Support: add llvm::unique_lock

Based on the STL class of the same name, it guards a mutex
while also allowing it to be unlocked conditionally before
destruction.

This eliminates the last naked usages of mutexes in LLVM and
clang.

It also uncovered and fixed a bug in callExternalFunction()
when compiled without USE_LIBFFI, where the mutex would never
be unlocked if the end of the function was reached.

llvm-svn: 216338

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp b/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
index e4b89c60b46..0fdcc5fd361 100644
--- a/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
+++ b/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
@@ -28,6 +28,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/Mutex.h"
+#include "llvm/Support/UniqueLock.h"
 #include <cmath>
 #include <csignal>
 #include <cstdio>
@@ -248,14 +249,14 @@ GenericValue Interpreter::callExternalFunction(Function *F,
                                      const std::vector<GenericValue> &ArgVals) {
   TheInterpreter = this;
 
-  FunctionsLock->lock();
+  unique_lock<sys::Mutex> Guard(*FunctionsLock);
 
   // Do a lookup to see if the function is in our cache... this should just be a
   // deferred annotation!
   std::map<const Function *, ExFunc>::iterator FI = ExportedFunctions->find(F);
   if (ExFunc Fn = (FI == ExportedFunctions->end()) ? lookupFunction(F)
                                                    : FI->second) {
-    FunctionsLock->unlock();
+    Guard.unlock();
     return Fn(F->getFunctionType(), ArgVals);
   }
 
@@ -273,7 +274,7 @@ GenericValue Interpreter::callExternalFunction(Function *F,
     RawFn = RF->second;
   }
 
-  FunctionsLock->unlock();
+  Guard.unlock();
 
   GenericValue Result;
   if (RawFn != 0 && ffiInvoke(RawFn, F, ArgVals, getDataLayout(), Result))