//===--- COFFPlatform.h -- Utilities for executing COFF in Orc --*- 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
//
//===----------------------------------------------------------------------===//
//
// Utilities for executing JIT'd COFF in Orc.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_EXECUTIONENGINE_ORC_COFFPLATFORM_H
#define LLVM_EXECUTIONENGINE_ORC_COFFPLATFORM_H

#include "llvm/ADT/StringRef.h"
#include "llvm/ExecutionEngine/Orc/COFFVCRuntimeSupport.h"
#include "llvm/ExecutionEngine/Orc/Core.h"
#include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
#include "llvm/ExecutionEngine/Orc/ExecutorProcessControl.h"
#include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
#include "llvm/ExecutionEngine/Orc/Shared/ExecutorAddress.h"

#include <future>
#include <memory>
#include <thread>
#include <vector>

namespace llvm {
namespace orc {

/// Mediates between COFF initialization and ExecutionSession state.
class COFFPlatform : public Platform {
public:
  /// A function that will be called with the name of dll file that must be
  /// loaded.
  using LoadDynamicLibrary =
      unique_function<Error(JITDylib &JD, StringRef DLLFileName)>;

  /// Try to create a COFFPlatform instance, adding the ORC runtime to the
  /// given JITDylib.
  static Expected<std::unique_ptr<COFFPlatform>>
  Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
         JITDylib &PlatformJD, const char *OrcRuntimePath,
         LoadDynamicLibrary LoadDynLibrary, bool StaticVCRuntime = false,
         const char *VCRuntimePath = nullptr,
         std::optional<SymbolAliasMap> RuntimeAliases = std::nullopt);

  ExecutionSession &getExecutionSession() const { return ES; }
  ObjectLinkingLayer &getObjectLinkingLayer() const { return ObjLinkingLayer; }

  Error setupJITDylib(JITDylib &JD) override;
  Error teardownJITDylib(JITDylib &JD) override;
  Error notifyAdding(ResourceTracker &RT,
                     const MaterializationUnit &MU) override;
  Error notifyRemoving(ResourceTracker &RT) override;

  /// Returns an AliasMap containing the default aliases for the COFFPlatform.
  /// This can be modified by clients when constructing the platform to add
  /// or remove aliases.
  static SymbolAliasMap standardPlatformAliases(ExecutionSession &ES);

  /// Returns the array of required CXX aliases.
  static ArrayRef<std::pair<const char *, const char *>> requiredCXXAliases();

  /// Returns the array of standard runtime utility aliases for COFF.
  static ArrayRef<std::pair<const char *, const char *>>
  standardRuntimeUtilityAliases();

  static bool isInitializerSection(StringRef Name) {
    return Name.startswith(".CRT");
  }

  static StringRef getSEHFrameSectionName() { return ".pdata"; }

private:
  using COFFJITDylibDepInfo = std::vector<ExecutorAddr>;
  using COFFJITDylibDepInfoMap =
      std::vector<std::pair<ExecutorAddr, COFFJITDylibDepInfo>>;
  using COFFObjectSectionsMap =
      SmallVector<std::pair<std::string, ExecutorAddrRange>>;
  using PushInitializersSendResultFn =
      unique_function<void(Expected<COFFJITDylibDepInfoMap>)>;
  using SendSymbolAddressFn = unique_function<void(Expected<ExecutorAddr>)>;
  using JITDylibDepMap = DenseMap<JITDylib *, SmallVector<JITDylib *>>;

  // The COFFPlatformPlugin scans/modifies LinkGraphs to support COFF
  // platform features including initializers, exceptions, and language
  // runtime registration.
  class COFFPlatformPlugin : public ObjectLinkingLayer::Plugin {
  public:
    COFFPlatformPlugin(COFFPlatform &CP) : CP(CP) {}

    void modifyPassConfig(MaterializationResponsibility &MR,
                          jitlink::LinkGraph &G,
                          jitlink::PassConfiguration &Config) override;

    SyntheticSymbolDependenciesMap
    getSyntheticSymbolDependencies(MaterializationResponsibility &MR) override;

    // FIXME: We should be tentatively tracking scraped sections and discarding
    // if the MR fails.
    Error notifyFailed(MaterializationResponsibility &MR) override {
      return Error::success();
    }

    Error notifyRemovingResources(JITDylib &JD, ResourceKey K) override {
      return Error::success();
    }

    void notifyTransferringResources(JITDylib &JD, ResourceKey DstKey,
                                     ResourceKey SrcKey) override {}

  private:
    using InitSymbolDepMap =
        DenseMap<MaterializationResponsibility *, JITLinkSymbolSet>;

    Error associateJITDylibHeaderSymbol(jitlink::LinkGraph &G,
                                        MaterializationResponsibility &MR,
                                        bool Bootstrap);

    Error preserveInitializerSections(jitlink::LinkGraph &G,
                                      MaterializationResponsibility &MR);
    Error registerObjectPlatformSections(jitlink::LinkGraph &G, JITDylib &JD);
    Error registerObjectPlatformSectionsInBootstrap(jitlink::LinkGraph &G,
                                                    JITDylib &JD);

    std::mutex PluginMutex;
    COFFPlatform &CP;
    InitSymbolDepMap InitSymbolDeps;
  };

  struct JDBootstrapState {
    JITDylib *JD = nullptr;
    std::string JDName;
    ExecutorAddr HeaderAddr;
    std::list<COFFObjectSectionsMap> ObjectSectionsMaps;
    SmallVector<std::pair<std::string, ExecutorAddr>> Initializers;
  };

  static bool supportedTarget(const Triple &TT);

  COFFPlatform(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
               JITDylib &PlatformJD, const char *OrcRuntimePath,
               LoadDynamicLibrary LoadDynLibrary, bool StaticVCRuntime,
               const char *VCRuntimePath, Error &Err);

  // Associate COFFPlatform JIT-side runtime support functions with handlers.
  Error associateRuntimeSupportFunctions(JITDylib &PlatformJD);

  // Records the addresses of runtime symbols used by the platform.
  Error bootstrapCOFFRuntime(JITDylib &PlatformJD);

  // Run a specific void function if it exists.
  Error runSymbolIfExists(JITDylib &PlatformJD, StringRef SymbolName);

  // Run collected initializers in boostrap stage.
  Error runBootstrapInitializers(JDBootstrapState &BState);
  Error runBootstrapSubsectionInitializers(JDBootstrapState &BState,
                                           StringRef Start, StringRef End);

  // Build dependency graph of a JITDylib
  Expected<JITDylibDepMap> buildJDDepMap(JITDylib &JD);

  Expected<MemoryBufferRef> getPerJDObjectFile();

  // Implements rt_pushInitializers by making repeat async lookups for
  // initializer symbols (each lookup may spawn more initializer symbols if
  // it pulls in new materializers, e.g. from objects in a static library).
  void pushInitializersLoop(PushInitializersSendResultFn SendResult,
                            JITDylibSP JD, JITDylibDepMap &JDDepMap);

  void rt_pushInitializers(PushInitializersSendResultFn SendResult,
                           ExecutorAddr JDHeaderAddr);

  void rt_lookupSymbol(SendSymbolAddressFn SendResult, ExecutorAddr Handle,
                       StringRef SymbolName);

  ExecutionSession &ES;
  ObjectLinkingLayer &ObjLinkingLayer;

  LoadDynamicLibrary LoadDynLibrary;
  std::unique_ptr<COFFVCRuntimeBootstrapper> VCRuntimeBootstrap;
  std::unique_ptr<MemoryBuffer> OrcRuntimeArchiveBuffer;
  std::unique_ptr<object::Archive> OrcRuntimeArchive;
  bool StaticVCRuntime;

  SymbolStringPtr COFFHeaderStartSymbol;

  // State of bootstrap in progress
  std::map<JITDylib *, JDBootstrapState> JDBootstrapStates;
  std::atomic<bool> Bootstrapping;

  ExecutorAddr orc_rt_coff_platform_bootstrap;
  ExecutorAddr orc_rt_coff_platform_shutdown;
  ExecutorAddr orc_rt_coff_register_object_sections;
  ExecutorAddr orc_rt_coff_deregister_object_sections;
  ExecutorAddr orc_rt_coff_register_jitdylib;
  ExecutorAddr orc_rt_coff_deregister_jitdylib;

  DenseMap<JITDylib *, ExecutorAddr> JITDylibToHeaderAddr;
  DenseMap<ExecutorAddr, JITDylib *> HeaderAddrToJITDylib;

  DenseMap<JITDylib *, SymbolLookupSet> RegisteredInitSymbols;

  std::set<std::string> DylibsToPreload;

  std::mutex PlatformMutex;
};

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

#endif // LLVM_EXECUTIONENGINE_ORC_COFFPLATFORM_H
