1 /* PR middle-end/103215 - bogus -Wstringop-overflow with two pointers with
2 different offsets each
3 Test for accesses into distinct arrays through pointers with different
4 offsets each.
5
6 If/when -Wstringop-overflow is enhanced to issue "maybe" kinds of
7 warnings some of the accesses here will trigger those and will need
8 updating.
9
10 { dg-do compile }
11 { dg-options "-O2 -Wall -ftrack-macro-expansion=0" } */
12
13 #define NOIPA __attribute__ ((noipa))
14
15 void sink (int[1]);
16 #define A(p, off) sink (p + off)
17
18 extern int a4[4], a8[8];
19
20
21
22
23 NOIPA void a4_p1_a8_p3 (int i)
24 {
25 int *a4_p1 = a4 + 1;
26 int *a8_p3 = a8 + 3;
27 int *q = i ? a4_p1 : a8_p3;
28 A (q, -4); // { dg-warning "-Wstringop-overflow" }
29 /* Because -3 is a valid offset into a8 but not a4, q must point
30 to the former and so subscripts between -3 and +4 refer to its
31 elements. */
32 A (q, -3); A (q, -2); A (q, -1); A (q, 0);
33 A (q, 1); A (q, 2); A (q, 3); A (q, 4);
34 A (q, 5); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
35 /* Both of the following are definitely out of bounds but the first isn't
36 diagnosed because the code conservatively merges the offsets into A4
37 and A8. */
38 A (q, 7); // { dg-warning "-Wstringop-overflow" }
39 }
40
41
42 NOIPA void a4_p1_a8_p5 (int i)
43 {
44 int *a4_p1 = a4 + 1;
45 int *a8_p5 = a8 + 5;
46 int *q = i ? a4_p1 : a8_p5;
47 A (q, -6); // { dg-warning "-Wstringop-overflow" }
48 /* Similarly to the above, because -5 is a valid offset into a8 but
49 not a4, q must point to the former and so subscripts between -5
50 and +2 refer to its elements. */
51 A (q, -5); A (q, -4); A (q, -3); A (q, -2);
52 A (q, -1); A (q, 0); A (q, 1); A (q, 2);
53 A (q, 3); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
54 A (q, 7); // { dg-warning "-Wstringop-overflow" }
55 }
56
57
58 NOIPA void a4_p1_a8_p7 (int i)
59 {
60 int *a4_p1 = a4 + 1;
61 int *a8_p7 = a8 + 7;
62 int *q = i ? a4_p1 : a8_p7;
63 A (q, -8); // { dg-warning "-Wstringop-overflow" }
64 A (q, -7); A (q, -6); A (q, -5); A (q, -4);
65 A (q, -3); A (q, -2); A (q, -1); A (q, 0);
66 /* Since -7 is valid, q must point to a8 and the last valid subscript
67 must be 0. */
68 A (q, 1); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
69 A (q, 2); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
70 A (q, 3); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
71 A (q, 7); // { dg-warning "-Wstringop-overflow" }
72 }
73
74
75 NOIPA void mp_1_a4_p1_a8_p7 (int i, int j)
76 {
77 int *a4_p1 = a4 + 1;
78 int *a8_p7 = a8 + 7;
79 int *p = i ? a4_p1 : a8_p7;
80 int *q = j ? p + 1 : p - 1;
81
82 A (q, -9); // { dg-warning "-Wstringop-overflow" }
83
84 /* q points either to a8 + [6, 8] or a4 + [0, 2]. */
85 A (q, -8); A (q, -7); A (q, -6); A (q, -5);
86 A (q, -4); A (q, -3); A (q, -2); A (q, -1);
87
88 /* Since all the above are valid, q must point to a8 + 8. But as
89 mentioned above, the warning for each subscript is independent
90 of prior subscripts into the same object so the access below
91 aren't diagnosed. */
92 A (q, 0); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
93 A (q, 1); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
94 A (q, 2); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
95 A (q, 3); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
96 A (q, 4); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
97 A (q, 8); // { dg-warning "-Wstringop-overflow" }
98 }
99
100
101 NOIPA void mp1_a4_p1_a8_p5 (int i, int j)
102 {
103 int *a4_p1 = a4 + 1;
104 int *a8_p5 = a8 + 5;
105 int *p = i ? a4_p1 : a8_p5;
106
107 int *q = j ? p + 1 : p - 1;
108
109 // q is assumed to point to a8 + 6
110 A (q, -7); // { dg-warning "-Wstringop-overflow" }
111 A (q, -6); A (q, -5); A (q, -4); A (q, -3);
112 A (q, -2); A (q, -1); A (q, 0); A (q, 1);
113 /* Even though the above accesses rule it out, q is now assumed
114 to point to either a4 + [0, 2] or a8 + [4, 5]. */
115 A (q, 2);
116 /* q is now assumed to point tp a4. Given that, only the first store
117 is valid. */
118 A (q, 3); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
119 A (q, 4); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
120 A (q, 5); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
121 A (q, 6); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
122 A (q, 7); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
123 A (q, 8); // { dg-warning "-Wstringop-overflow" }
124 }
125
126
127 NOIPA void mp1_a4_p1_a8_p4 (int i, int j)
128 {
129 int *a4_p1 = a4 + 1;
130 int *a8_p4 = a8 + 4;
131 int *p = i ? a4_p1 : a8_p4;
132
133 int *q = j ? p + 1 : p - 1;
134
135 // q is assumed to point to a8 + 5
136 A (q, -6); // { dg-warning "-Wstringop-overflow" }
137 A (q, -5);
138 A (q, -4);
139 A (q, -3);
140 A (q, -2);
141 A (q, -1);
142 A (q, 0);
143 A (q, 1);
144 A (q, 2);
145 /* Even though the above accesses rule it out, q is now assumed
146 to point tp a4. Given that, only the first store is valid. */
147 A (q, 3); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
148 A (q, 4); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
149 A (q, 5); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
150 A (q, 6); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
151 A (q, 7); // { dg-warning "-Wstringop-overflow" "pr??????" { xfail *-*-* } }
152 A (q, 8); // { dg-warning "-Wstringop-overflow" }
153 }