gcc/testsuite/gcc.dg/20030711-1.c

   1 /* Test whether strncmp has not been "optimized" into memcmp
   2    nor any code with memcmp semantics.  */
   3 /* { dg-do run { target mmap } } */
   4 /* { dg-options "-O2" } */
   5 #include <stddef.h>
   6 #include <stdio.h>
   7 #include <sys/mman.h>
   8 #ifndef MAP_ANONYMOUS
   9 #define MAP_ANONYMOUS MAP_ANON
  10 #endif
  11 #ifndef MAP_ANON
  12 #define MAP_ANON 0
  13 #endif
  14 #ifndef MAP_FAILED
  15 #define MAP_FAILED ((void *)-1)
  16 #endif
  17 #include <stdlib.h>
  18
  19 void __attribute__((noinline)) test (const char *p)
  20 {
  21   if (__builtin_strncmp (p, "abcdefghijklmnopq", 17) == 0)
  22     abort ();
  23 }
  24
  25 int main (void)
  26 {
  27   char *p = mmap (NULL, 131072, PROT_READ | PROT_WRITE,
  28                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  29   if (p == MAP_FAILED)
  30     return 0;
  31   if (munmap (p + 65536, 65536) < 0)
  32     return 0;
  33   __builtin_memcpy (p + 65536 - 5, "abcd", 5);
  34   test (p + 65536 - 5);
  35   return 0;
  36 }