Subzero. Allocate global initializers from a dedicated arena.

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.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 39 matching lines @@
   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; }
   T &operator*() const { return *Value; }
+  T *get() { return Value; }
 
 private:
   T *Value;
   GlobalLockType *Lock;
 };
 
 class GlobalContext {
   GlobalContext() = delete;
   GlobalContext(const GlobalContext &) = delete;
   GlobalContext &operator=(const GlobalContext &) = delete;
@@ skipping 358 matching lines @@
   /// 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;
   }
 
   static ClFlags Flags;
   static ClFlagsExtra ExtraFlags;
 
+  /// DisposeGlobalVariablesAfterLowering controls whether the memory used by
+  /// GlobaleVariables can be reclaimed right after they have been lowered.
+  /// @{
+  bool getDisposeGlobalVariablesAfterLowering() const {
+    return DisposeGlobalVariablesAfterLowering;
+  }
+
+  void setDisposeGlobalVariablesAfterLowering(bool Value) {
+    DisposeGlobalVariablesAfterLowering = Value;
+  }
+  /// @}
+
 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 getInitializerAllocator()
+  GlobalLockType InitAllocLock;
+  VariableDeclarationList Globals;
+
+  ICE_CACHELINE_BOUNDARY;
   // Managed by getDestructors()
   using DestructorArray = std::vector<std::function<void()>>;
   GlobalLockType DestructorsLock;
   DestructorArray Destructors;
 
   ICE_CACHELINE_BOUNDARY;
   // Managed by getConstantPool()
   GlobalLockType ConstPoolLock;
   std::unique_ptr<ConstantPool> ConstPool;
 
@@ skipping 34 matching lines @@
   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;
+  VariableDeclaration *ProfileBlockInfoVarDecl = nullptr;
+  std::vector<VariableDeclaration *> ProfileBlockInfos;
+  /// Indicates if global variable declarations can be disposed of right after
+  /// lowering.
+  bool DisposeGlobalVariablesAfterLowering = true;
 
   LockedPtr<ArenaAllocator> getAllocator() {
     return LockedPtr<ArenaAllocator>(&Allocator, &AllocLock);
   }
+  LockedPtr<VariableDeclarationList> getInitializerAllocator() {
+    return LockedPtr<VariableDeclarationList>(&Globals, &InitAllocLock);
+  }
   LockedPtr<ConstantPool> getConstPool() {
     return LockedPtr<ConstantPool>(ConstPool.get(), &ConstPoolLock);
   }
   LockedPtr<JumpTableDataList> getJumpTableList() {
     return LockedPtr<JumpTableDataList>(&JumpTableList, &JumpTablesLock);
   }
   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());
+    LockedPtr<VariableDeclarationList> _(&Globals, &InitAllocLock);
+    if (Globls != nullptr) {
+      Globals.merge(Globls.get());
+    }
   }
 
   void lowerGlobalsIfNoCodeHasBeenSeen() {
     if (HasSeenCode)
       return;
     constexpr char NoSuffix[] = "";
     lowerGlobals(NoSuffix);
     HasSeenCode = true;
   }
 
-  void addBlockInfoPtrs(VariableDeclaration *ProfileBlockInfo);
+  void saveBlockInfoPtrs();
 
   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);
 
 public:
   static void TlsInit() { ICE_TLS_INIT_FIELD(TLS); }
@@ skipping 47 matching lines @@
   explicit OstreamLocker(GlobalContext *Ctx) : Ctx(Ctx) { Ctx->lockStr(); }
   ~OstreamLocker() { Ctx->unlockStr(); }
 
 private:
   GlobalContext *const Ctx;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEGLOBALCONTEXT_H