[turbofan] Fix source position integration with Linux perf

src/perf-jit.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 194 matching lines @@
   base::LockGuard<base::RecursiveMutex> guard_file(file_mutex_.Pointer());
 
   if (perf_output_handle_ == nullptr) return;
 
   // We only support non-interpreted functions.
   if (!abstract_code->IsCode()) return;
   Code* code = abstract_code->GetCode();
   DCHECK(code->instruction_start() == code->address() + Code::kHeaderSize);
 
   // Debug info has to be emitted first.
-  if (FLAG_perf_prof_debug_info && shared != nullptr) {
+  if (FLAG_perf_prof && shared != nullptr) {
     LogWriteDebugInfo(code, shared);
   }
 
   const char* code_name = name;
   uint8_t* code_pointer = reinterpret_cast<uint8_t*>(code->instruction_start());
   uint32_t code_size = code->is_crankshafted() ? code->safepoint_table_offset()
                                                : code->instruction_size();
 
   // Unwinding info comes right after debug info.
   if (FLAG_perf_prof_unwinding_info) LogWriteUnwindingInfo(code);
@@ skipping 13 matching lines @@
   code_load.code_id_ = code_index_;
 
   code_index_++;
 
   LogWriteBytes(reinterpret_cast<const char*>(&code_load), sizeof(code_load));
   LogWriteBytes(code_name, length);
   LogWriteBytes(string_terminator, 1);
   LogWriteBytes(reinterpret_cast<const char*>(code_pointer), code_size);
 }
 
+namespace {
+
+std::unique_ptr<char[]> GetScriptName(Handle<Script> script) {
+  Handle<Object> name_or_url(Script::GetNameOrSourceURL(script));
+  int name_length = 0;
+  std::unique_ptr<char[]> name_string;
+  if (name_or_url->IsString()) {
+    return Handle<String>::cast(name_or_url)
+        ->ToCString(DISALLOW_NULLS, FAST_STRING_TRAVERSAL, &name_length);
+  } else {
+    const char unknown[] = "<unknown>";
+    name_length = static_cast<int>(strlen(unknown));
+    char* buffer = NewArray<char>(name_length);
+    base::OS::StrNCpy(buffer, name_length + 1, unknown,
+                      static_cast<size_t>(name_length));
+    return std::unique_ptr<char[]>(buffer);
+  }
+}
+
+SourcePositionInfo GetSourcePositionInfo(Handle<Code> code,
+                                         Handle<SharedFunctionInfo> function,
+                                         SourcePosition pos) {
+  if (code->is_turbofanned() || code->is_crankshafted()) {
+    return pos.InliningStack(code)[0];
+  } else {
+    return SourcePositionInfo(pos, function);

[Tobias Tebbi, 2016/12/09 14:57:51]

This does not compute the line and column. Why not just always use
pos.InliningStack(code)[0]?

[danno, 2016/12/12 09:53:56]

Good question. Full code gen uses the deopt input data vector slot in the code
object for something else rather than deopt info, so calling InliningStack
crashes on FGC code. Therefore, since there is no inlining, the source position
needs to be generated by hand.

+  }
+}
+
+}  // namespace
+
 void PerfJitLogger::LogWriteDebugInfo(Code* code, SharedFunctionInfo* shared) {
   // Compute the entry count and get the name of the script.
   uint32_t entry_count = 0;
   for (SourcePositionTableIterator iterator(code->source_position_table());
        !iterator.done(); iterator.Advance()) {
     entry_count++;
   }
   if (entry_count == 0) return;
   Handle<Script> script(Script::cast(shared->script()));
-  Handle<Object> name_or_url(Script::GetNameOrSourceURL(script));
-
-  int name_length = 0;
-  std::unique_ptr<char[]> name_string;
-  if (name_or_url->IsString()) {
-    name_string =
-        Handle<String>::cast(name_or_url)
-            ->ToCString(DISALLOW_NULLS, FAST_STRING_TRAVERSAL, &name_length);
-    DCHECK_EQ(0, name_string.get()[name_length]);
-  } else {
-    const char unknown[] = "<unknown>";
-    name_length = static_cast<int>(strlen(unknown));
-    char* buffer = NewArray<char>(name_length);
-    base::OS::StrNCpy(buffer, name_length + 1, unknown,
-                      static_cast<size_t>(name_length));
-    name_string = std::unique_ptr<char[]>(buffer);
-  }
-  DCHECK_EQ(name_length, static_cast<int>(strlen(name_string.get())));
 
   PerfJitCodeDebugInfo debug_info;
 
   debug_info.event_ = PerfJitCodeLoad::kDebugInfo;
   debug_info.time_stamp_ = GetTimestamp();
   debug_info.address_ = reinterpret_cast<uint64_t>(code->instruction_start());
   debug_info.entry_count_ = entry_count;
 
   uint32_t size = sizeof(debug_info);
   // Add the sizes of fixed parts of entries.
   size += entry_count * sizeof(PerfJitDebugEntry);
-  // Add the size of the name after the first entry.
-  size += (static_cast<uint32_t>(name_length) + 1) * entry_count;
+  // Add the size of the name after the each entry.

[Tobias Tebbi, 2016/12/09 14:57:51]

typo: after each entry.

[danno, 2016/12/12 09:53:56]

Done.

+
+  Handle<Code> code_handle(code);
+  Handle<SharedFunctionInfo> function_handle(shared);
+  for (SourcePositionTableIterator iterator(code->source_position_table());
+       !iterator.done(); iterator.Advance()) {
+    SourcePositionInfo info(GetSourcePositionInfo(code_handle, function_handle,
+                                                  iterator.source_position()));
+    Handle<Script> script(Script::cast(info.function->script()));
+    std::unique_ptr<char[]> name_string = GetScriptName(script);
+    size += (static_cast<uint32_t>(strlen(name_string.get())) + 1);
+  }
 
   int padding = ((size + 7) & (~7)) - size;
-
   debug_info.size_ = size + padding;
-
   LogWriteBytes(reinterpret_cast<const char*>(&debug_info), sizeof(debug_info));
 
-  int script_line_offset = script->line_offset();
   Handle<FixedArray> line_ends(FixedArray::cast(script->line_ends()));
   Address code_start = code->instruction_start();
 
   for (SourcePositionTableIterator iterator(code->source_position_table());
        !iterator.done(); iterator.Advance()) {
-    int position = iterator.source_position().ScriptOffset();
-    int line_number = Script::GetLineNumber(script, position);
-    // Compute column.
-    int relative_line_number = line_number - script_line_offset;
-    int start =
-        (relative_line_number == 0)
-            ? 0
-            : Smi::cast(line_ends->get(relative_line_number - 1))->value() + 1;
-    int column_offset = position - start;
-    if (relative_line_number == 0) {
-      // For the case where the code is on the same line as the script tag.
-      column_offset += script->column_offset();
-    }
-
+    SourcePositionInfo info(GetSourcePositionInfo(code_handle, function_handle,
+                                                  iterator.source_position()));
     PerfJitDebugEntry entry;
+    // TODO(danno): There seems to be a bug in the dwarf handling of JIT code in
+    // the perf tool. It seems to erroneously believe that the first instruction
+    // of functions is at offset 0x40 when displayed in "perf report". To
+    // compensate for this, add a magic constant to the position addresses when
+    // writing them out.
     entry.address_ =
-        reinterpret_cast<uint64_t>(code_start + iterator.code_offset());
-    entry.line_number_ = line_number;
-    entry.column_ = column_offset;
+        reinterpret_cast<intptr_t>(code_start + iterator.code_offset() + 0x40);
+    entry.line_number_ = info.line + 1;
+    entry.column_ = info.column + 1;
     LogWriteBytes(reinterpret_cast<const char*>(&entry), sizeof(entry));
-    LogWriteBytes(name_string.get(), name_length + 1);
+    Handle<Script> script(Script::cast(info.function->script()));
+    std::unique_ptr<char[]> name_string = GetScriptName(script);
+    LogWriteBytes(name_string.get(),
+                  static_cast<uint32_t>(strlen(name_string.get())) + 1);
   }
   char padding_bytes[] = "\0\0\0\0\0\0\0\0";
   LogWriteBytes(padding_bytes, padding);
 }
 
 void PerfJitLogger::LogWriteUnwindingInfo(Code* code) {
   PerfJitCodeUnwindingInfo unwinding_info_header;
   unwinding_info_header.event_ = PerfJitCodeLoad::kUnwindingInfo;
   unwinding_info_header.time_stamp_ = GetTimestamp();
   unwinding_info_header.eh_frame_hdr_size_ = EhFrameConstants::kEhFrameHdrSize;
@@ skipping 51 matching lines @@
   header.time_stamp_ =
       static_cast<uint64_t>(base::OS::TimeCurrentMillis() * 1000.0);
   header.flags_ = 0;
 
   LogWriteBytes(reinterpret_cast<const char*>(&header), sizeof(header));
 }
 
 #endif  // V8_OS_LINUX
 }  // namespace internal
 }  // namespace v8