lib/ExecutionEngine/JIT/JIT.cpp

//===-- JIT.cpp - LLVM Just in Time Compiler ------------------------------===//
//
// This file implements the top-level support for creating a Just-In-Time
// compiler for the current architecture.
//
//===----------------------------------------------------------------------===//

#include "VM.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetMachineImpls.h"
#include "llvm/Module.h"
#include "Support/CommandLine.h"

namespace {
  cl::opt<std::string>
  Arch("march", cl::desc("Architecture: `x86' or `sparc'"), cl::Prefix,
       cl::value_desc("machine architecture"));
  
  static std::string DefaultArch = 
#if defined(i386) || defined(__i386__) || defined(__x86__)
  "x86";
#elif defined(sparc) || defined(__sparc__) || defined(__sparcv9)
  "sparc";
#else
  "";
#endif

}


/// createJIT - Create an return a new JIT compiler if there is one available
/// for the current target.  Otherwise it returns null.
///
ExecutionEngine *ExecutionEngine::createJIT(Module *M, unsigned Config) {
  
  TargetMachine* (*TargetMachineAllocator)(unsigned) = 0;
  if (Arch == "")
    Arch = DefaultArch;

  // Allow a command-line switch to override what *should* be the default target
  // machine for this platform. This allows for debugging a Sparc JIT on X86 --
  // our X86 machines are much faster at recompiling LLVM and linking lli.
  if (Arch == "x86") {
    TargetMachineAllocator = allocateX86TargetMachine;
  } else if (Arch == "sparc") {
    TargetMachineAllocator = allocateSparcTargetMachine;
  }

  if (TargetMachineAllocator) {
    // Allocate a target...
    TargetMachine *Target = (*TargetMachineAllocator)(Config);
    assert(Target && "Could not allocate target machine!");

    // Create the virtual machine object...
    return new VM(M, Target);
  } else {
    return 0;
  }
}

VM::VM(Module *M, TargetMachine *tm) : ExecutionEngine(M), TM(*tm) {
  setTargetData(TM.getTargetData());

  // Initialize MCE
  MCE = createEmitter(*this);

  setupPassManager();
  emitGlobals();
}

int VM::run(const std::string &FnName, const std::vector<std::string> &Args) {
  Function *F = getModule().getNamedFunction(FnName);
  if (F == 0) {
    std::cerr << "Could not find function '" << FnName <<"' in module!\n";
    return 1;
  }

  int(*PF)(int, char**) = (int(*)(int, char**))getPointerToFunction(F);
  assert(PF != 0 && "Null pointer to function?");

  // Build an argv vector...
  char **Argv = (char**)CreateArgv(Args);

  // Call the main function...
  int Result = PF(Args.size(), Argv);

  // Run any atexit handlers now!
  runAtExitHandlers();
  return Result;
}