1 /* SPDX-License-Identifier: GPL-2.0-only */ 1
2 #ifndef __ASM_UNROLL_H__
3 #define __ASM_UNROLL_H__
4
5 /*
6 * Explicitly unroll a loop, for use in cases
7 * critical.
8 *
9 * Ideally we'd rely upon the compiler to prov
10 * available means to do so. For example GCC's
11 * functionality would be ideal but is only av
12 * -funroll-loops is an option but GCC tends t
13 * compiling our string functions. -funroll-al
14 * bloat, even if only applied to the string f
15 */
16 #define unroll(times, fn, ...) do {
17 extern void bad_unroll(void)
18 __compiletime_error("Unsupport
19
20 /*
21 * We can't unroll if the number of it
22 * compile-time constant. Unfortunatel
23 * up until 8.0 tend to miss obvious c
24 * this check to fail, even though the
25 * generate reasonable code for the sw
26 * so we skip the sanity check for tho
27 */
28 BUILD_BUG_ON(!__builtin_constant_p(tim
29
30 switch (times) {
31 case 32: fn(__VA_ARGS__); fallthrough;
32 case 31: fn(__VA_ARGS__); fallthrough;
33 case 30: fn(__VA_ARGS__); fallthrough;
34 case 29: fn(__VA_ARGS__); fallthrough;
35 case 28: fn(__VA_ARGS__); fallthrough;
36 case 27: fn(__VA_ARGS__); fallthrough;
37 case 26: fn(__VA_ARGS__); fallthrough;
38 case 25: fn(__VA_ARGS__); fallthrough;
39 case 24: fn(__VA_ARGS__); fallthrough;
40 case 23: fn(__VA_ARGS__); fallthrough;
41 case 22: fn(__VA_ARGS__); fallthrough;
42 case 21: fn(__VA_ARGS__); fallthrough;
43 case 20: fn(__VA_ARGS__); fallthrough;
44 case 19: fn(__VA_ARGS__); fallthrough;
45 case 18: fn(__VA_ARGS__); fallthrough;
46 case 17: fn(__VA_ARGS__); fallthrough;
47 case 16: fn(__VA_ARGS__); fallthrough;
48 case 15: fn(__VA_ARGS__); fallthrough;
49 case 14: fn(__VA_ARGS__); fallthrough;
50 case 13: fn(__VA_ARGS__); fallthrough;
51 case 12: fn(__VA_ARGS__); fallthrough;
52 case 11: fn(__VA_ARGS__); fallthrough;
53 case 10: fn(__VA_ARGS__); fallthrough;
54 case 9: fn(__VA_ARGS__); fallthrough;
55 case 8: fn(__VA_ARGS__); fallthrough;
56 case 7: fn(__VA_ARGS__); fallthrough;
57 case 6: fn(__VA_ARGS__); fallthrough;
58 case 5: fn(__VA_ARGS__); fallthrough;
59 case 4: fn(__VA_ARGS__); fallthrough;
60 case 3: fn(__VA_ARGS__); fallthrough;
61 case 2: fn(__VA_ARGS__); fallthrough;
62 case 1: fn(__VA_ARGS__); fallthrough;
63 case 0: break;
64
65 default:
66 /*
67 * Either the iteration count
68 * or we need to add more case
69 */
70 bad_unroll();
71 break;
72 }
73 } while (0)
74
75 #endif /* __ASM_UNROLL_H__ */
76
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