//===- KaleidoscopeJIT.h - A simple JIT for Kaleidoscope --------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Contains a simple JIT definition for use in the kaleidoscope tutorials.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_EXECUTIONENGINE_ORC_KALEIDOSCOPEJIT_H
#define LLVM_EXECUTIONENGINE_ORC_KALEIDOSCOPEJIT_H

#include "llvm/ADT/STLExtras.h"
#include "llvm/ExecutionEngine/ExecutionEngine.h"
#include "llvm/ExecutionEngine/JITSymbol.h"
#include "llvm/ExecutionEngine/Orc/CompileUtils.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/LegacyPassManager.h"
#include "llvm/IR/Mangler.h"
#include "llvm/Support/DynamicLibrary.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/InstCombine/InstCombine.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Scalar/GVN.h"
#include <algorithm>
#include <cassert>
#include <cstdlib>
#include <map>
#include <memory>
#include <string>
#include <vector>

class PrototypeAST;
class ExprAST;

/// FunctionAST - This class represents a function definition itself.
class FunctionAST {
  std::unique_ptr<PrototypeAST> Proto;
  std::unique_ptr<ExprAST> Body;

public:
  FunctionAST(std::unique_ptr<PrototypeAST> Proto,
              std::unique_ptr<ExprAST> Body)
      : Proto(std::move(Proto)), Body(std::move(Body)) {}

  const PrototypeAST& getProto() const;
  const std::string& getName() const;
  llvm::Function *codegen();
};

/// This will compile FnAST to IR, rename the function to add the given
/// suffix (needed to prevent a name-clash with the function's stub),
/// and then take ownership of the module that the function was compiled
/// into.
std::unique_ptr<llvm::Module>
irgenAndTakeOwnership(FunctionAST &FnAST, const std::string &Suffix);

namespace llvm {
namespace orc {

class KaleidoscopeJIT {
private:
  ExecutionSession ES;
  std::shared_ptr<SymbolResolver> Resolver;
  std::unique_ptr<TargetMachine> TM;
  const DataLayout DL;
  LegacyRTDyldObjectLinkingLayer ObjectLayer;
  LegacyIRCompileLayer<decltype(ObjectLayer), SimpleCompiler> CompileLayer;

  using OptimizeFunction =
      std::function<std::unique_ptr<Module>(std::unique_ptr<Module>)>;

  LegacyIRTransformLayer<decltype(CompileLayer), OptimizeFunction> OptimizeLayer;

  std::unique_ptr<JITCompileCallbackManager> CompileCallbackMgr;
  std::unique_ptr<IndirectStubsManager> IndirectStubsMgr;

public:
  KaleidoscopeJIT()
      : Resolver(createLegacyLookupResolver(
            ES,
            [this](const std::string &Name) -> JITSymbol {
              if (auto Sym = IndirectStubsMgr->findStub(Name, false))
                return Sym;
              if (auto Sym = OptimizeLayer.findSymbol(Name, false))
                return Sym;
              else if (auto Err = Sym.takeError())
                return std::move(Err);
              if (auto SymAddr =
                      RTDyldMemoryManager::getSymbolAddressInProcess(Name))
                return JITSymbol(SymAddr, JITSymbolFlags::Exported);
              return nullptr;
            },
            [](Error Err) { cantFail(std::move(Err), "lookupFlags failed"); })),
        TM(EngineBuilder().selectTarget()), DL(TM->createDataLayout()),
        ObjectLayer(ES,
                    [this](VModuleKey K) {
                      return LegacyRTDyldObjectLinkingLayer::Resources{
                          std::make_shared<SectionMemoryManager>(), Resolver};
                    }),
        CompileLayer(ObjectLayer, SimpleCompiler(*TM)),
        OptimizeLayer(CompileLayer,
                      [this](std::unique_ptr<Module> M) {
                        return optimizeModule(std::move(M));
                      }),
        CompileCallbackMgr(cantFail(orc::createLocalCompileCallbackManager(
            TM->getTargetTriple(), ES, 0))) {
    auto IndirectStubsMgrBuilder =
      orc::createLocalIndirectStubsManagerBuilder(TM->getTargetTriple());
    IndirectStubsMgr = IndirectStubsMgrBuilder();
    llvm::sys::DynamicLibrary::LoadLibraryPermanently(nullptr);
  }

  TargetMachine &getTargetMachine() { return *TM; }

  VModuleKey addModule(std::unique_ptr<Module> M) {
    // Add the module to the JIT with a new VModuleKey.
    auto K = ES.allocateVModule();
    cantFail(OptimizeLayer.addModule(K, std::move(M)));
    return K;
  }

  Error addFunctionAST(std::unique_ptr<FunctionAST> FnAST) {
    // Move ownership of FnAST to a shared pointer - C++11 lambdas don't support
    // capture-by-move, which is be required for unique_ptr.
    auto SharedFnAST = std::shared_ptr<FunctionAST>(std::move(FnAST));

    // Set the action to compile our AST. This lambda will be run if/when
    // execution hits the compile callback (via the stub).
    //
    // The steps to compile are:
    // (1) IRGen the function.
    // (2) Add the IR module to the JIT to make it executable like any other
    //     module.
    // (3) Use findSymbol to get the address of the compiled function.
    // (4) Update the stub pointer to point at the implementation so that
    ///    subsequent calls go directly to it and bypass the compiler.
    // (5) Return the address of the implementation: this lambda will actually
    //     be run inside an attempted call to the function, and we need to
    //     continue on to the implementation to complete the attempted call.
    //     The JIT runtime (the resolver block) will use the return address of
    //     this function as the address to continue at once it has reset the
    //     CPU state to what it was immediately before the call.
    auto CompileAction = [this, SharedFnAST]() {
      auto M = irgenAndTakeOwnership(*SharedFnAST, "$impl");
      addModule(std::move(M));
      auto Sym = findSymbol(SharedFnAST->getName() + "$impl");
      assert(Sym && "Couldn't find compiled function?");
      JITTargetAddress SymAddr = cantFail(Sym.getAddress());
      if (auto Err = IndirectStubsMgr->updatePointer(
              mangle(SharedFnAST->getName()), SymAddr)) {
        logAllUnhandledErrors(std::move(Err), errs(),
                              "Error updating function pointer: ");
        exit(1);
      }

      return SymAddr;
    };

    // Create a CompileCallback using the CompileAction - this is the re-entry
    // point into the compiler for functions that haven't been compiled yet.
    auto CCAddr = cantFail(
        CompileCallbackMgr->getCompileCallback(std::move(CompileAction)));

    // Create an indirect stub. This serves as the functions "canonical
    // definition" - an unchanging (constant address) entry point to the
    // function implementation.
    // Initially we point the stub's function-pointer at the compile callback
    // that we just created. When the compile action for the callback is run we
    // will update the stub's function pointer to point at the function
    // implementation that we just implemented.
    if (auto Err = IndirectStubsMgr->createStub(
            mangle(SharedFnAST->getName()), CCAddr, JITSymbolFlags::Exported))
      return Err;

    return Error::success();
  }

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

  void removeModule(VModuleKey K) {
    cantFail(OptimizeLayer.removeModule(K));
  }

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

  std::unique_ptr<Module> optimizeModule(std::unique_ptr<Module> M) {
    // Create a function pass manager.
    auto FPM = llvm::make_unique<legacy::FunctionPassManager>(M.get());

    // Add some optimizations.
    FPM->add(createInstructionCombiningPass());
    FPM->add(createReassociatePass());
    FPM->add(createGVNPass());
    FPM->add(createCFGSimplificationPass());
    FPM->doInitialization();

    // Run the optimizations over all functions in the module being added to
    // the JIT.
    for (auto &F : *M)
      FPM->run(F);

    return M;
  }
};

} // end namespace orc
} // end namespace llvm

#endif // LLVM_EXECUTIONENGINE_ORC_KALEIDOSCOPEJIT_H