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_gnu_debugdata_writer.h b/compiler/debug/elf_gnu_debugdata_writer.h
new file mode 100644
index 0000000..5c7d1c7
--- /dev/null
+++ b/compiler/debug/elf_gnu_debugdata_writer.h
@@ -0,0 +1,111 @@
+/*
+ * 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_GNU_DEBUGDATA_WRITER_H_
+#define ART_COMPILER_DEBUG_ELF_GNU_DEBUGDATA_WRITER_H_
+
+#include <vector>
+
+#include "arch/instruction_set.h"
+#include "elf_builder.h"
+#include "linker/vector_output_stream.h"
+
+// liblzma.
+#include "7zCrc.h"
+#include "XzCrc64.h"
+#include "XzEnc.h"
+
+namespace art {
+namespace debug {
+
+static void XzCompress(const std::vector<uint8_t>* src, std::vector<uint8_t>* dst) {
+  // Configure the compression library.
+  CrcGenerateTable();
+  Crc64GenerateTable();
+  CLzma2EncProps lzma2Props;
+  Lzma2EncProps_Init(&lzma2Props);
+  lzma2Props.lzmaProps.level = 1;  // Fast compression.
+  Lzma2EncProps_Normalize(&lzma2Props);
+  CXzProps props;
+  XzProps_Init(&props);
+  props.lzma2Props = &lzma2Props;
+  // Implement the required interface for communication (written in C so no virtual methods).
+  struct XzCallbacks : public ISeqInStream, public ISeqOutStream, public ICompressProgress {
+    static SRes ReadImpl(void* p, void* buf, size_t* size) {
+      auto* ctx = static_cast<XzCallbacks*>(reinterpret_cast<ISeqInStream*>(p));
+      *size = std::min(*size, ctx->src_->size() - ctx->src_pos_);
+      memcpy(buf, ctx->src_->data() + ctx->src_pos_, *size);
+      ctx->src_pos_ += *size;
+      return SZ_OK;
+    }
+    static size_t WriteImpl(void* p, const void* buf, size_t size) {
+      auto* ctx = static_cast<XzCallbacks*>(reinterpret_cast<ISeqOutStream*>(p));
+      const uint8_t* buffer = reinterpret_cast<const uint8_t*>(buf);
+      ctx->dst_->insert(ctx->dst_->end(), buffer, buffer + size);
+      return size;
+    }
+    static SRes ProgressImpl(void* , UInt64, UInt64) {
+      return SZ_OK;
+    }
+    size_t src_pos_;
+    const std::vector<uint8_t>* src_;
+    std::vector<uint8_t>* dst_;
+  };
+  XzCallbacks callbacks;
+  callbacks.Read = XzCallbacks::ReadImpl;
+  callbacks.Write = XzCallbacks::WriteImpl;
+  callbacks.Progress = XzCallbacks::ProgressImpl;
+  callbacks.src_pos_ = 0;
+  callbacks.src_ = src;
+  callbacks.dst_ = dst;
+  // Compress.
+  SRes res = Xz_Encode(&callbacks, &callbacks, &props, &callbacks);
+  CHECK_EQ(res, SZ_OK);
+}
+
+template <typename ElfTypes>
+static std::vector<uint8_t> MakeMiniDebugInfoInternal(
+    InstructionSet isa,
+    size_t rodata_section_size,
+    size_t text_section_size,
+    const ArrayRef<const MethodDebugInfo>& method_infos) {
+  std::vector<uint8_t> buffer;
+  buffer.reserve(KB);
+  VectorOutputStream out("Mini-debug-info ELF file", &buffer);
+  std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
+  builder->Start();
+  // Mirror .rodata and .text as NOBITS sections.
+  // It is needed to detected relocations after compression.
+  builder->GetRoData()->WriteNoBitsSection(rodata_section_size);
+  builder->GetText()->WriteNoBitsSection(text_section_size);
+  WriteDebugSymbols(builder.get(), method_infos, false /* with_signature */);
+  WriteCFISection(builder.get(),
+                  method_infos,
+                  dwarf::DW_DEBUG_FRAME_FORMAT,
+                  false /* write_oat_paches */);
+  builder->End();
+  CHECK(builder->Good());
+  std::vector<uint8_t> compressed_buffer;
+  compressed_buffer.reserve(buffer.size() / 4);
+  XzCompress(&buffer, &compressed_buffer);
+  return compressed_buffer;
+}
+
+}  // namespace debug
+}  // namespace art
+
+#endif  // ART_COMPILER_DEBUG_ELF_GNU_DEBUGDATA_WRITER_H_
+