src/IceGlobalContext.h

//===- subzero/src/IceGlobalContext.h - Global context defs -----*- C++ -*-===//
//
//                        The Subzero Code Generator
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares aspects of the compilation that persist across
// multiple functions.
//
//===----------------------------------------------------------------------===//

#ifndef SUBZERO_SRC_ICEGLOBALCONTEXT_H
#define SUBZERO_SRC_ICEGLOBALCONTEXT_H

#include "IceDefs.h"
#include "IceClFlags.h"
#include "IceIntrinsics.h"
#include "IceRNG.h"
#include "IceThreading.h"
#include "IceTimerTree.h"
#include "IceTypes.h"
#include "IceUtils.h"

#include <array>
#include <functional>
#include <mutex>
#include <thread>
#include <type_traits>
#include <vector>

namespace Ice {

class ClFlags;
class ConstantPool;
class EmitterWorkItem;
class FuncSigType;

// LockedPtr is a way to provide automatically locked access to some object.
template <typename T> class LockedPtr {
  LockedPtr() = delete;
  LockedPtr(const LockedPtr &) = delete;
  LockedPtr &operator=(const LockedPtr &) = delete;

public:
  LockedPtr(T *Value, GlobalLockType *Lock) : Value(Value), Lock(Lock) {
    Lock->lock();
  }
  LockedPtr(LockedPtr &&Other) : Value(Other.Value), Lock(Other.Lock) {
    Other.Value = nullptr;
    Other.Lock = nullptr;
  }
  ~LockedPtr() { Lock->unlock(); }
  T *operator->() const { return Value; }

private:
  T *Value;
  GlobalLockType *Lock;
};

class GlobalContext {
  GlobalContext() = delete;
  GlobalContext(const GlobalContext &) = delete;
  GlobalContext &operator=(const GlobalContext &) = delete;

  // CodeStats collects rudimentary statistics during translation.
  class CodeStats {
    CodeStats(const CodeStats &) = delete;
    CodeStats &operator=(const CodeStats &) = default;
#define CODESTATS_TABLE                                                        \
  /* dump string, enum value */                                                \
  X("Inst Count  ", InstCount)                                                 \
  X("Regs Saved  ", RegsSaved)                                                 \
  X("Frame Bytes ", FrameByte)                                                 \
  X("Spills      ", NumSpills)                                                 \
  X("Fills       ", NumFills)                                                  \
  X("R/P Imms    ", NumRPImms)
    //#define X(str, tag)

  public:
    enum CSTag {
#define X(str, tag) CS_##tag,
      CODESTATS_TABLE
#undef X
          CS_NUM
    };
    CodeStats() { reset(); }
    void reset() { Stats.fill(0); }
    void update(CSTag Tag, uint32_t Count = 1) {
      assert(Tag < Stats.size());
      Stats[Tag] += Count;
    }
    void add(const CodeStats &Other) {
      for (uint32_t i = 0; i < Stats.size(); ++i)
        Stats[i] += Other.Stats[i];
    }
    void dump(const IceString &Name, Ostream &Str);

  private:
    std::array<uint32_t, CS_NUM> Stats;
  };

  // TimerList is a vector of TimerStack objects, with extra methods
  // to initialize and merge these vectors.
  class TimerList : public std::vector<TimerStack> {
    TimerList(const TimerList &) = delete;
    TimerList &operator=(const TimerList &) = delete;

  public:
    TimerList() = default;
    // initInto() initializes a target list of timers based on the
    // current list.  In particular, it creates the same number of
    // timers, in the same order, with the same names, but initially
    // empty of timing data.
    void initInto(TimerList &Dest) const {
      if (!BuildDefs::dump())
        return;
      Dest.clear();
      for (const TimerStack &Stack : *this) {
        Dest.push_back(TimerStack(Stack.getName()));
      }
    }
    void mergeFrom(TimerList &Src) {
      if (!BuildDefs::dump())
        return;
      assert(size() == Src.size());
      size_type i = 0;
      for (TimerStack &Stack : *this) {
        assert(Stack.getName() == Src[i].getName());
        Stack.mergeFrom(Src[i]);
        ++i;
      }
    }
  };

  // ThreadContext contains thread-local data.  This data can be
  // combined/reduced as needed after all threads complete.
  class ThreadContext {
    ThreadContext(const ThreadContext &) = delete;
    ThreadContext &operator=(const ThreadContext &) = delete;

  public:
    ThreadContext() = default;
    CodeStats StatsFunction;
    CodeStats StatsCumulative;
    TimerList Timers;
  };

public:
  // The dump stream is a log stream while emit is the stream code
  // is emitted to. The error stream is strictly for logging errors.
  GlobalContext(Ostream *OsDump, Ostream *OsEmit, Ostream *OsError,
                ELFStreamer *ELFStreamer, const ClFlags &Flags);
  ~GlobalContext();

  //
  // The dump, error, and emit streams need to be used by only one
  // thread at a time.  This is done by exclusively reserving the
  // streams via lockStr() and unlockStr().  The OstreamLocker class
  // can be used to conveniently manage this.
  //
  // The model is that a thread grabs the stream lock, then does an
  // arbitrary amount of work during which far-away callees may grab
  // the stream and do something with it, and finally the thread
  // releases the stream lock.  This allows large chunks of output to
  // be dumped or emitted without risking interleaving from multiple
  // threads.
  void lockStr() { StrLock.lock(); }
  void unlockStr() { StrLock.unlock(); }
  Ostream &getStrDump() { return *StrDump; }
  Ostream &getStrError() { return *StrError; }
  Ostream &getStrEmit() { return *StrEmit; }

  LockedPtr<ErrorCode> getErrorStatus() {
    return LockedPtr<ErrorCode>(&ErrorStatus, &ErrorStatusLock);
  }

  // When emitting assembly, we allow a string to be prepended to
  // names of translated functions.  This makes it easier to create an
  // execution test against a reference translator like llc, with both
  // translators using the same bitcode as input.
  IceString mangleName(const IceString &Name) const;

  // Manage Constants.
  // getConstant*() functions are not const because they might add
  // something to the constant pool.
  Constant *getConstantInt(Type Ty, int64_t Value);
  Constant *getConstantInt1(int8_t ConstantInt1);
  Constant *getConstantInt8(int8_t ConstantInt8);
  Constant *getConstantInt16(int16_t ConstantInt16);
  Constant *getConstantInt32(int32_t ConstantInt32);
  Constant *getConstantInt64(int64_t ConstantInt64);
  Constant *getConstantFloat(float Value);
  Constant *getConstantDouble(double Value);
  // Returns a symbolic constant.
  Constant *getConstantSym(RelocOffsetT Offset, const IceString &Name,
                           bool SuppressMangling);
  Constant *getConstantExternSym(const IceString &Name);
  // Returns an undef.
  Constant *getConstantUndef(Type Ty);
  // Returns a zero value.
  Constant *getConstantZero(Type Ty);
  // getConstantPool() returns a copy of the constant pool for
  // constants of a given type.
  ConstantList getConstantPool(Type Ty);
  // Returns a copy of the list of external symbols.
  ConstantList getConstantExternSyms();

  const ClFlags &getFlags() const { return Flags; }

  bool isIRGenerationDisabled() const {
    return getFlags().getDisableIRGeneration();
  }

  // Allocate data of type T using the global allocator. We allow entities
  // allocated from this global allocator to be either trivially or
  // non-trivially destructible. We optimize the case when T is trivially
  // destructible by not registering a destructor. Destructors will be invoked
  // during GlobalContext destruction in the reverse object creation order.
  template <typename T>
  typename std::enable_if<std::is_trivially_destructible<T>::value, T>::type *
  allocate() {
    return getAllocator()->Allocate<T>();
  }

  template <typename T>
  typename std::enable_if<!std::is_trivially_destructible<T>::value, T>::type *
  allocate() {
    T *Ret = getAllocator()->Allocate<T>();
    getDestructors()->emplace_back([Ret]() { Ret->~T(); });
    return Ret;
  }

  const Intrinsics &getIntrinsicsInfo() const { return IntrinsicsInfo; }

  // TODO(wala,stichnot): Make the RNG play nicely with multithreaded
  // translation.
  RandomNumberGenerator &getRNG() { return RNG; }

  ELFObjectWriter *getObjectWriter() const { return ObjectWriter.get(); }

  // Reset stats at the beginning of a function.
  void resetStats() {
    if (BuildDefs::dump())
      ICE_TLS_GET_FIELD(TLS)->StatsFunction.reset();
  }
  void dumpStats(const IceString &Name, bool Final = false);
  void statsUpdateEmitted(uint32_t InstCount) {
    if (!getFlags().getDumpStats())
      return;
    ThreadContext *Tls = ICE_TLS_GET_FIELD(TLS);
    Tls->StatsFunction.update(CodeStats::CS_InstCount, InstCount);
    Tls->StatsCumulative.update(CodeStats::CS_InstCount, InstCount);
  }
  void statsUpdateRegistersSaved(uint32_t Num) {
    if (!getFlags().getDumpStats())
      return;
    ThreadContext *Tls = ICE_TLS_GET_FIELD(TLS);
    Tls->StatsFunction.update(CodeStats::CS_RegsSaved, Num);
    Tls->StatsCumulative.update(CodeStats::CS_RegsSaved, Num);
  }
  void statsUpdateFrameBytes(uint32_t Bytes) {
    if (!getFlags().getDumpStats())
      return;
    ThreadContext *Tls = ICE_TLS_GET_FIELD(TLS);
    Tls->StatsFunction.update(CodeStats::CS_FrameByte, Bytes);
    Tls->StatsCumulative.update(CodeStats::CS_FrameByte, Bytes);
  }
  void statsUpdateSpills() {
    if (!getFlags().getDumpStats())
      return;
    ThreadContext *Tls = ICE_TLS_GET_FIELD(TLS);
    Tls->StatsFunction.update(CodeStats::CS_NumSpills);
    Tls->StatsCumulative.update(CodeStats::CS_NumSpills);
  }
  void statsUpdateFills() {
    if (!getFlags().getDumpStats())
      return;
    ThreadContext *Tls = ICE_TLS_GET_FIELD(TLS);
    Tls->StatsFunction.update(CodeStats::CS_NumFills);
    Tls->StatsCumulative.update(CodeStats::CS_NumFills);
  }

  // Number of Randomized or Pooled Immediates
  void statsUpdateRPImms() {
    if (!getFlags().getDumpStats())
      return;
    ThreadContext *Tls = ICE_TLS_GET_FIELD(TLS);
    Tls->StatsFunction.update(CodeStats::CS_NumRPImms);
    Tls->StatsCumulative.update(CodeStats::CS_NumRPImms);
  }

  // These are predefined TimerStackIdT values.
  enum TimerStackKind { TSK_Default = 0, TSK_Funcs, TSK_Num };

  // newTimerStackID() creates a new TimerStack in the global space.
  // It does not affect any TimerStack objects in TLS.
  TimerStackIdT newTimerStackID(const IceString &Name);
  // dumpTimers() dumps the global timer data.  As such, one probably
  // wants to call mergeTimerStacks() as a prerequisite.
  void dumpTimers(TimerStackIdT StackID = TSK_Default,
                  bool DumpCumulative = true);
  // The following methods affect only the calling thread's TLS timer
  // data.
  TimerIdT getTimerID(TimerStackIdT StackID, const IceString &Name);
  void pushTimer(TimerIdT ID, TimerStackIdT StackID);
  void popTimer(TimerIdT ID, TimerStackIdT StackID);
  void resetTimer(TimerStackIdT StackID);
  void setTimerName(TimerStackIdT StackID, const IceString &NewName);

  // This is the first work item sequence number that the parser
  // produces, and correspondingly the first sequence number that the
  // emitter thread will wait for.  Start numbering at 1 to leave room
  // for a sentinel, in case e.g. we wish to inject items with a
  // special sequence number that may be executed out of order.
  static uint32_t getFirstSequenceNumber() { return 1; }
  // Adds a newly parsed and constructed function to the Cfg work
  // queue.  Notifies any idle workers that a new function is
  // available for translating.  May block if the work queue is too
  // large, in order to control memory footprint.
  void optQueueBlockingPush(std::unique_ptr<Cfg> Func);
  // Takes a Cfg from the work queue for translating.  May block if
  // the work queue is currently empty.  Returns nullptr if there is
  // no more work - the queue is empty and either end() has been
  // called or the Sequential flag was set.
  std::unique_ptr<Cfg> optQueueBlockingPop();
  // Notifies that no more work will be added to the work queue.
  void optQueueNotifyEnd() { OptQ.notifyEnd(); }

  // Emit file header for output file.
  void emitFileHeader();

  void lowerConstants();

  void emitQueueBlockingPush(EmitterWorkItem *Item);
  EmitterWorkItem *emitQueueBlockingPop();
  void emitQueueNotifyEnd() { EmitQ.notifyEnd(); }

  void initParserThread() {
    ThreadContext *Tls = new ThreadContext();
    auto Timers = getTimers();
    Timers->initInto(Tls->Timers);
    AllThreadContexts.push_back(Tls);
    ICE_TLS_SET_FIELD(TLS, Tls);
  }

  void startWorkerThreads() {
    size_t NumWorkers = getFlags().getNumTranslationThreads();
    auto Timers = getTimers();
    for (size_t i = 0; i < NumWorkers; ++i) {
      ThreadContext *WorkerTLS = new ThreadContext();
      Timers->initInto(WorkerTLS->Timers);
      AllThreadContexts.push_back(WorkerTLS);
      TranslationThreads.push_back(std::thread(
          &GlobalContext::translateFunctionsWrapper, this, WorkerTLS));
    }
    if (NumWorkers) {
      ThreadContext *WorkerTLS = new ThreadContext();
      Timers->initInto(WorkerTLS->Timers);
      AllThreadContexts.push_back(WorkerTLS);
      EmitterThreads.push_back(
          std::thread(&GlobalContext::emitterWrapper, this, WorkerTLS));
    }
  }

  void waitForWorkerThreads() {
    optQueueNotifyEnd();
    for (std::thread &Worker : TranslationThreads) {
      Worker.join();
    }
    TranslationThreads.clear();

    // Only notify the emit queue to end after all the translation
    // threads have ended.
    emitQueueNotifyEnd();
    for (std::thread &Worker : EmitterThreads) {
      Worker.join();
    }
    EmitterThreads.clear();

    if (BuildDefs::dump()) {
      auto Timers = getTimers();
      for (ThreadContext *TLS : AllThreadContexts)
        Timers->mergeFrom(TLS->Timers);
    }
    if (BuildDefs::dump()) {
      // Do a separate loop over AllThreadContexts to avoid holding
      // two locks at once.
      auto Stats = getStatsCumulative();
      for (ThreadContext *TLS : AllThreadContexts)
        Stats->add(TLS->StatsCumulative);
    }
  }

  // Translation thread startup routine.
  void translateFunctionsWrapper(ThreadContext *MyTLS) {
    ICE_TLS_SET_FIELD(TLS, MyTLS);
    translateFunctions();
  }
  // Translate functions from the Cfg queue until the queue is empty.
  void translateFunctions();

  // Emitter thread startup routine.
  void emitterWrapper(ThreadContext *MyTLS) {
    ICE_TLS_SET_FIELD(TLS, MyTLS);
    emitItems();
  }
  // Emit functions and global initializers from the emitter queue
  // until the queue is empty.
  void emitItems();

  // Uses DataLowering to lower Globals. Side effects:
  //  - discards the initializer list for the global variable in Globals.
  //  - clears the Globals array.
  void lowerGlobals(const IceString &SectionSuffix);

  // Lowers the profile information.
  void lowerProfileData();

  // Utility function to match a symbol name against a match string.
  // This is used in a few cases where we want to take some action on
  // a particular function or symbol based on a command-line argument,
  // such as changing the verbose level for a particular function.  An
  // empty Match argument means match everything.  Returns true if
  // there is a match.
  static bool matchSymbolName(const IceString &SymbolName,
                              const IceString &Match) {
    return Match.empty() || Match == SymbolName;
  }

  // Return the randomization cookie for diversification.
  // Initialize the cookie if necessary
  uint32_t getRandomizationCookie() const { return RandomizationCookie; }

private:
  // Try to ensure mutexes are allocated on separate cache lines.

  // Destructors collaborate with Allocator
  ICE_CACHELINE_BOUNDARY;
  // Managed by getAllocator()
  GlobalLockType AllocLock;
  ArenaAllocator<> Allocator;

  ICE_CACHELINE_BOUNDARY;
  // Managed by getDestructors()
  typedef std::vector<std::function<void()>> DestructorArray;
  GlobalLockType DestructorsLock;
  DestructorArray Destructors;

  ICE_CACHELINE_BOUNDARY;
  // Managed by getConstantPool()
  GlobalLockType ConstPoolLock;
  std::unique_ptr<ConstantPool> ConstPool;

  ICE_CACHELINE_BOUNDARY;
  // Managed by getErrorStatus()
  GlobalLockType ErrorStatusLock;
  ErrorCode ErrorStatus;

  ICE_CACHELINE_BOUNDARY;
  // Managed by getStatsCumulative()
  GlobalLockType StatsLock;
  CodeStats StatsCumulative;

  ICE_CACHELINE_BOUNDARY;
  // Managed by getTimers()
  GlobalLockType TimerLock;
  TimerList Timers;

  ICE_CACHELINE_BOUNDARY;
  // StrLock is a global lock on the dump and emit output streams.
  typedef std::mutex StrLockType;
  StrLockType StrLock;
  Ostream *StrDump;  // Stream for dumping / diagnostics
  Ostream *StrEmit;  // Stream for code emission
  Ostream *StrError; // Stream for logging errors.

  ICE_CACHELINE_BOUNDARY;

  Intrinsics IntrinsicsInfo;
  const ClFlags &Flags;
  RandomNumberGenerator RNG; // TODO(stichnot): Move into Cfg.
  // TODO(jpp): move to EmitterContext.
  std::unique_ptr<ELFObjectWriter> ObjectWriter;
  BoundedProducerConsumerQueue<Cfg> OptQ;
  BoundedProducerConsumerQueue<EmitterWorkItem> EmitQ;
  // DataLowering is only ever used by a single thread at a time (either in
  // emitItems(), or in IceCompiler::run before the compilation is over.)
  // TODO(jpp): move to EmitterContext.
  std::unique_ptr<TargetDataLowering> DataLowering;
  // If !HasEmittedCode, SubZero will accumulate all Globals (which are "true"
  // program global variables) until the first code WorkItem is seen.
  // TODO(jpp): move to EmitterContext.
  bool HasSeenCode = false;
  // TODO(jpp): move to EmitterContext.
  VariableDeclarationList Globals;
  // TODO(jpp): move to EmitterContext.
  VariableDeclaration *ProfileBlockInfoVarDecl;

  LockedPtr<ArenaAllocator<>> getAllocator() {
    return LockedPtr<ArenaAllocator<>>(&Allocator, &AllocLock);
  }
  LockedPtr<ConstantPool> getConstPool() {
    return LockedPtr<ConstantPool>(ConstPool.get(), &ConstPoolLock);
  }
  LockedPtr<CodeStats> getStatsCumulative() {
    return LockedPtr<CodeStats>(&StatsCumulative, &StatsLock);
  }
  LockedPtr<TimerList> getTimers() {
    return LockedPtr<TimerList>(&Timers, &TimerLock);
  }
  LockedPtr<DestructorArray> getDestructors() {
    return LockedPtr<DestructorArray>(&Destructors, &DestructorsLock);
  }

  void accumulateGlobals(std::unique_ptr<VariableDeclarationList> Globls) {
    if (Globls != nullptr)
      Globals.insert(Globals.end(), Globls->begin(), Globls->end());
  }

  void lowerGlobalsIfNoCodeHasBeenSeen() {
    if (HasSeenCode)
      return;
    constexpr char NoSuffix[] = "";
    lowerGlobals(NoSuffix);
    HasSeenCode = true;
  }

  llvm::SmallVector<ThreadContext *, 128> AllThreadContexts;
  llvm::SmallVector<std::thread, 128> TranslationThreads;
  llvm::SmallVector<std::thread, 128> EmitterThreads;
  // Each thread has its own TLS pointer which is also held in
  // AllThreadContexts.
  ICE_TLS_DECLARE_FIELD(ThreadContext *, TLS);

  // Private helpers for mangleName()
  typedef llvm::SmallVector<char, 32> ManglerVector;
  void incrementSubstitutions(ManglerVector &OldName) const;

  // Randomization Cookie
  // Managed by getRandomizationCookie()
  GlobalLockType RandomizationCookieLock;
  uint32_t RandomizationCookie = 0;

public:
  static void TlsInit() { ICE_TLS_INIT_FIELD(TLS); }
};

// Helper class to push and pop a timer marker.  The constructor
// pushes a marker, and the destructor pops it.  This is for
// convenient timing of regions of code.
class TimerMarker {
  TimerMarker() = delete;
  TimerMarker(const TimerMarker &) = delete;
  TimerMarker &operator=(const TimerMarker &) = delete;

public:
  TimerMarker(TimerIdT ID, GlobalContext *Ctx,
              TimerStackIdT StackID = GlobalContext::TSK_Default)
      : ID(ID), Ctx(Ctx), StackID(StackID) {
    if (BuildDefs::dump())
      push();
  }
  TimerMarker(TimerIdT ID, const Cfg *Func,
              TimerStackIdT StackID = GlobalContext::TSK_Default)
      : ID(ID), Ctx(nullptr), StackID(StackID) {
    // Ctx gets set at the beginning of pushCfg().
    if (BuildDefs::dump())
      pushCfg(Func);
  }

  ~TimerMarker() {
    if (BuildDefs::dump() && Active)
      Ctx->popTimer(ID, StackID);
  }

private:
  void push();
  void pushCfg(const Cfg *Func);
  const TimerIdT ID;
  GlobalContext *Ctx;
  const TimerStackIdT StackID;
  bool Active = false;
};

// Helper class for locking the streams and then automatically
// unlocking them.
class OstreamLocker {
private:
  OstreamLocker() = delete;
  OstreamLocker(const OstreamLocker &) = delete;
  OstreamLocker &operator=(const OstreamLocker &) = delete;

public:
  explicit OstreamLocker(GlobalContext *Ctx) : Ctx(Ctx) { Ctx->lockStr(); }
  ~OstreamLocker() { Ctx->unlockStr(); }

private:
  GlobalContext *const Ctx;
};

} // end of namespace Ice

#endif // SUBZERO_SRC_ICEGLOBALCONTEXT_H