compiler/utils/assembler_test_base.h - platform/art - Gitiles

 /*
  * Copyright (C) 2014 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_UTILS_ASSEMBLER_TEST_BASE_H_
 #define ART_COMPILER_UTILS_ASSEMBLER_TEST_BASE_H_

 #include <sys/stat.h>
 #include <cstdio>
 #include <cstdlib>
 #include <fstream>
 #include <iterator>

 #include "android-base/strings.h"

 #include "base/utils.h"
 #include "common_runtime_test.h"  // For ScratchFile
 #include "exec_utils.h"

 namespace art {

 // If you want to take a look at the differences between the ART assembler and GCC, set this flag
 // to true. The disassembled files will then remain in the tmp directory.
 static constexpr bool kKeepDisassembledFiles = false;

 // Use a glocal static variable to keep the same name for all test data. Else we'll just spam the
 // temp directory.
 static std::string tmpnam_;  // NOLINT [runtime/string] [4]

 // We put this into a class as gtests are self-contained, so this helper needs to be in an h-file.
 class AssemblerTestInfrastructure {
  public:
   AssemblerTestInfrastructure(std::string architecture,
                               std::string as,
                               std::string as_params,
                               std::string objdump,
                               std::string objdump_params,
                               std::string disasm,
                               std::string disasm_params,
                               const char* asm_header) :
       architecture_string_(architecture),
       asm_header_(asm_header),
       assembler_cmd_name_(as),
       assembler_parameters_(as_params),
       objdump_cmd_name_(objdump),
       objdump_parameters_(objdump_params),
       disassembler_cmd_name_(disasm),
       disassembler_parameters_(disasm_params) {
     // Fake a runtime test for ScratchFile
     CommonRuntimeTest::SetUpAndroidData(android_data_);
   }

   virtual ~AssemblerTestInfrastructure() {
     // We leave temporaries in case this failed so we can debug issues.
     CommonRuntimeTest::TearDownAndroidData(android_data_, false);
     tmpnam_ = "";
   }

   // This is intended to be run as a test.
   bool CheckTools() {
     std::string asm_tool = FindTool(assembler_cmd_name_);
     if (!FileExists(asm_tool)) {
       LOG(ERROR) << "Could not find assembler from " << assembler_cmd_name_;
       LOG(ERROR) << "FindTool returned " << asm_tool;
       FindToolDump(assembler_cmd_name_);
       return false;
     }
     LOG(INFO) << "Chosen assembler command: " << GetAssemblerCommand();

     std::string objdump_tool = FindTool(objdump_cmd_name_);
     if (!FileExists(objdump_tool)) {
       LOG(ERROR) << "Could not find objdump from " << objdump_cmd_name_;
       LOG(ERROR) << "FindTool returned " << objdump_tool;
       FindToolDump(objdump_cmd_name_);
       return false;
     }
     LOG(INFO) << "Chosen objdump command: " << GetObjdumpCommand();

     // Disassembly is optional.
     std::string disassembler = GetDisassembleCommand();
     if (disassembler.length() != 0) {
       std::string disassembler_tool = FindTool(disassembler_cmd_name_);
       if (!FileExists(disassembler_tool)) {
         LOG(ERROR) << "Could not find disassembler from " << disassembler_cmd_name_;
         LOG(ERROR) << "FindTool returned " << disassembler_tool;
         FindToolDump(disassembler_cmd_name_);
         return false;
       }
       LOG(INFO) << "Chosen disassemble command: " << GetDisassembleCommand();
     } else {
       LOG(INFO) << "No disassembler given.";
     }

     return true;
   }

   // Driver() assembles and compares the results. If the results are not equal and we have a
   // disassembler, disassemble both and check whether they have the same mnemonics (in which case
   // we just warn).
   void Driver(const std::vector<uint8_t>& data,
               const std::string& assembly_text,
               const std::string& test_name) {
     EXPECT_NE(assembly_text.length(), 0U) << "Empty assembly";

     NativeAssemblerResult res;
     Compile(assembly_text, &res, test_name);

     EXPECT_TRUE(res.ok) << res.error_msg;
     if (!res.ok) {
       // No way of continuing.
       return;
     }

     if (data == *res.code) {
       Clean(&res);
     } else {
       if (DisassembleBinaries(data, *res.code, test_name)) {
         if (data.size() > res.code->size()) {
           // Fail this test with a fancy colored warning being printed.
           EXPECT_TRUE(false) << "Assembly code is not identical, but disassembly of machine code "
               "is equal: this implies sub-optimal encoding! Our code size=" << data.size() <<
               ", gcc size=" << res.code->size();
         } else {
           // Otherwise just print an info message and clean up.
           LOG(INFO) << "GCC chose a different encoding than ours, but the overall length is the "
               "same.";
           Clean(&res);
         }
       } else {
         // This will output the assembly.
         EXPECT_EQ(*res.code, data) << "Outputs (and disassembly) not identical.";
       }
     }
   }

  protected:
   // Return the host assembler command for this test.
   virtual std::string GetAssemblerCommand() {
     // Already resolved it once?
     if (resolved_assembler_cmd_.length() != 0) {
       return resolved_assembler_cmd_;
     }

     std::string line = FindTool(assembler_cmd_name_);
     if (line.length() == 0) {
       return line;
     }

     resolved_assembler_cmd_ = line + assembler_parameters_;

     return resolved_assembler_cmd_;
   }

   // Return the host objdump command for this test.
   virtual std::string GetObjdumpCommand() {
     // Already resolved it once?
     if (resolved_objdump_cmd_.length() != 0) {
       return resolved_objdump_cmd_;
     }

     std::string line = FindTool(objdump_cmd_name_);
     if (line.length() == 0) {
       return line;
     }

     resolved_objdump_cmd_ = line + objdump_parameters_;

     return resolved_objdump_cmd_;
   }

   // Return the host disassembler command for this test.
   virtual std::string GetDisassembleCommand() {
     // Already resolved it once?
     if (resolved_disassemble_cmd_.length() != 0) {
       return resolved_disassemble_cmd_;
     }

     std::string line = FindTool(disassembler_cmd_name_);
     if (line.length() == 0) {
       return line;
     }

     resolved_disassemble_cmd_ = line + disassembler_parameters_;

     return resolved_disassemble_cmd_;
   }

  private:
   // Structure to store intermediates and results.
   struct NativeAssemblerResult {
     bool ok;
     std::string error_msg;
     std::string base_name;
     std::unique_ptr<std::vector<uint8_t>> code;
     uintptr_t length;
   };

   // Compile the assembly file from_file to a binary file to_file. Returns true on success.
   bool Assemble(const char* from_file, const char* to_file, std::string* error_msg) {
     bool have_assembler = FileExists(FindTool(assembler_cmd_name_));
     EXPECT_TRUE(have_assembler) << "Cannot find assembler:" << GetAssemblerCommand();
     if (!have_assembler) {
       return false;
     }

     std::vector<std::string> args;

     // Encaspulate the whole command line in a single string passed to
     // the shell, so that GetAssemblerCommand() may contain arguments
     // in addition to the program name.
     args.push_back(GetAssemblerCommand());
     args.push_back("-o");
     args.push_back(to_file);
     args.push_back(from_file);
     std::string cmd = android::base::Join(args, ' ');

     args.clear();
     args.push_back("/bin/sh");
     args.push_back("-c");
     args.push_back(cmd);

     bool success = Exec(args, error_msg);
     if (!success) {
       LOG(ERROR) << "Assembler command line:";
       for (const std::string& arg : args) {
         LOG(ERROR) << arg;
       }
     }
     return success;
   }

   // Runs objdump -h on the binary file and extracts the first line with .text.
   // Returns "" on failure.
   std::string Objdump(const std::string& file) {
     bool have_objdump = FileExists(FindTool(objdump_cmd_name_));
     EXPECT_TRUE(have_objdump) << "Cannot find objdump: " << GetObjdumpCommand();
     if (!have_objdump) {
       return "";
     }

     std::string error_msg;
     std::vector<std::string> args;

     // Encaspulate the whole command line in a single string passed to
     // the shell, so that GetObjdumpCommand() may contain arguments
     // in addition to the program name.
     args.push_back(GetObjdumpCommand());
     args.push_back(file);
     args.push_back(">");
     args.push_back(file+".dump");
     std::string cmd = android::base::Join(args, ' ');

     args.clear();
     args.push_back("/bin/sh");
     args.push_back("-c");
     args.push_back(cmd);

     if (!Exec(args, &error_msg)) {
       EXPECT_TRUE(false) << error_msg;
     }

     std::ifstream dump(file+".dump");

     std::string line;
     bool found = false;
     while (std::getline(dump, line)) {
       if (line.find(".text") != line.npos) {
         found = true;
         break;
       }
     }

     dump.close();

     if (found) {
       return line;
     } else {
       return "";
     }
   }

   // Disassemble both binaries and compare the text.
   bool DisassembleBinaries(const std::vector<uint8_t>& data,
                            const std::vector<uint8_t>& as,
                            const std::string& test_name) {
     std::string disassembler = GetDisassembleCommand();
     if (disassembler.length() == 0) {
       LOG(WARNING) << "No dissassembler command.";
       return false;
     }

     std::string data_name = WriteToFile(data, test_name + ".ass");
     std::string error_msg;
     if (!DisassembleBinary(data_name, &error_msg)) {
       LOG(INFO) << "Error disassembling: " << error_msg;
       std::remove(data_name.c_str());
       return false;
     }

     std::string as_name = WriteToFile(as, test_name + ".gcc");
     if (!DisassembleBinary(as_name, &error_msg)) {
       LOG(INFO) << "Error disassembling: " << error_msg;
       std::remove(data_name.c_str());
       std::remove((data_name + ".dis").c_str());
       std::remove(as_name.c_str());
       return false;
     }

     bool result = CompareFiles(data_name + ".dis", as_name + ".dis");

     if (!kKeepDisassembledFiles) {
       std::remove(data_name.c_str());
       std::remove(as_name.c_str());
       std::remove((data_name + ".dis").c_str());
       std::remove((as_name + ".dis").c_str());
     }

     return result;
   }

   bool DisassembleBinary(const std::string& file, std::string* error_msg) {
     std::vector<std::string> args;

     // Encaspulate the whole command line in a single string passed to
     // the shell, so that GetDisassembleCommand() may contain arguments
     // in addition to the program name.
     args.push_back(GetDisassembleCommand());
     args.push_back(file);
     args.push_back("| sed -n \'/<.data>/,$p\' | sed -e \'s/.*://\'");
     args.push_back(">");
     args.push_back(file+".dis");
     std::string cmd = android::base::Join(args, ' ');

     args.clear();
     args.push_back("/bin/sh");
     args.push_back("-c");
     args.push_back(cmd);

     return Exec(args, error_msg);
   }

   std::string WriteToFile(const std::vector<uint8_t>& buffer, const std::string& test_name) {
     std::string file_name = GetTmpnam() + std::string("---") + test_name;
     const char* data = reinterpret_cast<const char*>(buffer.data());
     std::ofstream s_out(file_name + ".o");
     s_out.write(data, buffer.size());
     s_out.close();
     return file_name + ".o";
   }

   bool CompareFiles(const std::string& f1, const std::string& f2) {
     std::ifstream f1_in(f1);
     std::ifstream f2_in(f2);

     bool result = std::equal(std::istreambuf_iterator<char>(f1_in),
                              std::istreambuf_iterator<char>(),
                              std::istreambuf_iterator<char>(f2_in));

     f1_in.close();
     f2_in.close();

     return result;
   }

   // Compile the given assembly code and extract the binary, if possible. Put result into res.
   bool Compile(const std::string& assembly_code,
                NativeAssemblerResult* res,
                const std::string& test_name) {
     res->ok = false;
     res->code.reset(nullptr);

     res->base_name = GetTmpnam() + std::string("---") + test_name;

     // TODO: Lots of error checking.

     std::ofstream s_out(res->base_name + ".S");
     if (asm_header_ != nullptr) {
       s_out << asm_header_;
     }
     s_out << assembly_code;
     s_out.close();

     if (!Assemble((res->base_name + ".S").c_str(), (res->base_name + ".o").c_str(),
                   &res->error_msg)) {
       res->error_msg = "Could not compile.";
       return false;
     }

     std::string odump = Objdump(res->base_name + ".o");
     if (odump.length() == 0) {
       res->error_msg = "Objdump failed.";
       return false;
     }

     std::istringstream iss(odump);
     std::istream_iterator<std::string> start(iss);
     std::istream_iterator<std::string> end;
     std::vector<std::string> tokens(start, end);

     if (tokens.size() < OBJDUMP_SECTION_LINE_MIN_TOKENS) {
       res->error_msg = "Objdump output not recognized: too few tokens.";
       return false;
     }

     if (tokens[1] != ".text") {
       res->error_msg = "Objdump output not recognized: .text not second token.";
       return false;
     }

     std::string lengthToken = "0x" + tokens[2];
     std::istringstream(lengthToken) >> std::hex >> res->length;

     std::string offsetToken = "0x" + tokens[5];
     uintptr_t offset;
     std::istringstream(offsetToken) >> std::hex >> offset;

     std::ifstream obj(res->base_name + ".o");
     obj.seekg(offset);
     res->code.reset(new std::vector<uint8_t>(res->length));
     obj.read(reinterpret_cast<char*>(&(*res->code)[0]), res->length);
     obj.close();

     res->ok = true;
     return true;
   }

   // Remove temporary files.
   void Clean(const NativeAssemblerResult* res) {
     std::remove((res->base_name + ".S").c_str());
     std::remove((res->base_name + ".o").c_str());
     std::remove((res->base_name + ".o.dump").c_str());
   }

   // Check whether file exists. Is used for commands, so strips off any parameters: anything after
   // the first space. We skip to the last slash for this, so it should work with directories with
   // spaces.
   static bool FileExists(const std::string& file) {
     if (file.length() == 0) {
       return false;
     }

     // Need to strip any options.
     size_t last_slash = file.find_last_of('/');
     if (last_slash == std::string::npos) {
       // No slash, start looking at the start.
       last_slash = 0;
     }
     size_t space_index = file.find(' ', last_slash);

     if (space_index == std::string::npos) {
       std::ifstream infile(file.c_str());
       return infile.good();
     } else {
       std::string copy = file.substr(0, space_index - 1);

       struct stat buf;
       return stat(copy.c_str(), &buf) == 0;
     }
   }

   static std::string GetGCCRootPath() {
     return "prebuilts/gcc/linux-x86";
   }

   static std::string GetRootPath() {
     // 1) Check ANDROID_BUILD_TOP
     char* build_top = getenv("ANDROID_BUILD_TOP");
     if (build_top != nullptr) {
       return std::string(build_top) + "/";
     }

     // 2) Do cwd
     char temp[1024];
     return getcwd(temp, 1024) ? std::string(temp) + "/" : std::string("");
   }

   std::string FindTool(const std::string& tool_name) {
     // Find the current tool. Wild-card pattern is "arch-string*tool-name".
     std::string gcc_path = GetRootPath() + GetGCCRootPath();
     std::vector<std::string> args;
     args.push_back("find");
     args.push_back(gcc_path);
     args.push_back("-name");
     args.push_back(architecture_string_ + "*" + tool_name);
     args.push_back("|");
     args.push_back("sort");
     args.push_back("|");
     args.push_back("tail");
     args.push_back("-n");
     args.push_back("1");
     std::string tmp_file = GetTmpnam();
     args.push_back(">");
     args.push_back(tmp_file);
     std::string sh_args = android::base::Join(args, ' ');

     args.clear();
     args.push_back("/bin/sh");
     args.push_back("-c");
     args.push_back(sh_args);

     std::string error_msg;
     if (!Exec(args, &error_msg)) {
       EXPECT_TRUE(false) << error_msg;
       UNREACHABLE();
     }

     std::ifstream in(tmp_file.c_str());
     std::string line;
     if (!std::getline(in, line)) {
       in.close();
       std::remove(tmp_file.c_str());
       return "";
     }
     in.close();
     std::remove(tmp_file.c_str());
     return line;
   }

   // Helper for below. If name_predicate is empty, search for all files, otherwise use it for the
   // "-name" option.
   static void FindToolDumpPrintout(const std::string& name_predicate,
                                    const std::string& tmp_file) {
     std::string gcc_path = GetRootPath() + GetGCCRootPath();
     std::vector<std::string> args;
     args.push_back("find");
     args.push_back(gcc_path);
     if (!name_predicate.empty()) {
       args.push_back("-name");
       args.push_back(name_predicate);
     }
     args.push_back("|");
     args.push_back("sort");
     args.push_back(">");
     args.push_back(tmp_file);
     std::string sh_args = android::base::Join(args, ' ');

     args.clear();
     args.push_back("/bin/sh");
     args.push_back("-c");
     args.push_back(sh_args);

     std::string error_msg;
     if (!Exec(args, &error_msg)) {
       EXPECT_TRUE(false) << error_msg;
       UNREACHABLE();
     }

     LOG(ERROR) << "FindToolDump: gcc_path=" << gcc_path
                << " cmd=" << sh_args;
     std::ifstream in(tmp_file.c_str());
     if (in) {
       std::string line;
       while (std::getline(in, line)) {
         LOG(ERROR) << line;
       }
     }
     in.close();
     std::remove(tmp_file.c_str());
   }

   // For debug purposes.
   void FindToolDump(const std::string& tool_name) {
     // Check with the tool name.
     FindToolDumpPrintout(architecture_string_ + "*" + tool_name, GetTmpnam());
     FindToolDumpPrintout("", GetTmpnam());
   }

   // Use a consistent tmpnam, so store it.
   std::string GetTmpnam() {
     if (tmpnam_.length() == 0) {
       ScratchFile tmp;
       tmpnam_ = tmp.GetFilename() + "asm";
     }
     return tmpnam_;
   }

   static constexpr size_t OBJDUMP_SECTION_LINE_MIN_TOKENS = 6;

   std::string architecture_string_;
   const char* asm_header_;

   std::string assembler_cmd_name_;
   std::string assembler_parameters_;

   std::string objdump_cmd_name_;
   std::string objdump_parameters_;

   std::string disassembler_cmd_name_;
   std::string disassembler_parameters_;

   std::string resolved_assembler_cmd_;
   std::string resolved_objdump_cmd_;
   std::string resolved_disassemble_cmd_;

   std::string android_data_;

   DISALLOW_COPY_AND_ASSIGN(AssemblerTestInfrastructure);
 };

 }  // namespace art

 #endif  // ART_COMPILER_UTILS_ASSEMBLER_TEST_BASE_H_
	/*
	* Copyright (C) 2014 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_UTILS_ASSEMBLER_TEST_BASE_H_
	#define ART_COMPILER_UTILS_ASSEMBLER_TEST_BASE_H_

	#include <sys/stat.h>
	#include <cstdio>
	#include <cstdlib>
	#include <fstream>
	#include <iterator>

	#include "android-base/strings.h"

	#include "base/utils.h"
	#include "common_runtime_test.h" // For ScratchFile
	#include "exec_utils.h"

	namespace art {

	// If you want to take a look at the differences between the ART assembler and GCC, set this flag
	// to true. The disassembled files will then remain in the tmp directory.
	static constexpr bool kKeepDisassembledFiles = false;

	// Use a glocal static variable to keep the same name for all test data. Else we'll just spam the
	// temp directory.
	static std::string tmpnam_; // NOLINT [runtime/string] [4]

	// We put this into a class as gtests are self-contained, so this helper needs to be in an h-file.
	class AssemblerTestInfrastructure {
	public:
	AssemblerTestInfrastructure(std::string architecture,
	std::string as,
	std::string as_params,
	std::string objdump,
	std::string objdump_params,
	std::string disasm,
	std::string disasm_params,
	const char* asm_header) :
	architecture_string_(architecture),
	asm_header_(asm_header),
	assembler_cmd_name_(as),
	assembler_parameters_(as_params),
	objdump_cmd_name_(objdump),
	objdump_parameters_(objdump_params),
	disassembler_cmd_name_(disasm),
	disassembler_parameters_(disasm_params) {
	// Fake a runtime test for ScratchFile
	CommonRuntimeTest::SetUpAndroidData(android_data_);
	}

	virtual ~AssemblerTestInfrastructure() {
	// We leave temporaries in case this failed so we can debug issues.
	CommonRuntimeTest::TearDownAndroidData(android_data_, false);
	tmpnam_ = "";
	}

	// This is intended to be run as a test.
	bool CheckTools() {
	std::string asm_tool = FindTool(assembler_cmd_name_);
	if (!FileExists(asm_tool)) {
	LOG(ERROR) << "Could not find assembler from " << assembler_cmd_name_;
	LOG(ERROR) << "FindTool returned " << asm_tool;
	FindToolDump(assembler_cmd_name_);
	return false;
	}
	LOG(INFO) << "Chosen assembler command: " << GetAssemblerCommand();

	std::string objdump_tool = FindTool(objdump_cmd_name_);
	if (!FileExists(objdump_tool)) {
	LOG(ERROR) << "Could not find objdump from " << objdump_cmd_name_;
	LOG(ERROR) << "FindTool returned " << objdump_tool;
	FindToolDump(objdump_cmd_name_);
	return false;
	}
	LOG(INFO) << "Chosen objdump command: " << GetObjdumpCommand();

	// Disassembly is optional.
	std::string disassembler = GetDisassembleCommand();
	if (disassembler.length() != 0) {
	std::string disassembler_tool = FindTool(disassembler_cmd_name_);
	if (!FileExists(disassembler_tool)) {
	LOG(ERROR) << "Could not find disassembler from " << disassembler_cmd_name_;
	LOG(ERROR) << "FindTool returned " << disassembler_tool;
	FindToolDump(disassembler_cmd_name_);
	return false;
	}
	LOG(INFO) << "Chosen disassemble command: " << GetDisassembleCommand();
	} else {
	LOG(INFO) << "No disassembler given.";
	}

	return true;
	}

	// Driver() assembles and compares the results. If the results are not equal and we have a
	// disassembler, disassemble both and check whether they have the same mnemonics (in which case
	// we just warn).
	void Driver(const std::vector<uint8_t>& data,
	const std::string& assembly_text,
	const std::string& test_name) {
	EXPECT_NE(assembly_text.length(), 0U) << "Empty assembly";

	NativeAssemblerResult res;
	Compile(assembly_text, &res, test_name);

	EXPECT_TRUE(res.ok) << res.error_msg;
	if (!res.ok) {
	// No way of continuing.
	return;
	}

	if (data == *res.code) {
	Clean(&res);
	} else {
	if (DisassembleBinaries(data, *res.code, test_name)) {
	if (data.size() > res.code->size()) {
	// Fail this test with a fancy colored warning being printed.
	EXPECT_TRUE(false) << "Assembly code is not identical, but disassembly of machine code "
	"is equal: this implies sub-optimal encoding! Our code size=" << data.size() <<
	", gcc size=" << res.code->size();
	} else {
	// Otherwise just print an info message and clean up.
	LOG(INFO) << "GCC chose a different encoding than ours, but the overall length is the "
	"same.";
	Clean(&res);
	}
	} else {
	// This will output the assembly.
	EXPECT_EQ(*res.code, data) << "Outputs (and disassembly) not identical.";
	}
	}
	}

	protected:
	// Return the host assembler command for this test.
	virtual std::string GetAssemblerCommand() {
	// Already resolved it once?
	if (resolved_assembler_cmd_.length() != 0) {
	return resolved_assembler_cmd_;
	}

	std::string line = FindTool(assembler_cmd_name_);
	if (line.length() == 0) {
	return line;
	}

	resolved_assembler_cmd_ = line + assembler_parameters_;

	return resolved_assembler_cmd_;
	}

	// Return the host objdump command for this test.
	virtual std::string GetObjdumpCommand() {
	// Already resolved it once?
	if (resolved_objdump_cmd_.length() != 0) {
	return resolved_objdump_cmd_;
	}

	std::string line = FindTool(objdump_cmd_name_);
	if (line.length() == 0) {
	return line;
	}

	resolved_objdump_cmd_ = line + objdump_parameters_;

	return resolved_objdump_cmd_;
	}

	// Return the host disassembler command for this test.
	virtual std::string GetDisassembleCommand() {
	// Already resolved it once?
	if (resolved_disassemble_cmd_.length() != 0) {
	return resolved_disassemble_cmd_;
	}

	std::string line = FindTool(disassembler_cmd_name_);
	if (line.length() == 0) {
	return line;
	}

	resolved_disassemble_cmd_ = line + disassembler_parameters_;

	return resolved_disassemble_cmd_;
	}

	private:
	// Structure to store intermediates and results.
	struct NativeAssemblerResult {
	bool ok;
	std::string error_msg;
	std::string base_name;
	std::unique_ptr<std::vector<uint8_t>> code;
	uintptr_t length;
	};

	// Compile the assembly file from_file to a binary file to_file. Returns true on success.
	bool Assemble(const char* from_file, const char* to_file, std::string* error_msg) {
	bool have_assembler = FileExists(FindTool(assembler_cmd_name_));
	EXPECT_TRUE(have_assembler) << "Cannot find assembler:" << GetAssemblerCommand();
	if (!have_assembler) {
	return false;
	}

	std::vector<std::string> args;

	// Encaspulate the whole command line in a single string passed to
	// the shell, so that GetAssemblerCommand() may contain arguments
	// in addition to the program name.
	args.push_back(GetAssemblerCommand());
	args.push_back("-o");
	args.push_back(to_file);
	args.push_back(from_file);
	std::string cmd = android::base::Join(args, ' ');

	args.clear();
	args.push_back("/bin/sh");
	args.push_back("-c");
	args.push_back(cmd);

	bool success = Exec(args, error_msg);
	if (!success) {
	LOG(ERROR) << "Assembler command line:";
	for (const std::string& arg : args) {
	LOG(ERROR) << arg;
	}
	}
	return success;
	}

	// Runs objdump -h on the binary file and extracts the first line with .text.
	// Returns "" on failure.
	std::string Objdump(const std::string& file) {
	bool have_objdump = FileExists(FindTool(objdump_cmd_name_));
	EXPECT_TRUE(have_objdump) << "Cannot find objdump: " << GetObjdumpCommand();
	if (!have_objdump) {
	return "";
	}

	std::string error_msg;
	std::vector<std::string> args;

	// Encaspulate the whole command line in a single string passed to
	// the shell, so that GetObjdumpCommand() may contain arguments
	// in addition to the program name.
	args.push_back(GetObjdumpCommand());
	args.push_back(file);
	args.push_back(">");
	args.push_back(file+".dump");
	std::string cmd = android::base::Join(args, ' ');

	args.clear();
	args.push_back("/bin/sh");
	args.push_back("-c");
	args.push_back(cmd);

	if (!Exec(args, &error_msg)) {
	EXPECT_TRUE(false) << error_msg;
	}

	std::ifstream dump(file+".dump");

	std::string line;
	bool found = false;
	while (std::getline(dump, line)) {
	if (line.find(".text") != line.npos) {
	found = true;
	break;
	}
	}

	dump.close();

	if (found) {
	return line;
	} else {
	return "";
	}
	}

	// Disassemble both binaries and compare the text.
	bool DisassembleBinaries(const std::vector<uint8_t>& data,
	const std::vector<uint8_t>& as,
	const std::string& test_name) {
	std::string disassembler = GetDisassembleCommand();
	if (disassembler.length() == 0) {
	LOG(WARNING) << "No dissassembler command.";
	return false;
	}

	std::string data_name = WriteToFile(data, test_name + ".ass");
	std::string error_msg;
	if (!DisassembleBinary(data_name, &error_msg)) {
	LOG(INFO) << "Error disassembling: " << error_msg;
	std::remove(data_name.c_str());
	return false;
	}

	std::string as_name = WriteToFile(as, test_name + ".gcc");
	if (!DisassembleBinary(as_name, &error_msg)) {
	LOG(INFO) << "Error disassembling: " << error_msg;
	std::remove(data_name.c_str());
	std::remove((data_name + ".dis").c_str());
	std::remove(as_name.c_str());
	return false;
	}

	bool result = CompareFiles(data_name + ".dis", as_name + ".dis");

	if (!kKeepDisassembledFiles) {
	std::remove(data_name.c_str());
	std::remove(as_name.c_str());
	std::remove((data_name + ".dis").c_str());
	std::remove((as_name + ".dis").c_str());
	}

	return result;
	}

	bool DisassembleBinary(const std::string& file, std::string* error_msg) {
	std::vector<std::string> args;

	// Encaspulate the whole command line in a single string passed to
	// the shell, so that GetDisassembleCommand() may contain arguments
	// in addition to the program name.
	args.push_back(GetDisassembleCommand());
	args.push_back(file);
	args.push_back("\| sed -n \'/<.data>/,$p\' \| sed -e \'s/.*://\'");
	args.push_back(">");
	args.push_back(file+".dis");
	std::string cmd = android::base::Join(args, ' ');

	args.clear();
	args.push_back("/bin/sh");
	args.push_back("-c");
	args.push_back(cmd);

	return Exec(args, error_msg);
	}

	std::string WriteToFile(const std::vector<uint8_t>& buffer, const std::string& test_name) {
	std::string file_name = GetTmpnam() + std::string("---") + test_name;
	const char* data = reinterpret_cast<const char*>(buffer.data());
	std::ofstream s_out(file_name + ".o");
	s_out.write(data, buffer.size());
	s_out.close();
	return file_name + ".o";
	}

	bool CompareFiles(const std::string& f1, const std::string& f2) {
	std::ifstream f1_in(f1);
	std::ifstream f2_in(f2);

	bool result = std::equal(std::istreambuf_iterator<char>(f1_in),
	std::istreambuf_iterator<char>(),
	std::istreambuf_iterator<char>(f2_in));

	f1_in.close();
	f2_in.close();

	return result;
	}

	// Compile the given assembly code and extract the binary, if possible. Put result into res.
	bool Compile(const std::string& assembly_code,
	NativeAssemblerResult* res,
	const std::string& test_name) {
	res->ok = false;
	res->code.reset(nullptr);

	res->base_name = GetTmpnam() + std::string("---") + test_name;

	// TODO: Lots of error checking.

	std::ofstream s_out(res->base_name + ".S");
	if (asm_header_ != nullptr) {
	s_out << asm_header_;
	}
	s_out << assembly_code;
	s_out.close();

	if (!Assemble((res->base_name + ".S").c_str(), (res->base_name + ".o").c_str(),
	&res->error_msg)) {
	res->error_msg = "Could not compile.";
	return false;
	}

	std::string odump = Objdump(res->base_name + ".o");
	if (odump.length() == 0) {
	res->error_msg = "Objdump failed.";
	return false;
	}

	std::istringstream iss(odump);
	std::istream_iterator<std::string> start(iss);
	std::istream_iterator<std::string> end;
	std::vector<std::string> tokens(start, end);

	if (tokens.size() < OBJDUMP_SECTION_LINE_MIN_TOKENS) {
	res->error_msg = "Objdump output not recognized: too few tokens.";
	return false;
	}

	if (tokens[1] != ".text") {
	res->error_msg = "Objdump output not recognized: .text not second token.";
	return false;
	}

	std::string lengthToken = "0x" + tokens[2];
	std::istringstream(lengthToken) >> std::hex >> res->length;

	std::string offsetToken = "0x" + tokens[5];
	uintptr_t offset;
	std::istringstream(offsetToken) >> std::hex >> offset;

	std::ifstream obj(res->base_name + ".o");
	obj.seekg(offset);
	res->code.reset(new std::vector<uint8_t>(res->length));
	obj.read(reinterpret_cast<char>(&(res->code)[0]), res->length);
	obj.close();

	res->ok = true;
	return true;
	}

	// Remove temporary files.
	void Clean(const NativeAssemblerResult* res) {
	std::remove((res->base_name + ".S").c_str());
	std::remove((res->base_name + ".o").c_str());
	std::remove((res->base_name + ".o.dump").c_str());
	}

	// Check whether file exists. Is used for commands, so strips off any parameters: anything after
	// the first space. We skip to the last slash for this, so it should work with directories with
	// spaces.
	static bool FileExists(const std::string& file) {
	if (file.length() == 0) {
	return false;
	}

	// Need to strip any options.
	size_t last_slash = file.find_last_of('/');
	if (last_slash == std::string::npos) {
	// No slash, start looking at the start.
	last_slash = 0;
	}
	size_t space_index = file.find(' ', last_slash);

	if (space_index == std::string::npos) {
	std::ifstream infile(file.c_str());
	return infile.good();
	} else {
	std::string copy = file.substr(0, space_index - 1);

	struct stat buf;
	return stat(copy.c_str(), &buf) == 0;
	}
	}

	static std::string GetGCCRootPath() {
	return "prebuilts/gcc/linux-x86";
	}

	static std::string GetRootPath() {
	// 1) Check ANDROID_BUILD_TOP
	char* build_top = getenv("ANDROID_BUILD_TOP");
	if (build_top != nullptr) {
	return std::string(build_top) + "/";
	}

	// 2) Do cwd
	char temp[1024];
	return getcwd(temp, 1024) ? std::string(temp) + "/" : std::string("");
	}

	std::string FindTool(const std::string& tool_name) {
	// Find the current tool. Wild-card pattern is "arch-string*tool-name".
	std::string gcc_path = GetRootPath() + GetGCCRootPath();
	std::vector<std::string> args;
	args.push_back("find");
	args.push_back(gcc_path);
	args.push_back("-name");
	args.push_back(architecture_string_ + "*" + tool_name);
	args.push_back("\|");
	args.push_back("sort");
	args.push_back("\|");
	args.push_back("tail");
	args.push_back("-n");
	args.push_back("1");
	std::string tmp_file = GetTmpnam();
	args.push_back(">");
	args.push_back(tmp_file);
	std::string sh_args = android::base::Join(args, ' ');

	args.clear();
	args.push_back("/bin/sh");
	args.push_back("-c");
	args.push_back(sh_args);

	std::string error_msg;
	if (!Exec(args, &error_msg)) {
	EXPECT_TRUE(false) << error_msg;
	UNREACHABLE();
	}

	std::ifstream in(tmp_file.c_str());
	std::string line;
	if (!std::getline(in, line)) {
	in.close();
	std::remove(tmp_file.c_str());
	return "";
	}
	in.close();
	std::remove(tmp_file.c_str());
	return line;
	}

	// Helper for below. If name_predicate is empty, search for all files, otherwise use it for the
	// "-name" option.
	static void FindToolDumpPrintout(const std::string& name_predicate,
	const std::string& tmp_file) {
	std::string gcc_path = GetRootPath() + GetGCCRootPath();
	std::vector<std::string> args;
	args.push_back("find");
	args.push_back(gcc_path);
	if (!name_predicate.empty()) {
	args.push_back("-name");
	args.push_back(name_predicate);
	}
	args.push_back("\|");
	args.push_back("sort");
	args.push_back(">");
	args.push_back(tmp_file);
	std::string sh_args = android::base::Join(args, ' ');

	args.clear();
	args.push_back("/bin/sh");
	args.push_back("-c");
	args.push_back(sh_args);

	std::string error_msg;
	if (!Exec(args, &error_msg)) {
	EXPECT_TRUE(false) << error_msg;
	UNREACHABLE();
	}

	LOG(ERROR) << "FindToolDump: gcc_path=" << gcc_path
	<< " cmd=" << sh_args;
	std::ifstream in(tmp_file.c_str());
	if (in) {
	std::string line;
	while (std::getline(in, line)) {
	LOG(ERROR) << line;
	}
	}
	in.close();
	std::remove(tmp_file.c_str());
	}

	// For debug purposes.
	void FindToolDump(const std::string& tool_name) {
	// Check with the tool name.
	FindToolDumpPrintout(architecture_string_ + "*" + tool_name, GetTmpnam());
	FindToolDumpPrintout("", GetTmpnam());
	}

	// Use a consistent tmpnam, so store it.
	std::string GetTmpnam() {
	if (tmpnam_.length() == 0) {
	ScratchFile tmp;
	tmpnam_ = tmp.GetFilename() + "asm";
	}
	return tmpnam_;
	}

	static constexpr size_t OBJDUMP_SECTION_LINE_MIN_TOKENS = 6;

	std::string architecture_string_;
	const char* asm_header_;

	std::string assembler_cmd_name_;
	std::string assembler_parameters_;

	std::string objdump_cmd_name_;
	std::string objdump_parameters_;

	std::string disassembler_cmd_name_;
	std::string disassembler_parameters_;

	std::string resolved_assembler_cmd_;
	std::string resolved_objdump_cmd_;
	std::string resolved_disassemble_cmd_;

	std::string android_data_;

	DISALLOW_COPY_AND_ASSIGN(AssemblerTestInfrastructure);
	};

	} // namespace art

	#endif // ART_COMPILER_UTILS_ASSEMBLER_TEST_BASE_H_