tools/fuzzing/libfuzzer/FuzzerBuiltinsMsvc.h

   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>(63 - (LeadZeroIdx + 32)); // Create a bit offset from the MSB.
  45   // Scan the low 32 bits.
  46   if (_BitScanReverse(&LeadZeroIdx, static_cast<unsigned long>(X)))
  47     return static_cast<int>(63 - LeadZeroIdx);
  48
  49 #else
  50   if (_BitScanReverse64(&LeadZeroIdx, X)) return 63 - LeadZeroIdx;
  51 #endif
  52   return 64;
  53 }
  54
  55 inline uint32_t Clz(uint32_t X) {
  56   unsigned long LeadZeroIdx = 0;
  57   if (_BitScanReverse(&LeadZeroIdx, X)) return 31 - LeadZeroIdx;
  58   return 32;
  59 }
  60
  61 inline int Popcountll(unsigned long long X) {
  62 #if !defined(_M_ARM) && !defined(_M_X64)
  63   return __popcnt(X) + __popcnt(X >> 32);
  64 #else
  65   return __popcnt64(X);
  66 #endif
  67 }
  68
  69 }  // namespace fuzzer
  70
  71 #endif  // LIBFUZER_MSVC
  72 #endif  // LLVM_FUZZER_BUILTINS_MSVC_H