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/* ===-- clzdi2.c - Implement __clzdi2 -------------------------------------===
*
* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
* See https://llvm.org/LICENSE.txt for license information.
* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
*
* ===----------------------------------------------------------------------===
*
* This file implements __clzdi2 for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
#include "int_lib.h"
/* Returns: the number of leading 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_clz to __clzdi2 rather than
* __clzsi2, leading to infinite recursion. */
#define __builtin_clz(a) __clzsi2(a)
extern si_int __clzsi2(si_int);
#endif
/* Precondition: a != 0 */
COMPILER_RT_ABI si_int
__clzdi2(di_int a)
{
dwords x;
x.all = a;
const si_int f = -(x.s.high == 0);
return __builtin_clz((x.s.high & ~f) | (x.s.low & f)) +
(f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
}
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