Fix compilation with gdbjit=on.

src/gdb-jit.cc

Index: src/gdb-jit.cc
diff --git a/src/gdb-jit.cc b/src/gdb-jit.cc
index c8dbf5d67e6a9b2e1fce48ecaf1e51464fe52de0..bf8ac19fb86aa27afc3eb78ddddf50d8d876cd72 100644
--- a/src/gdb-jit.cc
+++ b/src/gdb-jit.cc
@@ -1445,11 +1445,16 @@ static void AddUnwindInfo(CodeDescription *desc) {
 }
 
 
+Mutex* GDBJITInterface::mutex_ = OS::CreateMutex();
+
+
 void GDBJITInterface::AddCode(const char* name,
                               Code* code,
                               GDBJITInterface::CodeTag tag,
                               Script* script) {
   if (!FLAG_gdbjit) return;
+
+  ScopedLock lock(mutex_);
   AssertNoAllocation no_gc;
 
   HashMap::Entry* e = GetEntries()->Lookup(code, HashForCodeObject(code), true);
@@ -1518,6 +1523,7 @@ void GDBJITInterface::AddCode(GDBJITInterface::CodeTag tag, Code* code) {
 void GDBJITInterface::RemoveCode(Code* code) {
   if (!FLAG_gdbjit) return;
 
+  ScopedLock lock(mutex_);
   HashMap::Entry* e = GetEntries()->Lookup(code,
                                            HashForCodeObject(code),
                                            false);
@@ -1537,6 +1543,7 @@ void GDBJITInterface::RemoveCode(Code* code) {
 
 void GDBJITInterface::RegisterDetailedLineInfo(Code* code,
                                                GDBJITLineInfo* line_info) {
+  ScopedLock lock(mutex_);
   ASSERT(!IsLineInfoTagged(line_info));
   HashMap::Entry* e = GetEntries()->Lookup(code, HashForCodeObject(code), true);
   ASSERT(e->value == NULL);