| 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 | |