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, 2 insertions, 1 deletions

diff --git a/lldb/source/API/SystemInitializerFull.cpp b/lldb/source/API/SystemInitializerFull.cpp
index 23aec1d6fa0..6be352567e8 100644
--- a/lldb/source/API/SystemInitializerFull.cpp
+++ b/lldb/source/API/SystemInitializerFull.cpp
@@ -400,7 +400,8 @@ void SystemInitializerFull::InitializeSWIG() {
 }
 
 void SystemInitializerFull::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);
 
   Debugger::SettingsTerminate();