r184696 - Avoid adding entries to the DeclContext lookup table multiple times when lazily

[Richard Smith]

Author: rsmith
Date: Mon Jun 24 02:20:36 2013
New Revision: 184696

URL: http://llvm.org/viewvc/llvm-project?rev=184696&view=rev
Log:
Avoid adding entries to the DeclContext lookup table multiple times when lazily
constructing a lookup table.

Previously, buildLookup would add lookup table entries for each item lexically
within the DC, and adding the first entry with a given name would trigger the
external source to add all its entries with that name. Then buildLookup would
carry on and re-add those entries all over again.

Instead, follow a simple rule: a declaration from an external source is only
ever made visible by the external source. One exception to this: since we don't
usually build a lookup table for the TU in C, and we never serialize one, we
don't expect the external source to provide lookups in the TU in C, so we build
those ones ourselves.

Modified:
    cfe/trunk/lib/AST/DeclBase.cpp
    cfe/trunk/test/Modules/cxx-templates.cpp

Modified: cfe/trunk/lib/AST/DeclBase.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/DeclBase.cpp?rev=184696&r1=184695&r2=184696&view=diff
==============================================================================
--- cfe/trunk/lib/AST/DeclBase.cpp (original)
+++ cfe/trunk/lib/AST/DeclBase.cpp Mon Jun 24 02:20:36 2013
@@ -1216,8 +1216,16 @@ void DeclContext::buildLookupImpl(DeclCo
     // Insert this declaration into the lookup structure, but only if
     // it's semantically within its decl context. Any other decls which
     // should be found in this context are added eagerly.
+    //
+    // If it's from an AST file, don't add it now. It'll get handled by
+    // FindExternalVisibleDeclsByName if needed. Exception: if we're not
+    // in C++, we do not track external visible decls for the TU, so in
+    // that case we need to collect them all here.
     if (NamedDecl *ND = dyn_cast<NamedDecl>(D))
-      if (ND->getDeclContext() == DCtx && !shouldBeHidden(ND))
+      if (ND->getDeclContext() == DCtx && !shouldBeHidden(ND) &&
+          (!ND->isFromASTFile() ||
+           (isTranslationUnit() &&
+            !getParentASTContext().getLangOpts().CPlusPlus)))
         makeDeclVisibleInContextImpl(ND, false);
 
     // If this declaration is itself a transparent declaration context

Modified: cfe/trunk/test/Modules/cxx-templates.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Modules/cxx-templates.cpp?rev=184696&r1=184695&r2=184696&view=diff
==============================================================================
--- cfe/trunk/test/Modules/cxx-templates.cpp (original)
+++ cfe/trunk/test/Modules/cxx-templates.cpp Mon Jun 24 02:20:36 2013
@@ -27,10 +27,6 @@ void g() {
 // CHECK-GLOBAL-NEXT: |-FunctionTemplate {{.*}} 'f'
 // CHECK-GLOBAL-NEXT: |-FunctionTemplate {{.*}} 'f'
 // CHECK-GLOBAL-NEXT: |-FunctionTemplate {{.*}} 'f'
-// CHECK-GLOBAL-NEXT: |-FunctionTemplate {{.*}} 'f'
-// CHECK-GLOBAL-NEXT: |-FunctionTemplate {{.*}} 'f'
-// CHECK-GLOBAL-NEXT: |-FunctionTemplate {{.*}} 'f'
-// CHECK-GLOBAL-NEXT: |-FunctionTemplate {{.*}} 'f'
 // CHECK-GLOBAL-NEXT: `-FunctionTemplate {{.*}} 'f'
 
 // FIXME: There should only be two 'f's here.