Rework the shadow struct that is layed out for Objective-C classes.

 - Superclasses are now always laid out their shadow structure at the
   first field.

 - Prior to this, the entire class heirarchy was flattened into a
   single structure which meant that alignment, padding, and bitfields
   weren't packed correctly (the ASTRecordLayout was correct however,
   which meant our debug info didn't coincide with ivar offsets, for
   example).

 - This is still very suboptimal, but I believe the ivar layout itself
   is now at least close to correct.

 - <rdar://problem/6773388> error: objc[29823]: layout bitmap sliding
   backwards


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@69771 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 33 insertions, 10 deletions

diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index c4597e2235..a3a2778860 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -621,11 +621,9 @@ void ASTRecordLayout::LayoutField(const FieldDecl *FD, unsigned FieldNo,
   Alignment = std::max(Alignment, FieldAlign);
 }
 
-void ASTContext::CollectObjCIvars(const ObjCInterfaceDecl *OI,
-                             llvm::SmallVectorImpl<FieldDecl*> &Fields) {
-  const ObjCInterfaceDecl *SuperClass = OI->getSuperClass();
-  if (SuperClass)
-    CollectObjCIvars(SuperClass, Fields);
+static void CollectLocalObjCIvars(ASTContext *Ctx,
+                                  const ObjCInterfaceDecl *OI,
+                                  llvm::SmallVectorImpl<FieldDecl*> &Fields) {
   for (ObjCInterfaceDecl::ivar_iterator I = OI->ivar_begin(),
        E = OI->ivar_end(); I != E; ++I) {
     ObjCIvarDecl *IVDecl = *I;
@@ -633,20 +631,28 @@ void ASTContext::CollectObjCIvars(const ObjCInterfaceDecl *OI,
       Fields.push_back(cast<FieldDecl>(IVDecl));
   }
   // look into properties.
-  for (ObjCInterfaceDecl::prop_iterator I = OI->prop_begin(*this),
-       E = OI->prop_end(*this); I != E; ++I) {
+  for (ObjCInterfaceDecl::prop_iterator I = OI->prop_begin(*Ctx),
+       E = OI->prop_end(*Ctx); I != E; ++I) {
     if (ObjCIvarDecl *IV = (*I)->getPropertyIvarDecl())
       Fields.push_back(cast<FieldDecl>(IV));
   }
 }
 
+
+void ASTContext::CollectObjCIvars(const ObjCInterfaceDecl *OI,
+                             llvm::SmallVectorImpl<FieldDecl*> &Fields) {
+  if (const ObjCInterfaceDecl *SuperClass = OI->getSuperClass())
+    CollectObjCIvars(SuperClass, Fields);
+  CollectLocalObjCIvars(this, OI, Fields);
+}
+
 /// addRecordToClass - produces record info. for the class for its
 /// ivars and all those inherited.
 ///
 const RecordDecl *ASTContext::addRecordToClass(const ObjCInterfaceDecl *D) {
   // FIXME: The only client relying on this working in the presence of
-  // forward declarations is IRgen, which should not need it. Fix
-  // and simplify this code.
+  // forward declarations is CodeGenTypes in IRgen, which should not
+  // need it. Fix and simplify this code.
   RecordDecl *&RD = ASTRecordForInterface[D];
   if (RD) {
     // If we have a record decl already and it is either a definition or if 'D'
@@ -662,11 +668,28 @@ const RecordDecl *ASTContext::addRecordToClass(const ObjCInterfaceDecl *D) {
                                    D->getIdentifier());
   
   llvm::SmallVector<FieldDecl*, 32> RecFields;
-  CollectObjCIvars(D, RecFields);
+  CollectLocalObjCIvars(this, D, RecFields);
   
   if (RD == 0)
     RD = RecordDecl::Create(*this, TagDecl::TK_struct, 0, D->getLocation(),
                             D->getIdentifier());
+
+  
+  const RecordDecl *SRD;
+  if (const ObjCInterfaceDecl *SuperClass = D->getSuperClass()) {
+    SRD = addRecordToClass(SuperClass);
+  } else {
+    SRD = RecordDecl::Create(*this, TagDecl::TK_struct, 0, SourceLocation(), 0);
+    const_cast<RecordDecl*>(SRD)->completeDefinition(*this);
+  }
+
+  RD->addDecl(*this, 
+              FieldDecl::Create(*this, RD,
+                                SourceLocation(),
+                                0,
+                                getTagDeclType(const_cast<RecordDecl*>(SRD)),
+                                0, false));
+
   /// FIXME! Can do collection of ivars and adding to the record while
   /// doing it.
   for (unsigned i = 0, e = RecFields.size(); i != e; ++i) {