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From: Richard Biener <rguenther@suse.de>
To: Qing Zhao <qing.zhao@oracle.com>
Cc: gcc-patches Paul A Clarke via <gcc-patches@gcc.gnu.org>,
	 jakub Jelinek <jakub@redhat.com>,
	martin Sebor <msebor@gmail.com>,
	 kees Cook <keescook@chromium.org>,
	 "joseph@codesourcery.com" <joseph@codesourcery.com>
Subject: Re: [GCC13][Patch][V2][2/2]Add a new option -fstrict-flex-array[=n] and attribute strict_flex_array(n) and use it in PR101836
Date: Mon, 1 Aug 2022 07:13:20 +0000 (UTC)	[thread overview]
Message-ID: <nycvar.YFH.7.77.849.2208010712520.4208@jbgna.fhfr.qr> (raw)
In-Reply-To: <89AFBA07-674A-451A-9D63-BE398AC7B3EF@oracle.com>

On Fri, 29 Jul 2022, Qing Zhao wrote:

> 
> 
> > On Jul 28, 2022, at 3:28 AM, Richard Biener <rguenther@suse.de> wrote:
> > 
> > On Tue, 19 Jul 2022, Qing Zhao wrote:
> > 
> >> From a09f39ded462611286a44d9e8273de8342673ba2 Mon Sep 17 00:00:00 2001
> >> From: Qing Zhao <qing.zhao@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.

It has been that way since forever, so please don't (at least not as
part of this series).

> 
> 
> > 
> > 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 <rguenther@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 <rguenther@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)

  reply	other threads:[~2022-08-01  7:13 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-19 14:11 Qing Zhao
2022-07-28  7:28 ` Richard Biener
2022-07-29 14:23   ` Qing Zhao
2022-08-01  7:13     ` Richard Biener [this message]
2022-08-01 14:14       ` Qing Zhao
2022-08-02 15:30 ` Kees Cook
2022-08-02 15:41   ` Qing Zhao

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