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* [GCC13][Patch][V2][2/2]Add a new option -fstrict-flex-array[=n] and attribute strict_flex_array(n) and use it in PR101836
@ 2022-07-19 14:11 Qing Zhao
  2022-07-28  7:28 ` Richard Biener
  2022-08-02 15:30 ` Kees Cook
  0 siblings, 2 replies; 7+ messages in thread
From: Qing Zhao @ 2022-07-19 14:11 UTC (permalink / raw)
  To: gcc-patches Paul A Clarke via
  Cc: jakub Jelinek, richard Biener, martin Sebor, kees Cook, joseph

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));
		    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;
-- 
2.27.0

^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-08-02 15:41 UTC | newest]

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-- links below jump to the message on this page --
2022-07-19 14:11 [GCC13][Patch][V2][2/2]Add a new option -fstrict-flex-array[=n] and attribute strict_flex_array(n) and use it in PR101836 Qing Zhao
2022-07-28  7:28 ` Richard Biener
2022-07-29 14:23   ` Qing Zhao
2022-08-01  7:13     ` Richard Biener
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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