Sema: Track solver arena size in statistics

Author: slavapestov

include/swift/Sema/ConstraintSolverStats.def

@@ -18,6 +18,7 @@
 #  error #define CS_STATISTIC(Name, Description) before including
 #endif
 
+CS_STATISTIC(ASTBytesAllocated, "bytes allocated in solver arena")
 CS_STATISTIC(NumTypeVariablesBound, "# of type variables bound")
 CS_STATISTIC(NumTypeVariableBindings, "# of type variable bindings attempted")
 CS_STATISTIC(NumDisjunctions, "# of disjunctions explored")

lib/Sema/CSSolver.cpp

@@ -669,6 +669,10 @@ ConstraintSystem::SolverState::~SolverState() {
     CS.Options -= ConstraintSystemFlags::DebugConstraints;
   }
 
+  // This statistic is special because it's not a counter; we just update
+  // it in one shot at the end.
+  ASTBytesAllocated = CS.getASTContext().getSolverMemory();
+
   // Write our local statistics back to the overall statistics.
   #define CS_STATISTIC(Name, Description) JOIN2(Overall,Name) += Name;
   #include "swift/Sema/ConstraintSolverStats.def"