1 | /* ===-- clzdi2.c - Implement __clzdi2 -------------------------------------=== |
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 __clzdi2 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 | #if !defined(__clang__) && (defined(__sparc64__) || defined(__mips64)) |
20 | /* gcc resolves __builtin_clz -> __clzdi2 leading to infinite recursion */ |
21 | #define __builtin_clz(a) __clzsi2(a) |
22 | extern si_int __clzsi2(si_int); |
23 | #endif |
24 | |
25 | /* Precondition: a != 0 */ |
26 | |
27 | COMPILER_RT_ABI si_int |
28 | __clzdi2(di_int a) |
29 | { |
30 | dwords x; |
31 | x.all = a; |
32 | const si_int f = -(x.s.high == 0); |
33 | return __builtin_clz((x.s.high & ~f) | (x.s.low & f)) + |
34 | (f & ((si_int)(sizeof(si_int) * CHAR_BIT))); |
35 | } |
36 | |