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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 int __clzsi2(si_int);
#endif
// Precondition: a != 0
COMPILER_RT_ABI int __clzdi2(di_int a) {
dwords x;
x.all = a;
const si_int f = -(x.s.high == 0);
return clzsi((x.s.high & ~f) | (x.s.low & f)) +
(f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
}
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