1 /* ===-- clzti2.c - Implement __clzti2 -------------------------------------=== 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 __clzti2 for the compiler_rt library. 11 * 12 * ===----------------------------------------------------------------------=== 13 */ 14 15 #if __x86_64 16 17 #include "int_lib.h" 18 19 /* Returns: the number of leading 0-bits */ 20 21 /* Precondition: a != 0 */ 22 23 si_int __clzti2(ti_int a)24 __clzti2(ti_int a) 25 { 26 twords x; 27 x.all = a; 28 const di_int f = -(x.s.high == 0); 29 return __builtin_clzll((x.s.high & ~f) | (x.s.low & f)) + 30 ((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT))); 31 } 32 33 #endif /* __x86_64 */ 34