Subzero: Manage each Cfg as a std::unique_ptr<Cfg>.

src/IceGlobalContext.cpp

 //===- subzero/src/IceGlobalContext.cpp - Global context defs -------------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines aspects of the compilation that persist across
@@ skipping 142 matching lines @@
     newTimerStackID("Total across all functions");
     newTimerStackID("Per-function summary");
   }
   Timers.initInto(MyTLS->Timers);
   if (Flags.UseELFWriter) {
     ObjectWriter.reset(new ELFObjectWriter(*this, *ELFStr));
   }
 }
 
 void GlobalContext::translateFunctions() {
-  while (Cfg *Func = cfgQueueBlockingPop()) {
+  while (std::unique_ptr<Cfg> Func = cfgQueueBlockingPop()) {
+    // Install Func in TLS for Cfg-specific container allocators.
+    Cfg::updateTLS(Func.get());

[JF, 2015/02/02 20:59:19]

Hmm, now TLS is asymmetric. Maybe updateTLS(nullptr) should move to the end of
the loop instead of being in the dtor?

[Jim Stichnoth, 2015/02/03 00:48:51]

Done.

     // Reset per-function stats being accumulated in TLS.
     resetStats();
-    // Install Func in TLS for Cfg-specific container allocators.
-    Func->updateTLS();
     // Set verbose level to none if the current function does NOT
     // match the -verbose-focus command-line option.
     if (!matchSymbolName(Func->getFunctionName(), getFlags().VerboseFocusOn))
       Func->setVerbose(IceV_None);
     // Disable translation if -notranslate is specified, or if the
     // current function matches the -translate-only option.  If
     // translation is disabled, just dump the high-level IR and
     // continue.
     if (getFlags().DisableTranslation ||
         !matchSymbolName(Func->getFunctionName(), getFlags().TranslateOnly)) {
       Func->dump();
     } else {
       Func->translate();
       if (Func->hasError()) {
         getErrorStatus()->assign(EC_Translation);
         OstreamLocker L(this);
         getStrDump() << "ICE translation error: " << Func->getError() << "\n";
       } else {
         if (getFlags().UseIntegratedAssembler)
           Func->emitIAS();
         else
           Func->emit();
         // TODO(stichnot): actually add to emit queue
       }
-      // TODO(stichnot): fix multithreaded stats dumping.
       dumpStats(Func->getFunctionName());
     }
-    delete Func;
+    // The Cfg now gets deleted as Func goes out of scope.  This also
+    // resets the thread-local CurrentCfg field.
   }
 }
 
 // Scan a string for S[0-9A-Z]*_ patterns and replace them with
 // S<num>_ where <num> is the next base-36 value.  If a type name
 // legitimately contains that pattern, then the substitution will be
 // made in error and most likely the link will fail.  In this case,
 // the test classes can be rewritten not to use that pattern, which is
 // much simpler and more reliable than implementing a full demangling
 // parser.  Another substitution-in-error may occur if a type
@@ skipping 322 matching lines @@
   Timers->at(StackID).reset();
 }
 
 void GlobalContext::setTimerName(TimerStackIdT StackID,
                                  const IceString &NewName) {
   auto Timers = &ICE_TLS_GET_FIELD(TLS)->Timers;
   assert(StackID < Timers->size());
   Timers->at(StackID).setName(NewName);
 }
 
+void GlobalContext::cfgQueueBlockingPush(std::unique_ptr<Cfg> Func) {
+  CfgQ.blockingPush(Func.release());
+}
+
+std::unique_ptr<Cfg> GlobalContext::cfgQueueBlockingPop() {
+  return std::unique_ptr<Cfg>(CfgQ.blockingPop());
+}

[JF, 2015/02/02 20:59:19]

It would be nice to explain that the cfgQueue takes ownership of the Cfg, and
that these two functions make it look like it's unique_ptr all the way down, but
as an implementation detail it isn't because concurrency.

[Jim Stichnoth, 2015/02/03 00:48:51]

Done.

+
 void GlobalContext::dumpStats(const IceString &Name, bool Final) {
   if (!ALLOW_DUMP || !getFlags().DumpStats)
     return;
   OstreamLocker OL(this);
   if (Final) {
     getStatsCumulative()->dump(Name, getStrDump());
   } else {
     ICE_TLS_GET_FIELD(TLS)->StatsFunction.dump(Name, getStrDump());
   }
 }
@@ skipping 25 matching lines @@
 void TimerMarker::pushCfg(const Cfg *Func) {
   Ctx = Func->getContext();
   Active = Func->getFocusedTiming() || Ctx->getFlags().SubzeroTimingEnabled;
   if (Active)
     Ctx->pushTimer(ID, StackID);
 }
 
 ICE_TLS_DEFINE_FIELD(GlobalContext::ThreadContext *, GlobalContext, TLS);
 
 } // end of namespace Ice