memcheck/tests/test-plo.c

   1 #include "tests/malloc.h"
   2 #include <stdio.h>
   3 #include <assert.h>
   4
   5 typedef  unsigned long long int  ULong;
   6 typedef  unsigned long int       UWord;
   7
   8 __attribute__((noinline))
   9 static int my_ffsll ( ULong x )
  10 {
  11    int i;
  12    for (i = 0; i < 64; i++) {
  13       if ((x & 1ULL) == 1ULL)
  14          break;
  15       x >>= 1;
  16    }
  17    return i+1;
  18 }
  19
  20 /* Find length of string, assuming it is aligned and shorter than 8
  21    characters.  Little-endian only. */
  22 __attribute__((noinline))
  23 static int aligned_strlen(char *s)
  24 {
  25     /* This is for 64-bit platforms */
  26     assert(sizeof(ULong) == 8);
  27     /* ..and only works for aligned input */
  28     assert(((unsigned long)s & 0x7) == 0);
  29
  30     /* read 8 bytes */
  31     ULong val = *(ULong*)s;
  32     /* Subtract one from each byte */
  33     ULong val2 = val - 0x0101010101010101ULL;
  34     /* Find lowest byte whose high bit changed */
  35     val2 ^= val;
  36     val2 &= 0x8080808080808080ULL;
  37
  38     return (my_ffsll(val2) / 8) - 1;
  39 }
  40
  41 __attribute__((noinline)) void foo ( int x )
  42 {
  43    __asm__ __volatile__("":::"memory");
  44 }
  45
  46 int
  47 main(int argc, char *argv[])
  48 {
  49     char *buf = memalign16(5);
  50     buf[0] = 'a';
  51     buf[1] = 'b';
  52     buf[2] = 'c';
  53     buf[3] = 'd';
  54     buf[4] = '\0';
  55
  56     /* --partial-loads-ok=no:  expect addr error (here) */
  57     /* --partial-loads-ok=yes: expect no error */
  58     if (aligned_strlen(buf) == 4)
  59         foo(44);
  60
  61     /* --partial-loads-ok=no:  expect addr error (here) */
  62     /* --partial-loads-ok=yes: expect value error (in my_ffsll) */
  63     buf[4] = 'x';
  64     if (aligned_strlen(buf) == 0)
  65         foo(37);
  66
  67     free(buf);
  68
  69     /* Also, we need to check that a completely out-of-range,
  70        word-sized load gives an addressing error regardless of the
  71        start of --partial-loads-ok=.  *And* that the resulting
  72        value is completely defined. */
  73     UWord* words = malloc(3 * sizeof(UWord));
  74     free(words);
  75
  76     /* Should ALWAYS give an addr error. */
  77     UWord  w     = words[1];
  78
  79     /* Should NEVER give an error (you might expect a value one, but no.) */
  80     if (w == 0x31415927) {
  81        fprintf(stderr,
  82                "Elvis is alive and well and living in Milton Keynes.\n");
  83     }
  84
  85     return 0;
  86 }