gcc/testsuite/gcc.dg/20050826-1.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 /* Darwin spells this differently */
   9 #ifndef MAP_ANONYMOUS
  10 #define MAP_ANONYMOUS MAP_ANON
  11 #endif
  12 #ifndef MAP_ANON
  13 #define MAP_ANON 0
  14 #endif
  15 #ifndef MAP_FAILED
  16 #define MAP_FAILED ((void *)-1)
  17 #endif
  18 #include <stdlib.h>
  19
  20     struct Flags {
  21  int filler[18];
  22  unsigned int a:14;
  23  unsigned int b:14;
  24  unsigned int c:1;
  25  unsigned int d:1;
  26  unsigned int e:1;
  27  unsigned int f:1;
  28     };
  29 static void __attribute__((noinline)) set (struct Flags *);
  30 static void set (struct Flags *fp)
  31 {
  32   fp->b = 5;
  33   fp->d = 1;
  34 }
  35
  36 static int __attribute__((noinline)) bar (int);
  37 static int bar(int x) { return !(x==1); }
  38 int main (void)
  39 {
  40   char *p = mmap (NULL, 131072, PROT_READ | PROT_WRITE,
  41                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  42   struct Flags *fp;
  43   if (p == MAP_FAILED)
  44     return 0;
  45   if (munmap (p + 65536, 65536) < 0)
  46     return 0;
  47   fp = (struct Flags*)(p + 65536 - sizeof(struct Flags));
  48   set(fp);
  49   if (fp->b > 0)
  50     return (bar(fp->d));
  51   return 1;
  52 }