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/*
* This test stresses masking and sign-extension after int operations
* that cause overflow, producing bogus high-order bits.
* The basic overflow situation (x * x + y * y, for x = y = 1 << 21)
* actually happens in Olden-perimeter, in the function CheckOutside.
*
* Several things have to happen correctly:
* -- correct constant folding if it is done at compile-time
* -- correct sign-extensions during native code generation for -, * and /.
* -- correct handling of high bits during native code generation for
* a sequence of operations involving -, * and /.
*/
#include <stdio.h>
void compareOvf(int x, int y)
{
int sum = x * x + y * y;
if (sum < (1 << 22))
printf("compare after overflow is TRUE\n");
else
printf("compare after overflow is FALSE\n");
}
void divideOvf(int x, int y)
{
int sum = x * x + y * y;
int rem = (1 << 31) / sum;
printf("divide after overflow = %d (0x%x)\n", rem, rem);
}
void divideNeg(int x, int y)
{
int sum = x * x - y * y;
int rem = sum / (1 << 18);
printf("divide negative value by power-of-2 = %d (0x%x)\n", rem, rem);
}
void subtractOvf(int x, int y)
{
int sum = x * x + y * y;
int rem = (1u << 31) - sum;
printf("subtract after overflow = %d (0x%x)\n", rem, rem);
}
int main()
{
int b21 = 1 << 21;
compareOvf(b21, b21);
divideOvf(b21 + 1, b21 + 2);
divideNeg(b21 + 1, b21 + 2); /* arg1 must be < arg2 */
subtractOvf(b21 + 1, b21 + 2);
return 0;
}
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