> 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? -:) 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 >>