blob: 9384aa6055a1136a1108e3451ecb479ab2980996 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
|
//===-- ctzdi2.c - Implement __ctzdi2 -------------------------------------===//
//
// 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 __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)));
}
|
