Extend CPU profiler with mapping ticks to source lines

src/profile-generator.cc

Index: src/profile-generator.cc
diff --git a/src/profile-generator.cc b/src/profile-generator.cc
index 44f7555b350cfeff8f078ac0da75fa75f09547fd..c6fad51dfb0fe33a1e0c80a97ad592ac323810c0 100644
--- a/src/profile-generator.cc
+++ b/src/profile-generator.cc
@@ -144,6 +144,7 @@ const char* const CodeEntry::kEmptyBailoutReason = "";
 
 CodeEntry::~CodeEntry() {
   delete no_frame_ranges_;
+  delete line_info_;
 }
 
 
@@ -186,6 +187,14 @@ void CodeEntry::SetBuiltinId(Builtins::Name id) {
 }
 
 
+int CodeEntry::GetSourceLine(int pc_offset) const {
+  if (line_info_ && !line_info_->Empty()) {
+    return line_info_->GetSourceLineNumber(pc_offset);
+  }
+  return v8::CpuProfileNode::kNoLineNumberInfo;
+}
+
+
 ProfileNode* ProfileNode::FindChild(CodeEntry* entry) {
   HashMap::Entry* map_entry =
       children_.Lookup(entry, CodeEntryHash(entry), false);
@@ -207,6 +216,39 @@ ProfileNode* ProfileNode::FindOrAddChild(CodeEntry* entry) {
 }
 
 
+void ProfileNode::IncrementLineTicks(int src_line) {
+  if (src_line == v8::CpuProfileNode::kNoLineNumberInfo) return;
+  // Increment a hit counter of a certain source line.
+  // Add a new source line if not found.
+  HashMap::Entry* e =
+    line_ticks_.Lookup(reinterpret_cast<void*>(src_line), src_line, true);
+  ASSERT(e);
+  e->value = static_cast<char*>(e->value) + 1;

[alph, 2014/08/11 12:18:15]

should be cast to uintptr_t

[Denis Pravdin, 2014/08/11 13:00:13]

e->value is type of void* and used as a hit counter. To increment it by 1 void*
should be casted to char* but not uintptr*. otherwise it will be incremented by
sizeof(int).

[alph, 2014/08/11 13:41:04]

I didn't say uintptr*, I said uintptr_t :-)
uintptr_t is an integer type having a size of the platform pointer. The cast to
char* does also work, but it looks like a trick relying on the fact sizeof(char)
is 1.

I meant to use the following snippet to be strictly correct with types:
e->value = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(e->value) + 1);

+}
+
+
+bool ProfileNode::GetLineTicks(v8::CpuProfileNode::LineTick* entries,
+                               unsigned int length) const {
+  if (entries == NULL || length == 0) return false;
+
+  unsigned line_count = line_ticks_.occupancy();
+
+  if (line_count == 0) return false;
+  if (length < line_count) return false;
+
+  v8::CpuProfileNode::LineTick* entry = entries;
+
+  for (HashMap::Entry* p = line_ticks_.Start();
+       p != NULL;
+       p = line_ticks_.Next(p), entry++) {
+    entry->line = reinterpret_cast<uintptr_t>(p->key);

[alph, 2014/08/11 12:18:15]

I still bet it won't compile on x64 because of implicit 64->32 bits conversion.
You have to write something like:
static_cast<usigned int>(reinterpret_cast<uintptr_t>(p->key));

[Denis Pravdin, 2014/08/11 13:00:13]

Acknowledged.

+    entry->hit_count = reinterpret_cast<uintptr_t>(p->value);
+  }
+
+  return true;
+}
+
+
 void ProfileNode::Print(int indent) {
   base::OS::Print("%5u %*s %s%s %d #%d %s", self_ticks_, indent, "",
                   entry_->name_prefix(), entry_->name(), entry_->script_id(),
@@ -247,7 +289,8 @@ ProfileTree::~ProfileTree() {
 }
 
 
-ProfileNode* ProfileTree::AddPathFromEnd(const Vector<CodeEntry*>& path) {
+ProfileNode* ProfileTree::AddPathFromEnd(const Vector<CodeEntry*>& path,
+                                         int src_line) {
   ProfileNode* node = root_;
   for (CodeEntry** entry = path.start() + path.length() - 1;
        entry != path.start() - 1;
@@ -257,11 +300,15 @@ ProfileNode* ProfileTree::AddPathFromEnd(const Vector<CodeEntry*>& path) {
     }
   }
   node->IncrementSelfTicks();
+  if (src_line != v8::CpuProfileNode::kNoLineNumberInfo) {
+    node->IncrementLineTicks(src_line);
+  }
   return node;
 }
 
 
-void ProfileTree::AddPathFromStart(const Vector<CodeEntry*>& path) {
+void ProfileTree::AddPathFromStart(const Vector<CodeEntry*>& path,
+                                   int src_line) {
   ProfileNode* node = root_;
   for (CodeEntry** entry = path.start();
        entry != path.start() + path.length();
@@ -271,6 +318,9 @@ void ProfileTree::AddPathFromStart(const Vector<CodeEntry*>& path) {
     }
   }
   node->IncrementSelfTicks();
+  if (src_line != v8::CpuProfileNode::kNoLineNumberInfo) {
+    node->IncrementLineTicks(src_line);
+  }
 }
 
 
@@ -332,8 +382,9 @@ CpuProfile::CpuProfile(const char* title, bool record_samples)
 
 
 void CpuProfile::AddPath(base::TimeTicks timestamp,
-                         const Vector<CodeEntry*>& path) {
-  ProfileNode* top_frame_node = top_down_.AddPathFromEnd(path);
+                         const Vector<CodeEntry*>& path,
+                         int src_line) {
+  ProfileNode* top_frame_node = top_down_.AddPathFromEnd(path, src_line);
   if (record_samples_) {
     timestamps_.Add(timestamp);
     samples_.Add(top_frame_node);
@@ -522,13 +573,15 @@ void CpuProfilesCollection::RemoveProfile(CpuProfile* profile) {
 
 
 void CpuProfilesCollection::AddPathToCurrentProfiles(
-    base::TimeTicks timestamp, const Vector<CodeEntry*>& path) {
+    base::TimeTicks timestamp,
+    const Vector<CodeEntry*>& path,
+    int src_line) {
   // As starting / stopping profiles is rare relatively to this
   // method, we don't bother minimizing the duration of lock holding,
   // e.g. copying contents of the list to a local vector.
   current_profiles_semaphore_.Wait();
   for (int i = 0; i < current_profiles_.length(); ++i) {
-    current_profiles_[i]->AddPath(timestamp, path);
+    current_profiles_[i]->AddPath(timestamp, path, src_line);
   }
   current_profiles_semaphore_.Signal();
 }
@@ -540,13 +593,15 @@ CodeEntry* CpuProfilesCollection::NewCodeEntry(
       const char* name_prefix,
       const char* resource_name,
       int line_number,
-      int column_number) {
+      int column_number,
+      JITLineInfoTable* line_info) {
   CodeEntry* code_entry = new CodeEntry(tag,
                                         name,
                                         name_prefix,
                                         resource_name,
                                         line_number,
-                                        column_number);
+                                        column_number,
+                                        line_info);
   code_entries_.Add(code_entry);
   return code_entry;
 }
@@ -586,6 +641,14 @@ void ProfileGenerator::RecordTickSample(const TickSample& sample) {
   // entries vector with NULL values.
   CodeEntry** entry = entries.start();
   memset(entry, 0, entries.length() * sizeof(*entry));
+
+  // The ProfileNode knows nothing about all versions of generated code for
+  // the same JS function. The line number information associated with
+  // the latest version of generated code is used to find a source line number
+  // for a JS function. Then, the detected source line is passed to
+  // ProfileNode to accumulate the samples.
+  int src_line = v8::CpuProfileNode::kNoLineNumberInfo;
+
   if (sample.pc != NULL) {
     if (sample.has_external_callback && sample.state == EXTERNAL &&
         sample.top_frame_type == StackFrame::EXIT) {
@@ -602,10 +665,10 @@ void ProfileGenerator::RecordTickSample(const TickSample& sample) {
       // frame. Check for this case and just skip such samples.
       if (pc_entry) {
         List<OffsetRange>* ranges = pc_entry->no_frame_ranges();
+        Code* code = Code::cast(HeapObject::FromAddress(start));
+        int pc_offset = static_cast<int>(sample.pc - code->instruction_start());
+        src_line = pc_entry->GetSourceLine(pc_offset);
         if (ranges) {
-          Code* code = Code::cast(HeapObject::FromAddress(start));
-          int pc_offset = static_cast<int>(
-              sample.pc - code->instruction_start());
           for (int i = 0; i < ranges->length(); i++) {
             OffsetRange& range = ranges->at(i);
             if (range.from <= pc_offset && pc_offset < range.to) {
@@ -629,11 +692,29 @@ void ProfileGenerator::RecordTickSample(const TickSample& sample) {
       }
     }
 
+    bool src_line_not_found = src_line == v8::CpuProfileNode::kNoLineNumberInfo;
+
     for (const Address* stack_pos = sample.stack,
            *stack_end = stack_pos + sample.frames_count;
          stack_pos != stack_end;
          ++stack_pos) {
-      *entry++ = code_map_.FindEntry(*stack_pos);
+      Address start = NULL;
+      *entry = code_map_.FindEntry(*stack_pos, &start);
+
+      // Skip unresolved frames (e.g. internal frame) and get source line of
+      // the JS caller.
+      if (src_line_not_found && *entry) {
+        Code* code = Code::cast(HeapObject::FromAddress(start));
+        int pc_offset =
+            static_cast<int>(*stack_pos - code->instruction_start());
+        src_line = (*entry)->GetSourceLine(pc_offset);
+        if (src_line == v8::CpuProfileNode::kNoLineNumberInfo) {
+          src_line = (*entry)->line_number();
+        }
+        src_line_not_found = false;
+      }
+
+      entry++;
     }
   }
 
@@ -651,7 +732,7 @@ void ProfileGenerator::RecordTickSample(const TickSample& sample) {
     }
   }
 
-  profiles_->AddPathToCurrentProfiles(sample.timestamp, entries);
+  profiles_->AddPathToCurrentProfiles(sample.timestamp, entries, src_line);
 }