On Thu, 2 Feb 2023, Qing Zhao wrote:
>
>
> > On Feb 2, 2023, at 3:07 AM, Richard Biener <rguent...@suse.de> wrote:
> >
> > On Wed, 1 Feb 2023, Qing Zhao wrote:
> >
> >>
> >>
> >>> On Feb 1, 2023, at 6:41 AM, Richard Biener <rguent...@suse.de> wrote:
> >>>
> >>> On Tue, 31 Jan 2023, Qing Zhao wrote:
> >>>
> >>>> GCC extension accepts the case when a struct with a flexible array member
> >>>> is embedded into another struct (possibly recursively).
> >>>> __builtin_object_size should treat such struct as flexible size per
> >>>> -fstrict-flex-arrays.
> >>>>
> >>>> PR tree-optimization/101832
> >>>>
> >>>> gcc/ChangeLog:
> >>>>
> >>>> PR tree-optimization/101832
> >>>> * tree-object-size.cc (flexible_size_type_p): New function.
> >>>> (addr_object_size): Handle structure/union type when it has
> >>>> flexible size.
> >>>>
> >>>> gcc/testsuite/ChangeLog:
> >>>>
> >>>> PR tree-optimization/101832
> >>>> * gcc.dg/builtin-object-size-pr101832-2.c: New test.
> >>>> * gcc.dg/builtin-object-size-pr101832-3.c: New test.
> >>>> * gcc.dg/builtin-object-size-pr101832-4.c: New test.
> >>>> * gcc.dg/builtin-object-size-pr101832.c: New test.
> >>>> ---
> >>>> .../gcc.dg/builtin-object-size-pr101832-2.c | 135 ++++++++++++++++++
> >>>> .../gcc.dg/builtin-object-size-pr101832-3.c | 135 ++++++++++++++++++
> >>>> .../gcc.dg/builtin-object-size-pr101832-4.c | 135 ++++++++++++++++++
> >>>> .../gcc.dg/builtin-object-size-pr101832.c | 119 +++++++++++++++
> >>>> gcc/tree-object-size.cc | 115 +++++++++++----
> >>>> 5 files changed, 611 insertions(+), 28 deletions(-)
> >>>> create mode 100644 gcc/testsuite/gcc.dg/builtin-object-size-pr101832-2.c
> >>>> create mode 100644 gcc/testsuite/gcc.dg/builtin-object-size-pr101832-3.c
> >>>> create mode 100644 gcc/testsuite/gcc.dg/builtin-object-size-pr101832-4.c
> >>>> create mode 100644 gcc/testsuite/gcc.dg/builtin-object-size-pr101832.c
> >>>>
> >>>> diff --git a/gcc/testsuite/gcc.dg/builtin-object-size-pr101832-2.c
> >>>> b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832-2.c
> >>>> new file mode 100644
> >>>> index 00000000000..f38babc5415
> >>>> --- /dev/null
> >>>> +++ b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832-2.c
> >>>> @@ -0,0 +1,135 @@
> >>>> +/* PR 101832:
> >>>> + GCC extension accepts the case when a struct with a flexible array
> >>>> member
> >>>> + is embedded into another struct (possibly recursively).
> >>>> + __builtin_object_size will treat such struct as flexible size per
> >>>> + -fstrict-flex-arrays. */
> >>>> +/* { dg-do run } */
> >>>> +/* { dg-options "-O2 -fstrict-flex-arrays=1" } */
> >>>> +
> >>>> +#include <stdio.h>
> >>>> +
> >>>> +unsigned n_fails = 0;
> >>>> +
> >>>> +#define expect(p, _v) do { \
> >>>> + size_t v = _v; \
> >>>> + if (p == v) \
> >>>> + printf("ok: %s == %zd\n", #p, p); \
> >>>> + else {\
> >>>> + printf("WAT: %s == %zd (expected %zd)\n", #p, p, v); \
> >>>> + n_fails++; \
> >>>> + } \
> >>>> +} while (0);
> >>>> +
> >>>> +struct A {
> >>>> + int n;
> >>>> + char data[];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B {
> >>>> + int m;
> >>>> + struct A a;
> >>>> +};
> >>>> +
> >>>> +struct C {
> >>>> + int q;
> >>>> + struct B b;
> >>>> +};
> >>>> +
> >>>> +struct A0 {
> >>>> + int n;
> >>>> + char data[0];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B0 {
> >>>> + int m;
> >>>> + struct A0 a;
> >>>> +};
> >>>> +
> >>>> +struct C0 {
> >>>> + int q;
> >>>> + struct B0 b;
> >>>> +};
> >>>> +
> >>>> +struct A1 {
> >>>> + int n;
> >>>> + char data[1];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B1 {
> >>>> + int m;
> >>>> + struct A1 a;
> >>>> +};
> >>>> +
> >>>> +struct C1 {
> >>>> + int q;
> >>>> + struct B1 b;
> >>>> +};
> >>>> +
> >>>> +struct An {
> >>>> + int n;
> >>>> + char data[8];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct Bn {
> >>>> + int m;
> >>>> + struct An a;
> >>>> +};
> >>>> +
> >>>> +struct Cn {
> >>>> + int q;
> >>>> + struct Bn b;
> >>>> +};
> >>>> +
> >>>> +volatile void *magic1, *magic2;
> >>>> +
> >>>> +int main(int argc, char *argv[])
> >>>> +{
> >>>> + struct B *outer;
> >>>> + struct C *outest;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outer = (void *)magic1;
> >>>> + outest = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outest->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outest->b.a, 1), -1);
> >>>> +
> >>>> + struct B0 *outer0;
> >>>> + struct C0 *outest0;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outer0 = (void *)magic1;
> >>>> + outest0 = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer0->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outest0->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outest0->b.a, 1), -1);
> >>>> +
> >>>> + struct B1 *outer1;
> >>>> + struct C1 *outest1;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outer1 = (void *)magic1;
> >>>> + outest1 = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer1->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outest1->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outest1->b.a, 1), -1);
> >>>> +
> >>>> + struct Bn *outern;
> >>>> + struct Cn *outestn;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outern = (void *)magic1;
> >>>> + outestn = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outern->a, 1), sizeof(outern->a));
> >>>> + expect(__builtin_object_size(&outestn->b, 1), sizeof(outestn->b));
> >>>> + expect(__builtin_object_size(&outestn->b.a, 1),
> >>>> sizeof(outestn->b.a));
> >>>> +
> >>>> + if (n_fails > 0)
> >>>> + __builtin_abort ();
> >>>> +
> >>>> + return 0;
> >>>> +}
> >>>> diff --git a/gcc/testsuite/gcc.dg/builtin-object-size-pr101832-3.c
> >>>> b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832-3.c
> >>>> new file mode 100644
> >>>> index 00000000000..aaae99b8d67
> >>>> --- /dev/null
> >>>> +++ b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832-3.c
> >>>> @@ -0,0 +1,135 @@
> >>>> +/* PR 101832:
> >>>> + GCC extension accepts the case when a struct with a flexible array
> >>>> member
> >>>> + is embedded into another struct (possibly recursively).
> >>>> + __builtin_object_size will treat such struct as flexible size per
> >>>> + -fstrict-flex-arrays. */
> >>>> +/* { dg-do run } */
> >>>> +/* { dg-options "-O2 -fstrict-flex-arrays=2" } */
> >>>> +
> >>>> +#include <stdio.h>
> >>>> +
> >>>> +unsigned n_fails = 0;
> >>>> +
> >>>> +#define expect(p, _v) do { \
> >>>> + size_t v = _v; \
> >>>> + if (p == v) \
> >>>> + printf("ok: %s == %zd\n", #p, p); \
> >>>> + else {\
> >>>> + printf("WAT: %s == %zd (expected %zd)\n", #p, p, v); \
> >>>> + n_fails++; \
> >>>> + } \
> >>>> +} while (0);
> >>>> +
> >>>> +struct A {
> >>>> + int n;
> >>>> + char data[];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B {
> >>>> + int m;
> >>>> + struct A a;
> >>>> +};
> >>>> +
> >>>> +struct C {
> >>>> + int q;
> >>>> + struct B b;
> >>>> +};
> >>>> +
> >>>> +struct A0 {
> >>>> + int n;
> >>>> + char data[0];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B0 {
> >>>> + int m;
> >>>> + struct A0 a;
> >>>> +};
> >>>> +
> >>>> +struct C0 {
> >>>> + int q;
> >>>> + struct B0 b;
> >>>> +};
> >>>> +
> >>>> +struct A1 {
> >>>> + int n;
> >>>> + char data[1];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B1 {
> >>>> + int m;
> >>>> + struct A1 a;
> >>>> +};
> >>>> +
> >>>> +struct C1 {
> >>>> + int q;
> >>>> + struct B1 b;
> >>>> +};
> >>>> +
> >>>> +struct An {
> >>>> + int n;
> >>>> + char data[8];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct Bn {
> >>>> + int m;
> >>>> + struct An a;
> >>>> +};
> >>>> +
> >>>> +struct Cn {
> >>>> + int q;
> >>>> + struct Bn b;
> >>>> +};
> >>>> +
> >>>> +volatile void *magic1, *magic2;
> >>>> +
> >>>> +int main(int argc, char *argv[])
> >>>> +{
> >>>> + struct B *outer;
> >>>> + struct C *outest;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outer = (void *)magic1;
> >>>> + outest = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outest->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outest->b.a, 1), -1);
> >>>> +
> >>>> + struct B0 *outer0;
> >>>> + struct C0 *outest0;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outer0 = (void *)magic1;
> >>>> + outest0 = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer0->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outest0->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outest0->b.a, 1), -1);
> >>>> +
> >>>> + struct B1 *outer1;
> >>>> + struct C1 *outest1;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outer1 = (void *)magic1;
> >>>> + outest1 = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer1->a, 1), sizeof(outer1->a));
> >>>> + expect(__builtin_object_size(&outest1->b, 1), sizeof(outest1->b));
> >>>> + expect(__builtin_object_size(&outest1->b.a, 1),
> >>>> sizeof(outest1->b.a));
> >>>> +
> >>>> + struct Bn *outern;
> >>>> + struct Cn *outestn;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outern = (void *)magic1;
> >>>> + outestn = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outern->a, 1), sizeof(outern->a));
> >>>> + expect(__builtin_object_size(&outestn->b, 1), sizeof(outestn->b));
> >>>> + expect(__builtin_object_size(&outestn->b.a, 1),
> >>>> sizeof(outestn->b.a));
> >>>> +
> >>>> + if (n_fails > 0)
> >>>> + __builtin_abort ();
> >>>> +
> >>>> + return 0;
> >>>> +}
> >>>> diff --git a/gcc/testsuite/gcc.dg/builtin-object-size-pr101832-4.c
> >>>> b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832-4.c
> >>>> new file mode 100644
> >>>> index 00000000000..424264e2acd
> >>>> --- /dev/null
> >>>> +++ b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832-4.c
> >>>> @@ -0,0 +1,135 @@
> >>>> +/* PR 101832:
> >>>> + GCC extension accepts the case when a struct with a flexible array
> >>>> member
> >>>> + is embedded into another struct (possibly recursively).
> >>>> + __builtin_object_size will treat such struct as flexible size per
> >>>> + -fstrict-flex-arrays. */
> >>>> +/* { dg-do run } */
> >>>> +/* { dg-options "-O2 -fstrict-flex-arrays=3" } */
> >>>> +
> >>>> +#include <stdio.h>
> >>>> +
> >>>> +unsigned n_fails = 0;
> >>>> +
> >>>> +#define expect(p, _v) do { \
> >>>> + size_t v = _v; \
> >>>> + if (p == v) \
> >>>> + printf("ok: %s == %zd\n", #p, p); \
> >>>> + else {\
> >>>> + printf("WAT: %s == %zd (expected %zd)\n", #p, p, v); \
> >>>> + n_fails++; \
> >>>> + } \
> >>>> +} while (0);
> >>>> +
> >>>> +struct A {
> >>>> + int n;
> >>>> + char data[];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B {
> >>>> + int m;
> >>>> + struct A a;
> >>>> +};
> >>>> +
> >>>> +struct C {
> >>>> + int q;
> >>>> + struct B b;
> >>>> +};
> >>>> +
> >>>> +struct A0 {
> >>>> + int n;
> >>>> + char data[0];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B0 {
> >>>> + int m;
> >>>> + struct A0 a;
> >>>> +};
> >>>> +
> >>>> +struct C0 {
> >>>> + int q;
> >>>> + struct B0 b;
> >>>> +};
> >>>> +
> >>>> +struct A1 {
> >>>> + int n;
> >>>> + char data[1];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B1 {
> >>>> + int m;
> >>>> + struct A1 a;
> >>>> +};
> >>>> +
> >>>> +struct C1 {
> >>>> + int q;
> >>>> + struct B1 b;
> >>>> +};
> >>>> +
> >>>> +struct An {
> >>>> + int n;
> >>>> + char data[8];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct Bn {
> >>>> + int m;
> >>>> + struct An a;
> >>>> +};
> >>>> +
> >>>> +struct Cn {
> >>>> + int q;
> >>>> + struct Bn b;
> >>>> +};
> >>>> +
> >>>> +volatile void *magic1, *magic2;
> >>>> +
> >>>> +int main(int argc, char *argv[])
> >>>> +{
> >>>> + struct B *outer;
> >>>> + struct C *outest;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outer = (void *)magic1;
> >>>> + outest = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outest->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outest->b.a, 1), -1);
> >>>> +
> >>>> + struct B0 *outer0;
> >>>> + struct C0 *outest0;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outer0 = (void *)magic1;
> >>>> + outest0 = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer0->a, 1), sizeof(outer0->a));
> >>>> + expect(__builtin_object_size(&outest0->b, 1), sizeof(outest0->b));
> >>>> + expect(__builtin_object_size(&outest0->b.a, 1),
> >>>> sizeof(outest0->b.a));
> >>>> +
> >>>> + struct B1 *outer1;
> >>>> + struct C1 *outest1;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outer1 = (void *)magic1;
> >>>> + outest1 = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer1->a, 1), sizeof(outer1->a));
> >>>> + expect(__builtin_object_size(&outest1->b, 1), sizeof(outest1->b));
> >>>> + expect(__builtin_object_size(&outest1->b.a, 1),
> >>>> sizeof(outest1->b.a));
> >>>> +
> >>>> + struct Bn *outern;
> >>>> + struct Cn *outestn;
> >>>> +
> >>>> + /* Make sure optimization can't find some other object size. */
> >>>> + outern = (void *)magic1;
> >>>> + outestn = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outern->a, 1), sizeof(outern->a));
> >>>> + expect(__builtin_object_size(&outestn->b, 1), sizeof(outestn->b));
> >>>> + expect(__builtin_object_size(&outestn->b.a, 1),
> >>>> sizeof(outestn->b.a));
> >>>> +
> >>>> + if (n_fails > 0)
> >>>> + __builtin_abort ();
> >>>> +
> >>>> + return 0;
> >>>> +}
> >>>> diff --git a/gcc/testsuite/gcc.dg/builtin-object-size-pr101832.c
> >>>> b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832.c
> >>>> new file mode 100644
> >>>> index 00000000000..8ed6980edf0
> >>>> --- /dev/null
> >>>> +++ b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832.c
> >>>> @@ -0,0 +1,119 @@
> >>>> +/* PR 101832:
> >>>> + GCC extension accepts the case when a struct with a flexible array
> >>>> member
> >>>> + is embedded into another struct (possibly recursively).
> >>>> + __builtin_object_size will treat such struct as flexible size per
> >>>> + -fstrict-flex-arrays. */
> >>>> +/* { dg-do run } */
> >>>> +/* { dg-options "-O2" } */
> >>>> +
> >>>> +#include <stdio.h>
> >>>> +
> >>>> +unsigned n_fails = 0;
> >>>> +
> >>>> +#define expect(p, _v) do { \
> >>>> + size_t v = _v; \
> >>>> + if (p == v) \
> >>>> + printf("ok: %s == %zd\n", #p, p); \
> >>>> + else {\
> >>>> + printf("WAT: %s == %zd (expected %zd)\n", #p, p, v); \
> >>>> + n_fails++; \
> >>>> + } \
> >>>> +} while (0);
> >>>> +
> >>>> +struct A {
> >>>> + int n;
> >>>> + char data[];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B {
> >>>> + int m;
> >>>> + struct A a;
> >>>> +};
> >>>> +
> >>>> +struct C {
> >>>> + int q;
> >>>> + struct B b;
> >>>> +};
> >>>> +
> >>>> +struct A0 {
> >>>> + int n;
> >>>> + char data[0];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B0 {
> >>>> + int m;
> >>>> + struct A0 a;
> >>>> +};
> >>>> +
> >>>> +struct C0 {
> >>>> + int q;
> >>>> + struct B0 b;
> >>>> +};
> >>>> +
> >>>> +struct A1 {
> >>>> + int n;
> >>>> + char data[1];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct B1 {
> >>>> + int m;
> >>>> + struct A1 a;
> >>>> +};
> >>>> +
> >>>> +struct C1 {
> >>>> + int q;
> >>>> + struct B1 b;
> >>>> +};
> >>>> +
> >>>> +struct An {
> >>>> + int n;
> >>>> + char data[8];/* Content following header */
> >>>> +};
> >>>> +
> >>>> +struct Bn {
> >>>> + int m;
> >>>> + struct An a;
> >>>> +};
> >>>> +
> >>>> +struct Cn {
> >>>> + int q;
> >>>> + struct Bn b;
> >>>> +};
> >>>> +
> >>>> +volatile void *magic1, *magic2;
> >>>> +
> >>>> +int main(int argc, char *argv[])
> >>>> +{
> >>>> + struct B *outer = (void *)magic1;
> >>>> + struct C *outest = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outest->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outest->b.a, 1), -1);
> >>>> +
> >>>> + struct B0 *outer0 = (void *)magic1;
> >>>> + struct C0 *outest0 = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer0->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outest0->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outest0->b.a, 1), -1);
> >>>> +
> >>>> + struct B1 *outer1 = (void *)magic1;
> >>>> + struct C1 *outest1 = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outer1->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outest1->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outest1->b.a, 1), -1);
> >>>> +
> >>>> + struct Bn *outern = (void *)magic1;
> >>>> + struct Cn *outestn = (void *)magic2;
> >>>> +
> >>>> + expect(__builtin_object_size(&outern->a, 1), -1);
> >>>> + expect(__builtin_object_size(&outestn->b, 1), -1);
> >>>> + expect(__builtin_object_size(&outestn->b.a, 1), -1);
> >>>> +
> >>>> + if (n_fails > 0)
> >>>> + __builtin_abort ();
> >>>> +
> >>>> + return 0;
> >>>> +}
> >>>> diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc
> >>>> index 9a936a91983..56b78ca2a8c 100644
> >>>> --- a/gcc/tree-object-size.cc
> >>>> +++ b/gcc/tree-object-size.cc
> >>>> @@ -500,6 +500,42 @@ decl_init_size (tree decl, bool min)
> >>>> return size;
> >>>> }
> >>>>
> >>>> +/* Determine whether TYPE is a structure with a flexible array member
> >>>> + per -fstrict-flex-array or a union containing such a structure
> >>>> + (possibly recursively). */
> >>>> +static bool
> >>>> +flexible_size_type_p (const_tree type)
> >>>> +{
> >>>> + tree x = NULL_TREE;
> >>>> + tree last = NULL_TREE;
> >>>> + switch (TREE_CODE (type))
> >>>> + {
> >>>> + case RECORD_TYPE:
> >>>> + for (x = TYPE_FIELDS (type); x != NULL_TREE; x = DECL_CHAIN (x))
> >>>> + if (TREE_CODE (x) == FIELD_DECL)
> >>>> + last = x;
> >>>> + if (last == NULL_TREE)
> >>>> + return false;
> >>>> + if (TREE_CODE (TREE_TYPE (last)) == ARRAY_TYPE
> >>>> + && !DECL_NOT_FLEXARRAY (last))
> >>>> + return true;
> >>>> + else if (TREE_CODE (TREE_TYPE (last)) == RECORD_TYPE
> >>>> + || TREE_CODE (TREE_TYPE (last)) == UNION_TYPE)
> >>>> + return flexible_size_type_p (TREE_TYPE (last));
> >>>
> >>> For types with many members this can become quite slow (IIRC we had
> >>> bugs about similar walks of all fields in types), and this function
> >>> looks like it's invoked multiple times on the same type per TU.
> >>>
> >>> In principle the property is fixed at the time we lay out a record
> >>> type, so we might want to compute it at that time and record the
> >>> result.
> >>
> >> You mean in FE?
> >
> > Yes, either in the frontend or in the middle-ends layout_type.
> >
> >> Yes, that?s better and cleaner.
> >>
> >> I will add one more field in the TYPE structure to record this information
> >> and check this field during middle end.
> >>
> >> I had the same thought in the beginning, but not sure whether adding a
> >> new field in IR is necessary or not, other places in middle end might
> >> not use this new field.
> >
> > It might be interesting to search for other code walking all fields of
> > a type to determine this or similar info.
>
> There is one which is defined in tree.cc but only is referenced in
> c/c-decl.cc:
>
> /* Determine whether TYPE is a structure with a flexible array member,
> or a union containing such a structure (possibly recursively). */
> flexible_array_type_p
>
> However, this routine is a little different than the one I tried to add:
>
> In the current routine ?flexible_array_type_p?, only one level nesting in
> the structure is accepted, multiple nesting in structure is not permitted.
>
> So, my question is: shall we accept multiple nesting in structure? i.e.
If we don't reject the testcase with an error, then yes.
> struct A {
> int n;
> char data[];/* Content following header */
> };
>
> struct B {
> int m;
> struct A a;
> };
>
> struct C {
> int q;
> struct B b;
> };
>
> Qing
> >
> >> thanks.
> >>
> >> Qing
> >>
> >>>
> >>>> + return false;
> >>>> + case UNION_TYPE:
> >>>> + for (x = TYPE_FIELDS (type); x != NULL_TREE; x = DECL_CHAIN (x))
> >>>> + {
> >>>> + if (TREE_CODE (x) == FIELD_DECL
> >>>> + && flexible_array_type_p (TREE_TYPE (x)))
> >>>> + return true;
> >>>> + }
> >>>> + return false;
> >>>> + default:
> >>>> + return false;
> >>>> + }
> >>>> +}
> >>>> +
> >>>> /* Compute __builtin_object_size for PTR, which is a ADDR_EXPR.
> >>>> OBJECT_SIZE_TYPE is the second argument from __builtin_object_size.
> >>>> If unknown, return size_unknown (object_size_type). */
> >>>> @@ -633,45 +669,68 @@ addr_object_size (struct object_size_info *osi,
> >>>> const_tree ptr,
> >>>> v = NULL_TREE;
> >>>> break;
> >>>> case COMPONENT_REF:
> >>>> - if (TREE_CODE (TREE_TYPE (v)) != ARRAY_TYPE)
> >>>> + /* When the ref is not to an array, a record or a
> >>>> union, it
> >>>> + will not have flexible size, compute the object
> >>>> size
> >>>> + directly. */
> >>>> + if ((TREE_CODE (TREE_TYPE (v)) != ARRAY_TYPE)
> >>>> + && (TREE_CODE (TREE_TYPE (v)) != RECORD_TYPE)
> >>>> + && (TREE_CODE (TREE_TYPE (v)) != UNION_TYPE))
> >>>> {
> >>>> v = NULL_TREE;
> >>>> break;
> >>>> }
> >>>> - is_flexible_array_mem_ref =
> >>>> array_ref_flexible_size_p (v);
> >>>> - while (v != pt_var && TREE_CODE (v) ==
> >>>> COMPONENT_REF)
> >>>> - if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
> >>>> - != UNION_TYPE
> >>>> - && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
> >>>> - != QUAL_UNION_TYPE)
> >>>> - break;
> >>>> - else
> >>>> - v = TREE_OPERAND (v, 0);
> >>>> - if (TREE_CODE (v) == COMPONENT_REF
> >>>> - && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
> >>>> - == RECORD_TYPE)
> >>>> + /* if the record or union does not have flexible
> >>>> size
> >>>> + compute the object size directly. */
> >>>> + if (TREE_CODE (TREE_TYPE (v)) == RECORD_TYPE
> >>>> + || TREE_CODE (TREE_TYPE (v)) == UNION_TYPE)
> >>>> {
> >>>> - /* compute object size only if v is not a
> >>>> - flexible array member. */
> >>>> - if (!is_flexible_array_mem_ref)
> >>>> + if (!flexible_size_type_p (TREE_TYPE (v)))
> >>>> {
> >>>> v = NULL_TREE;
> >>>> break;
> >>>> }
> >>>> - v = TREE_OPERAND (v, 0);
> >>>> + else
> >>>> + v = TREE_OPERAND (v, 0);
> >>>> }
> >>>> - while (v != pt_var && TREE_CODE (v) ==
> >>>> COMPONENT_REF)
> >>>> - if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
> >>>> - != UNION_TYPE
> >>>> - && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
> >>>> - != QUAL_UNION_TYPE)
> >>>> - break;
> >>>> - else
> >>>> - v = TREE_OPERAND (v, 0);
> >>>> - if (v != pt_var)
> >>>> - v = NULL_TREE;
> >>>> else
> >>>> - v = pt_var;
> >>>> + {
> >>>> + /* Now the ref is to an array type. */
> >>>> + is_flexible_array_mem_ref
> >>>> + = array_ref_flexible_size_p (v);
> >>>> + while (v != pt_var && TREE_CODE (v) ==
> >>>> COMPONENT_REF)
> >>>> + if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
> >>>> + != UNION_TYPE
> >>>> + && TREE_CODE (TREE_TYPE (TREE_OPERAND (v,
> >>>> 0)))
> >>>> + != QUAL_UNION_TYPE)
> >>>> + break;
> >>>> + else
> >>>> + v = TREE_OPERAND (v, 0);
> >>>> + if (TREE_CODE (v) == COMPONENT_REF
> >>>> + && TREE_CODE (TREE_TYPE (TREE_OPERAND (v,
> >>>> 0)))
> >>>> + == RECORD_TYPE)
> >>>> + {
> >>>> + /* compute object size only if v is not a
> >>>> + flexible array member. */
> >>>> + if (!is_flexible_array_mem_ref)
> >>>> + {
> >>>> + v = NULL_TREE;
> >>>> + break;
> >>>> + }
> >>>> + v = TREE_OPERAND (v, 0);
> >>>> + }
> >>>> + while (v != pt_var && TREE_CODE (v) ==
> >>>> COMPONENT_REF)
> >>>> + if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v,
> >>>> 0)))
> >>>> + != UNION_TYPE
> >>>> + && TREE_CODE (TREE_TYPE (TREE_OPERAND (v,
> >>>> 0)))
> >>>> + != QUAL_UNION_TYPE)
> >>>> + break;
> >>>> + else
> >>>> + v = TREE_OPERAND (v, 0);
> >>>> + if (v != pt_var)
> >>>> + v = NULL_TREE;
> >>>> + else
> >>>> + v = pt_var;
> >>>> + }
> >>>> break;
> >>>> default:
> >>>> v = pt_var;
> >>>>
> >>>
> >>> --
> >>> Richard Biener <rguent...@suse.de>
> >>> SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
> >>> Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
> >>> HRB 36809 (AG Nuernberg)
> >>
> >>
> >
> > --
> > Richard Biener <rguent...@suse.de>
> > SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
> > Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
> > HRB 36809 (AG Nuernberg)
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)
