1 //===- FuzzerBuiltinsMSVC.h - Internal header for builtins ------*- C++ -* ===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 // Wrapper functions and marcos that use intrinsics instead of builtin functions
9 // which cannot be compiled by MSVC.
10 //===----------------------------------------------------------------------===//
11 
12 #ifndef LLVM_FUZZER_BUILTINS_MSVC_H
13 #define LLVM_FUZZER_BUILTINS_MSVC_H
14 
15 #include "FuzzerPlatform.h"
16 
17 #if LIBFUZZER_MSVC
18 #include <intrin.h>
19 #include <cstdint>
20 #include <cstdlib>
21 
22 // __builtin_return_address() cannot be compiled with MSVC. Use the equivalent
23 // from <intrin.h>
24 #define GET_CALLER_PC() _ReturnAddress()
25 
26 namespace fuzzer {
27 
28 inline uint8_t  Bswap(uint8_t x)  { return x; }
29 // Use alternatives to __builtin functions from <stdlib.h> and <intrin.h> on
30 // Windows since the builtins are not supported by MSVC.
31 inline uint16_t Bswap(uint16_t x) { return _byteswap_ushort(x); }
32 inline uint32_t Bswap(uint32_t x) { return _byteswap_ulong(x); }
33 inline uint64_t Bswap(uint64_t x) { return _byteswap_uint64(x); }
34 
35 // The functions below were mostly copied from
36 // compiler-rt/lib/builtins/int_lib.h which defines the __builtin functions used
37 // outside of Windows.
38 inline uint32_t Clzll(uint64_t X) {
39   unsigned long LeadZeroIdx = 0;
40 
41 #if !defined(_M_ARM) && !defined(_M_X64)
42   // Scan the high 32 bits.
43   if (_BitScanReverse(&LeadZeroIdx, static_cast<unsigned long>(X >> 32)))
44     return static_cast<int>(
45         63 - (LeadZeroIdx + 32)); // Create a bit offset from the MSB.
46   // Scan the low 32 bits.
47   if (_BitScanReverse(&LeadZeroIdx, static_cast<unsigned long>(X)))
48     return static_cast<int>(63 - LeadZeroIdx);
49 
50 #else
51   if (_BitScanReverse64(&LeadZeroIdx, X)) return 63 - LeadZeroIdx;
52 #endif
53   return 64;
54 }
55 
56 inline int Popcountll(unsigned long long X) {
57 #if !defined(_M_ARM) && !defined(_M_X64)
58   return __popcnt(X) + __popcnt(X >> 32);
59 #else
60   return __popcnt64(X);
61 #endif
62 }
63 
64 }  // namespace fuzzer
65 
66 #endif  // LIBFUZER_MSVC
67 #endif  // LLVM_FUZZER_BUILTINS_MSVC_H
68