xref: /llvm-project/compiler-rt/lib/builtins/clzti2.c (revision 0ee439b705e82a4fe20e266bc8fea96d0e60e1ec)
10ba22f51SPetr Hosek //===-- clzti2.c - Implement __clzti2 -------------------------------------===//
20ba22f51SPetr Hosek //
30ba22f51SPetr Hosek // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
40ba22f51SPetr Hosek // See https://llvm.org/LICENSE.txt for license information.
50ba22f51SPetr Hosek // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
60ba22f51SPetr Hosek //
70ba22f51SPetr Hosek //===----------------------------------------------------------------------===//
80ba22f51SPetr Hosek //
90ba22f51SPetr Hosek // This file implements __clzti2 for the compiler_rt library.
100ba22f51SPetr Hosek //
110ba22f51SPetr Hosek //===----------------------------------------------------------------------===//
12a6b264b5SAlexey Samsonov 
13a6b264b5SAlexey Samsonov #include "int_lib.h"
14a6b264b5SAlexey Samsonov 
15938b0df7SJoerg Sonnenberger #ifdef CRT_HAS_128BIT
16a6b264b5SAlexey Samsonov 
170ba22f51SPetr Hosek // Returns: the number of leading 0-bits
18a6b264b5SAlexey Samsonov 
190ba22f51SPetr Hosek // Precondition: a != 0
20a6b264b5SAlexey Samsonov 
__clzti2(ti_int a)21*0ee439b7SAnatoly Trosinenko COMPILER_RT_ABI int __clzti2(ti_int a) {
22a6b264b5SAlexey Samsonov   twords x;
23a6b264b5SAlexey Samsonov   x.all = a;
24a6b264b5SAlexey Samsonov   const di_int f = -(x.s.high == 0);
25a6b264b5SAlexey Samsonov   return __builtin_clzll((x.s.high & ~f) | (x.s.low & f)) +
26a6b264b5SAlexey Samsonov          ((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT)));
27a6b264b5SAlexey Samsonov }
28a6b264b5SAlexey Samsonov 
290ba22f51SPetr Hosek #endif // CRT_HAS_128BIT
30