> On Jul 28, 2022, at 3:28 AM, Richard Biener <rguent...@suse.de> wrote:
>
> On Tue, 19 Jul 2022, Qing Zhao wrote:
>
>> From a09f39ded462611286a44d9e8273de8342673ba2 Mon Sep 17 00:00:00 2001
>> From: Qing Zhao <qing.z...@oracle.com>
>> Date: Mon, 18 Jul 2022 18:12:26 +0000
>> Subject: [PATCH 2/2] Use new flag DECL_NOT_FLEXARRAY in __builtin_object_size
>> [PR101836]
>>
>> Use new flag DECL_NOT_FLEXARRAY to determine whether the trailing array
>> of a structure is flexible array member in __builtin_object_size.
>>
>> gcc/ChangeLog:
>>
>> PR tree-optimization/101836
>> * tree-object-size.cc (addr_object_size): Use array_at_struct_end_p
>> and DECL_NOT_FLEXARRAY to determine a flexible array member reference.
>>
>> gcc/testsuite/ChangeLog:
>>
>> PR tree-optimization/101836
>> * gcc.dg/pr101836.c: New test.
>> * gcc.dg/pr101836_1.c: New test.
>> * gcc.dg/pr101836_2.c: New test.
>> * gcc.dg/pr101836_3.c: New test.
>> * gcc.dg/pr101836_4.c: New test.
>> * gcc.dg/pr101836_5.c: New test.
>> * gcc.dg/strict-flex-array-2.c: New test.
>> * gcc.dg/strict-flex-array-3.c: New test.
>> ---
>> gcc/testsuite/gcc.dg/pr101836.c | 60 ++++++++++++++++++++++
>> gcc/testsuite/gcc.dg/pr101836_1.c | 60 ++++++++++++++++++++++
>> gcc/testsuite/gcc.dg/pr101836_2.c | 60 ++++++++++++++++++++++
>> gcc/testsuite/gcc.dg/pr101836_3.c | 60 ++++++++++++++++++++++
>> gcc/testsuite/gcc.dg/pr101836_4.c | 60 ++++++++++++++++++++++
>> gcc/testsuite/gcc.dg/pr101836_5.c | 60 ++++++++++++++++++++++
>> gcc/testsuite/gcc.dg/strict-flex-array-2.c | 60 ++++++++++++++++++++++
>> gcc/testsuite/gcc.dg/strict-flex-array-3.c | 60 ++++++++++++++++++++++
>> gcc/tree-object-size.cc | 18 +++----
>> 9 files changed, 489 insertions(+), 9 deletions(-)
>> create mode 100644 gcc/testsuite/gcc.dg/pr101836.c
>> create mode 100644 gcc/testsuite/gcc.dg/pr101836_1.c
>> create mode 100644 gcc/testsuite/gcc.dg/pr101836_2.c
>> create mode 100644 gcc/testsuite/gcc.dg/pr101836_3.c
>> create mode 100644 gcc/testsuite/gcc.dg/pr101836_4.c
>> create mode 100644 gcc/testsuite/gcc.dg/pr101836_5.c
>> create mode 100644 gcc/testsuite/gcc.dg/strict-flex-array-2.c
>> create mode 100644 gcc/testsuite/gcc.dg/strict-flex-array-3.c
>>
>> diff --git a/gcc/testsuite/gcc.dg/pr101836.c
>> b/gcc/testsuite/gcc.dg/pr101836.c
>> new file mode 100644
>> index 00000000000..e5b4e5160a4
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr101836.c
>> @@ -0,0 +1,60 @@
>> +/* -fstrict-flex-array is aliased with -ftrict-flex-array=3, which is the
>> + strictest, only [] is treated as flexible array. */
>> +/* PR tree-optimization/101836 */
>> +/* { dg-do run } */
>> +/* { dg-options "-O2 -fstrict-flex-array" } */
>> +
>> +#include <stdio.h>
>> +
>> +#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); \
>> + __builtin_abort (); \
>> + } \
>> +} while (0);
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[4];
>> +};
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1];
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0];
>> +};
>> +struct trailing_array_4 {
>> + int a;
>> + int b;
>> + int c[];
>> +};
>> +
>> +void __attribute__((__noinline__)) stuff(
>> + struct trailing_array_1 *normal,
>> + struct trailing_array_2 *trailing_1,
>> + struct trailing_array_3 *trailing_0,
>> + struct trailing_array_4 *trailing_flex)
>> +{
>> + expect(__builtin_object_size(normal->c, 1), 16);
>> + expect(__builtin_object_size(trailing_1->c, 1), 4);
>> + expect(__builtin_object_size(trailing_0->c, 1), 0);
>> + expect(__builtin_object_size(trailing_flex->c, 1), -1);
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> + stuff((void *)argv[0], (void *)argv[0], (void *)argv[0], (void
>> *)argv[0]);
>> +
>> + return 0;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/pr101836_1.c
>> b/gcc/testsuite/gcc.dg/pr101836_1.c
>> new file mode 100644
>> index 00000000000..30ea20427a5
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr101836_1.c
>> @@ -0,0 +1,60 @@
>> +/* -fstrict-flex-array=3 is the strictest, only [] is treated as
>> + flexible array. */
>> +/* PR tree-optimization/101836 */
>> +/* { dg-do run } */
>> +/* { dg-options "-O2 -fstrict-flex-array=3" } */
>> +
>> +#include <stdio.h>
>> +
>> +#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); \
>> + __builtin_abort (); \
>> + } \
>> +} while (0);
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[4];
>> +};
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1];
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0];
>> +};
>> +struct trailing_array_4 {
>> + int a;
>> + int b;
>> + int c[];
>> +};
>> +
>> +void __attribute__((__noinline__)) stuff(
>> + struct trailing_array_1 *normal,
>> + struct trailing_array_2 *trailing_1,
>> + struct trailing_array_3 *trailing_0,
>> + struct trailing_array_4 *trailing_flex)
>> +{
>> + expect(__builtin_object_size(normal->c, 1), 16);
>> + expect(__builtin_object_size(trailing_1->c, 1), 4);
>> + expect(__builtin_object_size(trailing_0->c, 1), 0);
>> + expect(__builtin_object_size(trailing_flex->c, 1), -1);
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> + stuff((void *)argv[0], (void *)argv[0], (void *)argv[0], (void
>> *)argv[0]);
>> +
>> + return 0;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/pr101836_2.c
>> b/gcc/testsuite/gcc.dg/pr101836_2.c
>> new file mode 100644
>> index 00000000000..ebbe88f433c
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr101836_2.c
>> @@ -0,0 +1,60 @@
>> +/* When -fstrict-flex-array=2, only [] and [0] are treated as flexiable
>> + arrays. */
>> +/* PR tree-optimization/101836 */
>> +/* { dg-do run } */
>> +/* { dg-options "-O2 -fstrict-flex-array=2" } */
>> +
>> +#include <stdio.h>
>> +
>> +#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); \
>> + __builtin_abort (); \
>> + } \
>> +} while (0);
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[4];
>> +};
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1];
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0];
>> +};
>> +struct trailing_array_4 {
>> + int a;
>> + int b;
>> + int c[];
>> +};
>> +
>> +void __attribute__((__noinline__)) stuff(
>> + struct trailing_array_1 *normal,
>> + struct trailing_array_2 *trailing_1,
>> + struct trailing_array_3 *trailing_0,
>> + struct trailing_array_4 *trailing_flex)
>> +{
>> + expect(__builtin_object_size(normal->c, 1), 16);
>> + expect(__builtin_object_size(trailing_1->c, 1), 4);
>> + expect(__builtin_object_size(trailing_0->c, 1), -1);
>> + expect(__builtin_object_size(trailing_flex->c, 1), -1);
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> + stuff((void *)argv[0], (void *)argv[0], (void *)argv[0], (void
>> *)argv[0]);
>> +
>> + return 0;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/pr101836_3.c
>> b/gcc/testsuite/gcc.dg/pr101836_3.c
>> new file mode 100644
>> index 00000000000..d4ba0afe5bc
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr101836_3.c
>> @@ -0,0 +1,60 @@
>> +/* When -fstrict-flex-array=1, [], [0], and [1] are treated as flexible
>> + arrays. */
>> +/* PR tree-optimization/101836 */
>> +/* { dg-do run } */
>> +/* { dg-options "-O2 -fstrict-flex-array=1" } */
>> +
>> +#include <stdio.h>
>> +
>> +#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); \
>> + __builtin_abort (); \
>> + } \
>> +} while (0);
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[4];
>> +};
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1];
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0];
>> +};
>> +struct trailing_array_4 {
>> + int a;
>> + int b;
>> + int c[];
>> +};
>> +
>> +void __attribute__((__noinline__)) stuff(
>> + struct trailing_array_1 *normal,
>> + struct trailing_array_2 *trailing_1,
>> + struct trailing_array_3 *trailing_0,
>> + struct trailing_array_4 *trailing_flex)
>> +{
>> + expect(__builtin_object_size(normal->c, 1), 16);
>> + expect(__builtin_object_size(trailing_1->c, 1), -1);
>> + expect(__builtin_object_size(trailing_0->c, 1), -1);
>> + expect(__builtin_object_size(trailing_flex->c, 1), -1);
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> + stuff((void *)argv[0], (void *)argv[0], (void *)argv[0], (void
>> *)argv[0]);
>> +
>> + return 0;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/pr101836_4.c
>> b/gcc/testsuite/gcc.dg/pr101836_4.c
>> new file mode 100644
>> index 00000000000..b10d3ce312d
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr101836_4.c
>> @@ -0,0 +1,60 @@
>> +/* when -fstrict-flex-array=0, all trailing arrays are treated as
>> + flexible arrays. */
>> +/* PR tree-optimization/101836 */
>> +/* { dg-do run } */
>> +/* { dg-options "-O2 -fstrict-flex-array=0" } */
>> +
>> +#include <stdio.h>
>> +
>> +#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); \
>> + __builtin_abort (); \
>> + } \
>> +} while (0);
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[4];
>> +};
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1];
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0];
>> +};
>> +struct trailing_array_4 {
>> + int a;
>> + int b;
>> + int c[];
>> +};
>> +
>> +void __attribute__((__noinline__)) stuff(
>> + struct trailing_array_1 *normal,
>> + struct trailing_array_2 *trailing_1,
>> + struct trailing_array_3 *trailing_0,
>> + struct trailing_array_4 *trailing_flex)
>> +{
>> + expect(__builtin_object_size(normal->c, 1), -1);
>> + expect(__builtin_object_size(trailing_1->c, 1), -1);
>> + expect(__builtin_object_size(trailing_0->c, 1), -1);
>> + expect(__builtin_object_size(trailing_flex->c, 1), -1);
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> + stuff((void *)argv[0], (void *)argv[0], (void *)argv[0], (void
>> *)argv[0]);
>> +
>> + return 0;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/pr101836_5.c
>> b/gcc/testsuite/gcc.dg/pr101836_5.c
>> new file mode 100644
>> index 00000000000..2f6b5f7ae1f
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr101836_5.c
>> @@ -0,0 +1,60 @@
>> +/* -fno-strict-flex-array is aliased to -fstrict-flex-array=0,
>> + all trailing arrays are treated as flexible array. */
>> +/* PR tree-optimization/101836 */
>> +/* { dg-do run } */
>> +/* { dg-options "-O2 -fno-strict-flex-array" } */
>> +
>> +#include <stdio.h>
>> +
>> +#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); \
>> + __builtin_abort (); \
>> + } \
>> +} while (0);
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[4];
>> +};
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1];
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0];
>> +};
>> +struct trailing_array_4 {
>> + int a;
>> + int b;
>> + int c[];
>> +};
>> +
>> +void __attribute__((__noinline__)) stuff(
>> + struct trailing_array_1 *normal,
>> + struct trailing_array_2 *trailing_1,
>> + struct trailing_array_3 *trailing_0,
>> + struct trailing_array_4 *trailing_flex)
>> +{
>> + expect(__builtin_object_size(normal->c, 1), -1);
>> + expect(__builtin_object_size(trailing_1->c, 1), -1);
>> + expect(__builtin_object_size(trailing_0->c, 1), -1);
>> + expect(__builtin_object_size(trailing_flex->c, 1), -1);
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> + stuff((void *)argv[0], (void *)argv[0], (void *)argv[0], (void
>> *)argv[0]);
>> +
>> + return 0;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/strict-flex-array-2.c
>> b/gcc/testsuite/gcc.dg/strict-flex-array-2.c
>> new file mode 100644
>> index 00000000000..326ddcfeda5
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/strict-flex-array-2.c
>> @@ -0,0 +1,60 @@
>> +/* test the combination of attribute strict_flex_array and option
>> + -fstrict-flex-array: when both attribute and option specified,
>> + attribute will have higher priority. */
>> +/* { dg-do run } */
>> +/* { dg-options "-O2 -fstrict-flex-array=3" } */
>> +
>> +#include <stdio.h>
>> +
>> +#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); \
>> + __builtin_abort (); \
>> + } \
>> +} while (0);
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[4] __attribute__ ((strict_flex_array (0)));
>> +};
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1] __attribute__ ((strict_flex_array (1)));
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0] __attribute__ ((strict_flex_array (2)));
>> +};
>> +struct trailing_array_4 {
>> + int a;
>> + int b;
>> + int c[];
>> +};
>> +
>> +void __attribute__((__noinline__)) stuff(
>> + struct trailing_array_1 *normal,
>> + struct trailing_array_2 *trailing_1,
>> + struct trailing_array_3 *trailing_0,
>> + struct trailing_array_4 *trailing_flex)
>> +{
>> + expect(__builtin_object_size(normal->c, 1), -1);
>> + expect(__builtin_object_size(trailing_1->c, 1), -1);
>> + expect(__builtin_object_size(trailing_0->c, 1), -1);
>> + expect(__builtin_object_size(trailing_flex->c, 1), -1);
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> + stuff((void *)argv[0], (void *)argv[0], (void *)argv[0], (void
>> *)argv[0]);
>> +
>> + return 0;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/strict-flex-array-3.c
>> b/gcc/testsuite/gcc.dg/strict-flex-array-3.c
>> new file mode 100644
>> index 00000000000..990c5bb6223
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/strict-flex-array-3.c
>> @@ -0,0 +1,60 @@
>> +/* test the combination of attribute strict_flex_array and option
>> + -fstrict-flex-array: when both attribute and option specified,
>> + attribute will have higher priority. */
>> +/* { dg-do run } */
>> +/* { dg-options "-O2 -fstrict-flex-array=0" } */
>> +
>> +#include <stdio.h>
>> +
>> +#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); \
>> + __builtin_abort (); \
>> + } \
>> +} while (0);
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[4] __attribute__ ((strict_flex_array (1)));
>> +};
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1] __attribute__ ((strict_flex_array (2)));
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0] __attribute__ ((strict_flex_array (3)));
>> +};
>> +struct trailing_array_4 {
>> + int a;
>> + int b;
>> + int c[];
>> +};
>> +
>> +void __attribute__((__noinline__)) stuff(
>> + struct trailing_array_1 *normal,
>> + struct trailing_array_2 *trailing_1,
>> + struct trailing_array_3 *trailing_0,
>> + struct trailing_array_4 *trailing_flex)
>> +{
>> + expect(__builtin_object_size(normal->c, 1), 16);
>> + expect(__builtin_object_size(trailing_1->c, 1), 4);
>> + expect(__builtin_object_size(trailing_0->c, 1), 0);
>> + expect(__builtin_object_size(trailing_flex->c, 1), -1);
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> + stuff((void *)argv[0], (void *)argv[0], (void *)argv[0], (void
>> *)argv[0]);
>> +
>> + return 0;
>> +}
>> diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc
>> index 4eb454a4a33..90710ecba72 100644
>> --- a/gcc/tree-object-size.cc
>> +++ b/gcc/tree-object-size.cc
>> @@ -604,9 +604,9 @@ addr_object_size (struct object_size_info *osi,
>> const_tree ptr,
>> else if (var != pt_var && TREE_CODE (pt_var) == MEM_REF)
>> {
>> tree v = var;
>> - /* For &X->fld, compute object size only if fld isn't the last
>> - field, as struct { int i; char c[1]; } is often used instead
>> - of flexible array member. */
>> + bool is_flexible_array_mem_ref = false;
>> + /* For &X->fld, compute object size if fld isn't a flexible array
>> + member. */
>> while (v && v != pt_var)
>> switch (TREE_CODE (v))
>> {
>> @@ -633,6 +633,9 @@ addr_object_size (struct object_size_info *osi,
>> const_tree ptr,
>> v = NULL_TREE;
>> break;
>> }
>> + is_flexible_array_mem_ref
>> + = array_at_struct_end_p (v)
>> + && !DECL_NOT_FLEXARRAY (TREE_OPERAND (v, 1));
>
> As said in the review for the first patch array_at_struct_end_p should
> check DECL_NOT_FLEXARRAY.
Okay.
Then, should we change the name of “array_at_struct_end_p” to a more
descriptive name, for example,”flexible_array_member_p”? Otherwise,
It’s really confusing.
>
> OK with removing the extra check here.
Okay.
thanks.
Qing
>
>> while (v != pt_var && TREE_CODE (v) == COMPONENT_REF)
>> if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>> != UNION_TYPE
>> @@ -645,12 +648,9 @@ addr_object_size (struct object_size_info *osi,
>> const_tree ptr,
>> && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>> == RECORD_TYPE)
>> {
>> - tree fld_chain = DECL_CHAIN (TREE_OPERAND (v, 1));
>> - for (; fld_chain; fld_chain = DECL_CHAIN (fld_chain))
>> - if (TREE_CODE (fld_chain) == FIELD_DECL)
>> - break;
>> -
>> - if (fld_chain)
>> + /* compute object size only if v is not a
>> + flexible array member. */
>> + if (!is_flexible_array_mem_ref)
>> {
>> v = NULL_TREE;
>> break;
>>
>
> --
> 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)
