Remove isIgnored()-test that is more expensive than the analysis behind it

[djasper]

Summary

In many translation units I have tried, the calls to isIgnored() removed in this patch are more expensive than doing the analysis that is behind it. The speed-up in translation units I have tried is between 10 and 20%.

[djasper]

Landed as r290842.

lib/Sema/SemaTemplate.cpp

class UnnamedLocalNoLinkageFinder
     SourceRange SR;
 
     typedef TypeVisitor<UnnamedLocalNoLinkageFinder, bool> inherited;
 
   public:
     UnnamedLocalNoLinkageFinder(Sema &S, SourceRange SR) : S(S), SR(SR) { }
 
     bool Visit(QualType T) {
-      return inherited::Visit(T.getTypePtr());
+      return T.isNull() ? false : inherited::Visit(T.getTypePtr());
     }
 
 #define TYPE(Class, Parent) \
     bool Visit##Class##Type(const Class##Type *);
 #define ABSTRACT_TYPE(Class, Parent) \
     bool Visit##Class##Type(const Class##Type *) { return false; }
 #define NON_CANONICAL_TYPE(Class, Parent) \
     bool Visit##Class##Type(const Class##Type *) { return false; }
bool Sema::CheckTemplateArgument(TemplateTypeParmDecl *Param,
 
   // C++03 [temp.arg.type]p2:
   //   A local type, a type with no linkage, an unnamed type or a type
   //   compounded from any of these types shall not be used as a
   //   template-argument for a template type-parameter.
   //
   // C++11 allows these, and even in C++03 we allow them as an extension with
   // a warning.
-  bool NeedsCheck;
-  if (LangOpts.CPlusPlus11)
-    NeedsCheck =
-        !Diags.isIgnored(diag::warn_cxx98_compat_template_arg_unnamed_type,
-                         SR.getBegin()) ||
-        !Diags.isIgnored(diag::warn_cxx98_compat_template_arg_local_type,
-                         SR.getBegin());
-  else
-    NeedsCheck = Arg->hasUnnamedOrLocalType();
-
-  if (NeedsCheck) {
+  if (LangOpts.CPlusPlus11 || Arg->hasUnnamedOrLocalType()) {
     UnnamedLocalNoLinkageFinder Finder(*this, SR);
     (void)Finder.Visit(Context.getCanonicalType(Arg));
   }
 
   return false;
 }
 
 enum NullPointerValueKind {