Reduce wait times for very large PEXE files.

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 459 matching lines @@
 
   void setDisposeGlobalVariablesAfterLowering(bool Value) {
     DisposeGlobalVariablesAfterLowering = Value;
   }
   /// @}
 
   LockedPtr<StringPool> getStrings() const {
     return LockedPtr<StringPool>(Strings.get(), &StringsLock);
   }
 
+  /// Number of function blocks that can be queued before waiting for
+  /// translation
+  /// threads to consume.
+  static constexpr size_t MaxOptQSize = 1 << 16;

[John, 2016/04/11 16:28:00]

Can this be moved to the .cpp file? I see no uses of it, except in
IceGlobalContext.cpp

[Karl, 2016/04/11 21:48:54]

It is used to define OptQ below.

+
 private:
   // Try to ensure mutexes are allocated on separate cache lines.
 
   // Destructors collaborate with Allocator
   ICE_CACHELINE_BOUNDARY;
   // Managed by getAllocator()
   mutable GlobalLockType AllocLock;
   ArenaAllocator Allocator;
 
   ICE_CACHELINE_BOUNDARY;
@@ skipping 46 matching lines @@
   Ostream *StrError; /// Stream for logging errors.
 
   // True if waitForWorkerThreads() has been called.
   std::atomic_bool WaitForWorkerThreadsCalled;
 
   ICE_CACHELINE_BOUNDARY;
 
   Intrinsics IntrinsicsInfo;
   // TODO(jpp): move to EmitterContext.
   std::unique_ptr<ELFObjectWriter> ObjectWriter;
-  static constexpr size_t MaxOptQSize = 1 << 16;
+  // Value defining when to wake up the main parse thread.
+  const size_t OptQWakeupSize;
   BoundedProducerConsumerQueue<OptWorkItem, MaxOptQSize> 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;
@@ skipping 121 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