[PDB] Add native reading support for UDT / class types.

This allows the native reader to find records of class/struct/
union type and dump them.  This behavior is tested by using the
diadump subcommand against golden output produced by actual DIA
SDK on the same PDB file, and again using pretty -native to
confirm that we actually dump the classes.  We don't find class
members or anything like that yet, for now it's just the class
itself.

llvm-svn: 342779

2 files changed, 54 insertions, 0 deletions

diff --git a/llvm/lib/DebugInfo/CodeView/CMakeLists.txt b/llvm/lib/DebugInfo/CodeView/CMakeLists.txt
index 0515788d85e..e1bdffd30ee 100644
--- a/llvm/lib/DebugInfo/CodeView/CMakeLists.txt
+++ b/llvm/lib/DebugInfo/CodeView/CMakeLists.txt
@@ -34,6 +34,7 @@ add_llvm_library(LLVMDebugInfoCodeView
   TypeIndex.cpp
   TypeIndexDiscovery.cpp
   TypeHashing.cpp
+  TypeRecordHelpers.cpp
   TypeRecordMapping.cpp
   TypeStreamMerger.cpp
   TypeTableCollection.cpp
diff --git a/llvm/lib/DebugInfo/CodeView/TypeRecordHelpers.cpp b/llvm/lib/DebugInfo/CodeView/TypeRecordHelpers.cpp
new file mode 100644
index 00000000000..2a66474cf5b
--- /dev/null
+++ b/llvm/lib/DebugInfo/CodeView/TypeRecordHelpers.cpp
@@ -0,0 +1,53 @@
+//===- TypeRecordHelpers.cpp ------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/CodeView/TypeRecordHelpers.h"
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/DebugInfo/CodeView/TypeIndexDiscovery.h"
+#include "llvm/DebugInfo/CodeView/TypeDeserializer.h"
+
+using namespace llvm;
+using namespace llvm::codeview;
+
+template <typename RecordT> static ClassOptions getUdtOptions(CVType CVT) {
+  RecordT Record;
+  if (auto EC = TypeDeserializer::deserializeAs<RecordT>(CVT, Record)) {
+    consumeError(std::move(EC));
+    return ClassOptions::None;
+  }
+  return Record.getOptions();
+}
+
+bool llvm::codeview::isUdtForwardRef(CVType CVT) {
+  ClassOptions UdtOptions = ClassOptions::None;
+  switch (CVT.kind()) {
+  case LF_STRUCTURE:
+  case LF_CLASS:
+  case LF_INTERFACE:
+    UdtOptions = getUdtOptions<ClassRecord>(std::move(CVT));
+    break;
+  case LF_ENUM:
+    UdtOptions = getUdtOptions<EnumRecord>(std::move(CVT));
+    break;
+  case LF_UNION:
+    UdtOptions = getUdtOptions<UnionRecord>(std::move(CVT));
+    break;
+  default:
+    return false;
+  }
+  return (UdtOptions & ClassOptions::ForwardReference) != ClassOptions::None;
+}
+
+TypeIndex llvm::codeview::getModifiedType(const CVType &CVT) {
+  assert(CVT.kind() == LF_MODIFIER);
+  SmallVector<TypeIndex, 1> Refs;
+  discoverTypeIndices(CVT, Refs);
+  return Refs.front();
+}