Create a stub for DWARF parser unittests

Moves one DWARF-specific header to include/llvm/DebugInfo from lib/.
Add a short unittest for r179095.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179678 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/DebugInfo/DWARFFormValue.h

@@ -0,0 +1,82 @@
+//===-- DWARFFormValue.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_DWARFFORMVALUE_H
+#define LLVM_DEBUGINFO_DWARFFORMVALUE_H
+
+#include "llvm/Support/DataExtractor.h"
+
+namespace llvm {
+
+class DWARFCompileUnit;
+class raw_ostream;
+
+class DWARFFormValue {
+public:
+  struct ValueType {
+    ValueType() : data(NULL) {
+      uval = 0;
+    }
+
+    union {
+      uint64_t uval;
+      int64_t sval;
+      const char* cstr;
+    };
+    const uint8_t* data;
+  };
+
+  enum {
+    eValueTypeInvalid = 0,
+    eValueTypeUnsigned,
+    eValueTypeSigned,
+    eValueTypeCStr,
+    eValueTypeBlock
+  };
+
+private:
+  uint16_t Form;   // Form for this value.
+  ValueType Value; // Contains all data for the form.
+
+public:
+  DWARFFormValue(uint16_t form = 0) : Form(form) {}
+  uint16_t getForm() const { return Form; }
+  const ValueType& value() const { return Value; }
+  void dump(raw_ostream &OS, const DWARFCompileUnit* cu) const;
+  bool extractValue(DataExtractor data, uint32_t *offset_ptr,
+                    const DWARFCompileUnit *cu);
+  bool isInlinedCStr() const {
+    return Value.data != NULL && Value.data == (const uint8_t*)Value.cstr;
+  }
+  const uint8_t *BlockData() const;
+  uint64_t getReference(const DWARFCompileUnit* cu) const;
+
+  /// Resolve any compile unit specific references so that we don't need
+  /// the compile unit at a later time in order to work with the form
+  /// value.
+  bool resolveCompileUnitReferences(const DWARFCompileUnit* cu);
+  uint64_t getUnsigned() const { return Value.uval; }
+  int64_t getSigned() const { return Value.sval; }
+  const char *getAsCString(const DataExtractor *debug_str_data_ptr) const;
+  const char *getIndirectCString(const DataExtractor *,
+                                 const DataExtractor *) const;
+  uint64_t getIndirectAddress(const DataExtractor *,
+                              const DWARFCompileUnit *) const;
+  bool skipValue(DataExtractor debug_info_data, uint32_t *offset_ptr,
+                 const DWARFCompileUnit *cu) const;
+  static bool skipValue(uint16_t form, DataExtractor debug_info_data,
+                        uint32_t *offset_ptr, const DWARFCompileUnit *cu);
+  static bool isBlockForm(uint16_t form);
+  static bool isDataForm(uint16_t form);
+  static const uint8_t *getFixedFormSizes(uint8_t AddrSize, uint16_t Version);
+};
+
+}
+
+#endif