Viewing file:  pr47538.c (1.45 KB) -rw-r--r--
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/* PR tree-optimization/47538 */
struct S
{
double a, b, *c;
unsigned long d;
};
__attribute__((noinline, noclone)) void
foo (struct S *x, const struct S *y)
{
const unsigned long n = y->d + 1;
const double m = 0.25 * (y->b - y->a);
x->a = y->a;
x->b = y->b;
if (n == 1)
{
x->c[0] = 0.;
}
else if (n == 2)
{
x->c[1] = m * y->c[0];
x->c[0] = 2.0 * x->c[1];
}
else
{
double o = 0.0, p = 1.0;
unsigned long i;
for (i = 1; i <= n - 2; i++)
{
x->c[i] = m * (y->c[i - 1] - y->c[i + 1]) / (double) i;
o += p * x->c[i];
p = -p;
}
x->c[n - 1] = m * y->c[n - 2] / (n - 1.0);
o += p * x->c[n - 1];
x->c[0] = 2.0 * o;
}
}
int
main (void)
{
struct S x, y;
double c[4] = { 10, 20, 30, 40 }, d[4], e[4] = { 118, 118, 118, 118 };
y.a = 10;
y.b = 6;
y.c = c;
x.c = d;
y.d = 3;
__builtin_memcpy (d, e, sizeof d);
foo (&x, &y);
if (d[0] != 0 || d[1] != 20 || d[2] != 10 || d[3] != -10)
__builtin_abort ();
y.d = 2;
__builtin_memcpy (d, e, sizeof d);
foo (&x, &y);
if (d[0] != 60 || d[1] != 20 || d[2] != -10 || d[3] != 118)
__builtin_abort ();
y.d = 1;
__builtin_memcpy (d, e, sizeof d);
foo (&x, &y);
if (d[0] != -20 || d[1] != -10 || d[2] != 118 || d[3] != 118)
__builtin_abort ();
y.d = 0;
__builtin_memcpy (d, e, sizeof d);
foo (&x, &y);
if (d[0] != 0 || d[1] != 118 || d[2] != 118 || d[3] != 118)
__builtin_abort ();
return 0;
}
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