[PATCH] Thread the info about vbptr sharing through ASTRecordLayout

[Timur Iskhodzhanov]

Hi rnk,

This addresses the post-commit comments on r194082.

http://llvm-reviews.chandlerc.com/D2120

Files:
  include/clang/AST/RecordLayout.h
  lib/AST/RecordLayout.cpp
  lib/AST/RecordLayoutBuilder.cpp
  lib/AST/VTableBuilder.cpp

Index: include/clang/AST/RecordLayout.h
===================================================================
--- include/clang/AST/RecordLayout.h
+++ include/clang/AST/RecordLayout.h
@@ -110,6 +110,9 @@
     
     /// PrimaryBase - The primary base info for this record.
     llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> PrimaryBase;
+
+    /// BaseSharingVBPtr - The base we share vbptr with.
+    const CXXRecordDecl *BaseSharingVBPtr;
     
     /// FIXME: This should really use a SmallPtrMap, once we have one in LLVM :)
     typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
@@ -143,6 +146,7 @@
                   CharUnits SizeOfLargestEmptySubobject,
                   const CXXRecordDecl *PrimaryBase,
                   bool IsPrimaryBaseVirtual,
+                  const CXXRecordDecl *BaseSharingVBPtr,
                   bool ForceAlign,
                   const BaseOffsetsMapTy& BaseOffsets,
                   const VBaseOffsetsMapTy& VBaseOffsets);
@@ -277,6 +281,11 @@
     return CXXInfo->VBPtrOffset;
   }
 
+  const CXXRecordDecl *getBaseSharingVBPtr() const {
+    assert(CXXInfo && "Record layout does not have C++ specific info!");
+    return CXXInfo->BaseSharingVBPtr;
+  }
+
   const VBaseOffsetsMapTy &getVBaseOffsetsMap() const {
     assert(CXXInfo && "Record layout does not have C++ specific info!");
     return CXXInfo->VBaseOffsets;
Index: lib/AST/RecordLayout.cpp
===================================================================
--- lib/AST/RecordLayout.cpp
+++ lib/AST/RecordLayout.cpp
@@ -54,6 +54,7 @@
                                  CharUnits SizeOfLargestEmptySubobject,
                                  const CXXRecordDecl *PrimaryBase,
                                  bool IsPrimaryBaseVirtual,
+                                 const CXXRecordDecl *BaseSharingVBPtr,
                                  bool AlignAfterVBases,
                                  const BaseOffsetsMapTy& BaseOffsets,
                                  const VBaseOffsetsMapTy& VBaseOffsets)
@@ -76,6 +77,7 @@
   CXXInfo->VBPtrOffset = vbptroffset;
   CXXInfo->HasVFPtr = hasVFPtr;
   CXXInfo->HasOwnVBPtr = hasOwnVBPtr;
+  CXXInfo->BaseSharingVBPtr = BaseSharingVBPtr;
   CXXInfo->AlignAfterVBases = AlignAfterVBases;
 
 
Index: lib/AST/RecordLayoutBuilder.cpp
===================================================================
--- lib/AST/RecordLayoutBuilder.cpp
+++ lib/AST/RecordLayoutBuilder.cpp
@@ -2677,7 +2677,8 @@
         Builder.DataSize, Builder.FieldOffsets.data(),
         Builder.FieldOffsets.size(), Builder.DataSize,
         Builder.NonVirtualAlignment, CharUnits::Zero(), Builder.PrimaryBase,
-        false, Builder.AlignAfterVBases, Builder.Bases, Builder.VBases);
+        false, Builder.SharedVBPtrBase, Builder.AlignAfterVBases,
+        Builder.Bases, Builder.VBases);
   } else {
     Builder.layout(D);
     return new (*this) ASTRecordLayout(
@@ -2745,7 +2746,7 @@
                                   EmptySubobjects.SizeOfLargestEmptySubobject,
                                   Builder.PrimaryBase,
                                   Builder.PrimaryBaseIsVirtual,
-                                  true,
+                                  0, true,
                                   Builder.Bases, Builder.VBases);
   } else {
     RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/0);
Index: lib/AST/VTableBuilder.cpp
===================================================================
--- lib/AST/VTableBuilder.cpp
+++ lib/AST/VTableBuilder.cpp
@@ -3363,30 +3363,17 @@
   const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
   BasesSetVectorTy VisitedBases;
 
-  // First, see if the Derived class shared the vbptr
-  // with the first non-virtual base.
-  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
-       E = RD->bases_end(); I != E; ++I) {
-    if (I->isVirtual())
-      continue;
-
-    const CXXRecordDecl *CurBase = I->getType()->getAsCXXRecordDecl();
-    CharUnits DerivedVBPtrOffset = Layout.getVBPtrOffset(),
-              BaseOffset = Layout.getBaseClassOffset(CurBase);
-    const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(CurBase);
-    if (!BaseLayout.hasVBPtr() ||
-        DerivedVBPtrOffset != BaseOffset + BaseLayout.getVBPtrOffset())
-      continue;
-
+  // First, see if the Derived class shared the vbptr with a non-virtual base.
+  if (const CXXRecordDecl *VBPtrBase = Layout.getBaseSharingVBPtr()) {
     // If the Derived class shares the vbptr with a non-virtual base,
     // it inherits its vbase indices.
-    computeVBTableRelatedInformation(CurBase);
-    for (CXXRecordDecl::base_class_const_iterator J = CurBase->vbases_begin(),
-         F = CurBase->vbases_end(); J != F; ++J) {
-      const CXXRecordDecl *SubVBase = J->getType()->getAsCXXRecordDecl();
-      assert(VBTableIndices.count(ClassPairTy(CurBase, SubVBase)));
+    computeVBTableRelatedInformation(VBPtrBase);
+    for (CXXRecordDecl::base_class_const_iterator I = VBPtrBase->vbases_begin(),
+         E = VBPtrBase->vbases_end(); I != E; ++I) {
+      const CXXRecordDecl *SubVBase = I->getType()->getAsCXXRecordDecl();
+      assert(VBTableIndices.count(ClassPairTy(VBPtrBase, SubVBase)));
       VBTableIndices[ClassPairTy(RD, SubVBase)] =
-          VBTableIndices[ClassPairTy(CurBase, SubVBase)];
+          VBTableIndices[ClassPairTy(VBPtrBase, SubVBase)];
       VisitedBases.insert(SubVBase);
     }
   }
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