[AST] Add OriginalDC argument to ExternalASTSource::FindExternalVisibleDeclsByName (#123152)

Part for relanding https://github.com/llvm/llvm-project/pull/122887.

I split this to test where the performance regession comes from if
modules are not used.

1 files changed, 14 insertions, 5 deletions

diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index fb701f7..7c2dcf9 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -1856,9 +1856,16 @@ DeclContext::lookup(DeclarationName Name) const {
   if (getDeclKind() == Decl::LinkageSpec || getDeclKind() == Decl::Export)
     return getParent()->lookup(Name);
 
-  const DeclContext *PrimaryContext = getPrimaryContext();
-  if (PrimaryContext != this)
-    return PrimaryContext->lookup(Name);
+  return getPrimaryContext()->lookupImpl(Name, this);
+}
+
+DeclContext::lookup_result
+DeclContext::lookupImpl(DeclarationName Name,
+                        const DeclContext *OriginalLookupDC) const {
+  assert(this == getPrimaryContext() &&
+         "lookupImpl should only be called with primary DC!");
+  assert(getDeclKind() != Decl::LinkageSpec && getDeclKind() != Decl::Export &&
+         "We shouldn't lookup in transparent DC.");
 
   // If we have an external source, ensure that any later redeclarations of this
   // context have been loaded, since they may add names to the result of this
@@ -1889,7 +1896,8 @@ DeclContext::lookup(DeclarationName Name) const {
     if (!R.second && !R.first->second.hasExternalDecls())
       return R.first->second.getLookupResult();
 
-    if (Source->FindExternalVisibleDeclsByName(this, Name) || !R.second) {
+    if (Source->FindExternalVisibleDeclsByName(this, Name, OriginalLookupDC) ||
+        !R.second) {
       if (StoredDeclsMap *Map = LookupPtr) {
         StoredDeclsMap::iterator I = Map->find(Name);
         if (I != Map->end())
@@ -2115,7 +2123,8 @@ void DeclContext::makeDeclVisibleInContextImpl(NamedDecl *D, bool Internal) {
     if (ExternalASTSource *Source = getParentASTContext().getExternalSource())
       if (hasExternalVisibleStorage() &&
           Map->find(D->getDeclName()) == Map->end())
-        Source->FindExternalVisibleDeclsByName(this, D->getDeclName());
+        Source->FindExternalVisibleDeclsByName(this, D->getDeclName(),
+                                               D->getDeclContext());
 
   // Insert this declaration into the map.
   StoredDeclsList &DeclNameEntries = (*Map)[D->getDeclName()];