xref: /openbmc/qemu/tests/tcg/i386/test-i386-fscale.c (revision 5acc270a)
1 /* Test fscale instruction.  */
2 
3 #include <stdint.h>
4 #include <stdio.h>
5 
6 union u {
7     struct { uint64_t sig; uint16_t sign_exp; } s;
8     long double ld;
9 };
10 
11 volatile long double ld_third = 1.0L / 3.0L;
12 volatile long double ld_four_thirds = 4.0L / 3.0L;
13 volatile union u ld_invalid_1 = { .s = { 1, 1234 } };
14 volatile union u ld_invalid_2 = { .s = { 0, 1234 } };
15 volatile union u ld_invalid_3 = { .s = { 0, 0x7fff } };
16 volatile union u ld_invalid_4 = { .s = { (UINT64_C(1) << 63) - 1, 0x7fff } };
17 
18 volatile long double ld_res;
19 
isnan_ld(long double x)20 int isnan_ld(long double x)
21 {
22   union u tmp = { .ld = x };
23   return ((tmp.s.sign_exp & 0x7fff) == 0x7fff &&
24           (tmp.s.sig >> 63) != 0 &&
25           (tmp.s.sig << 1) != 0);
26 }
27 
issignaling_ld(long double x)28 int issignaling_ld(long double x)
29 {
30     union u tmp = { .ld = x };
31     return isnan_ld(x) && (tmp.s.sig & UINT64_C(0x4000000000000000)) == 0;
32 }
33 
main(void)34 int main(void)
35 {
36     short cw;
37     int ret = 0;
38     __asm__ volatile ("fscale" : "=t" (ld_res) :
39                       "0" (2.5L), "u" (__builtin_nansl("")));
40     if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
41         printf("FAIL: fscale snan\n");
42         ret = 1;
43     }
44     __asm__ volatile ("fscale" : "=t" (ld_res) :
45                       "0" (2.5L), "u" (ld_invalid_1.ld));
46     if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
47         printf("FAIL: fscale invalid 1\n");
48         ret = 1;
49     }
50     __asm__ volatile ("fscale" : "=t" (ld_res) :
51                       "0" (2.5L), "u" (ld_invalid_2.ld));
52     if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
53         printf("FAIL: fscale invalid 2\n");
54         ret = 1;
55     }
56     __asm__ volatile ("fscale" : "=t" (ld_res) :
57                       "0" (2.5L), "u" (ld_invalid_3.ld));
58     if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
59         printf("FAIL: fscale invalid 3\n");
60         ret = 1;
61     }
62     __asm__ volatile ("fscale" : "=t" (ld_res) :
63                       "0" (2.5L), "u" (ld_invalid_4.ld));
64     if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
65         printf("FAIL: fscale invalid 4\n");
66         ret = 1;
67     }
68     __asm__ volatile ("fscale" : "=t" (ld_res) :
69                       "0" (0.0L), "u" (__builtin_infl()));
70     if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
71         printf("FAIL: fscale 0 up inf\n");
72         ret = 1;
73     }
74     __asm__ volatile ("fscale" : "=t" (ld_res) :
75                       "0" (__builtin_infl()), "u" (-__builtin_infl()));
76     if (!isnan_ld(ld_res) || issignaling_ld(ld_res)) {
77         printf("FAIL: fscale inf down inf\n");
78         ret = 1;
79     }
80     /* Set round-downward.  */
81     __asm__ volatile ("fnstcw %0" : "=m" (cw));
82     cw = (cw & ~0xc00) | 0x400;
83     __asm__ volatile ("fldcw %0" : : "m" (cw));
84     __asm__ volatile ("fscale" : "=t" (ld_res) :
85                       "0" (1.0L), "u" (__builtin_infl()));
86     if (ld_res != __builtin_infl()) {
87         printf("FAIL: fscale finite up inf\n");
88         ret = 1;
89     }
90     __asm__ volatile ("fscale" : "=t" (ld_res) :
91                       "0" (-1.0L), "u" (-__builtin_infl()));
92     if (ld_res != -0.0L || __builtin_copysignl(1.0L, ld_res) != -1.0L) {
93         printf("FAIL: fscale finite down inf\n");
94         ret = 1;
95     }
96     /* Set round-to-nearest with single-precision rounding.  */
97     cw = cw & ~0xf00;
98     __asm__ volatile ("fldcw %0" : : "m" (cw));
99     __asm__ volatile ("fscale" : "=t" (ld_res) :
100                       "0" (ld_third), "u" (2.0L));
101     cw = cw | 0x300;
102     __asm__ volatile ("fldcw %0" : : "m" (cw));
103     if (ld_res != ld_four_thirds) {
104         printf("FAIL: fscale single-precision\n");
105         ret = 1;
106     }
107     return ret;
108 }
109