this function is the POINTER type pointing
> >> to the original flexible array type.
> >> @@ -2652,6 +2653,9 @@ build_counted_by_ref (tree datum, tree subdatum,
> >> tree *counted_by_type)
> >> The 4th argument of the call is a constant 0 with the TYPE of the
> >> object pointed by COUNTED_BY_REF.
> >>
> >> + The 6th argument of the call is a constant 0 with the pointer TYPE
> >> + to the original flexible array type.
> >> +
> >> */
> >> static tree
> >> build_access_with_size_for_counted_by (location_t loc, tree ref,
> >> @@ -2664,12 +2668,13 @@ build_access_with_size_for_counted_by (location_t
> >> loc, tree ref,
> >>
> >> tree call
> >> = build_call_expr_internal_loc (loc, IFN_ACCESS_WITH_SIZE,
> >> - result_type, 5,
> >> + result_type, 6,
> >> array_to_pointer_conversion (loc, ref),
> >> counted_by_ref,
> >> build_int_cst (integer_type_node, 1),
> >> build_int_cst (counted_by_type, 0),
> >> - build_int_cst (integer_type_node, -1));
> >> + build_int_cst (integer_type_node, -1),
> >> + build_int_cst (result_type, 0));
> >> /* Wrap the call with an INDIRECT_REF with the flexible array type. */
> >> call = build1 (INDIRECT_REF, TREE_TYPE (ref), call);
> >> SET_EXPR_LOCATION (call, loc);
> >> diff --git a/gcc/internal-fn.cc b/gcc/internal-fn.cc
> >> index e744080ee670..34e4a4aea534 100644
> >> --- a/gcc/internal-fn.cc
> >> +++ b/gcc/internal-fn.cc
> >> @@ -3411,6 +3411,8 @@ expand_DEFERRED_INIT (internal_fn, gcall *stmt)
> >> 1: read_only
> >> 2: write_only
> >> 3: read_write
> >> + 6th argument: A constant 0 with the pointer TYPE to the original
> >> flexible
> >> + array type.
> >>
> >> Both the return type and the type of the first argument of this
> >> function have been converted from the incomplete array type to
> >> diff --git a/gcc/testsuite/gcc.dg/flex-array-counted-by-6.c
> >> b/gcc/testsuite/gcc.dg/flex-array-counted-by-6.c
> >> new file mode 100644
> >> index 000000000000..65fa01443d95
> >> --- /dev/null
> >> +++ b/gcc/testsuite/gcc.dg/flex-array-counted-by-6.c
> >> @@ -0,0 +1,46 @@
> >> +/* Test the attribute counted_by and its usage in
> >> + * __builtin_dynamic_object_size: when the type of the flexible array
> >> member
> >> + * 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) + 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);
> >> +}
> >> +
> >> +int main(int argc, char *argv[])
> >> +{
> >> + struct info *p = setup();
> >> + report(p);
> >> + return 0;
> >> +}
> >> diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc
> >> index 8de264d1dee2..4c1fa9b555fa 100644
> >> --- a/gcc/tree-object-size.cc
> >> +++ b/gcc/tree-object-size.cc
> >> @@ -762,9 +762,11 @@ addr_object_size (struct object_size_info *osi,
> >> const_tree ptr,
> >> 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
> >> + 6th argument: A constant 0 with the pointer TYPE to the original
> >> flexible
> >> + array type.
> >>
> >> - The size of the element can be retrived from the result type of the
> >> call,
> >> - which is the pointer to the array 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. */
> >> static tree
> >> access_with_size_object_size (const gcall *call, int object_size_type)
> >> {
> >> @@ -773,10 +775,12 @@ access_with_size_object_size (const gcall *call, int
> >> object_size_type)
> >> 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)));
> >> + /* The type of the 6th argument type is the pointer TYPE to the original
> >> + flexible array 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));
> >> + tree element_size = TYPE_SIZE_UNIT (element_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));
> >> --
> >> 2.31.1
> >>
>
