[Tracing] Implement IC statistics in tracing.

src/code-stubs.cc

Index: src/code-stubs.cc
diff --git a/src/code-stubs.cc b/src/code-stubs.cc
index f0f38ebe9376962df326dab42cc1abff0f67958a..52ca32f6a6bd83fc2f29abdc60ce5d3753487224 100644
--- a/src/code-stubs.cc
+++ b/src/code-stubs.cc
@@ -14,8 +14,10 @@
 #include "src/gdb-jit.h"
 #include "src/ic/accessor-assembler.h"
 #include "src/ic/handler-compiler.h"
+#include "src/ic/ic-stats.h"
 #include "src/ic/ic.h"
 #include "src/macro-assembler.h"
+#include "src/tracing/tracing-category-observer.h"
 
 namespace v8 {
 namespace internal {
@@ -2290,11 +2292,23 @@ void HydrogenCodeStub::TraceTransition(StateType from, StateType to) {
   // Note: Although a no-op transition is semantically OK, it is hinting at a
   // bug somewhere in our state transition machinery.
   DCHECK(from != to);
-  if (!FLAG_trace_ic) return;
-  OFStream os(stdout);
-  os << "[";
-  PrintBaseName(os);
-  os << ": " << from << "=>" << to << "]" << std::endl;
+  if (V8_LIKELY(!FLAG_ic_stats)) return;
+  if (FLAG_ic_stats &

[Camillo Bruni, 2016/12/02 12:12:55]

no need to check the flag again.

[lpy, 2016/12/05 17:49:10]

but we want to check if the flag is enabled by tracing or not, and if the flag
is set and not enabled by tracing, then it's enabled by command line.

+      v8::tracing::TracingCategoryObserver::ENABLED_BY_TRACING) {
+    auto ic_stats = ICStats::instance();
+    ic_stats->Begin();
+    ICInfo& ic_info = ic_stats->Current();
+    ic_info.type = MajorName(MajorKey());
+    ic_info.state = ToString(from);
+    ic_info.state += "=>";
+    ic_info.state += ToString(to);
+    ic_stats->End();
+  } else if (FLAG_ic_stats) {

[Camillo Bruni, 2016/12/02 12:12:55]

same here.

[lpy, 2016/12/05 17:49:10]

see explanation above.

[Camillo Bruni, 2016/12/05 20:13:50]

Argh, sorry I misread the single & above, but nevertheless, you can drop this
second check then as this will be certainly true.

+    OFStream os(stdout);
+    os << "[";
+    PrintBaseName(os);
+    os << ": " << from << "=>" << to << "]" << std::endl;
+  }
 }
 
 void CallICStub::PrintState(std::ostream& os) const {  // NOLINT