Subzero: Add locking to prepare for multithreaded translation.

src/IceGlobalContext.cpp

Index: src/IceGlobalContext.cpp
diff --git a/src/IceGlobalContext.cpp b/src/IceGlobalContext.cpp
index aaa3275d67c600c7364ad3d63f6f60fe661c319a..f8f3393fddde1418be449b2fe39de645c2cd5173 100644
--- a/src/IceGlobalContext.cpp
+++ b/src/IceGlobalContext.cpp
@@ -108,7 +108,7 @@ public:
   UndefPool Undefs;
 };
 
-void CodeStats::dump(const IceString &Name, Ostream &Str) {
+void GlobalContext::CodeStats::dump(const IceString &Name, Ostream &Str) {
   if (!ALLOW_DUMP)
     return;
   Str << "|" << Name << "|Inst Count  |" << InstructionsEmitted << "\n";
@@ -129,11 +129,16 @@ GlobalContext::GlobalContext(Ostream *OsDump, Ostream *OsEmit,
                              ELFStreamer *ELFStr, VerboseMask Mask,
                              TargetArch Arch, OptLevel Opt,
                              IceString TestPrefix, const ClFlags &Flags)
-    : StrDump(OsDump), StrEmit(OsEmit), VMask(Mask),
+    : IsStrLocked(false), StrDump(OsDump), StrEmit(OsEmit), VMask(Mask),
       ConstPool(new ConstantPool()), Arch(Arch), Opt(Opt),
       TestPrefix(TestPrefix), Flags(Flags), RNG(""), ObjectWriter() {
+  // Create a new ThreadContext for the current thread.
+  AllThreadContexts.push_back(new ThreadContext());

[JF, 2015/01/15 01:31:01]

Do you need to lock AllThreadContexts when doing a push_back?

[Jim Stichnoth, 2015/01/15 07:16:29]

No since no other thread would have access to this GlobalContext object until at
least after the ctor runs.  Added that to the comment.

+  TLS = AllThreadContexts.back();
   // Pre-register built-in stack names.
   if (ALLOW_DUMP) {
+    // TODO(stichnot): There needs to be a strong relationship between
+    // the newTimerStackID() return values and TSK_Default/TSK_Funcs.
     newTimerStackID("Total across all functions");
     newTimerStackID("Per-function summary");
   }
@@ -308,8 +313,10 @@ IceString GlobalContext::mangleName(const IceString &Name) const {
 
 GlobalContext::~GlobalContext() {
   llvm::DeleteContainerPointers(GlobalDeclarations);
+  llvm::DeleteContainerPointers(AllThreadContexts);
 }
 
+// All locking is done by the getConstantInt[0-9]+() target function.
 Constant *GlobalContext::getConstantInt(Type Ty, int64_t Value) {
   switch (Ty) {
   case IceType_i1:
@@ -329,45 +336,55 @@ Constant *GlobalContext::getConstantInt(Type Ty, int64_t Value) {
 }
 
 Constant *GlobalContext::getConstantInt1(int8_t ConstantInt1) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   ConstantInt1 &= INT8_C(1);
   return ConstPool->Integers1.getOrAdd(this, ConstantInt1);
 }
 
 Constant *GlobalContext::getConstantInt8(int8_t ConstantInt8) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   return ConstPool->Integers8.getOrAdd(this, ConstantInt8);
 }
 
 Constant *GlobalContext::getConstantInt16(int16_t ConstantInt16) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   return ConstPool->Integers16.getOrAdd(this, ConstantInt16);
 }
 
 Constant *GlobalContext::getConstantInt32(int32_t ConstantInt32) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   return ConstPool->Integers32.getOrAdd(this, ConstantInt32);
 }
 
 Constant *GlobalContext::getConstantInt64(int64_t ConstantInt64) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   return ConstPool->Integers64.getOrAdd(this, ConstantInt64);
 }
 
 Constant *GlobalContext::getConstantFloat(float ConstantFloat) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   return ConstPool->Floats.getOrAdd(this, ConstantFloat);
 }
 
 Constant *GlobalContext::getConstantDouble(double ConstantDouble) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   return ConstPool->Doubles.getOrAdd(this, ConstantDouble);
 }
 
 Constant *GlobalContext::getConstantSym(RelocOffsetT Offset,
                                         const IceString &Name,
                                         bool SuppressMangling) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   return ConstPool->Relocatables.getOrAdd(
       this, RelocatableTuple(Offset, Name, SuppressMangling));
 }
 
 Constant *GlobalContext::getConstantUndef(Type Ty) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   return ConstPool->Undefs.getOrAdd(this, Ty);
 }
 
+// All locking is done by the getConstant*() target function.

[JF, 2015/01/15 01:31:01]

Can't all of the above known constants be create at Context creation time, and
locking only occur for the other constants?

[Jim Stichnoth, 2015/01/15 07:16:29]

It's true that most of the known lowering constants could be looked up at Target
creation time.

I think the best way to reduce contention (if it actually turns out to be a
problem) is keep a thread-local cache of constant pool entries.

Added a TODO about this.

 Constant *GlobalContext::getConstantZero(Type Ty) {
   switch (Ty) {
   case IceType_i1:
@@ -403,7 +420,8 @@ Constant *GlobalContext::getConstantZero(Type Ty) {
   llvm_unreachable("Unknown type");
 }
 
-ConstantList GlobalContext::getConstantPool(Type Ty) const {
+ConstantList GlobalContext::getConstantPool(Type Ty) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   switch (Ty) {
   case IceType_i1:
   case IceType_i8:
@@ -435,6 +453,7 @@ ConstantList GlobalContext::getConstantPool(Type Ty) const {
   llvm_unreachable("Unknown type");
 }
 
+// No locking because only the bitcode parser thread calls it.
 FunctionDeclaration *
 GlobalContext::newFunctionDeclaration(const FuncSigType *Signature,
                                       unsigned CallingConv, unsigned Linkage,
@@ -446,57 +465,64 @@ GlobalContext::newFunctionDeclaration(const FuncSigType *Signature,
   return Func;
 }
 
+// No locking because only the bitcode parser thread calls it.
 VariableDeclaration *GlobalContext::newVariableDeclaration() {
   VariableDeclaration *Var = new VariableDeclaration();
   GlobalDeclarations.push_back(Var);
   return Var;
 }
 
-TimerIdT GlobalContext::getTimerID(TimerStackIdT StackID,
-                                   const IceString &Name) {
-  assert(StackID < Timers.size());
-  return Timers[StackID].getTimerID(Name);
-}
-
 TimerStackIdT GlobalContext::newTimerStackID(const IceString &Name) {
   if (!ALLOW_DUMP)
     return 0;
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   TimerStackIdT NewID = Timers.size();
   Timers.push_back(TimerStack(Name));
   return NewID;
 }
 
+TimerIdT GlobalContext::getTimerID(TimerStackIdT StackID,
+                                   const IceString &Name) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
+  assert(StackID < Timers.size());
+  return Timers[StackID].getTimerID(Name);
+}
+
 void GlobalContext::pushTimer(TimerIdT ID, TimerStackIdT StackID) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   assert(StackID < Timers.size());
   Timers[StackID].push(ID);
 }
 
 void GlobalContext::popTimer(TimerIdT ID, TimerStackIdT StackID) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   assert(StackID < Timers.size());
   Timers[StackID].pop(ID);
 }
 
 void GlobalContext::resetTimer(TimerStackIdT StackID) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   assert(StackID < Timers.size());
   Timers[StackID].reset();
 }
 
 void GlobalContext::setTimerName(TimerStackIdT StackID,
                                  const IceString &NewName) {
+  std::lock_guard<GlobalLockType> L(GlobalLock);
   assert(StackID < Timers.size());
   Timers[StackID].setName(NewName);
 }
 
 void GlobalContext::dumpStats(const IceString &Name, bool Final) {
-  if (!ALLOW_DUMP)
+  if (!ALLOW_DUMP || !getFlags().DumpStats)
     return;
-  if (Flags.DumpStats) {
-    if (Final) {
-      StatsCumulative.dump(Name, getStrDump());
-    } else {
-      StatsFunction.dump(Name, getStrDump());
-      StatsCumulative.dump("_TOTAL_", getStrDump());
-    }
+  std::lock_guard<GlobalLockType> L(GlobalLock);
+  OstreamLocker OL(this);
+  if (Final) {
+    StatsCumulative.dump(Name, getStrDump());
+  } else {
+    TLS->StatsFunction.dump(Name, getStrDump());
+    StatsCumulative.dump("_TOTAL_", getStrDump());
   }
 }
 
@@ -504,6 +530,7 @@ void GlobalContext::dumpTimers(TimerStackIdT StackID, bool DumpCumulative) {
   if (!ALLOW_DUMP)
     return;
   assert(Timers.size() > StackID);
+  OstreamLocker L(this);
   Timers[StackID].dump(getStrDump(), DumpCumulative);
 }
 
@@ -516,4 +543,6 @@ TimerMarker::TimerMarker(TimerIdT ID, const Cfg *Func)
   }
 }
 
+thread_local GlobalContext::ThreadContext *GlobalContext::TLS;
+
 } // end of namespace Ice