tools/llvm-isel-fuzzer/llvm-isel-fuzzer.cpp

   1 //===--- llvm-isel-fuzzer.cpp - Fuzzer for instruction selection ----------===//
   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 //
   9 // Tool to fuzz instruction selection using libFuzzer.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/ADT/StringRef.h"
  14 #include "llvm/Analysis/TargetLibraryInfo.h"
  15 #include "llvm/Bitcode/BitcodeReader.h"
  16 #include "llvm/Bitcode/BitcodeWriter.h"
  17 #include "llvm/CodeGen/CommandFlags.inc"
  18 #include "llvm/FuzzMutate/FuzzerCLI.h"
  19 #include "llvm/FuzzMutate/IRMutator.h"
  20 #include "llvm/FuzzMutate/Operations.h"
  21 #include "llvm/IR/Constants.h"
  22 #include "llvm/IR/LLVMContext.h"
  23 #include "llvm/IR/LegacyPassManager.h"
  24 #include "llvm/IR/Module.h"
  25 #include "llvm/IR/Verifier.h"
  26 #include "llvm/IRReader/IRReader.h"
  27 #include "llvm/Support/DataTypes.h"
  28 #include "llvm/Support/Debug.h"
  29 #include "llvm/Support/SourceMgr.h"
  30 #include "llvm/Support/TargetRegistry.h"
  31 #include "llvm/Support/TargetSelect.h"
  32 #include "llvm/Target/TargetMachine.h"
  33
  34 #define DEBUG_TYPE "isel-fuzzer"
  35
  36 using namespace llvm;
  37
  38 static cl::opt<char>
  39 OptLevel("O",
  40          cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
  41                   "(default = '-O2')"),
  42          cl::Prefix,
  43          cl::ZeroOrMore,
  44          cl::init(' '));
  45
  46 static cl::opt<std::string>
  47 TargetTriple("mtriple", cl::desc("Override target triple for module"));
  48
  49 static std::unique_ptr<TargetMachine> TM;
  50 static std::unique_ptr<IRMutator> Mutator;
  51
  52 std::unique_ptr<IRMutator> createISelMutator() {
  53   std::vector<TypeGetter> Types{
  54       Type::getInt1Ty,  Type::getInt8Ty,  Type::getInt16Ty, Type::getInt32Ty,
  55       Type::getInt64Ty, Type::getFloatTy, Type::getDoubleTy};
  56
  57   std::vector<std::unique_ptr<IRMutationStrategy>> Strategies;
  58   Strategies.emplace_back(
  59       new InjectorIRStrategy(InjectorIRStrategy::getDefaultOps()));
  60   Strategies.emplace_back(new InstDeleterIRStrategy());
  61
  62   return std::make_unique<IRMutator>(std::move(Types), std::move(Strategies));
  63 }
  64
  65 extern "C" LLVM_ATTRIBUTE_USED size_t LLVMFuzzerCustomMutator(
  66     uint8_t *Data, size_t Size, size_t MaxSize, unsigned int Seed) {
  67   LLVMContext Context;
  68   std::unique_ptr<Module> M;
  69   if (Size <= 1)
  70     // We get bogus data given an empty corpus - just create a new module.
  71     M.reset(new Module("M", Context));
  72   else
  73     M = parseModule(Data, Size, Context);
  74
  75   Mutator->mutateModule(*M, Seed, Size, MaxSize);
  76
  77   return writeModule(*M, Data, MaxSize);
  78 }
  79
  80 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
  81   if (Size <= 1)
  82     // We get bogus data given an empty corpus - ignore it.
  83     return 0;
  84
  85   LLVMContext Context;
  86   auto M = parseAndVerify(Data, Size, Context);
  87   if (!M) {
  88     errs() << "error: input module is broken!\n";
  89     return 0;
  90   }
  91
  92   // Set up the module to build for our target.
  93   M->setTargetTriple(TM->getTargetTriple().normalize());
  94   M->setDataLayout(TM->createDataLayout());
  95
  96   // Build up a PM to do instruction selection.
  97   legacy::PassManager PM;
  98   TargetLibraryInfoImpl TLII(TM->getTargetTriple());
  99   PM.add(new TargetLibraryInfoWrapperPass(TLII));
 100   raw_null_ostream OS;
 101   TM->addPassesToEmitFile(PM, OS, nullptr, TargetMachine::CGFT_Null);
 102   PM.run(*M);
 103
 104   return 0;
 105 }
 106
 107 static void handleLLVMFatalError(void *, const std::string &Message, bool) {
 108   // TODO: Would it be better to call into the fuzzer internals directly?
 109   dbgs() << "LLVM ERROR: " << Message << "\n"
 110          << "Aborting to trigger fuzzer exit handling.\n";
 111   abort();
 112 }
 113
 114 extern "C" LLVM_ATTRIBUTE_USED int LLVMFuzzerInitialize(int *argc,
 115                                                         char ***argv) {
 116   EnableDebugBuffering = true;
 117
 118   InitializeAllTargets();
 119   InitializeAllTargetMCs();
 120   InitializeAllAsmPrinters();
 121   InitializeAllAsmParsers();
 122
 123   handleExecNameEncodedBEOpts(*argv[0]);
 124   parseFuzzerCLOpts(*argc, *argv);
 125
 126   if (TargetTriple.empty()) {
 127     errs() << *argv[0] << ": -mtriple must be specified\n";
 128     exit(1);
 129   }
 130
 131   Triple TheTriple = Triple(Triple::normalize(TargetTriple));
 132
 133   // Get the target specific parser.
 134   std::string Error;
 135   const Target *TheTarget =
 136       TargetRegistry::lookupTarget(MArch, TheTriple, Error);
 137   if (!TheTarget) {
 138     errs() << argv[0] << ": " << Error;
 139     return 1;
 140   }
 141
 142   // Set up the pipeline like llc does.
 143   std::string CPUStr = getCPUStr(), FeaturesStr = getFeaturesStr();
 144
 145   CodeGenOpt::Level OLvl = CodeGenOpt::Default;
 146   switch (OptLevel) {
 147   default:
 148     errs() << argv[0] << ": invalid optimization level.\n";
 149     return 1;
 150   case ' ': break;
 151   case '0': OLvl = CodeGenOpt::None; break;
 152   case '1': OLvl = CodeGenOpt::Less; break;
 153   case '2': OLvl = CodeGenOpt::Default; break;
 154   case '3': OLvl = CodeGenOpt::Aggressive; break;
 155   }
 156
 157   TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
 158   TM.reset(TheTarget->createTargetMachine(TheTriple.getTriple(), CPUStr,
 159                                           FeaturesStr, Options, getRelocModel(),
 160                                           getCodeModel(), OLvl));
 161   assert(TM && "Could not allocate target machine!");
 162
 163   // Make sure we print the summary and the current unit when LLVM errors out.
 164   install_fatal_error_handler(handleLLVMFatalError, nullptr);
 165
 166   // Finally, create our mutator.
 167   Mutator = createISelMutator();
 168   return 0;
 169 }