//===-- JIT.cpp - MC-based Just-in-Time Compiler --------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "MCJIT.h"
#include "llvm/Function.h"
#include "llvm/ExecutionEngine/GenericValue.h"
#include "llvm/ExecutionEngine/MCJIT.h"
#include "llvm/ExecutionEngine/JITMemoryManager.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/DynamicLibrary.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Target/TargetData.h"

using namespace llvm;

namespace {

static struct RegisterJIT {
  RegisterJIT() { MCJIT::Register(); }
} JITRegistrator;

}

extern "C" void LLVMLinkInMCJIT() {
}

ExecutionEngine *MCJIT::createJIT(Module *M,
                                  std::string *ErrorStr,
                                  JITMemoryManager *JMM,
                                  CodeGenOpt::Level OptLevel,
                                  bool GVsWithCode,
                                  CodeModel::Model CMM,
                                  StringRef MArch,
                                  StringRef MCPU,
                                  const SmallVectorImpl<std::string>& MAttrs) {
  // Try to register the program as a source of symbols to resolve against.
  //
  // FIXME: Don't do this here.
  sys::DynamicLibrary::LoadLibraryPermanently(0, NULL);

  // Pick a target either via -march or by guessing the native arch.
  //
  // FIXME: This should be lifted out of here, it isn't something which should
  // be part of the JIT policy, rather the burden for this selection should be
  // pushed to clients.
  TargetMachine *TM = MCJIT::selectTarget(M, MArch, MCPU, MAttrs, ErrorStr);
  if (!TM || (ErrorStr && ErrorStr->length() > 0)) return 0;
  TM->setCodeModel(CMM);

  // If the target supports JIT code generation, create the JIT.
  if (TargetJITInfo *TJ = TM->getJITInfo())
    return new MCJIT(M, TM, *TJ, JMM, OptLevel, GVsWithCode);

  if (ErrorStr)
    *ErrorStr = "target does not support JIT code generation";
  return 0;
}

MCJIT::MCJIT(Module *m, TargetMachine *tm, TargetJITInfo &tji,
             JITMemoryManager *JMM, CodeGenOpt::Level OptLevel,
             bool AllocateGVsWithCode)
  : ExecutionEngine(m), TM(tm), M(m), OS(Buffer) {

  PM.add(new TargetData(*TM->getTargetData()));

  // Turn the machine code intermediate representation into bytes in memory
  // that may be executed.
  if (TM->addPassesToEmitMC(PM, Ctx, OS, CodeGenOpt::Default, false)) {
    report_fatal_error("Target does not support MC emission!");
  }

  // Initialize passes.
  ExecutionEngine::addModule(M);
  // FIXME: When we support multiple modules, we'll want to move the code
  // gen and finalization out of the constructor here and do it more
  // on-demand as part of getPointerToFunction().
  PM.run(*M);
  // Flush the output buffer so the SmallVector gets its data.
  OS.flush();

  // Load the object into the dynamic linker.
  // FIXME: It would be nice to avoid making yet another copy.
  MemoryBuffer *MB = MemoryBuffer::getMemBufferCopy(StringRef(Buffer.data(),
                                                              Buffer.size()));
  Dyld.loadObject(MB);
}

MCJIT::~MCJIT() {
}

void *MCJIT::getPointerToBasicBlock(BasicBlock *BB) {
  report_fatal_error("not yet implemented");
  return 0;
}

void *MCJIT::getPointerToFunction(Function *F) {
  Twine Name = TM->getMCAsmInfo()->getGlobalPrefix() + F->getName();
  return Dyld.getSymbolAddress(Name.str());
}

void *MCJIT::recompileAndRelinkFunction(Function *F) {
  report_fatal_error("not yet implemented");
}

void MCJIT::freeMachineCodeForFunction(Function *F) {
  report_fatal_error("not yet implemented");
}

GenericValue MCJIT::runFunction(Function *F,
                                const std::vector<GenericValue> &ArgValues) {
  assert(ArgValues.size() == 0 && "JIT arg passing not supported yet");
  void *FPtr = getPointerToFunction(F);
  if (!FPtr)
    report_fatal_error("Unable to locate function: '" + F->getName() + "'");
  ((void(*)(void))(intptr_t)FPtr)();
  return GenericValue();
}