Sketch out a DWARF parser.

This introduces a new library to LLVM: libDebugInfo. It will provide debug information
parsing to LLVM. Much of the design and some of the code is taken from the LLDB project.

It also contains an llvm-dwarfdump tool that can dump the abbrevs and DIEs from an
object file. It can be used to write tests for DWARF input and output easily.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139627 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/DebugInfo/DWARFAbbreviationDeclaration.h b/lib/DebugInfo/DWARFAbbreviationDeclaration.h
new file mode 100644
index 0000000..2463a3c
--- /dev/null
+++ b/lib/DebugInfo/DWARFAbbreviationDeclaration.h
@@ -0,0 +1,54 @@
+//===-- DWARFAbbreviationDeclaration.h --------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEBUGINFO_DWARFABBREVIATIONDECLARATION_H
+#define LLVM_DEBUGINFO_DWARFABBREVIATIONDECLARATION_H
+
+#include "DWARFAttribute.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/DataExtractor.h"
+
+namespace llvm {
+
+class raw_ostream;
+
+class DWARFAbbreviationDeclaration {
+  uint32_t Code;
+  uint32_t Tag;
+  bool HasChildren;
+  SmallVector<DWARFAttribute, 8> Attributes;
+public:
+  enum { InvalidCode = 0 };
+  DWARFAbbreviationDeclaration()
+    : Code(InvalidCode), Tag(0), HasChildren(0) {}
+
+  uint32_t getCode() const { return Code; }
+  uint32_t getTag() const { return Tag; }
+  bool hasChildren() const { return HasChildren; }
+  uint32_t getNumAttributes() const { return Attributes.size(); }
+  uint16_t getAttrByIndex(uint32_t idx) const {
+    return Attributes.size() > idx ? Attributes[idx].getAttribute() : 0;
+  }
+  uint16_t getFormByIndex(uint32_t idx) const {
+    return Attributes.size() > idx ? Attributes[idx].getForm() : 0;
+  }
+
+  uint32_t findAttributeIndex(uint16_t attr) const;
+  bool extract(DataExtractor data, uint32_t* offset_ptr);
+  bool extract(DataExtractor data, uint32_t* offset_ptr, uint32_t code);
+  bool isValid() const { return Code != 0 && Tag != 0; }
+  void dump(raw_ostream &OS) const;
+  const SmallVectorImpl<DWARFAttribute> &getAttributes() const {
+    return Attributes;
+  }
+};
+
+}
+
+#endif