Reduce wait times for very large PEXE files.

src/IceThreading.h

 //===- subzero/src/IceThreading.h - Threading functions ---------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 49 matching lines @@
   void blockingPush(std::unique_ptr<T> Item) {
     {
       std::unique_lock<GlobalLockType> L(Lock);
       // If the work queue is already "full", wait for a consumer to grab an
       // element and shrink the queue.
       Shrunk.wait(L, [this] { return size() < MaxSize || Sequential; });
       push(std::move(Item));
     }
     GrewOrEnded.notify_one();
   }
-  std::unique_ptr<T> blockingPop() {
+  std::unique_ptr<T> blockingPop(size_t NotifyWhenDownToSize = MaxStaticSize) {
     std::unique_ptr<T> Item;
     bool ShouldNotifyProducer = false;
     {
       std::unique_lock<GlobalLockType> L(Lock);
       GrewOrEnded.wait(L, [this] { return IsEnded || !empty() || Sequential; });
       if (!empty()) {
         Item = pop();
-        ShouldNotifyProducer = !IsEnded;
+        ShouldNotifyProducer = (size() < NotifyWhenDownToSize) && !IsEnded;
       }
     }
     if (ShouldNotifyProducer)
       Shrunk.notify_one();
     return Item;
   }
   void notifyEnd() {
     {
       std::lock_guard<GlobalLockType> L(Lock);
       IsEnded = true;
@@ skipping 103 matching lines @@
   const uint32_t Sequence;
   const ItemKind Kind;
   std::unique_ptr<VariableDeclarationList> GlobalInits;
   std::unique_ptr<Assembler> Function;
   std::unique_ptr<Cfg> RawFunc;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETHREADING_H