Move DWARF related code in ElfWriter to its own file.

This is purely for organisation.  The DWARF related code
is becoming more complex and I do not want to keep mixing
it with the ElfWriter.  The ElfWriter probably should not
be dealing with the fine details of DWARF generation.

I intend to do much more work on DWARF in the future so
this situatuion would only get worse as the code grows.

The code could also use some refactoring and splitting.
However, I have mostly just moved it in this CL.

Change-Id: I6e3401a2b745ddf991b440ad7899ad7d4b921be6

1 files changed, 360 insertions, 0 deletions

diff --git a/compiler/elf_writer_debug.cc b/compiler/elf_writer_debug.cc
new file mode 100644
index 000000000..5e8e24b03
--- /dev/null
+++ b/compiler/elf_writer_debug.cc
@@ -0,0 +1,360 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#include "elf_writer_debug.h"
+
+#include "compiled_method.h"
+#include "driver/compiler_driver.h"
+#include "dex_file-inl.h"
+#include "dwarf/headers.h"
+#include "dwarf/register.h"
+#include "oat_writer.h"
+
+namespace art {
+namespace dwarf {
+
+static void WriteEhFrameCIE(InstructionSet isa, std::vector<uint8_t>* eh_frame) {
+  // Scratch registers should be marked as undefined.  This tells the
+  // debugger that its value in the previous frame is not recoverable.
+  bool is64bit = Is64BitInstructionSet(isa);
+  switch (isa) {
+    case kArm:
+    case kThumb2: {
+      DebugFrameOpCodeWriter<> opcodes;
+      opcodes.DefCFA(Reg::ArmCore(13), 0);  // R13(SP).
+      // core registers.
+      for (int reg = 0; reg < 13; reg++) {
+        if (reg < 4 || reg == 12) {
+          opcodes.Undefined(Reg::ArmCore(reg));
+        } else {
+          opcodes.SameValue(Reg::ArmCore(reg));
+        }
+      }
+      // fp registers.
+      for (int reg = 0; reg < 32; reg++) {
+        if (reg < 16) {
+          opcodes.Undefined(Reg::ArmFp(reg));
+        } else {
+          opcodes.SameValue(Reg::ArmFp(reg));
+        }
+      }
+      auto return_address_reg = Reg::ArmCore(14);  // R14(LR).
+      WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+      return;
+    }
+    case kArm64: {
+      DebugFrameOpCodeWriter<> opcodes;
+      opcodes.DefCFA(Reg::Arm64Core(31), 0);  // R31(SP).
+      // core registers.
+      for (int reg = 0; reg < 30; reg++) {
+        if (reg < 8 || reg == 16 || reg == 17) {
+          opcodes.Undefined(Reg::Arm64Core(reg));
+        } else {
+          opcodes.SameValue(Reg::Arm64Core(reg));
+        }
+      }
+      // fp registers.
+      for (int reg = 0; reg < 32; reg++) {
+        if (reg < 8 || reg >= 16) {
+          opcodes.Undefined(Reg::Arm64Fp(reg));
+        } else {
+          opcodes.SameValue(Reg::Arm64Fp(reg));
+        }
+      }
+      auto return_address_reg = Reg::Arm64Core(30);  // R30(LR).
+      WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+      return;
+    }
+    case kMips:
+    case kMips64: {
+      DebugFrameOpCodeWriter<> opcodes;
+      opcodes.DefCFA(Reg::MipsCore(29), 0);  // R29(SP).
+      // core registers.
+      for (int reg = 1; reg < 26; reg++) {
+        if (reg < 16 || reg == 24 || reg == 25) {  // AT, V*, A*, T*.
+          opcodes.Undefined(Reg::MipsCore(reg));
+        } else {
+          opcodes.SameValue(Reg::MipsCore(reg));
+        }
+      }
+      auto return_address_reg = Reg::MipsCore(31);  // R31(RA).
+      WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+      return;
+    }
+    case kX86: {
+      DebugFrameOpCodeWriter<> opcodes;
+      opcodes.DefCFA(Reg::X86Core(4), 4);   // R4(ESP).
+      opcodes.Offset(Reg::X86Core(8), -4);  // R8(EIP).
+      // core registers.
+      for (int reg = 0; reg < 8; reg++) {
+        if (reg <= 3) {
+          opcodes.Undefined(Reg::X86Core(reg));
+        } else if (reg == 4) {
+          // Stack pointer.
+        } else {
+          opcodes.SameValue(Reg::X86Core(reg));
+        }
+      }
+      // fp registers.
+      for (int reg = 0; reg < 8; reg++) {
+        opcodes.Undefined(Reg::X86Fp(reg));
+      }
+      auto return_address_reg = Reg::X86Core(8);  // R8(EIP).
+      WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+      return;
+    }
+    case kX86_64: {
+      DebugFrameOpCodeWriter<> opcodes;
+      opcodes.DefCFA(Reg::X86_64Core(4), 8);  // R4(RSP).
+      opcodes.Offset(Reg::X86_64Core(16), -8);  // R16(RIP).
+      // core registers.
+      for (int reg = 0; reg < 16; reg++) {
+        if (reg == 4) {
+          // Stack pointer.
+        } else if (reg < 12 && reg != 3 && reg != 5) {  // except EBX and EBP.
+          opcodes.Undefined(Reg::X86_64Core(reg));
+        } else {
+          opcodes.SameValue(Reg::X86_64Core(reg));
+        }
+      }
+      // fp registers.
+      for (int reg = 0; reg < 16; reg++) {
+        if (reg < 12) {
+          opcodes.Undefined(Reg::X86_64Fp(reg));
+        } else {
+          opcodes.SameValue(Reg::X86_64Fp(reg));
+        }
+      }
+      auto return_address_reg = Reg::X86_64Core(16);  // R16(RIP).
+      WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+      return;
+    }
+    case kNone:
+      break;
+  }
+  LOG(FATAL) << "Can not write CIE frame for ISA " << isa;
+  UNREACHABLE();
+}
+
+/*
+ * @brief Generate the DWARF sections.
+ * @param oat_writer The Oat file Writer.
+ * @param eh_frame Call Frame Information.
+ * @param debug_info Compilation unit information.
+ * @param debug_abbrev Abbreviations used to generate dbg_info.
+ * @param debug_str Debug strings.
+ * @param debug_line Line number table.
+ */
+void WriteDebugSections(const CompilerDriver* compiler,
+                        const OatWriter* oat_writer,
+                        uint32_t text_section_offset,
+                        std::vector<uint8_t>* eh_frame,
+                        std::vector<uint8_t>* debug_info,
+                        std::vector<uint8_t>* debug_abbrev,
+                        std::vector<uint8_t>* debug_str,
+                        std::vector<uint8_t>* debug_line) {
+  const std::vector<OatWriter::DebugInfo>& method_infos = oat_writer->GetMethodDebugInfo();
+  const InstructionSet isa = compiler->GetInstructionSet();
+  uint32_t cunit_low_pc = static_cast<uint32_t>(-1);
+  uint32_t cunit_high_pc = 0;
+  for (auto method_info : method_infos) {
+    cunit_low_pc = std::min(cunit_low_pc, method_info.low_pc_);
+    cunit_high_pc = std::max(cunit_high_pc, method_info.high_pc_);
+  }
+
+  // Write .eh_frame section.
+  size_t cie_offset = eh_frame->size();
+  WriteEhFrameCIE(isa, eh_frame);
+  for (const OatWriter::DebugInfo& mi : method_infos) {
+    const SwapVector<uint8_t>* opcodes = mi.compiled_method_->GetCFIInfo();
+    if (opcodes != nullptr) {
+      WriteEhFrameFDE(Is64BitInstructionSet(isa), cie_offset,
+                      text_section_offset + mi.low_pc_, mi.high_pc_ - mi.low_pc_,
+                      opcodes, eh_frame);
+    }
+  }
+
+  // Write .debug_info section.
+  size_t debug_abbrev_offset = debug_abbrev->size();
+  DebugInfoEntryWriter<> info(false /* 32 bit */, debug_abbrev);
+  info.StartTag(DW_TAG_compile_unit, DW_CHILDREN_yes);
+  info.WriteStrp(DW_AT_producer, "Android dex2oat", debug_str);
+  info.WriteData1(DW_AT_language, DW_LANG_Java);
+  info.WriteAddr(DW_AT_low_pc, cunit_low_pc + text_section_offset);
+  info.WriteAddr(DW_AT_high_pc, cunit_high_pc + text_section_offset);
+  info.WriteData4(DW_AT_stmt_list, debug_line->size());
+  for (auto method_info : method_infos) {
+    std::string method_name = PrettyMethod(method_info.dex_method_index_,
+                                           *method_info.dex_file_, true);
+    if (method_info.deduped_) {
+      // TODO We should place the DEDUPED tag on the first instance of a deduplicated symbol
+      // so that it will show up in a debuggerd crash report.
+      method_name += " [ DEDUPED ]";
+    }
+    info.StartTag(DW_TAG_subprogram, DW_CHILDREN_no);
+    info.WriteStrp(DW_AT_name, method_name.data(), debug_str);
+    info.WriteAddr(DW_AT_low_pc, method_info.low_pc_ + text_section_offset);
+    info.WriteAddr(DW_AT_high_pc, method_info.high_pc_ + text_section_offset);
+    info.EndTag();  // DW_TAG_subprogram
+  }
+  info.EndTag();  // DW_TAG_compile_unit
+  WriteDebugInfoCU(debug_abbrev_offset, info, debug_info);
+
+  // TODO: in gdb info functions <regexp> - reports Java functions, but
+  // source file is <unknown> because .debug_line is formed as one
+  // compilation unit. To fix this it is possible to generate
+  // a separate compilation unit for every distinct Java source.
+  // Each of the these compilation units can have several non-adjacent
+  // method ranges.
+
+  // Write .debug_line section.
+  std::vector<FileEntry> files;
+  std::unordered_map<std::string, size_t> files_map;
+  std::vector<std::string> directories;
+  std::unordered_map<std::string, size_t> directories_map;
+  int code_factor_bits_ = 0;
+  int dwarf_isa = -1;
+  switch (isa) {
+    case kArm:  // arm actually means thumb2.
+    case kThumb2:
+      code_factor_bits_ = 1;  // 16-bit instuctions
+      dwarf_isa = 1;  // DW_ISA_ARM_thumb.
+      break;
+    case kArm64:
+    case kMips:
+    case kMips64:
+      code_factor_bits_ = 2;  // 32-bit instructions
+      break;
+    case kNone:
+    case kX86:
+    case kX86_64:
+      break;
+  }
+  DebugLineOpCodeWriter<> opcodes(false /* 32bit */, code_factor_bits_);
+  opcodes.SetAddress(text_section_offset + cunit_low_pc);
+  if (dwarf_isa != -1) {
+    opcodes.SetISA(dwarf_isa);
+  }
+  for (const OatWriter::DebugInfo& mi : method_infos) {
+    // Addresses in the line table should be unique and increasing.
+    if (mi.deduped_) {
+      continue;
+    }
+
+    struct DebugInfoCallbacks {
+      static bool NewPosition(void* ctx, uint32_t address, uint32_t line) {
+        auto* context = reinterpret_cast<DebugInfoCallbacks*>(ctx);
+        context->dex2line_.push_back({address, static_cast<int32_t>(line)});
+        return false;
+      }
+      DefaultSrcMap dex2line_;
+    } debug_info_callbacks;
+
+    const DexFile* dex = mi.dex_file_;
+    if (mi.code_item_ != nullptr) {
+      dex->DecodeDebugInfo(mi.code_item_,
+                           (mi.access_flags_ & kAccStatic) != 0,
+                           mi.dex_method_index_,
+                           DebugInfoCallbacks::NewPosition,
+                           nullptr,
+                           &debug_info_callbacks);
+    }
+
+    // Get and deduplicate directory and filename.
+    int file_index = 0;  // 0 - primary source file of the compilation.
+    auto& dex_class_def = dex->GetClassDef(mi.class_def_index_);
+    const char* source_file = dex->GetSourceFile(dex_class_def);
+    if (source_file != nullptr) {
+      std::string file_name(source_file);
+      size_t file_name_slash = file_name.find_last_of('/');
+      std::string class_name(dex->GetClassDescriptor(dex_class_def));
+      size_t class_name_slash = class_name.find_last_of('/');
+      std::string full_path(file_name);
+
+      // Guess directory from package name.
+      int directory_index = 0;  // 0 - current directory of the compilation.
+      if (file_name_slash == std::string::npos &&  // Just filename.
+          class_name.front() == 'L' &&  // Type descriptor for a class.
+          class_name_slash != std::string::npos) {  // Has package name.
+        std::string package_name = class_name.substr(1, class_name_slash - 1);
+        auto it = directories_map.find(package_name);
+        if (it == directories_map.end()) {
+          directory_index = 1 + directories.size();
+          directories_map.emplace(package_name, directory_index);
+          directories.push_back(package_name);
+        } else {
+          directory_index = it->second;
+        }
+        full_path = package_name + "/" + file_name;
+      }
+
+      // Add file entry.
+      auto it2 = files_map.find(full_path);
+      if (it2 == files_map.end()) {
+        file_index = 1 + files.size();
+        files_map.emplace(full_path, file_index);
+        files.push_back(FileEntry {
+          file_name,
+          directory_index,
+          0,  // Modification time - NA.
+          0,  // File size - NA.
+        });
+      } else {
+        file_index = it2->second;
+      }
+    }
+    opcodes.SetFile(file_index);
+
+    // Generate mapping opcodes from PC to Java lines.
+    const DefaultSrcMap& dex2line_map = debug_info_callbacks.dex2line_;
+    uint32_t low_pc = text_section_offset + mi.low_pc_;
+    if (file_index != 0 && !dex2line_map.empty()) {
+      bool first = true;
+      for (SrcMapElem pc2dex : mi.compiled_method_->GetSrcMappingTable()) {
+        uint32_t pc = pc2dex.from_;
+        int dex_pc = pc2dex.to_;
+        auto dex2line = dex2line_map.Find(static_cast<uint32_t>(dex_pc));
+        if (dex2line.first) {
+          int line = dex2line.second;
+          if (first) {
+            first = false;
+            if (pc > 0) {
+              // Assume that any preceding code is prologue.
+              int first_line = dex2line_map.front().to_;
+              // Prologue is not a sensible place for a breakpoint.
+              opcodes.NegateStmt();
+              opcodes.AddRow(low_pc, first_line);
+              opcodes.NegateStmt();
+              opcodes.SetPrologueEnd();
+            }
+            opcodes.AddRow(low_pc + pc, line);
+          } else if (line != opcodes.CurrentLine()) {
+            opcodes.AddRow(low_pc + pc, line);
+          }
+        }
+      }
+    } else {
+      // line 0 - instruction cannot be attributed to any source line.
+      opcodes.AddRow(low_pc, 0);
+    }
+  }
+  opcodes.AdvancePC(text_section_offset + cunit_high_pc);
+  opcodes.EndSequence();
+  WriteDebugLineTable(directories, files, opcodes, debug_line);
+}
+
+}  // namespace dwarf
+}  // namespace art