pio4_hi
pio4_hi = 0.78539816339744828, /* 0x1921fb54442d18.0p-53 */
#define pio4 ((long double)pio4_hi + pio4_lo)
q = pio4_hi-2.0*w;
t = pio4_hi-(p-q);
pio4_hi = 7.85398163397448278999e-01, /* 0x3FE921FB, 0x54442D18 */
q = pio4_hi-2.0*w;
t = pio4_hi-(p-q);