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

src/IceGlobalContext.cpp

Index: src/IceGlobalContext.cpp
diff --git a/src/IceGlobalContext.cpp b/src/IceGlobalContext.cpp
index 8805cea111ec69b3760ac52ffe6ce8009a744686..2caf7aead4457c8ffbb221ed4be5b149683af222 100644
--- a/src/IceGlobalContext.cpp
+++ b/src/IceGlobalContext.cpp
@@ -160,11 +160,11 @@ GlobalContext::GlobalContext(Ostream *OsDump, Ostream *OsEmit,
 }
 
 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))
@@ -189,10 +189,10 @@ void GlobalContext::translateFunctions() {
           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.
   }
 }
 
@@ -535,6 +535,14 @@ void GlobalContext::setTimerName(TimerStackIdT StackID,
   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;