//===- OrcLazyJIT.h - Basic Orc-based JIT for lazy execution ----*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Simple Orc-based JIT. Uses the compile-on-demand layer to break up and
// lazily compile modules.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_TOOLS_LLI_ORCLAZYJIT_H
#define LLVM_TOOLS_LLI_ORCLAZYJIT_H

#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/ExecutionEngine/JITSymbol.h"
#include "llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h"
#include "llvm/ExecutionEngine/Orc/CompileUtils.h"
#include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
#include "llvm/ExecutionEngine/Orc/IRCompileLayer.h"
#include "llvm/ExecutionEngine/Orc/IRTransformLayer.h"
#include "llvm/ExecutionEngine/Orc/IndirectionUtils.h"
#include "llvm/ExecutionEngine/Orc/LambdaResolver.h"
#include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
#include "llvm/ExecutionEngine/SectionMemoryManager.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include <algorithm>
#include <functional>
#include <memory>
#include <set>
#include <string>
#include <vector>

namespace llvm {

class OrcLazyJIT {
public:

  using CompileCallbackMgr = orc::JITCompileCallbackManager;
  using ObjLayerT = orc::RTDyldObjectLinkingLayer;
  using CompileLayerT = orc::IRCompileLayer<ObjLayerT, orc::SimpleCompiler>;
  using TransformFtor =
          std::function<std::shared_ptr<Module>(std::shared_ptr<Module>)>;
  using IRDumpLayerT = orc::IRTransformLayer<CompileLayerT, TransformFtor>;
  using CODLayerT = orc::CompileOnDemandLayer<IRDumpLayerT, CompileCallbackMgr>;
  using IndirectStubsManagerBuilder = CODLayerT::IndirectStubsManagerBuilderT;
  using ModuleHandleT = CODLayerT::ModuleHandleT;

  OrcLazyJIT(std::unique_ptr<TargetMachine> TM,
             std::unique_ptr<CompileCallbackMgr> CCMgr,
             IndirectStubsManagerBuilder IndirectStubsMgrBuilder,
             bool InlineStubs)
      : TM(std::move(TM)), DL(this->TM->createDataLayout()),
        CCMgr(std::move(CCMgr)),
        ObjectLayer([]() { return std::make_shared<SectionMemoryManager>(); }),
        CompileLayer(ObjectLayer, orc::SimpleCompiler(*this->TM)),
        IRDumpLayer(CompileLayer, createDebugDumper()),
        CODLayer(IRDumpLayer, extractSingleFunction, *this->CCMgr,
                 std::move(IndirectStubsMgrBuilder), InlineStubs),
        CXXRuntimeOverrides(
            [this](const std::string &S) { return mangle(S); }) {}

  ~OrcLazyJIT() {
    // Run any destructors registered with __cxa_atexit.
    CXXRuntimeOverrides.runDestructors();
    // Run any IR destructors.
    for (auto &DtorRunner : IRStaticDestructorRunners)
      if (auto Err = DtorRunner.runViaLayer(CODLayer)) {
        // FIXME: OrcLazyJIT should probably take a "shutdownError" callback to
        //        report these errors on.
        report_fatal_error(std::move(Err));
      }
  }

  Error addModule(std::shared_ptr<Module> M) {
    if (M->getDataLayout().isDefault())
      M->setDataLayout(DL);

    // Rename, bump linkage and record static constructors and destructors.
    // We have to do this before we hand over ownership of the module to the
    // JIT.
    std::vector<std::string> CtorNames, DtorNames;
    {
      unsigned CtorId = 0, DtorId = 0;
      for (auto Ctor : orc::getConstructors(*M)) {
        std::string NewCtorName = ("$static_ctor." + Twine(CtorId++)).str();
        Ctor.Func->setName(NewCtorName);
        Ctor.Func->setLinkage(GlobalValue::ExternalLinkage);
        Ctor.Func->setVisibility(GlobalValue::HiddenVisibility);
        CtorNames.push_back(mangle(NewCtorName));
      }
      for (auto Dtor : orc::getDestructors(*M)) {
        std::string NewDtorName = ("$static_dtor." + Twine(DtorId++)).str();
        Dtor.Func->setLinkage(GlobalValue::ExternalLinkage);
        Dtor.Func->setVisibility(GlobalValue::HiddenVisibility);
        DtorNames.push_back(mangle(Dtor.Func->getName()));
        Dtor.Func->setName(NewDtorName);
      }
    }

    // Symbol resolution order:
    //   1) Search the JIT symbols.
    //   2) Check for C++ runtime overrides.
    //   3) Search the host process (LLI)'s symbol table.
    if (!ModulesHandle) {
      auto Resolver =
        orc::createLambdaResolver(
          [this](const std::string &Name) -> JITSymbol {
            if (auto Sym = CODLayer.findSymbol(Name, true))
              return Sym;
            return CXXRuntimeOverrides.searchOverrides(Name);
          },
          [](const std::string &Name) {
            if (auto Addr =
                RTDyldMemoryManager::getSymbolAddressInProcess(Name))
              return JITSymbol(Addr, JITSymbolFlags::Exported);
            return JITSymbol(nullptr);
          }
        );

      // Add the module to the JIT.
      if (auto ModulesHandleOrErr =
          CODLayer.addModule(std::move(M), std::move(Resolver)))
        ModulesHandle = std::move(*ModulesHandleOrErr);
      else
        return ModulesHandleOrErr.takeError();

    } else if (auto Err = CODLayer.addExtraModule(*ModulesHandle, std::move(M)))
      return Err;

    // Run the static constructors, and save the static destructor runner for
    // execution when the JIT is torn down.
    orc::CtorDtorRunner<CODLayerT> CtorRunner(std::move(CtorNames),
                                              *ModulesHandle);
    if (auto Err = CtorRunner.runViaLayer(CODLayer))
      return Err;

    IRStaticDestructorRunners.emplace_back(std::move(DtorNames),
                                           *ModulesHandle);

    return Error::success();
  }

  JITSymbol findSymbol(const std::string &Name) {
    return CODLayer.findSymbol(mangle(Name), true);
  }

  JITSymbol findSymbolIn(ModuleHandleT H, const std::string &Name) {
    return CODLayer.findSymbolIn(H, mangle(Name), true);
  }

private:
  std::string mangle(const std::string &Name) {
    std::string MangledName;
    {
      raw_string_ostream MangledNameStream(MangledName);
      Mangler::getNameWithPrefix(MangledNameStream, Name, DL);
    }
    return MangledName;
  }

  static std::set<Function*> extractSingleFunction(Function &F) {
    std::set<Function*> Partition;
    Partition.insert(&F);
    return Partition;
  }

  static TransformFtor createDebugDumper();

  std::unique_ptr<TargetMachine> TM;
  DataLayout DL;
  SectionMemoryManager CCMgrMemMgr;

  std::unique_ptr<CompileCallbackMgr> CCMgr;
  ObjLayerT ObjectLayer;
  CompileLayerT CompileLayer;
  IRDumpLayerT IRDumpLayer;
  CODLayerT CODLayer;

  orc::LocalCXXRuntimeOverrides CXXRuntimeOverrides;
  std::vector<orc::CtorDtorRunner<CODLayerT>> IRStaticDestructorRunners;
  llvm::Optional<CODLayerT::ModuleHandleT> ModulesHandle;
};

int runOrcLazyJIT(std::vector<std::unique_ptr<Module>> Ms,
                  const std::vector<std::string> &Args);

} // end namespace llvm

#endif // LLVM_TOOLS_LLI_ORCLAZYJIT_H