1 files changed, 52 insertions, 2 deletions

diff --git a/lib/Frontend/PCHWriterDecl.cpp b/lib/Frontend/PCHWriterDecl.cpp
index f0d563297b..06266d2282 100644
--- a/lib/Frontend/PCHWriterDecl.cpp
+++ b/lib/Frontend/PCHWriterDecl.cpp
@@ -16,7 +16,6 @@
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/Expr.h"
-#include "clang/CodeGen/BackendUtil.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Bitcode/BitstreamWriter.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -1079,12 +1078,63 @@ void PCHWriter::WriteDeclsBlockAbbrevs() {
 /// clients to use a separate API call to "realize" the decl. This should be
 /// relatively painless since they would presumably only do it for top-level
 /// decls.
+//
+// FIXME: This predicate is essentially IRgen's predicate to determine whether a
+// declaration can be deferred. Merge them somehow.
 static bool isRequiredDecl(const Decl *D, ASTContext &Context) {
   // File scoped assembly must be seen.
   if (isa<FileScopeAsmDecl>(D))
     return true;
 
-  return DeclIsRequiredFunctionOrFileScopedVar(D);
+  // Otherwise if this isn't a function or a file scoped variable it doesn't
+  // need to be seen.
+  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
+    if (!VD->isFileVarDecl())
+      return false;
+  } else if (!isa<FunctionDecl>(D))
+    return false;
+
+  // Aliases and used decls must be seen.
+  if (D->hasAttr<AliasAttr>() || D->hasAttr<UsedAttr>())
+    return true;
+
+  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+    // Forward declarations don't need to be seen.
+    if (!FD->isThisDeclarationADefinition())
+      return false;
+
+    // Constructors and destructors must be seen.
+    if (FD->hasAttr<ConstructorAttr>() || FD->hasAttr<DestructorAttr>())
+      return true;
+
+    // Otherwise, this is required unless it is static.
+    //
+    // FIXME: Inlines.
+    return FD->getStorageClass() != FunctionDecl::Static;
+  } else {
+    const VarDecl *VD = cast<VarDecl>(D);
+
+    // Structs that have non-trivial constructors or destructors must be seen.
+    if (const RecordType *RT = VD->getType()->getAs<RecordType>()) {
+      if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
+        if (!RD->hasTrivialConstructor() || !RD->hasTrivialDestructor())
+          return true;
+      }
+    }
+
+    // In C++, this doesn't need to be seen if it is marked "extern".
+    if (Context.getLangOptions().CPlusPlus && !VD->getInit() &&
+        (VD->getStorageClass() == VarDecl::Extern ||
+         VD->isExternC()))
+      return false;
+
+    // In C, this doesn't need to be seen unless it is a definition.
+    if (!Context.getLangOptions().CPlusPlus && !VD->getInit())
+      return false;
+
+    // Otherwise, this is required unless it is static.
+    return VD->getStorageClass() != VarDecl::Static;
+  }
 }
 
 void PCHWriter::WriteDecl(ASTContext &Context, Decl *D) {