Split elf_writer_debug.cc to several files.

Refactoring only. The file has grown significantly over time,
and it is time to split it so it can be better managed.

Change-Id: Idce0231718add722292f4701df353d5baf31de5f
diff --git a/compiler/debug/elf_debug_info_writer.h b/compiler/debug/elf_debug_info_writer.h
new file mode 100644
index 0000000..eed032f
--- /dev/null
+++ b/compiler/debug/elf_debug_info_writer.h
@@ -0,0 +1,649 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_COMPILER_DEBUG_ELF_DEBUG_INFO_WRITER_H_
+#define ART_COMPILER_DEBUG_ELF_DEBUG_INFO_WRITER_H_
+
+#include <map>
+#include <unordered_set>
+#include <vector>
+
+#include "debug/dwarf/debug_abbrev_writer.h"
+#include "debug/dwarf/debug_info_entry_writer.h"
+#include "debug/elf_compilation_unit.h"
+#include "debug/elf_debug_loc_writer.h"
+#include "debug/method_debug_info.h"
+#include "dex_file-inl.h"
+#include "dex_file.h"
+#include "elf_builder.h"
+#include "linear_alloc.h"
+#include "mirror/array.h"
+#include "mirror/class-inl.h"
+#include "mirror/class.h"
+
+namespace art {
+namespace debug {
+
+typedef std::vector<DexFile::LocalInfo> LocalInfos;
+
+static void LocalInfoCallback(void* ctx, const DexFile::LocalInfo& entry) {
+  static_cast<LocalInfos*>(ctx)->push_back(entry);
+}
+
+static std::vector<const char*> GetParamNames(const MethodDebugInfo* mi) {
+  std::vector<const char*> names;
+  if (mi->code_item != nullptr) {
+    const uint8_t* stream = mi->dex_file->GetDebugInfoStream(mi->code_item);
+    if (stream != nullptr) {
+      DecodeUnsignedLeb128(&stream);  // line.
+      uint32_t parameters_size = DecodeUnsignedLeb128(&stream);
+      for (uint32_t i = 0; i < parameters_size; ++i) {
+        uint32_t id = DecodeUnsignedLeb128P1(&stream);
+        names.push_back(mi->dex_file->StringDataByIdx(id));
+      }
+    }
+  }
+  return names;
+}
+
+// Helper class to write .debug_info and its supporting sections.
+template<typename ElfTypes>
+class ElfDebugInfoWriter {
+  using Elf_Addr = typename ElfTypes::Addr;
+
+ public:
+  explicit ElfDebugInfoWriter(ElfBuilder<ElfTypes>* builder)
+      : builder_(builder),
+        debug_abbrev_(&debug_abbrev_buffer_) {
+  }
+
+  void Start() {
+    builder_->GetDebugInfo()->Start();
+  }
+
+  void End(bool write_oat_patches) {
+    builder_->GetDebugInfo()->End();
+    if (write_oat_patches) {
+      builder_->WritePatches(".debug_info.oat_patches",
+                             ArrayRef<const uintptr_t>(debug_info_patches_));
+    }
+    builder_->WriteSection(".debug_abbrev", &debug_abbrev_buffer_);
+    if (!debug_loc_.empty()) {
+      builder_->WriteSection(".debug_loc", &debug_loc_);
+    }
+    if (!debug_ranges_.empty()) {
+      builder_->WriteSection(".debug_ranges", &debug_ranges_);
+    }
+  }
+
+ private:
+  ElfBuilder<ElfTypes>* builder_;
+  std::vector<uintptr_t> debug_info_patches_;
+  std::vector<uint8_t> debug_abbrev_buffer_;
+  dwarf::DebugAbbrevWriter<> debug_abbrev_;
+  std::vector<uint8_t> debug_loc_;
+  std::vector<uint8_t> debug_ranges_;
+
+  std::unordered_set<const char*> defined_dex_classes_;  // For CHECKs only.
+
+  template<typename ElfTypes2>
+  friend class ElfCompilationUnitWriter;
+};
+
+// Helper class to write one compilation unit.
+// It holds helper methods and temporary state.
+template<typename ElfTypes>
+class ElfCompilationUnitWriter {
+  using Elf_Addr = typename ElfTypes::Addr;
+
+ public:
+  explicit ElfCompilationUnitWriter(ElfDebugInfoWriter<ElfTypes>* owner)
+    : owner_(owner),
+      info_(Is64BitInstructionSet(owner_->builder_->GetIsa()), &owner->debug_abbrev_) {
+  }
+
+  void Write(const ElfCompilationUnit& compilation_unit) {
+    CHECK(!compilation_unit.methods.empty());
+    const Elf_Addr text_address = owner_->builder_->GetText()->Exists()
+        ? owner_->builder_->GetText()->GetAddress()
+        : 0;
+    const uintptr_t cu_size = compilation_unit.high_pc - compilation_unit.low_pc;
+    using namespace dwarf;  // NOLINT. For easy access to DWARF constants.
+
+    info_.StartTag(DW_TAG_compile_unit);
+    info_.WriteString(DW_AT_producer, "Android dex2oat");
+    info_.WriteData1(DW_AT_language, DW_LANG_Java);
+    info_.WriteString(DW_AT_comp_dir, "$JAVA_SRC_ROOT");
+    info_.WriteAddr(DW_AT_low_pc, text_address + compilation_unit.low_pc);
+    info_.WriteUdata(DW_AT_high_pc, dchecked_integral_cast<uint32_t>(cu_size));
+    info_.WriteSecOffset(DW_AT_stmt_list, compilation_unit.debug_line_offset);
+
+    const char* last_dex_class_desc = nullptr;
+    for (auto mi : compilation_unit.methods) {
+      const DexFile* dex = mi->dex_file;
+      const DexFile::CodeItem* dex_code = mi->code_item;
+      const DexFile::MethodId& dex_method = dex->GetMethodId(mi->dex_method_index);
+      const DexFile::ProtoId& dex_proto = dex->GetMethodPrototype(dex_method);
+      const DexFile::TypeList* dex_params = dex->GetProtoParameters(dex_proto);
+      const char* dex_class_desc = dex->GetMethodDeclaringClassDescriptor(dex_method);
+      const bool is_static = (mi->access_flags & kAccStatic) != 0;
+
+      // Enclose the method in correct class definition.
+      if (last_dex_class_desc != dex_class_desc) {
+        if (last_dex_class_desc != nullptr) {
+          EndClassTag();
+        }
+        // Write reference tag for the class we are about to declare.
+        size_t reference_tag_offset = info_.StartTag(DW_TAG_reference_type);
+        type_cache_.emplace(std::string(dex_class_desc), reference_tag_offset);
+        size_t type_attrib_offset = info_.size();
+        info_.WriteRef4(DW_AT_type, 0);
+        info_.EndTag();
+        // Declare the class that owns this method.
+        size_t class_offset = StartClassTag(dex_class_desc);
+        info_.UpdateUint32(type_attrib_offset, class_offset);
+        info_.WriteFlagPresent(DW_AT_declaration);
+        // Check that each class is defined only once.
+        bool unique = owner_->defined_dex_classes_.insert(dex_class_desc).second;
+        CHECK(unique) << "Redefinition of " << dex_class_desc;
+        last_dex_class_desc = dex_class_desc;
+      }
+
+      int start_depth = info_.Depth();
+      info_.StartTag(DW_TAG_subprogram);
+      WriteName(dex->GetMethodName(dex_method));
+      info_.WriteAddr(DW_AT_low_pc, text_address + mi->low_pc);
+      info_.WriteUdata(DW_AT_high_pc, dchecked_integral_cast<uint32_t>(mi->high_pc-mi->low_pc));
+      std::vector<uint8_t> expr_buffer;
+      Expression expr(&expr_buffer);
+      expr.WriteOpCallFrameCfa();
+      info_.WriteExprLoc(DW_AT_frame_base, expr);
+      WriteLazyType(dex->GetReturnTypeDescriptor(dex_proto));
+
+      // Write parameters. DecodeDebugLocalInfo returns them as well, but it does not
+      // guarantee order or uniqueness so it is safer to iterate over them manually.
+      // DecodeDebugLocalInfo might not also be available if there is no debug info.
+      std::vector<const char*> param_names = GetParamNames(mi);
+      uint32_t arg_reg = 0;
+      if (!is_static) {
+        info_.StartTag(DW_TAG_formal_parameter);
+        WriteName("this");
+        info_.WriteFlagPresent(DW_AT_artificial);
+        WriteLazyType(dex_class_desc);
+        if (dex_code != nullptr) {
+          // Write the stack location of the parameter.
+          const uint32_t vreg = dex_code->registers_size_ - dex_code->ins_size_ + arg_reg;
+          const bool is64bitValue = false;
+          WriteRegLocation(mi, vreg, is64bitValue, compilation_unit.low_pc);
+        }
+        arg_reg++;
+        info_.EndTag();
+      }
+      if (dex_params != nullptr) {
+        for (uint32_t i = 0; i < dex_params->Size(); ++i) {
+          info_.StartTag(DW_TAG_formal_parameter);
+          // Parameter names may not be always available.
+          if (i < param_names.size()) {
+            WriteName(param_names[i]);
+          }
+          // Write the type.
+          const char* type_desc = dex->StringByTypeIdx(dex_params->GetTypeItem(i).type_idx_);
+          WriteLazyType(type_desc);
+          const bool is64bitValue = type_desc[0] == 'D' || type_desc[0] == 'J';
+          if (dex_code != nullptr) {
+            // Write the stack location of the parameter.
+            const uint32_t vreg = dex_code->registers_size_ - dex_code->ins_size_ + arg_reg;
+            WriteRegLocation(mi, vreg, is64bitValue, compilation_unit.low_pc);
+          }
+          arg_reg += is64bitValue ? 2 : 1;
+          info_.EndTag();
+        }
+        if (dex_code != nullptr) {
+          DCHECK_EQ(arg_reg, dex_code->ins_size_);
+        }
+      }
+
+      // Write local variables.
+      LocalInfos local_infos;
+      if (dex->DecodeDebugLocalInfo(dex_code,
+                                    is_static,
+                                    mi->dex_method_index,
+                                    LocalInfoCallback,
+                                    &local_infos)) {
+        for (const DexFile::LocalInfo& var : local_infos) {
+          if (var.reg_ < dex_code->registers_size_ - dex_code->ins_size_) {
+            info_.StartTag(DW_TAG_variable);
+            WriteName(var.name_);
+            WriteLazyType(var.descriptor_);
+            bool is64bitValue = var.descriptor_[0] == 'D' || var.descriptor_[0] == 'J';
+            WriteRegLocation(mi, var.reg_, is64bitValue, compilation_unit.low_pc,
+                             var.start_address_, var.end_address_);
+            info_.EndTag();
+          }
+        }
+      }
+
+      info_.EndTag();
+      CHECK_EQ(info_.Depth(), start_depth);  // Balanced start/end.
+    }
+    if (last_dex_class_desc != nullptr) {
+      EndClassTag();
+    }
+    FinishLazyTypes();
+    CloseNamespacesAboveDepth(0);
+    info_.EndTag();  // DW_TAG_compile_unit
+    CHECK_EQ(info_.Depth(), 0);
+    std::vector<uint8_t> buffer;
+    buffer.reserve(info_.data()->size() + KB);
+    const size_t offset = owner_->builder_->GetDebugInfo()->GetSize();
+    // All compilation units share single table which is at the start of .debug_abbrev.
+    const size_t debug_abbrev_offset = 0;
+    WriteDebugInfoCU(debug_abbrev_offset, info_, offset, &buffer, &owner_->debug_info_patches_);
+    owner_->builder_->GetDebugInfo()->WriteFully(buffer.data(), buffer.size());
+  }
+
+  void Write(const ArrayRef<mirror::Class*>& types) SHARED_REQUIRES(Locks::mutator_lock_) {
+    using namespace dwarf;  // NOLINT. For easy access to DWARF constants.
+
+    info_.StartTag(DW_TAG_compile_unit);
+    info_.WriteString(DW_AT_producer, "Android dex2oat");
+    info_.WriteData1(DW_AT_language, DW_LANG_Java);
+
+    // Base class references to be patched at the end.
+    std::map<size_t, mirror::Class*> base_class_references;
+
+    // Already written declarations or definitions.
+    std::map<mirror::Class*, size_t> class_declarations;
+
+    std::vector<uint8_t> expr_buffer;
+    for (mirror::Class* type : types) {
+      if (type->IsPrimitive()) {
+        // For primitive types the definition and the declaration is the same.
+        if (type->GetPrimitiveType() != Primitive::kPrimVoid) {
+          WriteTypeDeclaration(type->GetDescriptor(nullptr));
+        }
+      } else if (type->IsArrayClass()) {
+        mirror::Class* element_type = type->GetComponentType();
+        uint32_t component_size = type->GetComponentSize();
+        uint32_t data_offset = mirror::Array::DataOffset(component_size).Uint32Value();
+        uint32_t length_offset = mirror::Array::LengthOffset().Uint32Value();
+
+        CloseNamespacesAboveDepth(0);  // Declare in root namespace.
+        info_.StartTag(DW_TAG_array_type);
+        std::string descriptor_string;
+        WriteLazyType(element_type->GetDescriptor(&descriptor_string));
+        WriteLinkageName(type);
+        info_.WriteUdata(DW_AT_data_member_location, data_offset);
+        info_.StartTag(DW_TAG_subrange_type);
+        Expression count_expr(&expr_buffer);
+        count_expr.WriteOpPushObjectAddress();
+        count_expr.WriteOpPlusUconst(length_offset);
+        count_expr.WriteOpDerefSize(4);  // Array length is always 32-bit wide.
+        info_.WriteExprLoc(DW_AT_count, count_expr);
+        info_.EndTag();  // DW_TAG_subrange_type.
+        info_.EndTag();  // DW_TAG_array_type.
+      } else if (type->IsInterface()) {
+        // Skip.  Variables cannot have an interface as a dynamic type.
+        // We do not expose the interface information to the debugger in any way.
+      } else {
+        std::string descriptor_string;
+        const char* desc = type->GetDescriptor(&descriptor_string);
+        size_t class_offset = StartClassTag(desc);
+        class_declarations.emplace(type, class_offset);
+
+        if (!type->IsVariableSize()) {
+          info_.WriteUdata(DW_AT_byte_size, type->GetObjectSize());
+        }
+
+        WriteLinkageName(type);
+
+        if (type->IsObjectClass()) {
+          // Generate artificial member which is used to get the dynamic type of variable.
+          // The run-time value of this field will correspond to linkage name of some type.
+          // We need to do it only once in j.l.Object since all other types inherit it.
+          info_.StartTag(DW_TAG_member);
+          WriteName(".dynamic_type");
+          WriteLazyType(sizeof(uintptr_t) == 8 ? "J" : "I");
+          info_.WriteFlagPresent(DW_AT_artificial);
+          // Create DWARF expression to get the value of the methods_ field.
+          Expression expr(&expr_buffer);
+          // The address of the object has been implicitly pushed on the stack.
+          // Dereference the klass_ field of Object (32-bit; possibly poisoned).
+          DCHECK_EQ(type->ClassOffset().Uint32Value(), 0u);
+          DCHECK_EQ(sizeof(mirror::HeapReference<mirror::Class>), 4u);
+          expr.WriteOpDerefSize(4);
+          if (kPoisonHeapReferences) {
+            expr.WriteOpNeg();
+            // DWARF stack is pointer sized. Ensure that the high bits are clear.
+            expr.WriteOpConstu(0xFFFFFFFF);
+            expr.WriteOpAnd();
+          }
+          // Add offset to the methods_ field.
+          expr.WriteOpPlusUconst(mirror::Class::MethodsOffset().Uint32Value());
+          // Top of stack holds the location of the field now.
+          info_.WriteExprLoc(DW_AT_data_member_location, expr);
+          info_.EndTag();  // DW_TAG_member.
+        }
+
+        // Base class.
+        mirror::Class* base_class = type->GetSuperClass();
+        if (base_class != nullptr) {
+          info_.StartTag(DW_TAG_inheritance);
+          base_class_references.emplace(info_.size(), base_class);
+          info_.WriteRef4(DW_AT_type, 0);
+          info_.WriteUdata(DW_AT_data_member_location, 0);
+          info_.WriteSdata(DW_AT_accessibility, DW_ACCESS_public);
+          info_.EndTag();  // DW_TAG_inheritance.
+        }
+
+        // Member variables.
+        for (uint32_t i = 0, count = type->NumInstanceFields(); i < count; ++i) {
+          ArtField* field = type->GetInstanceField(i);
+          info_.StartTag(DW_TAG_member);
+          WriteName(field->GetName());
+          WriteLazyType(field->GetTypeDescriptor());
+          info_.WriteUdata(DW_AT_data_member_location, field->GetOffset().Uint32Value());
+          uint32_t access_flags = field->GetAccessFlags();
+          if (access_flags & kAccPublic) {
+            info_.WriteSdata(DW_AT_accessibility, DW_ACCESS_public);
+          } else if (access_flags & kAccProtected) {
+            info_.WriteSdata(DW_AT_accessibility, DW_ACCESS_protected);
+          } else if (access_flags & kAccPrivate) {
+            info_.WriteSdata(DW_AT_accessibility, DW_ACCESS_private);
+          }
+          info_.EndTag();  // DW_TAG_member.
+        }
+
+        if (type->IsStringClass()) {
+          // Emit debug info about an artifical class member for java.lang.String which represents
+          // the first element of the data stored in a string instance. Consumers of the debug
+          // info will be able to read the content of java.lang.String based on the count (real
+          // field) and based on the location of this data member.
+          info_.StartTag(DW_TAG_member);
+          WriteName("value");
+          // We don't support fields with C like array types so we just say its type is java char.
+          WriteLazyType("C");  // char.
+          info_.WriteUdata(DW_AT_data_member_location,
+                           mirror::String::ValueOffset().Uint32Value());
+          info_.WriteSdata(DW_AT_accessibility, DW_ACCESS_private);
+          info_.EndTag();  // DW_TAG_member.
+        }
+
+        EndClassTag();
+      }
+    }
+
+    // Write base class declarations.
+    for (const auto& base_class_reference : base_class_references) {
+      size_t reference_offset = base_class_reference.first;
+      mirror::Class* base_class = base_class_reference.second;
+      const auto& it = class_declarations.find(base_class);
+      if (it != class_declarations.end()) {
+        info_.UpdateUint32(reference_offset, it->second);
+      } else {
+        // Declare base class.  We can not use the standard WriteLazyType
+        // since we want to avoid the DW_TAG_reference_tag wrapping.
+        std::string tmp_storage;
+        const char* base_class_desc = base_class->GetDescriptor(&tmp_storage);
+        size_t base_class_declaration_offset = StartClassTag(base_class_desc);
+        info_.WriteFlagPresent(DW_AT_declaration);
+        WriteLinkageName(base_class);
+        EndClassTag();
+        class_declarations.emplace(base_class, base_class_declaration_offset);
+        info_.UpdateUint32(reference_offset, base_class_declaration_offset);
+      }
+    }
+
+    FinishLazyTypes();
+    CloseNamespacesAboveDepth(0);
+    info_.EndTag();  // DW_TAG_compile_unit.
+    CHECK_EQ(info_.Depth(), 0);
+    std::vector<uint8_t> buffer;
+    buffer.reserve(info_.data()->size() + KB);
+    const size_t offset = owner_->builder_->GetDebugInfo()->GetSize();
+    // All compilation units share single table which is at the start of .debug_abbrev.
+    const size_t debug_abbrev_offset = 0;
+    WriteDebugInfoCU(debug_abbrev_offset, info_, offset, &buffer, &owner_->debug_info_patches_);
+    owner_->builder_->GetDebugInfo()->WriteFully(buffer.data(), buffer.size());
+  }
+
+  // Write table into .debug_loc which describes location of dex register.
+  // The dex register might be valid only at some points and it might
+  // move between machine registers and stack.
+  void WriteRegLocation(const MethodDebugInfo* method_info,
+                        uint16_t vreg,
+                        bool is64bitValue,
+                        uint32_t compilation_unit_low_pc,
+                        uint32_t dex_pc_low = 0,
+                        uint32_t dex_pc_high = 0xFFFFFFFF) {
+    WriteDebugLocEntry(method_info,
+                       vreg,
+                       is64bitValue,
+                       compilation_unit_low_pc,
+                       dex_pc_low,
+                       dex_pc_high,
+                       owner_->builder_->GetIsa(),
+                       &info_,
+                       &owner_->debug_loc_,
+                       &owner_->debug_ranges_);
+  }
+
+  // Linkage name uniquely identifies type.
+  // It is used to determine the dynamic type of objects.
+  // We use the methods_ field of class since it is unique and it is not moved by the GC.
+  void WriteLinkageName(mirror::Class* type) SHARED_REQUIRES(Locks::mutator_lock_) {
+    auto* methods_ptr = type->GetMethodsPtr();
+    if (methods_ptr == nullptr) {
+      // Some types might have no methods.  Allocate empty array instead.
+      LinearAlloc* allocator = Runtime::Current()->GetLinearAlloc();
+      void* storage = allocator->Alloc(Thread::Current(), sizeof(LengthPrefixedArray<ArtMethod>));
+      methods_ptr = new (storage) LengthPrefixedArray<ArtMethod>(0);
+      type->SetMethodsPtr(methods_ptr, 0, 0);
+      DCHECK(type->GetMethodsPtr() != nullptr);
+    }
+    char name[32];
+    snprintf(name, sizeof(name), "0x%" PRIXPTR, reinterpret_cast<uintptr_t>(methods_ptr));
+    info_.WriteString(dwarf::DW_AT_linkage_name, name);
+  }
+
+  // Some types are difficult to define as we go since they need
+  // to be enclosed in the right set of namespaces. Therefore we
+  // just define all types lazily at the end of compilation unit.
+  void WriteLazyType(const char* type_descriptor) {
+    if (type_descriptor != nullptr && type_descriptor[0] != 'V') {
+      lazy_types_.emplace(std::string(type_descriptor), info_.size());
+      info_.WriteRef4(dwarf::DW_AT_type, 0);
+    }
+  }
+
+  void FinishLazyTypes() {
+    for (const auto& lazy_type : lazy_types_) {
+      info_.UpdateUint32(lazy_type.second, WriteTypeDeclaration(lazy_type.first));
+    }
+    lazy_types_.clear();
+  }
+
+ private:
+  void WriteName(const char* name) {
+    if (name != nullptr) {
+      info_.WriteString(dwarf::DW_AT_name, name);
+    }
+  }
+
+  // Convert dex type descriptor to DWARF.
+  // Returns offset in the compilation unit.
+  size_t WriteTypeDeclaration(const std::string& desc) {
+    using namespace dwarf;  // NOLINT. For easy access to DWARF constants.
+
+    DCHECK(!desc.empty());
+    const auto& it = type_cache_.find(desc);
+    if (it != type_cache_.end()) {
+      return it->second;
+    }
+
+    size_t offset;
+    if (desc[0] == 'L') {
+      // Class type. For example: Lpackage/name;
+      size_t class_offset = StartClassTag(desc.c_str());
+      info_.WriteFlagPresent(DW_AT_declaration);
+      EndClassTag();
+      // Reference to the class type.
+      offset = info_.StartTag(DW_TAG_reference_type);
+      info_.WriteRef(DW_AT_type, class_offset);
+      info_.EndTag();
+    } else if (desc[0] == '[') {
+      // Array type.
+      size_t element_type = WriteTypeDeclaration(desc.substr(1));
+      CloseNamespacesAboveDepth(0);  // Declare in root namespace.
+      size_t array_type = info_.StartTag(DW_TAG_array_type);
+      info_.WriteFlagPresent(DW_AT_declaration);
+      info_.WriteRef(DW_AT_type, element_type);
+      info_.EndTag();
+      offset = info_.StartTag(DW_TAG_reference_type);
+      info_.WriteRef4(DW_AT_type, array_type);
+      info_.EndTag();
+    } else {
+      // Primitive types.
+      DCHECK_EQ(desc.size(), 1u);
+
+      const char* name;
+      uint32_t encoding;
+      uint32_t byte_size;
+      switch (desc[0]) {
+      case 'B':
+        name = "byte";
+        encoding = DW_ATE_signed;
+        byte_size = 1;
+        break;
+      case 'C':
+        name = "char";
+        encoding = DW_ATE_UTF;
+        byte_size = 2;
+        break;
+      case 'D':
+        name = "double";
+        encoding = DW_ATE_float;
+        byte_size = 8;
+        break;
+      case 'F':
+        name = "float";
+        encoding = DW_ATE_float;
+        byte_size = 4;
+        break;
+      case 'I':
+        name = "int";
+        encoding = DW_ATE_signed;
+        byte_size = 4;
+        break;
+      case 'J':
+        name = "long";
+        encoding = DW_ATE_signed;
+        byte_size = 8;
+        break;
+      case 'S':
+        name = "short";
+        encoding = DW_ATE_signed;
+        byte_size = 2;
+        break;
+      case 'Z':
+        name = "boolean";
+        encoding = DW_ATE_boolean;
+        byte_size = 1;
+        break;
+      case 'V':
+        LOG(FATAL) << "Void type should not be encoded";
+        UNREACHABLE();
+      default:
+        LOG(FATAL) << "Unknown dex type descriptor: \"" << desc << "\"";
+        UNREACHABLE();
+      }
+      CloseNamespacesAboveDepth(0);  // Declare in root namespace.
+      offset = info_.StartTag(DW_TAG_base_type);
+      WriteName(name);
+      info_.WriteData1(DW_AT_encoding, encoding);
+      info_.WriteData1(DW_AT_byte_size, byte_size);
+      info_.EndTag();
+    }
+
+    type_cache_.emplace(desc, offset);
+    return offset;
+  }
+
+  // Start DW_TAG_class_type tag nested in DW_TAG_namespace tags.
+  // Returns offset of the class tag in the compilation unit.
+  size_t StartClassTag(const char* desc) {
+    std::string name = SetNamespaceForClass(desc);
+    size_t offset = info_.StartTag(dwarf::DW_TAG_class_type);
+    WriteName(name.c_str());
+    return offset;
+  }
+
+  void EndClassTag() {
+    info_.EndTag();
+  }
+
+  // Set the current namespace nesting to one required by the given class.
+  // Returns the class name with namespaces, 'L', and ';' stripped.
+  std::string SetNamespaceForClass(const char* desc) {
+    DCHECK(desc != nullptr && desc[0] == 'L');
+    desc++;  // Skip the initial 'L'.
+    size_t depth = 0;
+    for (const char* end; (end = strchr(desc, '/')) != nullptr; desc = end + 1, ++depth) {
+      // Check whether the name at this depth is already what we need.
+      if (depth < current_namespace_.size()) {
+        const std::string& name = current_namespace_[depth];
+        if (name.compare(0, name.size(), desc, end - desc) == 0) {
+          continue;
+        }
+      }
+      // Otherwise we need to open a new namespace tag at this depth.
+      CloseNamespacesAboveDepth(depth);
+      info_.StartTag(dwarf::DW_TAG_namespace);
+      std::string name(desc, end - desc);
+      WriteName(name.c_str());
+      current_namespace_.push_back(std::move(name));
+    }
+    CloseNamespacesAboveDepth(depth);
+    return std::string(desc, strchr(desc, ';') - desc);
+  }
+
+  // Close namespace tags to reach the given nesting depth.
+  void CloseNamespacesAboveDepth(size_t depth) {
+    DCHECK_LE(depth, current_namespace_.size());
+    while (current_namespace_.size() > depth) {
+      info_.EndTag();
+      current_namespace_.pop_back();
+    }
+  }
+
+  // For access to the ELF sections.
+  ElfDebugInfoWriter<ElfTypes>* owner_;
+  // Temporary buffer to create and store the entries.
+  dwarf::DebugInfoEntryWriter<> info_;
+  // Cache of already translated type descriptors.
+  std::map<std::string, size_t> type_cache_;  // type_desc -> definition_offset.
+  // 32-bit references which need to be resolved to a type later.
+  // Given type may be used multiple times.  Therefore we need a multimap.
+  std::multimap<std::string, size_t> lazy_types_;  // type_desc -> patch_offset.
+  // The current set of open namespace tags which are active and not closed yet.
+  std::vector<std::string> current_namespace_;
+};
+
+}  // namespace debug
+}  // namespace art
+
+#endif  // ART_COMPILER_DEBUG_ELF_DEBUG_INFO_WRITER_H_
+