Make ASTContext explicitly keep track of the declaration for the C

FILE type, rather than using name lookup to find FILE within the
translation unit. Within precompiled headers, FILE is treated as yet
another "special type" (like __builtin_va_list).

This change should provide a performance improvement (not verified),
since the lookup into the translation unit declaration 
forces the (otherwise unneeded) construction of a large hash table.
More importantly, with precompiled headers, the construction
of that table requires deserializing most of the top-level
declarations from the precompiled header, which are then unused.

Fixes PR 4509.

llvm-svn: 74911

1 files changed, 15 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index f148e8d0e14..a1ab68ac2a8 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -1691,6 +1691,14 @@ Sema::ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
       }
     }
   }
+
+  // If this is the C FILE type, notify the AST context.
+  if (IdentifierInfo *II = NewTD->getIdentifier())
+    if (!NewTD->isInvalidDecl() &&
+        NewTD->getDeclContext()->getLookupContext()->isTranslationUnit() &&        
+        II->isStr("FILE"))
+      Context.setFILEDecl(NewTD);
+  
   return NewTD;
 }
 
@@ -3768,6 +3776,13 @@ CreateNewDecl:
     CurContext->addDecl(New);
   }
 
+  // If this is the C FILE type, notify the AST context.
+  if (IdentifierInfo *II = New->getIdentifier())
+    if (!New->isInvalidDecl() &&
+        New->getDeclContext()->getLookupContext()->isTranslationUnit() &&        
+        II->isStr("FILE"))
+      Context.setFILEDecl(New);
+  
   OwnedDecl = true;
   return DeclPtrTy::make(New);
 }