hanchenye-llvm-project/compiler-rt/lib/clzdi2.c

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//===-- clzdi2.c - Implement __clzdi2 -------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements __clzdi2 for the compiler_rt library.
//
//===----------------------------------------------------------------------===//
#include "int_lib.h"
// Returns: the number of leading 0-bits
// Precondition: a != 0
si_int
__clzdi2(di_int a)
{
dwords x;
x.all = a;
const si_int f = -(x.high == 0);
return __builtin_clz((x.high & ~f) | (x.low & f)) +
(f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
}