tools/lli/lli.cpp

//===- lli.cpp - LLVM Interpreter / Dynamic compiler ----------------------===//
// 
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
// 
//===----------------------------------------------------------------------===//
//
// This utility provides a simple wrapper around the LLVM Execution Engines,
// which allow the direct execution of LLVM programs through a Just-In-Time
// compiler, or through an intepreter if no JIT is available for this platform.
//
//===----------------------------------------------------------------------===//

#include "llvm/Module.h"
#include "llvm/ModuleProvider.h"
#include "llvm/Type.h"
#include "llvm/Bytecode/Reader.h"
#include "llvm/ExecutionEngine/ExecutionEngine.h"
#include "llvm/ExecutionEngine/GenericValue.h"
#include "Support/CommandLine.h"

using namespace llvm;

namespace {
  cl::opt<std::string>
  InputFile(cl::desc("<input bytecode>"), cl::Positional, cl::init("-"));

  cl::list<std::string>
  InputArgv(cl::ConsumeAfter, cl::desc("<program arguments>..."));

  cl::opt<bool> ForceInterpreter("force-interpreter",
                                 cl::desc("Force interpretation: disable JIT"),
                                 cl::init(false));

  cl::opt<std::string>
  FakeArgv0("fake-argv0",
            cl::desc("Override the 'argv[0]' value passed into the executing"
                     " program"), cl::value_desc("executable"));
}

//===----------------------------------------------------------------------===//
// main Driver function
//
int main(int argc, char **argv, char * const *envp) {
  cl::ParseCommandLineOptions(argc, argv,
                              " llvm interpreter & dynamic compiler\n");

  // Load the bytecode...
  std::string ErrorMsg;
  ModuleProvider *MP = 0;
  try {
    MP = getBytecodeModuleProvider(InputFile);
  } catch (std::string &err) {
    std::cerr << "Error loading program '" << InputFile << "': " << err << "\n";
    exit(1);
  }

  ExecutionEngine *EE =
    ExecutionEngine::create(MP, ForceInterpreter);
  assert(EE && "Couldn't create an ExecutionEngine, not even an interpreter?");

  // If the user specifically requested an argv[0] to pass into the program, do
  // it now.
  if (!FakeArgv0.empty()) {
    InputFile = FakeArgv0;
  } else {
    // Otherwise, if there is a .bc suffix on the executable strip it off, it
    // might confuse the program.
    if (InputFile.rfind(".bc") == InputFile.length() - 3)
      InputFile.erase(InputFile.length() - 3);
  }

  // Add the module's name to the start of the vector of arguments to main().
  InputArgv.insert(InputArgv.begin(), InputFile);

  // Call the main function from M as if its signature were:
  //   int main (int argc, char **argv, const char **envp)
  // using the contents of Args to determine argc & argv, and the contents of
  // EnvVars to determine envp.
  //
  Function *Fn = MP->getModule()->getMainFunction();
  if (!Fn) {
    std::cerr << "'main' function not found in module.\n";
    return -1;
  }

  // Run main...
  int Result = EE->runFunctionAsMain(Fn, InputArgv, envp);

  // If the program didn't explicitly call exit, call exit now, for the program.
  // This ensures that any atexit handlers get called correctly.
  Function *Exit = MP->getModule()->getOrInsertFunction("exit", Type::VoidTy,
                                                        Type::IntTy, 0);

  std::vector<GenericValue> Args;
  GenericValue ResultGV;
  ResultGV.IntVal = Result;
  Args.push_back(ResultGV);
  EE->runFunction(Exit, Args);

  std::cerr << "ERROR: exit(" << Result << ") returned!\n";
  abort();
}