gcc/testsuite/gcc.dg/Wstringop-overflow-85.c

   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 }