Vendor import of llvm release_30 branch r142614:

http://llvm.org/svn/llvm-project/llvm/branches/release_30@142614

1 files changed, 10 insertions, 8 deletions

diff --git a/include/llvm/ADT/Statistic.h b/include/llvm/ADT/Statistic.h
index fda99c6..b8a1a2f 100644
--- a/include/llvm/ADT/Statistic.h
+++ b/include/llvm/ADT/Statistic.h
@@ -54,7 +54,7 @@ public:
     Value = Val;
     return init();
   }
-  
+
   const Statistic &operator++() {
     // FIXME: This function and all those that follow carefully use an
     // atomic operation to update the value safely in the presence of
@@ -63,41 +63,43 @@ public:
     sys::AtomicIncrement(&Value);
     return init();
   }
-  
+
   unsigned operator++(int) {
     init();
     unsigned OldValue = Value;
     sys::AtomicIncrement(&Value);
     return OldValue;
   }
-  
+
   const Statistic &operator--() {
     sys::AtomicDecrement(&Value);
     return init();
   }
-  
+
   unsigned operator--(int) {
     init();
     unsigned OldValue = Value;
     sys::AtomicDecrement(&Value);
     return OldValue;
   }
-  
+
   const Statistic &operator+=(const unsigned &V) {
+    if (!V) return *this;
     sys::AtomicAdd(&Value, V);
     return init();
   }
-  
+
   const Statistic &operator-=(const unsigned &V) {
+    if (!V) return *this;
     sys::AtomicAdd(&Value, -V);
     return init();
   }
-  
+
   const Statistic &operator*=(const unsigned &V) {
     sys::AtomicMul(&Value, V);
     return init();
   }
-  
+
   const Statistic &operator/=(const unsigned &V) {
     sys::AtomicDiv(&Value, V);
     return init();