1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
|
/* { dg-do run } */
/* { dg-options "-fdump-tree-crc-details" } */
/* { dg-skip-if "" { *-*-* } { "-O0" "-O1" "-Os" "-flto" } } */
/* { dg-require-effective-target int32plus } */
#include <stdint.h>
#include <stdlib.h>
#define POLY (0x1070U << 3)
#define u8 uint8_t
#define u16 uint16_t
__attribute__ ((noinline,optimize(0)))
u8 crc8_O0 (u16 data) {
int i;
for (i = 0; i < 8; i++) {
if (data & 0x8000)
data = data ^ POLY;
data = data << 1;
}
return (u8)(data >> 8);
}
u8 crc8 (u16 data) {
int i;
for (i = 0; i < 8; i++) {
if (data & 0x8000)
data = data ^ POLY;
data = data << 1;
}
return (u8)(data >> 8);
}
int main ()
{
for (u8 i = 0; i < 255; i++)
{
u8 res1 = crc8_O0 (i);
u8 res2 = crc8 (i);
if (res1 != res2)
__builtin_abort ();
}
__builtin_exit (0);
}
/* { dg-final { scan-tree-dump "function maybe contains CRC calculation." "crc" } } */
/* { dg-final { scan-tree-dump "Loop iteration number is 7" "crc" } } */
/* { dg-final { scan-tree-dump "Bit forward" "crc" } } */
/* { dg-final { scan-tree-dump "Polynomial's value is \\\{0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0\\\}" "crc" } } */
/* { dg-final { scan-tree-dump "calculates CRC!" "crc" } } */
/* { dg-final { scan-tree-dump-times "Couldn't generate faster CRC code." 0 "crc" } } */
|
