1 /* ===-- ctzdi2.c - Implement __ctzdi2 -------------------------------------=== 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 __ctzdi2 for the compiler_rt library. 11 * 12 * ===----------------------------------------------------------------------=== 13 */ 14 15 #include "int_lib.h" 16 17 /* Returns: the number of trailing 0-bits */ 18 19 #if !defined(__clang__) && (defined(__sparc64__) || defined(__mips64) || defined(__riscv__)) 20 /* gcc resolves __builtin_ctz -> __ctzdi2 leading to infinite recursion */ 21 #define __builtin_ctz(a) __ctzsi2(a) 22 extern si_int __ctzsi2(si_int); 23 #endif 24 25 /* Precondition: a != 0 */ 26 27 COMPILER_RT_ABI si_int __ctzdi2(di_int a)28__ctzdi2(di_int a) 29 { 30 dwords x; 31 x.all = a; 32 const si_int f = -(x.s.low == 0); 33 return __builtin_ctz((x.s.high & f) | (x.s.low & ~f)) + 34 (f & ((si_int)(sizeof(si_int) * CHAR_BIT))); 35 } 36