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, 2 deletions

diff --git a/lldb/source/Commands/CommandObjectTarget.cpp b/lldb/source/Commands/CommandObjectTarget.cpp
index 56da1da34cb..343530ea4f3 100644
--- a/lldb/source/Commands/CommandObjectTarget.cpp
+++ b/lldb/source/Commands/CommandObjectTarget.cpp
@@ -269,8 +269,8 @@ protected:
       }
 
       const char *file_path = command.GetArgumentAtIndex(0);
-      Timer scoped_timer(LLVM_PRETTY_FUNCTION, "(lldb) target create '%s'",
-                         file_path);
+      static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
+      Timer scoped_timer(func_cat, "(lldb) target create '%s'", file_path);
       FileSpec file_spec;
 
       if (file_path)