[turbofan] Fix source position integration with Linux perf

src/perf-jit.cc

Index: src/perf-jit.cc
diff --git a/src/perf-jit.cc b/src/perf-jit.cc
index 6641a1259b0278442bb0c3b1535f069242089d16..53ffc5becf5c8ea47bddf8a355b3d46184d708bb 100644
--- a/src/perf-jit.cc
+++ b/src/perf-jit.cc
@@ -212,7 +212,7 @@ void PerfJitLogger::LogRecordedBuffer(AbstractCode* abstract_code,
   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);
   }
 
@@ -246,33 +246,46 @@ void PerfJitLogger::LogRecordedBuffer(AbstractCode* abstract_code,
   LogWriteBytes(reinterpret_cast<const char*>(code_pointer), code_size);
 }
 
-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));
+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()) {
-    name_string =
-        Handle<String>::cast(name_or_url)
-            ->ToCString(DISALLOW_NULLS, FAST_STRING_TRAVERSAL, &name_length);
-    DCHECK_EQ(0, name_string.get()[name_length]);
+    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));
-    name_string = std::unique_ptr<char[]>(buffer);
+    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++;
   }
-  DCHECK_EQ(name_length, static_cast<int>(strlen(name_string.get())));
+  if (entry_count == 0) return;
+  Handle<Script> script(Script::cast(shared->script()));
 
   PerfJitCodeDebugInfo debug_info;
 
@@ -284,42 +297,45 @@ void PerfJitLogger::LogWriteDebugInfo(Code* code, SharedFunctionInfo* shared) {
   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.

 
-  int padding = ((size + 7) & (~7)) - size;
+  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);