Fix record layout when synthesizing class types.

Prior to this patch, we would try to synthesize class types by
iterating over a DenseMap of FieldDecls and adding each one to
a CXXRecordDecl.  Since a DenseMap doesn't provide a deterministic
ordering of the elements, this would not add the fields in
FieldOffset order, but rather in some random order determined by
the memory layout of the DenseMap.

This patch fixes the issue by changing DenseMaps to vectors.  The
ability to lookup a value in the DenseMap was hardly being used,
and where it is sufficient to do a vector lookup.

Differential Revision: http://reviews.llvm.org/D8512

llvm-svn: 233090

12 files changed, 142 insertions, 188 deletions

diff --git a/lldb/include/lldb/Expression/ClangASTSource.h b/lldb/include/lldb/Expression/ClangASTSource.h
index 028bfb3666f..ab62e491766 100644
--- a/lldb/include/lldb/Expression/ClangASTSource.h
+++ b/lldb/include/lldb/Expression/ClangASTSource.h
@@ -11,6 +11,7 @@
 #define liblldb_ClangASTSource_h_
 
 #include <set>
+#include <vector>
 
 #include "clang/Basic/IdentifierTable.h"
 #include "lldb/Symbol/ClangExternalASTSourceCommon.h"
@@ -20,6 +21,12 @@
 
 #include "llvm/ADT/SmallSet.h"
 
+namespace clang
+{
+class CharUnits;
+class FieldDecl;
+}
+
 namespace lldb_private {
     
 //----------------------------------------------------------------------
@@ -122,7 +129,10 @@ public:
     FindExternalLexicalDecls (const clang::DeclContext *DC,
                               bool (*isKindWeWant)(clang::Decl::Kind),
                               llvm::SmallVectorImpl<clang::Decl*> &Decls);
-    
+
+    typedef std::vector<std::pair<const clang::FieldDecl *, uint64_t>> FieldOffsetList;
+    typedef std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> BaseOffsetList;
+
     //------------------------------------------------------------------
     /// Specify the layout of the contents of a RecordDecl.
     ///
@@ -155,15 +165,11 @@ public:
     ///
     /// @return
     ///     True <=> the layout is valid.
-    //-----------------------------------------------------------------    
-    bool 
-    layoutRecordType(const clang::RecordDecl *Record,
-                     uint64_t &Size, 
-                     uint64_t &Alignment,
-                     llvm::DenseMap <const clang::FieldDecl *, uint64_t> &FieldOffsets,
-                     llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &BaseOffsets,
-                     llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &VirtualBaseOffsets);
-    
+    //-----------------------------------------------------------------
+    bool layoutRecordType(const clang::RecordDecl *Record, uint64_t &Size, uint64_t &Alignment,
+                          FieldOffsetList &FieldOffsets, BaseOffsetList &BaseOffsets,
+                          BaseOffsetList &VirtualBaseOffsets);
+
     //------------------------------------------------------------------
     /// Complete a TagDecl.
     ///
@@ -277,14 +283,10 @@ public:
         {
             return m_original.CompleteType(Class);
         }
-        
-        bool 
-        layoutRecordType(const clang::RecordDecl *Record,
-                         uint64_t &Size, 
-                         uint64_t &Alignment,
-                         llvm::DenseMap <const clang::FieldDecl *, uint64_t> &FieldOffsets,
-                         llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &BaseOffsets,
-                         llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &VirtualBaseOffsets)
+
+        bool
+        layoutRecordType(const clang::RecordDecl *Record, uint64_t &Size, uint64_t &Alignment,
+                         FieldOffsetList &FieldOffsets, BaseOffsetList &BaseOffsets, BaseOffsetList &VirtualBaseOffsets)
         {
             return m_original.layoutRecordType(Record,
                                                Size, 
diff --git a/lldb/include/lldb/Symbol/ClangExternalASTSourceCallbacks.h b/lldb/include/lldb/Symbol/ClangExternalASTSourceCallbacks.h
index 0c8121135ef..70db4e3c458 100644
--- a/lldb/include/lldb/Symbol/ClangExternalASTSourceCallbacks.h
+++ b/lldb/include/lldb/Symbol/ClangExternalASTSourceCallbacks.h
@@ -34,13 +34,11 @@ public:
     typedef void (*CompleteTagDeclCallback)(void *baton, clang::TagDecl *);
     typedef void (*CompleteObjCInterfaceDeclCallback)(void *baton, clang::ObjCInterfaceDecl *);
     typedef void (*FindExternalVisibleDeclsByNameCallback)(void *baton, const clang::DeclContext *DC, clang::DeclarationName Name, llvm::SmallVectorImpl <clang::NamedDecl *> *results);
-    typedef bool (*LayoutRecordTypeCallback)(void *baton, 
-                                             const clang::RecordDecl *Record,
-                                             uint64_t &Size, 
-                                             uint64_t &Alignment,
-                                             llvm::DenseMap <const clang::FieldDecl *, uint64_t> &FieldOffsets,
-                                             llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &BaseOffsets,
-                                             llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &VirtualBaseOffsets);
+    typedef bool (*LayoutRecordTypeCallback)(
+        void *baton, const clang::RecordDecl *Record, uint64_t &Size, uint64_t &Alignment,
+        std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &FieldOffsets,
+        std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &BaseOffsets,
+        std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &VirtualBaseOffsets);
 
     ClangExternalASTSourceCallbacks (CompleteTagDeclCallback tag_decl_callback,
                                      CompleteObjCInterfaceDeclCallback objc_decl_callback,
@@ -121,14 +119,11 @@ public:
     
     virtual void
     CompleteType (clang::ObjCInterfaceDecl *objc_decl);
-    
-    bool 
-    layoutRecordType(const clang::RecordDecl *Record,
-                     uint64_t &Size, 
-                     uint64_t &Alignment,
-                     llvm::DenseMap <const clang::FieldDecl *, uint64_t> &FieldOffsets,
-                     llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &BaseOffsets,
-                     llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &VirtualBaseOffsets);
+
+    bool layoutRecordType(const clang::RecordDecl *Record, uint64_t &Size, uint64_t &Alignment,
+                          std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &FieldOffsets,
+                          std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &BaseOffsets,
+                          std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &VirtualBaseOffsets);
     void
     SetExternalSourceCallbacks (CompleteTagDeclCallback tag_decl_callback,
                                 CompleteObjCInterfaceDeclCallback objc_decl_callback,
diff --git a/lldb/source/Expression/ClangASTSource.cpp b/lldb/source/Expression/ClangASTSource.cpp
index dacd4cc57a6..8a39b7a38b5 100644
--- a/lldb/source/Expression/ClangASTSource.cpp
+++ b/lldb/source/Expression/ClangASTSource.cpp
@@ -1532,46 +1532,37 @@ ClangASTSource::FindObjCPropertyAndIvarDecls (NameSearchContext &context)
     while(0);
 }
 
-typedef llvm::DenseMap <const FieldDecl *, uint64_t> FieldOffsetMap;
-typedef llvm::DenseMap <const CXXRecordDecl *, CharUnits> BaseOffsetMap;
-
 template <class D, class O>
 static bool
-ImportOffsetMap (llvm::DenseMap <const D*, O> &destination_map,
-                 llvm::DenseMap <const D*, O> &source_map,
-                 ClangASTImporter *importer,
+ImportOffsetList(std::vector<std::pair<const D *, O>> &destination_list,
+                 const std::vector<std::pair<const D *, O>> &source_list, ClangASTImporter *importer,
                  ASTContext &dest_ctx)
 {
-    typedef llvm::DenseMap <const D*, O> MapType;
+    typedef std::vector<std::pair<const D *, O>> ListType;
 
-    for (typename MapType::iterator fi = source_map.begin(), fe = source_map.end();
-         fi != fe;
-         ++fi)
+    for (const auto &fi : source_list)
     {
-        DeclFromUser <D> user_decl(const_cast<D*>(fi->first));
+        DeclFromUser<D> user_decl(const_cast<D *>(fi.first));
         DeclFromParser <D> parser_decl(user_decl.Import(importer, dest_ctx));
         if (parser_decl.IsInvalid())
             return false;
-        destination_map.insert(std::pair<const D *, O>(parser_decl.decl, fi->second));
+        destination_list.push_back(std::pair<const D *, O>(parser_decl.decl, fi.second));
     }
 
     return true;
 }
 
-template <bool IsVirtual> bool ExtractBaseOffsets (const ASTRecordLayout &record_layout,
-                                                   DeclFromUser<const CXXRecordDecl> &record,
-                                                   BaseOffsetMap &base_offsets)
+template <bool IsVirtual>
+bool
+ExtractBaseOffsets(const ASTRecordLayout &record_layout, DeclFromUser<const CXXRecordDecl> &record,
+                   ClangASTSource::BaseOffsetList &base_offsets)
 {
-    for (CXXRecordDecl::base_class_const_iterator
-            bi = (IsVirtual ? record->vbases_begin() : record->bases_begin()),
-            be = (IsVirtual ? record->vbases_end() : record->bases_end());
-         bi != be;
-         ++bi)
+    for (const auto &base : (IsVirtual ? record->vbases() : record->bases()))
     {
-        if (!IsVirtual && bi->isVirtual())
+        if (!IsVirtual && base.isVirtual())
             continue;
 
-        const clang::Type *origin_base_type = bi->getType().getTypePtr();
+        const clang::Type *origin_base_type = base.getType().getTypePtr();
         const clang::RecordType *origin_base_record_type = origin_base_type->getAs<RecordType>();
 
         if (!origin_base_record_type)
@@ -1594,19 +1585,16 @@ template <bool IsVirtual> bool ExtractBaseOffsets (const ASTRecordLayout &record
         else
             base_offset = record_layout.getBaseClassOffset(origin_base_cxx_record.decl);
 
-        base_offsets.insert(std::pair<const CXXRecordDecl *, CharUnits>(origin_base_cxx_record.decl, base_offset));
+        base_offsets.push_back(std::make_pair(origin_base_cxx_record.decl, base_offset));
     }
 
     return true;
 }
 
 bool
-ClangASTSource::layoutRecordType(const RecordDecl *record,
-                                 uint64_t &size,
-                                 uint64_t &alignment,
-                                 FieldOffsetMap &field_offsets,
-                                 BaseOffsetMap &base_offsets,
-                                 BaseOffsetMap &virtual_base_offsets)
+ClangASTSource::layoutRecordType(const RecordDecl *record, uint64_t &size, uint64_t &alignment,
+                                 FieldOffsetList &field_offsets, BaseOffsetList &base_offsets,
+                                 BaseOffsetList &virtual_base_offsets)
 {
     ClangASTMetrics::RegisterRecordLayout();
 
@@ -1627,9 +1615,9 @@ ClangASTSource::layoutRecordType(const RecordDecl *record,
     if (origin_record.IsInvalid())
         return false;
 
-    FieldOffsetMap origin_field_offsets;
-    BaseOffsetMap origin_base_offsets;
-    BaseOffsetMap origin_virtual_base_offsets;
+    FieldOffsetList origin_field_offsets;
+    BaseOffsetList origin_base_offsets;
+    BaseOffsetList origin_virtual_base_offsets;
 
     ClangASTContext::GetCompleteDecl(&origin_record->getASTContext(), const_cast<RecordDecl*>(origin_record.decl));
 
@@ -1640,16 +1628,15 @@ ClangASTSource::layoutRecordType(const RecordDecl *record,
 
     int field_idx = 0, field_count = record_layout.getFieldCount();
 
-    for (RecordDecl::field_iterator fi = origin_record->field_begin(), fe = origin_record->field_end();
-         fi != fe;
-         ++fi)
+    origin_field_offsets.reserve(field_count);
+    for (const auto &field : origin_record->fields())
     {
         if (field_idx >= field_count)
             return false; // Layout didn't go well.  Bail out.
 
         uint64_t field_offset = record_layout.getFieldOffset(field_idx);
 
-        origin_field_offsets.insert(std::pair<const FieldDecl *, uint64_t>(*fi, field_offset));
+        origin_field_offsets.push_back(std::pair<const FieldDecl *, uint64_t>(field, field_offset));
 
         field_idx++;
     }
@@ -1665,9 +1652,9 @@ ClangASTSource::layoutRecordType(const RecordDecl *record,
             return false;
     }
 
-    if (!ImportOffsetMap(field_offsets, origin_field_offsets, m_ast_importer, parser_ast_context) ||
-        !ImportOffsetMap(base_offsets, origin_base_offsets, m_ast_importer, parser_ast_context) ||
-        !ImportOffsetMap(virtual_base_offsets, origin_virtual_base_offsets, m_ast_importer, parser_ast_context))
+    if (!ImportOffsetList(field_offsets, origin_field_offsets, m_ast_importer, parser_ast_context) ||
+        !ImportOffsetList(base_offsets, origin_base_offsets, m_ast_importer, parser_ast_context) ||
+        !ImportOffsetList(virtual_base_offsets, origin_virtual_base_offsets, m_ast_importer, parser_ast_context))
         return false;
 
     size = record_layout.getSize().getQuantity() * m_ast_context->getCharWidth();
@@ -1685,9 +1672,10 @@ ClangASTSource::layoutRecordType(const RecordDecl *record,
              fi != fe;
              ++fi)
         {
-            log->Printf("LRT[%u]     (FieldDecl*)%p, Name = '%s', Offset = %" PRId64 " bits",
-                        current_id, static_cast<void*>(*fi),
-                        fi->getNameAsString().c_str(), field_offsets[*fi]);
+
+            log->Printf("LRT[%u]     (FieldDecl*)%p, Name = '%s', Offset = %" PRId64 " bits", current_id,
+                        static_cast<void *>(*fi), fi->getNameAsString().c_str(),
+                        record_layout.getFieldOffset(fi->getFieldIndex()));
         }
         DeclFromParser <const CXXRecordDecl> parser_cxx_record = DynCast<const CXXRecordDecl>(parser_record);
         if (parser_cxx_record.IsValid())
@@ -1704,13 +1692,11 @@ ClangASTSource::layoutRecordType(const RecordDecl *record,
                 DeclFromParser <RecordDecl> base_record(base_record_type->getDecl());
                 DeclFromParser <CXXRecordDecl> base_cxx_record = DynCast<CXXRecordDecl>(base_record);
 
-                log->Printf("LRT[%u]     %s(CXXRecordDecl*)%p, Name = '%s', Offset = %" PRId64 " chars",
-                            current_id, (is_virtual ? "Virtual " : ""),
-                            static_cast<void*>(base_cxx_record.decl),
-                            base_cxx_record.decl->getNameAsString().c_str(),
-                            (is_virtual
-                                ? virtual_base_offsets[base_cxx_record.decl].getQuantity()
-                                : base_offsets[base_cxx_record.decl].getQuantity()));
+                clang::CharUnits base_offset = is_virtual ? record_layout.getVBaseClassOffset(base_cxx_record.decl)
+                                                          : record_layout.getBaseClassOffset(base_cxx_record.decl);
+                log->Printf("LRT[%u]     %s(CXXRecordDecl*)%p, Name = '%s', Offset = %" PRId64 " chars", current_id,
+                            (is_virtual ? "Virtual " : ""), static_cast<void *>(base_cxx_record.decl),
+                            base_cxx_record.decl->getNameAsString().c_str(), base_offset);
             }
         }
         else
diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCDeclVendor.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCDeclVendor.cpp
index ee5e3183508..9d949e4b33c 100644
--- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCDeclVendor.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCDeclVendor.cpp
@@ -141,12 +141,10 @@ public:
     }
 
     bool
-    layoutRecordType(const clang::RecordDecl *Record,
-                     uint64_t &Size,
-                     uint64_t &Alignment,
-                     llvm::DenseMap <const clang::FieldDecl *, uint64_t> &FieldOffsets,
-                     llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &BaseOffsets,
-                     llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &VirtualBaseOffsets)
+    layoutRecordType(const clang::RecordDecl *Record, uint64_t &Size, uint64_t &Alignment,
+                     std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &FieldOffsets,
+                     std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &BaseOffsets,
+                     std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &VirtualBaseOffsets)
     {
         return false;
     }
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 3323bded4f4..6984c86afd7 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -2073,8 +2073,9 @@ SymbolFileDWARF::ParseChildMembers
                                                                                                                              GetClangASTContext().GetBuiltinTypeForEncodingAndBitSize(eEncodingSint, word_width),
                                                                                                                              accessibility,
                                                                                                                              anon_field_info.bit_size);
-                                            
-                                            layout_info.field_offsets.insert(std::make_pair(unnamed_bitfield_decl, anon_field_info.bit_offset));
+
+                                            layout_info.field_offsets.push_back(
+                                                std::make_pair(unnamed_bitfield_decl, anon_field_info.bit_offset));
                                         }
                                     }
                                     last_field_info = this_field_info;
@@ -2124,9 +2125,8 @@ SymbolFileDWARF::ParseChildMembers
                                                                                     bit_size);
                                 
                                 GetClangASTContext().SetMetadataAsUserID (field_decl, MakeUserID(die->GetOffset()));
-                                
-                                layout_info.field_offsets.insert(std::make_pair(field_decl, field_bit_offset));
 
+                                layout_info.field_offsets.push_back(std::make_pair(field_decl, field_bit_offset));
                             }
                             else
                             {
@@ -2287,8 +2287,9 @@ SymbolFileDWARF::ParseChildMembers
                         }
                         else
                         {
-                            layout_info.base_offsets.insert(std::make_pair(base_class_clang_type.GetAsCXXRecordDecl(),
-                                                                           clang::CharUnits::fromQuantity(member_byte_offset)));
+                            layout_info.base_offsets.push_back(
+                                std::make_pair(base_class_clang_type.GetAsCXXRecordDecl(),
+                                               clang::CharUnits::fromQuantity(member_byte_offset)));
                         }
                     }
                 }
@@ -2669,43 +2670,36 @@ SymbolFileDWARF::ResolveClangOpaqueTypeDefinition (ClangASTType &clang_type)
                                                                   static_cast<uint32_t>(layout_info.base_offsets.size()),
                                                                   static_cast<uint32_t>(layout_info.vbase_offsets.size()));
 
-                        uint32_t idx;
-                        {
-                        llvm::DenseMap <const clang::FieldDecl *, uint64_t>::const_iterator pos, end = layout_info.field_offsets.end();
-                        for (idx = 0, pos = layout_info.field_offsets.begin(); pos != end; ++pos, ++idx)
+                        for (const auto &entry : layout_info.field_offsets)
                         {
-                            GetObjectFile()->GetModule()->LogMessage (log,
-                                                                      "SymbolFileDWARF::ResolveClangOpaqueTypeDefinition (clang_type = %p) field[%u] = { bit_offset=%u, name='%s' }",
-                                                                      static_cast<void*>(clang_type.GetOpaqueQualType()),
-                                                                      idx,
-                                                                      static_cast<uint32_t>(pos->second),
-                                                                      pos->first->getNameAsString().c_str());
-                        }
+                            GetObjectFile()->GetModule()->LogMessage(
+                                log, "SymbolFileDWARF::ResolveClangOpaqueTypeDefinition (clang_type = %p) field[%u] = "
+                                     "{ bit_offset=%u, name='%s' }",
+                                static_cast<void *>(clang_type.GetOpaqueQualType()), entry.first->getFieldIndex(),
+                                static_cast<uint32_t>(entry.second), entry.first->getNameAsString().c_str());
                         }
 
+                        uint32_t idx = 0;
+                        for (const auto &entry : layout_info.base_offsets)
                         {
-                        llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits>::const_iterator base_pos, base_end = layout_info.base_offsets.end();
-                        for (idx = 0, base_pos = layout_info.base_offsets.begin(); base_pos != base_end; ++base_pos, ++idx)
-                        {
-                            GetObjectFile()->GetModule()->LogMessage (log,
-                                                                      "SymbolFileDWARF::ResolveClangOpaqueTypeDefinition (clang_type = %p) base[%u] = { byte_offset=%u, name='%s' }",
-                                                                      clang_type.GetOpaqueQualType(),
-                                                                      idx,
-                                                                      (uint32_t)base_pos->second.getQuantity(),
-                                                                      base_pos->first->getNameAsString().c_str());
+                            GetObjectFile()->GetModule()->LogMessage(
+                                log, "SymbolFileDWARF::ResolveClangOpaqueTypeDefinition (clang_type = %p) base[%u] = { "
+                                     "byte_offset=%u, name='%s' }",
+                                clang_type.GetOpaqueQualType(), idx, (uint32_t)entry.second.getQuantity(),
+                                entry.first->getNameAsString().c_str());
+                            ++idx;
                         }
-                        }
-                        {
-                        llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits>::const_iterator vbase_pos, vbase_end = layout_info.vbase_offsets.end();
-                        for (idx = 0, vbase_pos = layout_info.vbase_offsets.begin(); vbase_pos != vbase_end; ++vbase_pos, ++idx)
+
+                        idx = 0;
+                        for (const auto &entry : layout_info.vbase_offsets)
                         {
-                            GetObjectFile()->GetModule()->LogMessage (log,
-                                                                      "SymbolFileDWARF::ResolveClangOpaqueTypeDefinition (clang_type = %p) vbase[%u] = { byte_offset=%u, name='%s' }",
-                                                                      static_cast<void*>(clang_type.GetOpaqueQualType()),
-                                                                      idx,
-                                                                      static_cast<uint32_t>(vbase_pos->second.getQuantity()),
-                                                                      vbase_pos->first->getNameAsString().c_str());
-                        }
+                            GetObjectFile()->GetModule()->LogMessage(
+                                log, "SymbolFileDWARF::ResolveClangOpaqueTypeDefinition (clang_type = %p) vbase[%u] = "
+                                     "{ byte_offset=%u, name='%s' }",
+                                static_cast<void *>(clang_type.GetOpaqueQualType()), idx,
+                                static_cast<uint32_t>(entry.second.getQuantity()),
+                                entry.first->getNameAsString().c_str());
+                            ++idx;
                         }
                     }
                     m_record_decl_to_layout_map.insert(std::make_pair(record_decl, layout_info));
@@ -7918,27 +7912,22 @@ SymbolFileDWARF::FindExternalVisibleDeclsByName (void *baton,
     }
 }
 
-bool 
-SymbolFileDWARF::LayoutRecordType (void *baton, 
-                                   const clang::RecordDecl *record_decl,
-                                   uint64_t &size, 
-                                   uint64_t &alignment,
-                                   llvm::DenseMap <const clang::FieldDecl *, uint64_t> &field_offsets,
-                                   llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &base_offsets,
-                                   llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &vbase_offsets)
+bool
+SymbolFileDWARF::LayoutRecordType(void *baton, const clang::RecordDecl *record_decl, uint64_t &size,
+                                  uint64_t &alignment,
+                                  std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &field_offsets,
+                                  std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &base_offsets,
+                                  std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &vbase_offsets)
 {
     SymbolFileDWARF *symbol_file_dwarf = (SymbolFileDWARF *)baton;
     return symbol_file_dwarf->LayoutRecordType (record_decl, size, alignment, field_offsets, base_offsets, vbase_offsets);
 }
 
-
-bool 
-SymbolFileDWARF::LayoutRecordType (const clang::RecordDecl *record_decl,
-                                   uint64_t &bit_size, 
-                                   uint64_t &alignment,
-                                   llvm::DenseMap <const clang::FieldDecl *, uint64_t> &field_offsets,
-                                   llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &base_offsets,
-                                   llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &vbase_offsets)
+bool
+SymbolFileDWARF::LayoutRecordType(const clang::RecordDecl *record_decl, uint64_t &bit_size, uint64_t &alignment,
+                                  std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &field_offsets,
+                                  std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &base_offsets,
+                                  std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &vbase_offsets)
 {
     Log *log (LogChannelDWARF::GetLogIfAll(DWARF_LOG_DEBUG_INFO));
     RecordDeclToLayoutMap::iterator pos = m_record_decl_to_layout_map.find (record_decl);
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
index 5ebb60e1367..4551d6ef56b 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -151,22 +151,16 @@ public:
                                     clang::DeclarationName Name,
                                     llvm::SmallVectorImpl <clang::NamedDecl *> *results);
 
-    static bool 
-    LayoutRecordType (void *baton, 
-                      const clang::RecordDecl *record_decl,
-                      uint64_t &size, 
-                      uint64_t &alignment,
-                      llvm::DenseMap <const clang::FieldDecl *, uint64_t> &field_offsets,
-                      llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &base_offsets,
-                      llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &vbase_offsets);
-
-    bool 
-    LayoutRecordType (const clang::RecordDecl *record_decl,
-                      uint64_t &size, 
-                      uint64_t &alignment,
-                      llvm::DenseMap <const clang::FieldDecl *, uint64_t> &field_offsets,
-                      llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &base_offsets,
-                      llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &vbase_offsets);
+    static bool
+    LayoutRecordType(void *baton, const clang::RecordDecl *record_decl, uint64_t &size, uint64_t &alignment,
+                     std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &FieldOffsets,
+                     std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &BaseOffsets,
+                     std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &VirtualBaseOffsets);
+
+    bool LayoutRecordType(const clang::RecordDecl *record_decl, uint64_t &size, uint64_t &alignment,
+                          std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &FieldOffsets,
+                          std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &BaseOffsets,
+                          std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &VirtualBaseOffsets);
 
     struct LayoutInfo
     {
@@ -180,9 +174,9 @@ public:
         }
         uint64_t bit_size;
         uint64_t alignment;
-        llvm::DenseMap <const clang::FieldDecl *, uint64_t> field_offsets;
-        llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> base_offsets;
-        llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> vbase_offsets;
+        std::vector<std::pair<const clang::FieldDecl *, uint64_t>> field_offsets;
+        std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> base_offsets;
+        std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> vbase_offsets;
     };
     //------------------------------------------------------------------
     // PluginInterface protocol
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
index e7c68595b6f..eeb3ef8242a 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
@@ -1474,14 +1474,12 @@ SymbolFileDWARFDebugMap::CompleteObjCInterfaceDecl (void *baton, clang::ObjCInte
     }
 }
 
-bool 
-SymbolFileDWARFDebugMap::LayoutRecordType (void *baton, 
-                                           const clang::RecordDecl *record_decl,
-                                           uint64_t &size, 
-                                           uint64_t &alignment,
-                                           llvm::DenseMap <const clang::FieldDecl *, uint64_t> &field_offsets,
-                                           llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &base_offsets,
-                                           llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &vbase_offsets)
+bool
+SymbolFileDWARFDebugMap::LayoutRecordType(
+    void *baton, const clang::RecordDecl *record_decl, uint64_t &size, uint64_t &alignment,
+    std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &field_offsets,
+    std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &base_offsets,
+    std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &vbase_offsets)
 {
     SymbolFileDWARFDebugMap *symbol_file_dwarf = (SymbolFileDWARFDebugMap *)baton;
     SymbolFileDWARF *oso_dwarf;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
index 1493292d4b9..cecd6396784 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
@@ -102,16 +102,12 @@ public:
     
     static void
     CompleteObjCInterfaceDecl (void *baton, clang::ObjCInterfaceDecl *);
-    
-    static bool 
-    LayoutRecordType (void *baton, 
-                      const clang::RecordDecl *record_decl,
-                      uint64_t &size, 
-                      uint64_t &alignment,
-                      llvm::DenseMap <const clang::FieldDecl *, uint64_t> &field_offsets,
-                      llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &base_offsets,
-                      llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &vbase_offsets);
 
+    static bool
+    LayoutRecordType(void *baton, const clang::RecordDecl *record_decl, uint64_t &size, uint64_t &alignment,
+                     std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &FieldOffsets,
+                     std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &BaseOffsets,
+                     std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &VirtualBaseOffsets);
 
     //------------------------------------------------------------------
     // PluginInterface protocol
diff --git a/lldb/source/Symbol/ClangExternalASTSourceCallbacks.cpp b/lldb/source/Symbol/ClangExternalASTSourceCallbacks.cpp
index bdc32654cc1..b8e78fe0c63 100644
--- a/lldb/source/Symbol/ClangExternalASTSourceCallbacks.cpp
+++ b/lldb/source/Symbol/ClangExternalASTSourceCallbacks.cpp
@@ -141,13 +141,12 @@ ClangExternalASTSourceCallbacks::CompleteType (ObjCInterfaceDecl *objc_decl)
         m_callback_objc_decl (m_callback_baton, objc_decl);
 }
 
-bool 
-ClangExternalASTSourceCallbacks::layoutRecordType(const clang::RecordDecl *Record,
-                                                  uint64_t &Size, 
-                                                  uint64_t &Alignment,
-                                                  llvm::DenseMap <const clang::FieldDecl *, uint64_t> &FieldOffsets,
-                                                  llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &BaseOffsets,
-                                                  llvm::DenseMap <const clang::CXXRecordDecl *, clang::CharUnits> &VirtualBaseOffsets)
+bool
+ClangExternalASTSourceCallbacks::layoutRecordType(
+    const clang::RecordDecl *Record, uint64_t &Size, uint64_t &Alignment,
+    std::vector<std::pair<const clang::FieldDecl *, uint64_t>> &FieldOffsets,
+    std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &BaseOffsets,
+    std::vector<std::pair<const clang::CXXRecordDecl *, clang::CharUnits>> &VirtualBaseOffsets)
 {
     if (m_callback_layout_record_type)
         return m_callback_layout_record_type(m_callback_baton,
diff --git a/lldb/test/functionalities/data-formatter/data-formatter-stl/libcxx/vbool/TestDataFormatterLibcxxVBool.py b/lldb/test/functionalities/data-formatter/data-formatter-stl/libcxx/vbool/TestDataFormatterLibcxxVBool.py
index aad75d46dcd..c5f78ad82aa 100644
--- a/lldb/test/functionalities/data-formatter/data-formatter-stl/libcxx/vbool/TestDataFormatterLibcxxVBool.py
+++ b/lldb/test/functionalities/data-formatter/data-formatter-stl/libcxx/vbool/TestDataFormatterLibcxxVBool.py
@@ -20,7 +20,7 @@ class LibcxxVBoolDataFormatterTestCase(TestBase):
         self.data_formatter_commands()
 
     @skipIfLinux # No standard locations for libc++ on Linux, so skip for now 
-    @skipIfWindows # http://llvm.org/pr21800
+    @skipIfWindows # Windows doesn't have libcxx
     @dwarf_test
     def test_with_dwarf_and_run_command(self):
         """Test data formatter commands."""
diff --git a/lldb/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/vbool/TestDataFormatterStdVBool.py b/lldb/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/vbool/TestDataFormatterStdVBool.py
index 314b5b9a17a..28d0001b7a4 100644
--- a/lldb/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/vbool/TestDataFormatterStdVBool.py
+++ b/lldb/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/vbool/TestDataFormatterStdVBool.py
@@ -22,7 +22,6 @@ class StdVBoolDataFormatterTestCase(TestBase):
 
     @expectedFailureFreeBSD("llvm.org/pr20548") # fails to build on lab.llvm.org buildbot
     @dwarf_test
-    @skipIfWindows # http://llvm.org/pr21800
     @skipIfDarwin
     def test_with_dwarf_and_run_command(self):
         """Test data formatter commands."""
diff --git a/lldb/test/lang/c/bitfields/TestBitfields.py b/lldb/test/lang/c/bitfields/TestBitfields.py
index 573d161ff75..380246ddd6b 100644
--- a/lldb/test/lang/c/bitfields/TestBitfields.py
+++ b/lldb/test/lang/c/bitfields/TestBitfields.py
@@ -26,7 +26,6 @@ class BitfieldsTestCase(TestBase):
         self.bitfields_variable_python()
 
     @dwarf_test
-    @unittest2.skipIf(sys.platform.startswith("win32"), "BitFields exhibit crashes in record layout on Windows (http://llvm.org/pr21800)")
     def test_with_dwarf_and_run_command(self):
         """Test 'frame variable ...' on a variable with bitfields."""
         self.buildDwarf()
@@ -34,7 +33,6 @@ class BitfieldsTestCase(TestBase):
 
     @python_api_test
     @dwarf_test
-    @unittest2.skipIf(sys.platform.startswith("win32"), "BitFields exhibit crashes in record layout on Windows (http://llvm.org/pr21800)")
     @expectedFailureGcc # GCC (4.6/4.7) generates incorrect code with unnamed bitfields.
     def test_with_dwarf_and_python_api(self):
         """Use Python APIs to inspect a bitfields variable."""