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/* Testing the alias analysis on ill-defined codes
where it should remain conservative. */
typedef unsigned int uintptr_t;
/* For testing with GCC */
#define NOINLINE __attribute__((noinline))
/* Passing a pointer through a long long */
void NOINLINE set1(long long x)
{
int * p = (int *) (uintptr_t) x;
*p = 1;
}
int get1(void)
{
int x = 0;
set1((uintptr_t) &x);
return x;
}
/* Passing a pointer through a double */
void NOINLINE set2(double x)
{
int * p = (int *) (uintptr_t) x;
*p = 1;
}
int get2(void)
{
int x = 0;
set2((uintptr_t) &x);
return x;
}
/* Tagging a pointer */
void NOINLINE set3(uintptr_t x)
{
int * p = (int *) (x & ~1);
*p = 1;
}
int get3(void)
{
int x = 0;
set3((uintptr_t) &x | 1);
return x;
}
/* XOR-ing a pointer */
static uintptr_t key = 0xDEADBEEF;
void NOINLINE set4(uintptr_t x)
{
int * p = (int *) (x ^ key);
*p = 1;
}
int get4(void)
{
int x = 0;
set4((uintptr_t) &x ^ key);
return x;
}
/* Byte-swapping a pointer */
inline uintptr_t bswap(uintptr_t x)
{
return (x >> 24)
| (((x >> 16) & 0xFF) << 8)
| (((x >> 8) & 0xFF) << 16)
| ((x & 0xFF) << 24);
}
void NOINLINE set5(uintptr_t x)
{
int * p = (int *) bswap(x);
*p = 1;
}
int get5(void)
{
int x = 0;
set5(bswap((uintptr_t) &x));
return x;
}
/* Even more fun with xor */
int x;
void NOINLINE set6(int * p, uintptr_t z)
{
int * q = (int *) ((uintptr_t) p ^ z);
*q = 1;
}
int get6(void)
{
int y = 0;
uintptr_t z = (uintptr_t) &x ^ (uintptr_t) &y;
set6(&x, z);
int res1 = y;
x = 0;
set6(&y, z);
int res2 = x;
return res1 & res2;
}
/* Aligning pointers the hard way */
int offset = 3; /* but not const */
int get7(void)
{
union { int i; char c[4]; } u; /* force alignment to 4 */
u.c[0] = 0;
uintptr_t x = (uintptr_t) &(u.c[offset]);
x = x & ~3;
*((char *) x) = 1;
return u.c[0];
}
/* Test harness */
#include <stdio.h>
int main()
{
printf("Test 1: %d\n", get1());
printf("Test 2: %d\n", get2());
printf("Test 3: %d\n", get3());
printf("Test 4: %d\n", get4());
printf("Test 5: %d\n", get5());
printf("Test 6: %d\n", get6());
printf("Test 7: %d\n", get7());
return 0;
}
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