GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcompiler_rt/clzsi2.c Lines: 0 12 0.0 %
Date: 2017-11-13 Branches: 0 0 0.0 %

Line Branch Exec Source
1
/* ===-- clzsi2.c - Implement __clzsi2 -------------------------------------===
2
 *
3
 *               The LLVM Compiler Infrastructure
4
 *
5
 * This file is dual licensed under the MIT and the University of Illinois Open
6
 * Source Licenses. See LICENSE.TXT for details.
7
 *
8
 * ===----------------------------------------------------------------------===
9
 *
10
 * This file implements __clzsi2 for the compiler_rt library.
11
 *
12
 * ===----------------------------------------------------------------------===
13
 */
14
15
#include "int_lib.h"
16
17
/* Returns: the number of leading 0-bits */
18
19
/* Precondition: a != 0 */
20
21
COMPILER_RT_ABI si_int
22
__clzsi2(si_int a)
23
{
24
    su_int x = (su_int)a;
25
    si_int t = ((x & 0xFFFF0000) == 0) << 4;  /* if (x is small) t = 16 else 0 */
26
    x >>= 16 - t;      /* x = [0 - 0xFFFF] */
27
    su_int r = t;       /* r = [0, 16] */
28
    /* return r + clz(x) */
29
    t = ((x & 0xFF00) == 0) << 3;
30
    x >>= 8 - t;       /* x = [0 - 0xFF] */
31
    r += t;            /* r = [0, 8, 16, 24] */
32
    /* return r + clz(x) */
33
    t = ((x & 0xF0) == 0) << 2;
34
    x >>= 4 - t;       /* x = [0 - 0xF] */
35
    r += t;            /* r = [0, 4, 8, 12, 16, 20, 24, 28] */
36
    /* return r + clz(x) */
37
    t = ((x & 0xC) == 0) << 1;
38
    x >>= 2 - t;       /* x = [0 - 3] */
39
    r += t;            /* r = [0 - 30] and is even */
40
    /* return r + clz(x) */
41
/*     switch (x)
42
 *     {
43
 *     case 0:
44
 *         return r + 2;
45
 *     case 1:
46
 *         return r + 1;
47
 *     case 2:
48
 *     case 3:
49
 *         return r;
50
 *     }
51
 */
52
    return r + ((2 - x) & -((x & 2) == 0));
53
}