//==-- handle_llvm.cpp - Helper function for Clang fuzzers -----------------==//

//

// 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

//

//===----------------------------------------------------------------------===//

//

// Implements HandleLLVM for use by the Clang fuzzers. First runs a loop

// vectorizer optimization pass over the given IR code. Then mimics lli on both

// versions to JIT the generated code and execute it. Currently, functions are 

// executed on dummy inputs.

//

//===----------------------------------------------------------------------===//

#include "handle_llvm.h"

#include "input_arrays.h"

#include "llvm/ADT/Triple.h"

#include "llvm/Analysis/TargetLibraryInfo.h"

#include "llvm/Analysis/TargetTransformInfo.h"

#include "llvm/CodeGen/CommandFlags.h"

#include "llvm/CodeGen/MachineModuleInfo.h"

#include "llvm/CodeGen/TargetPassConfig.h"

#include "llvm/ExecutionEngine/JITEventListener.h"

#include "llvm/ExecutionEngine/JITSymbol.h"

#include "llvm/ExecutionEngine/MCJIT.h"

#include "llvm/ExecutionEngine/ObjectCache.h"

#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"

#include "llvm/ExecutionEngine/SectionMemoryManager.h"

#include "llvm/IR/IRPrintingPasses.h"

#include "llvm/IR/LLVMContext.h"

#include "llvm/IR/LegacyPassManager.h"

#include "llvm/IR/LegacyPassNameParser.h"

#include "llvm/IR/Module.h"

#include "llvm/IR/Verifier.h"

#include "llvm/IRReader/IRReader.h"

#include "llvm/MC/TargetRegistry.h"

#include "llvm/Pass.h"

#include "llvm/PassRegistry.h"

#include "llvm/Support/MemoryBuffer.h"

#include "llvm/Support/SourceMgr.h"

#include "llvm/Support/TargetSelect.h"

#include "llvm/Target/TargetMachine.h"

#include "llvm/Transforms/IPO.h"

#include "llvm/Transforms/IPO/PassManagerBuilder.h"

#include "llvm/Transforms/Vectorize.h"

using namespace llvm;

static codegen::RegisterCodeGenFlags CGF;

// Define a type for the functions that are compiled and executed

typedef void (*LLVMFunc)(int*, int*, int*, int);

// Helper function to parse command line args and find the optimization level

static void getOptLevel(const std::vector<const char *> &ExtraArgs,

                              CodeGenOpt::Level &OLvl) {

  // Find the optimization level from the command line args

  OLvl = CodeGenOpt::Default;

  for (auto &A : ExtraArgs) {

    if (A[0] == '-' && A[1] == 'O') {

      switch(A[2]) {

        case '0': OLvl = CodeGenOpt::None; break;

        case '1': OLvl = CodeGenOpt::Less; break;

        case '2': OLvl = CodeGenOpt::Default; break;

        case '3': OLvl = CodeGenOpt::Aggressive; break;

        default:

          errs() << "error: opt level must be between 0 and 3.\n";

          std::exit(1);

      }

    }

  }

}

static void ErrorAndExit(std::string message) {

  errs()<< "ERROR: " << message << "\n";

  std::exit(1);

}

// Helper function to add optimization passes to the TargetMachine at the 

// specified optimization level, OptLevel

static void AddOptimizationPasses(legacy::PassManagerBase &MPM,

                                  CodeGenOpt::Level OptLevel,

                                  unsigned SizeLevel) {

  // Create and initialize a PassManagerBuilder

  PassManagerBuilder Builder;

  Builder.OptLevel = OptLevel;

  Builder.SizeLevel = SizeLevel;

  Builder.Inliner = createFunctionInliningPass(OptLevel, SizeLevel, false);

  Builder.LoopVectorize = true;

  Builder.populateModulePassManager(MPM);

}

// Mimics the opt tool to run an optimization pass over the provided IR

static std::string OptLLVM(const std::string &IR, CodeGenOpt::Level OLvl) {

  // Create a module that will run the optimization passes

  SMDiagnostic Err;

  LLVMContext Context;

  std::unique_ptr<Module> M = parseIR(MemoryBufferRef(IR, "IR"), Err, Context);

  if (!M || verifyModule(*M, &errs()))

    ErrorAndExit("Could not parse IR");

  Triple ModuleTriple(M->getTargetTriple());

  const TargetOptions Options =

      codegen::InitTargetOptionsFromCodeGenFlags(ModuleTriple);

  std::string E;

  const Target *TheTarget =

      TargetRegistry::lookupTarget(codegen::getMArch(), ModuleTriple, E);

  if (!TheTarget)

    ErrorAndExit(E);

  std::unique_ptr<TargetMachine> TM(TheTarget->createTargetMachine(

      M->getTargetTriple(), codegen::getCPUStr(), codegen::getFeaturesStr(),

      Options, codegen::getExplicitRelocModel(),

      codegen::getExplicitCodeModel(), OLvl));

  if (!TM)

    ErrorAndExit("Could not create target machine");

  codegen::setFunctionAttributes(codegen::getCPUStr(),

                                 codegen::getFeaturesStr(), *M);

  legacy::PassManager Passes;

  Passes.add(new TargetLibraryInfoWrapperPass(ModuleTriple));

  Passes.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));

  LLVMTargetMachine &LTM = static_cast<LLVMTargetMachine &>(*TM);

  Passes.add(LTM.createPassConfig(Passes));

  Passes.add(createVerifierPass());

  AddOptimizationPasses(Passes, OLvl, 0);

  // Add a pass that writes the optimized IR to an output stream

  std::string outString;

  raw_string_ostream OS(outString);

  Passes.add(createPrintModulePass(OS, "", false));

  Passes.run(*M);

  return outString;

}

// Takes a function and runs it on a set of inputs

// First determines whether f is the optimized or unoptimized function

static void RunFuncOnInputs(LLVMFunc f, int Arr[kNumArrays][kArraySize]) {

  for (int i = 0; i < kNumArrays / 3; i++)

    f(Arr[i], Arr[i + (kNumArrays / 3)], Arr[i + (2 * kNumArrays / 3)],

      kArraySize);

}

// Takes a string of IR and compiles it using LLVM's JIT Engine

static void CreateAndRunJITFunc(const std::string &IR, CodeGenOpt::Level OLvl) {

  SMDiagnostic Err;

  LLVMContext Context;

  std::unique_ptr<Module> M = parseIR(MemoryBufferRef(IR, "IR"), Err, Context);

  if (!M)

    ErrorAndExit("Could not parse IR");

  Function *EntryFunc = M->getFunction("foo");

  if (!EntryFunc)

    ErrorAndExit("Function not found in module");

  std::string ErrorMsg;

  Triple ModuleTriple(M->getTargetTriple());

  EngineBuilder builder(std::move(M));

  builder.setMArch(codegen::getMArch());

  builder.setMCPU(codegen::getCPUStr());

  builder.setMAttrs(codegen::getFeatureList());

  builder.setErrorStr(&ErrorMsg);

  builder.setEngineKind(EngineKind::JIT);

  builder.setMCJITMemoryManager(std::make_unique<SectionMemoryManager>());

  builder.setOptLevel(OLvl);

  builder.setTargetOptions(

      codegen::InitTargetOptionsFromCodeGenFlags(ModuleTriple));

  std::unique_ptr<ExecutionEngine> EE(builder.create());

  if (!EE)

    ErrorAndExit("Could not create execution engine");

  EE->finalizeObject();

  EE->runStaticConstructorsDestructors(false);

#if defined(__GNUC__) && !defined(__clang) &&                                  \

    ((__GNUC__ == 4) && (__GNUC_MINOR__ < 9))

// Silence

//

//   warning: ISO C++ forbids casting between pointer-to-function and

//   pointer-to-object [-Wpedantic]

//

// Since C++11 this casting is conditionally supported and GCC versions

// starting from 4.9.0 don't warn about the cast.

#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Wpedantic"

#endif

  LLVMFunc f = reinterpret_cast<LLVMFunc>(EE->getPointerToFunction(EntryFunc));

#if defined(__GNUC__) && !defined(__clang) &&                                  \

    ((__GNUC__ == 4) && (__GNUC_MINOR__ < 9))

#pragma GCC diagnostic pop

#endif

  // Figure out if we are running the optimized func or the unoptimized func

  RunFuncOnInputs(f, (OLvl == CodeGenOpt::None) ? UnoptArrays : OptArrays);

  EE->runStaticConstructorsDestructors(true);

}

// Main fuzz target called by ExampleClangLLVMProtoFuzzer.cpp

// Mimics the lli tool to JIT the LLVM IR code and execute it

void clang_fuzzer::HandleLLVM(const std::string &IR,

                              const std::vector<const char *> &ExtraArgs) {

  // Populate OptArrays and UnoptArrays with the arrays from InputArrays

  memcpy(OptArrays, InputArrays, kTotalSize);

  memcpy(UnoptArrays, InputArrays, kTotalSize);

  // Parse ExtraArgs to set the optimization level

  CodeGenOpt::Level OLvl;

  getOptLevel(ExtraArgs, OLvl);

  // First we optimize the IR by running a loop vectorizer pass

  std::string OptIR = OptLLVM(IR, OLvl);

  CreateAndRunJITFunc(OptIR, OLvl);

  CreateAndRunJITFunc(IR, CodeGenOpt::None);

  if (memcmp(OptArrays, UnoptArrays, kTotalSize))

    ErrorAndExit("!!!BUG!!!");

}