AST: Avoid expensive calls to getAttachedPropertyWrappers()

Check for the presence of a CustomAttr first, before calling into the
request evaluator.

Also clean up the logic a tiny bit.

Author: slavapestov

lib/AST/Decl.cpp

@@ -5937,17 +5937,33 @@ llvm::TinyPtrVector<CustomAttr *> VarDecl::getAttachedPropertyWrappers() const {
 
 /// Whether this property has any attached property wrappers.
 bool VarDecl::hasAttachedPropertyWrapper() const {
-  return !getAttachedPropertyWrappers().empty() || hasImplicitPropertyWrapper();
+  if (getAttrs().hasAttribute<CustomAttr>()) {
+    if (!getAttachedPropertyWrappers().empty())
+      return true;
+  }
+
+  if (hasImplicitPropertyWrapper())
+    return true;
+
+  return false;
 }
 
 bool VarDecl::hasImplicitPropertyWrapper() const {
-  if (!getAttachedPropertyWrappers().empty())
+  if (getAttrs().hasAttribute<CustomAttr>()) {
+    if (!getAttachedPropertyWrappers().empty())
+      return false;
+  }
+
+  if (isImplicit())
     return false;
 
-  auto *dc = getDeclContext();
-  bool isClosureParam = isa<ParamDecl>(this) &&
-      dc->getContextKind() == DeclContextKind::AbstractClosureExpr;
-  return !isImplicit() && getName().hasDollarPrefix() && isClosureParam;
+  if (!isa<ParamDecl>(this))
+    return false;
+
+  if (!isa<AbstractClosureExpr>(getDeclContext()))
+    return false;
+
+  return getName().hasDollarPrefix();
 }
 
 bool VarDecl::hasExternalPropertyWrapper() const {