Add support for dumping code in jitdump file format

runtime/vm/os_linux.cc

Index: runtime/vm/os_linux.cc
diff --git a/runtime/vm/os_linux.cc b/runtime/vm/os_linux.cc
index 97e9e553b2ebad3b44ef4a32d1781cb5053eefef..283fb338f0c813075249b7bea68b62415bd0ebbb 100644
--- a/runtime/vm/os_linux.cc
+++ b/runtime/vm/os_linux.cc
@@ -14,6 +14,9 @@
 #include <sys/resource.h>  // NOLINT
 #include <sys/time.h>  // NOLINT
 #include <sys/types.h>  // NOLINT
+#include <sys/syscall.h>  // NOLINT
+#include <sys/stat.h>  // NOLINT
+#include <fcntl.h>  // NOLINT
 #include <unistd.h>  // NOLINT
 
 #include "platform/utils.h"
@@ -37,6 +40,8 @@ DEFINE_FLAG(bool, ll_prof, false,
     "Generate compiled code log file for processing with ll_prof.py.");
 DEFINE_FLAG(charp, generate_pprof_symbols, NULL,
     "Writes pprof events symbols to the provided file");
+DEFINE_FLAG(bool, generate_perf_jitdump, true,
+    "Writes jitdump data for profiling with perf annotate");
 
 class LowLevelProfileCodeObserver : public CodeObserver {
  public:
@@ -269,6 +274,190 @@ class GdbCodeObserver : public CodeObserver {
 };
 
 
+#define CLOCKFD 3
+#define FD_TO_CLOCKID(fd)       ((~(clockid_t) (fd) << 3) | CLOCKFD)  // NOLINT
+#define CLOCKID_TO_FD(id)       ((~(int) (id) >> 3) & ~CLOCKFD)  // NOLINT
+
+class JitdumpCodeObserver : public CodeObserver {
+ public:
+  JitdumpCodeObserver() {

[Ivan Posva, 2014/02/06 00:33:26]

ASSERT that the relevant flag is set.

[Cutch, 2014/02/13 19:16:58]

Done.

+    Dart_FileOpenCallback file_open = Isolate::file_open_callback();
+    if (file_open == NULL) {
+      return;
+    }
+    Dart_FileWriteCallback file_write = Isolate::file_write_callback();
+    if (file_write == NULL) {
+      return;
+    }

[Ivan Posva, 2014/02/06 00:33:26]

Don't you want to check the file_close callback here as well?

[Cutch, 2014/02/13 19:16:58]

Done.

+    const char* format = "/tmp/jit-%ld.dump";

[Ivan Posva, 2014/02/06 00:33:26]

// Comments please. What are we going to access here?

[Cutch, 2014/02/13 19:16:58]

Done.

+    intptr_t pid = getpid();
+    intptr_t len = OS::SNPrint(NULL, 0, format, pid);
+    char* filename = new char[len + 1];
+    OS::SNPrint(filename, len + 1, format, pid);
+    out_file_ = (*file_open)(filename, true);
+    ASSERT(out_file_ != NULL);
+    clock_id_ = kInvalidClockId;
+    clock_fd_ = open("/dev/trace_clock", O_RDONLY);
+    if (clock_fd_ >= 0) {
+      clock_id_ = FD_TO_CLOCKID(clock_fd_);
+      printf("Using /dev/trace_clock as timesource (%x).\n", clock_id_);

[Ivan Posva, 2014/02/06 00:33:26]

Do you really want to print this every time?

[Cutch, 2014/02/13 19:16:58]

Removed.

+    }
+    WriteHeader();
+  }
+
+  ~JitdumpCodeObserver() {
+    Dart_FileCloseCallback file_close = Isolate::file_close_callback();
+    if (file_close == NULL) {
+      return;
+    }
+    ASSERT(out_file_ != NULL);
+    (*file_close)(out_file_);
+    if (clock_fd_ >= 0) {
+      close(clock_fd_);
+    }
+  }
+
+  virtual bool IsActive() const {
+    return FLAG_generate_perf_jitdump && (out_file_ != NULL);
+  }
+
+  virtual void Notify(const char* name,
+                      uword base,
+                      uword prologue_offset,
+                      uword size,
+                      bool optimized) {
+    WriteCodeLoad(name, base, prologue_offset, size, optimized);
+  }
+
+ private:
+  void* out_file_;
+
+  static const uint32_t kJitHeaderMagic = 0x4F74496A;
+  static const uint32_t kJitHeaderVersion = 0x2;
+  static const uint32_t kElfMachIA32 = 3;
+  static const uint32_t kElfMachX64 = 62;
+  static const uint32_t kElfMachARM = 40;
+  static const uint32_t kElfMachMIPS = 10;
+  static const int kInvalidClockId = -1;
+
+  struct jitheader {
+    uint32_t magic;
+    uint32_t version;
+    uint32_t total_size;
+    uint32_t elf_mach;
+    uint32_t pad1;
+    uint32_t pid;
+    uint64_t timestamp;
+  };
+
+  enum jit_record_type {
+    JIT_CODE_LOAD = 0,
+    /* JIT_CODE_UNLOAD = 1, */
+    /* JIT_CODE_CLOSE = 2, */
+    /* JIT_CODE_DEBUG_INFO = 3, */
+    JIT_CODE_MAX = 4,
+  };
+
+  struct jr_code_load {
+    uint32_t id;
+    uint32_t total_size;
+    uint64_t timestamp;
+    uint32_t pid;
+    uint32_t tid;
+    uint64_t vma;
+    uint64_t code_addr;
+    uint32_t code_size;
+    uint32_t align;
+  };
+
+  const char* GenerateCodeName(const char* name, bool optimized) {
+    const char* format = "%s%s";
+    const char* marker = optimized ? "*" : "";
+    intptr_t len = OS::SNPrint(NULL, 0, format, marker, name);
+    char* buffer = Isolate::Current()->current_zone()->Alloc<char>(len + 1);
+    OS::SNPrint(buffer, len + 1, format, marker, name);
+    return buffer;
+  }
+
+  uint32_t GetElfMach() {
+#if defined(TARGET_ARCH_IA32)
+    return kElfMachIA32;
+#elif defined(TARGET_ARCH_X64)
+    return kElfMachX64;
+#elif defined(TARGET_ARCH_ARM)
+    return kElfMachARM;
+#elif defined(TARGET_ARCH_MIPS)
+    return kElfMachMIPS;
+#else

[Ivan Posva, 2014/02/06 00:33:26]

Generally we want to get compilation errors if we can. In this case we can:

#else
#error Unknown architecture.
#endif

[Cutch, 2014/02/13 19:16:58]

Done.

+    UNIMPLEMENTED();
+#endif
+  }
+
+  pid_t gettid() {
+    return syscall(SYS_gettid);

[Ivan Posva, 2014/02/06 00:33:26]

Why do we have to go through syscall here? Is there no way to call this
directly? At least please add a comment explaining what is happening here.

[Cutch, 2014/02/13 19:16:58]

libc doesn't wrap Linux-specific gettid, i've added a note.

+  }
+
+  uint64_t GetKernelTimeNanos() {
+    if (clock_id_ != kInvalidClockId) {
+      struct timespec ts;
+      int r = clock_gettime(clock_id_, &ts);
+      ASSERT(r == 0);
+      uint64_t nanos = static_cast<uint64_t>(ts.tv_sec) *
+                       static_cast<uint64_t>(kNanosecondsPerSecond);
+      nanos += static_cast<uint64_t>(ts.tv_nsec);
+      return nanos;
+    } else {
+      return OS::GetCurrentTimeMicros() * kNanosecondsPerMicrosecond;
+    }
+  }
+
+  void WriteHeader() {
+    Dart_FileWriteCallback file_write = Isolate::file_write_callback();
+    ASSERT(file_write != NULL);
+    ASSERT(out_file_ != NULL);
+    jitheader header;
+    header.magic = kJitHeaderMagic;
+    header.version = kJitHeaderVersion;
+    header.total_size = sizeof(jitheader);
+    header.pad1 = 0xdeadbeef;
+    header.elf_mach = GetElfMach();
+    header.pid = getpid();
+    header.timestamp = GetKernelTimeNanos();
+    (*file_write)(&header, sizeof(header), out_file_);
+  }
+
+  void WriteCodeLoad(const char* name, uword base, uword prologue_offset,
+                     uword code_size, bool optimized) {
+    Dart_FileWriteCallback file_write = Isolate::file_write_callback();
+    ASSERT(file_write != NULL);
+    ASSERT(out_file_ != NULL);
+
+    const char* code_name = GenerateCodeName(name, optimized);
+    const intptr_t code_name_size = strlen(code_name) + 1;
+    uint8_t* code_pointer = reinterpret_cast<uint8_t*>(base);
+
+    jr_code_load code_load;
+    code_load.id = JIT_CODE_LOAD;
+    code_load.total_size = sizeof(code_load) + code_name_size + code_size;
+    code_load.timestamp = GetKernelTimeNanos();
+    code_load.pid = getpid();
+    code_load.tid = gettid();
+    code_load.vma = 0x0;  //  Our addresses are absolute.
+    code_load.code_addr = base;
+    code_load.code_size = code_size;
+    code_load.align = OS::PreferredCodeAlignment();
+
+    (*file_write)(&code_load, sizeof(code_load), out_file_);

[Ivan Posva, 2014/02/06 00:33:26]

Multiple isolates will collide here.

Please verify other observers. Thanks!

[Cutch, 2014/02/13 19:16:58]

Done.

+    (*file_write)(code_name, code_name_size, out_file_);
+    (*file_write)(code_pointer, code_size, out_file_);
+  }
+
+  int clock_fd_;
+  int clock_id_;
+  DISALLOW_COPY_AND_ASSIGN(JitdumpCodeObserver);
+};
+
+
 const char* OS::Name() {
   return "linux";
 }
@@ -512,6 +701,9 @@ void OS::RegisterCodeObservers() {
   if (FLAG_generate_pprof_symbols != NULL) {
     CodeObservers::Register(new PprofCodeObserver);
   }
+  if (FLAG_generate_perf_jitdump) {
+    CodeObservers::Register(new JitdumpCodeObserver);
+  }
 #if defined(DART_VTUNE_SUPPORT)
   CodeObservers::Register(new VTuneCodeObserver);
 #endif