[ConstraintSolver] When ranking bindings prefer type vars with literal bindings

Change the potential binding ranking logic to prefer type variables
which don't have other type variables related to them, but have literal
bindings, over the ones that do have other type variables.

Author: xedin

lib/Sema/ConstraintSystem.h

@@ -2551,8 +2551,8 @@ class ConstraintSystem {
   };
 
   struct PotentialBindings {
-    typedef std::tuple<bool, bool, bool, bool, unsigned char,
-                       bool, unsigned int> BindingScore;
+    typedef std::tuple<bool, bool, bool, bool, bool,
+                       unsigned char, unsigned int> BindingScore;
 
     /// The set of potential bindings.
     SmallVector<PotentialBinding, 4> Bindings;
@@ -2591,8 +2591,8 @@ class ConstraintSystem {
                              b.FullyBound,
                              b.IsRHSOfBindParam,
                              b.SubtypeOfExistentialType,
-                             static_cast<unsigned char>(b.LiteralBinding),
                              b.InvolvesTypeVariables,
+                             static_cast<unsigned char>(b.LiteralBinding),
                              -(b.Bindings.size() - b.NumDefaultableBindings));
     }
 

validation-test/Sema/type_checker_perf/slow/rdar21720888.swift.gyb renamed to validation-test/Sema/type_checker_perf/fast/rdar21720888.swift.gyb

@@ -1,4 +1,4 @@
-// RUN: %scale-test --invert-result --begin 2 --end 7 --step 1 --select incrementScopeCounter %s
+// RUN: %scale-test --begin 1 --end 10 --step 1 --select incrementScopeCounter %s
 // REQUIRES: OS=macosx
 // REQUIRES: asserts