Remove an expensive lock from Timer

The Timer destructor would grab a global mutex in order to update
execution time. Add a class to define a category once, statically; the
class adds itself to an atomic singly linked list, and thus subsequent
updates only need to use an atomic rather than grab a lock and perform a
hashtable lookup.

Differential Revision: https://reviews.llvm.org/D32823
Patch by Scott Smith <scott.smith@purestorage.com>.

llvm-svn: 303058

1 files changed, 4 insertions, 2 deletions

diff --git a/lldb/source/Initialization/SystemInitializerCommon.cpp b/lldb/source/Initialization/SystemInitializerCommon.cpp
index 805e6091e68..77869807c79 100644
--- a/lldb/source/Initialization/SystemInitializerCommon.cpp
+++ b/lldb/source/Initialization/SystemInitializerCommon.cpp
@@ -72,7 +72,8 @@ void SystemInitializerCommon::Initialize() {
   llvm::EnablePrettyStackTrace();
   InitializeLog();
   HostInfo::Initialize();
-  Timer scoped_timer(LLVM_PRETTY_FUNCTION, LLVM_PRETTY_FUNCTION);
+  static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
+  Timer scoped_timer(func_cat, LLVM_PRETTY_FUNCTION);
 
   process_gdb_remote::ProcessGDBRemoteLog::Initialize();
 
@@ -102,7 +103,8 @@ void SystemInitializerCommon::Initialize() {
 }
 
 void SystemInitializerCommon::Terminate() {
-  Timer scoped_timer(LLVM_PRETTY_FUNCTION, LLVM_PRETTY_FUNCTION);
+  static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
+  Timer scoped_timer(func_cat, LLVM_PRETTY_FUNCTION);
   ObjectContainerBSDArchive::Terminate();
   ObjectFileELF::Terminate();
   ObjectFilePECOFF::Terminate();