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* [gcc/devel/autopar_devel] Avoid warning for memset writing over multiple members.
@ 2020-08-22 22:50 Giuliano Belinassi
0 siblings, 0 replies; only message in thread
From: Giuliano Belinassi @ 2020-08-22 22:50 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:a0e06e32c1d8a34c484a13f854b485328eddbc6d
commit a0e06e32c1d8a34c484a13f854b485328eddbc6d
Author: Martin Sebor <msebor@redhat.com>
Date: Thu Jun 18 12:00:36 2020 -0600
Avoid warning for memset writing over multiple members.
Resolves:
PR middle-end/95667 - unintended warning for memset writing across multiple members
PR middle-end/92814 - missing -Wstringop-overflow writing into a dynamically allocated flexible array member
gcc/ChangeLog:
PR middle-end/95667
PR middle-end/92814
* builtins.c (compute_objsize): Remove call to
compute_builtin_object_size and instead compute conservative sizes
directly here.
gcc/testsuite/ChangeLog:
PR middle-end/95667
PR middle-end/92814
* gcc.dg/Wstringop-overflow-25.c: Remove xfails.
* gcc.dg/Wstringop-overflow-39.c: New test.
Diff:
---
gcc/builtins.c | 48 ++++-------
gcc/testsuite/gcc.dg/Wstringop-overflow-25.c | 8 +-
gcc/testsuite/gcc.dg/Wstringop-overflow-39.c | 118 +++++++++++++++++++++++++++
3 files changed, 140 insertions(+), 34 deletions(-)
diff --git a/gcc/builtins.c b/gcc/builtins.c
index caab188e81c..4754602e0ec 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -4009,31 +4009,6 @@ static bool
compute_objsize (tree ptr, int ostype, access_ref *pref,
bitmap *visited, const vr_values *rvals /* = NULL */)
{
- if (ostype == 0)
- {
- /* Use BOS only for raw memory functions like memcpy to get
- the size of the largest enclosing object. */
- tree off = NULL_TREE;
- unsigned HOST_WIDE_INT size;
- if (compute_builtin_object_size (ptr, ostype, &size, &pref->ref, &off))
- {
- if (off)
- {
- offset_int offset = wi::to_offset (off);
- pref->offrng[0] += offset;
- pref->offrng[1] += offset;
-
- /* compute_builtin_object_size() returns the remaining
- size in PTR. Add the offset to it to get the full
- size. */
- pref->sizrng[0] = pref->sizrng[1] = size + offset;
- }
- else
- pref->sizrng[0] = pref->sizrng[1] = size;
- return true;
- }
- }
-
const bool addr = TREE_CODE (ptr) == ADDR_EXPR;
if (addr)
ptr = TREE_OPERAND (ptr, 0);
@@ -4058,18 +4033,28 @@ compute_objsize (tree ptr, int ostype, access_ref *pref,
if (code == COMPONENT_REF)
{
+ tree field = TREE_OPERAND (ptr, 1);
+
if (ostype == 0)
{
/* For raw memory functions like memcpy bail if the size
of the enclosing object cannot be determined. */
- access_ref tmpref;
tree ref = TREE_OPERAND (ptr, 0);
- if (!compute_objsize (ref, ostype, &tmpref, visited, rvals)
- || !tmpref.ref)
+ if (!compute_objsize (ref, ostype, pref, visited, rvals)
+ || !pref->ref)
return false;
+
+ /* Otherwise, use the size of the enclosing object and add
+ the offset of the member to the offset computed so far. */
+ tree offset = byte_position (field);
+ if (TREE_CODE (offset) != INTEGER_CST)
+ return false;
+ offset_int off = wi::to_offset (offset);
+ pref->offrng[0] += off;
+ pref->offrng[1] += off;
+ return true;
}
- tree field = TREE_OPERAND (ptr, 1);
/* Bail if the reference is to the pointer itself (as opposed
to what it points to). */
if (!addr && POINTER_TYPE_P (TREE_TYPE (field)))
@@ -4147,8 +4132,11 @@ compute_objsize (tree ptr, int ostype, access_ref *pref,
orng[0] *= sz;
orng[1] *= sz;
- if (TREE_CODE (eltype) == ARRAY_TYPE)
+ if (ostype && TREE_CODE (eltype) == ARRAY_TYPE)
{
+ /* Execpt for the permissive raw memory functions which
+ use the size of the whole object determined above,
+ use the size of the referenced array. */
pref->sizrng[0] = pref->offrng[0] + orng[0] + sz;
pref->sizrng[1] = pref->offrng[1] + orng[1] + sz;
}
diff --git a/gcc/testsuite/gcc.dg/Wstringop-overflow-25.c b/gcc/testsuite/gcc.dg/Wstringop-overflow-25.c
index 01807207acc..109a1dd9127 100644
--- a/gcc/testsuite/gcc.dg/Wstringop-overflow-25.c
+++ b/gcc/testsuite/gcc.dg/Wstringop-overflow-25.c
@@ -370,14 +370,14 @@ NOIPA void test_strcpy_malloc_flexarray (void)
size_t r_2_3 = UR (2, 3);
T (char, S (0), r_0_1);
- T (char, S (1), r_0_1); // { dg-warning "\\\[-Wstringop-overflow" "pr92814" { xfail *-*-* } }
+ T (char, S (1), r_0_1); // { dg-warning "\\\[-Wstringop-overflow" "pr92814" }
T (char, S (0), r_1_2);
T (char, S (1), r_1_2);
- T (char, S (2), r_1_2); // { dg-warning "\\\[-Wstringop-overflow" "pr92814" { xfail *-*-* } }
+ T (char, S (2), r_1_2); // { dg-warning "\\\[-Wstringop-overflow" "pr92814" }
T (char, S (0), r_2_3);
T (char, S (2), r_2_3);
- T (char, S (3), r_2_3); // { dg-warning "\\\[-Wstringop-overflow" "pr92814" { xfail *-*-* } }
- T (char, S (9), r_2_3); // { dg-warning "\\\[-Wstringop-overflow" "pr92814" { xfail *-*-* } }
+ T (char, S (3), r_2_3); // { dg-warning "\\\[-Wstringop-overflow" "pr92814" }
+ T (char, S (9), r_2_3); // { dg-warning "\\\[-Wstringop-overflow" "pr92814" }
}
diff --git a/gcc/testsuite/gcc.dg/Wstringop-overflow-39.c b/gcc/testsuite/gcc.dg/Wstringop-overflow-39.c
new file mode 100644
index 00000000000..f83646a3721
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wstringop-overflow-39.c
@@ -0,0 +1,118 @@
+/* PR middle-end/95667 - unintended warning for memset writing across multiple
+ members
+ { dg-do compile }
+ { dg-options "-O2 -Wall" } */
+
+extern void sink (void*);
+
+struct S1 { char a[3], b[5]; };
+
+void warn_strcpy_s1 (void)
+{
+ struct S1 *p = __builtin_malloc (sizeof *p);
+ char s[] = "1234567";
+ __builtin_strcpy (p->a, s); // { dg-warning "\\\[-Wstringop-overflow" }
+ sink (p);
+}
+
+void nowarn_memset_s1 (void)
+{
+ struct S1 *p = __builtin_malloc (sizeof *p);
+ __builtin_memset (p->a, 0, 8); // { dg-bogus "\\\[-Wstringop-overflow" }
+ sink (p);
+}
+
+struct S2 { char a[2], b[2][2], c[3]; };
+
+void nowarn_memset_s2 (void)
+{
+ struct S2 *p = __builtin_malloc (sizeof *p);
+
+ __builtin_memset (p->a, 0, sizeof *p);
+ sink (p);
+
+ __builtin_memset (p->b, 0, 7);
+ sink (p);
+
+ __builtin_memset (&p->b[0], 0, 7);
+ sink (p);
+
+ __builtin_memset (&p->b[1], 0, 5);
+ sink (p);
+
+ __builtin_memset (&p->b[0][0], 0, 7);
+ sink (p);
+
+ __builtin_memset (&p->b[0][1], 0, 6);
+ sink (p);
+
+ __builtin_memset (&p->b[1][0], 0, 5);
+ sink (p);
+
+ __builtin_memset (&p->b[1][1], 0, 4);
+ sink (p);
+}
+
+void warn_memset_s2 (void)
+{
+ const unsigned n = sizeof (struct S2);
+ struct S2 *p = __builtin_malloc (n);
+
+ /* These should trigger -Wstringop-overflow rather than -Warray-bounds
+ but the main purpose of the test is to verify the absence of warnings
+ above so the exact warning for these overflwing calls isn't important
+ here. */
+
+ __builtin_memset (p->a, 0, n + 1); // { dg-warning "\\\[-Warray-bounds|-Wstringop-overflow" }
+ sink (p);
+
+ __builtin_memset (p->b, 0, 8); // { dg-warning "\\\[-Warray-bounds|-Wstringop-overflow" }
+ sink (p);
+
+ __builtin_memset (&p->b[0], 0, 8); // { dg-warning "\\\[-Warray-bounds|-Wstringop-overflow" }
+ sink (p);
+
+ __builtin_memset (&p->b[0][0], 0, 8); // { dg-warning "\\\[-Warray-bounds|-Wstringop-overflow" }
+ sink (p);
+
+ __builtin_memset (&p->b[1], 0, 6); // { dg-warning "\\\[-Warray-bounds|-Wstringop-overflow" }
+ sink (p);
+
+ __builtin_memset (&p->b[0][1], 0, 7); // { dg-warning "\\\[-Warray-bounds|-Wstringop-overflow" }
+ sink (p);
+}
+
+void nowarn_vl_struct (unsigned n)
+{
+ if (n < 3 || 5 < n)
+ n = 3;
+
+ struct V { char a[3], b[n], c[7]; } v;
+
+ __builtin_memset (v.a, 0, 15);
+ sink (&v);
+
+ __builtin_memset (v.b, 0, 12);
+ sink (&v);
+
+ __builtin_memset (v.c, 0, 7);
+ sink (&v);
+
+ __builtin_memset (v.a, 0, 16); // { dg-warning "\\\[-Warray-bounds|-Wstringop-overflow" }
+ sink (&v);
+
+ __builtin_memset (v.b, 0, 13); // { dg-warning "\\\[-Warray-bounds|-Wstringop-overflow" }
+ sink (&v);
+
+ /* The &V.C argument is represented as a variable offset from
+ the beginning of the allocated object and there's no good
+ way to figure out from its variable offset that it's base
+ is the C member:
+ s.1_12 = __builtin_alloca_with_align (prephitmp_24, 8);
+ _9 = s.1_12 + prephitmp_27;
+ __builtin_memset (_9, 0, 2);
+ */
+
+ __builtin_memset (v.c, 0, 8); // { dg-warning "\\\[-Warray-bounds|-Wstringop-overflow" "pr?????" { xfail *-*-* } }
+ sink (&v);
+}
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