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/* ===-- ctzdi2.c - Implement __ctzdi2 -------------------------------------===
*
* The LLVM Compiler Infrastructure
*
* This file is dual licensed under the MIT and the University of Illinois Open
* Source Licenses. See LICENSE.TXT for details.
*
* ===----------------------------------------------------------------------===
*
* This file implements __ctzdi2 for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
#include "int_lib.h"
/* Returns: the number of trailing 0-bits */
#if !defined(__clang__) && \
((defined(__sparc__) && defined(__arch64__)) || \
defined(__mips64) || \
(defined(__riscv) && __SIZEOF_POINTER__ >= 8))
/* On 64-bit architectures with neither a native clz instruction nor a native
* ctz instruction, gcc resolves __builtin_ctz to __ctzdi2 rather than
* __ctzsi2, leading to infinite recursion. */
#define __builtin_ctz(a) __ctzsi2(a)
extern si_int __ctzsi2(si_int);
#endif
/* Precondition: a != 0 */
COMPILER_RT_ABI si_int
__ctzdi2(di_int a)
{
dwords x;
x.all = a;
const si_int f = -(x.s.low == 0);
return __builtin_ctz((x.s.high & f) | (x.s.low & ~f)) +
(f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
}
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