AllocationSites for all literals

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index af3c39e45ed07f5650a0af2859d6dfa67e4f8997..d945550b641f5fff504706232779d1d532a68c09 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -31,6 +31,7 @@
 #include "v8.h"
 
 #include "accessors.h"
+#include "allocation-site-scopes.h"
 #include "api.h"
 #include "arguments.h"
 #include "bootstrapper.h"
@@ -486,19 +487,35 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_CreateObjectLiteral) {
   bool has_function_literal = (flags & ObjectLiteral::kHasFunction) != 0;
 
   // Check if boilerplate exists. If not, create it first.
-  Handle<Object> boilerplate(literals->get(literals_index), isolate);
-  if (*boilerplate == isolate->heap()->undefined_value()) {
+  Handle<Object> literal_site(literals->get(literals_index), isolate);
+  Handle<AllocationSite> site;
+  Handle<Object> boilerplate;
+  if (*literal_site == isolate->heap()->undefined_value()) {
     boilerplate = CreateObjectLiteralBoilerplate(isolate,
                                                  literals,
                                                  constant_properties,
                                                  should_have_fast_elements,
                                                  has_function_literal);
     RETURN_IF_EMPTY_HANDLE(isolate, boilerplate);
+
+    AllocationSiteContext site_context(isolate, true);
+    AllocationSiteCreationScope site_scope(&site_context);
+    Handle<Object> same = JSObject::DeepWalk(
+        Handle<JSObject>::cast(boilerplate), &site_context);
+    site_scope.RecordTransitionInfo(same);
+    site = site_context.top();
+
     // Update the functions literal and return the boilerplate.
-    literals->set(literals_index, *boilerplate);
+    literals->set(literals_index, *site);
+  } else {
+    site = Handle<AllocationSite>::cast(literal_site);
+    boilerplate = Handle<Object>(site->transition_info(), isolate);
   }
 
-  Handle<Object> copy = JSObject::DeepCopy(Handle<JSObject>::cast(boilerplate));
+  AllocationSiteContext site_context(isolate, true);
+  AllocationSiteUsageScope site_scope(&site_context, site, boilerplate);

[Hannes Payer (out of office), 2013/10/11 12:55:44]

As discussed offline, right now we would emit mementos also in optimized code.
We should turn that off (in a different cl if it does not tank performance).

[mvstanton, 2013/10/11 13:41:47]

Good catch. I added this TODO in HOptimizedGraphBuilder::VisitObjectLiteral and
VisitArrayLiteral:

// TODO(mvstanton): Add a flag to turn off creation of any
// AllocationMementos for this call: we are in crankshaft and should have
// learned enough about transition behavior to stop emitting mementos.    

Performance-wise, I think we are okay at the moment because the mementos are
only turned on for:

1) Any nested or standalone Fast Smi Arrays, which also
2) don't meet the criteria of IsFastLiteral()

It should be a corner case. I see by instrumenting kraken that only a few tests
emit this code and only stanford-crypto-pbkdf2 makes any actual calls on it (6
times).

Still, the todos will be addressed to ensure a simpler system and to protect
performance in the pretenuring case, when all literals will get mementos from
this call in ordinary circumstances.

+  Handle<Object> copy = JSObject::DeepCopy(Handle<JSObject>::cast(boilerplate),
+                                           &site_context);
   RETURN_IF_EMPTY_HANDLE(isolate, copy);
   return *copy;
 }
@@ -516,12 +533,15 @@ static Handle<AllocationSite> GetLiteralAllocationSite(
     ASSERT(*elements != isolate->heap()->empty_fixed_array());
     Handle<Object> boilerplate =
         Runtime::CreateArrayLiteralBoilerplate(isolate, literals, elements);
-    if (boilerplate.is_null()) {
-      ASSERT(site.is_null());
-      return site;
-    }
-    site = isolate->factory()->NewAllocationSite();
-    site->set_transition_info(*boilerplate);
+    if (boilerplate.is_null()) return Handle<AllocationSite>::null();
+
+    AllocationSiteContext site_context(isolate, true);
+    AllocationSiteCreationScope site_scope(&site_context);
+    Handle<Object> same = JSObject::DeepWalk(
+        Handle<JSObject>::cast(boilerplate), &site_context);
+    site_scope.RecordTransitionInfo(same);
+    site = site_context.top();
+
     literals->set(literals_index, *site);
   } else {
     site = Handle<AllocationSite>::cast(literal_site);
@@ -543,7 +563,9 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_CreateArrayLiteral) {
   RETURN_IF_EMPTY_HANDLE(isolate, site);
 
   Handle<JSObject> boilerplate(JSObject::cast(site->transition_info()));
-  Handle<JSObject> copy = JSObject::DeepCopy(boilerplate);
+  AllocationSiteContext site_context(isolate, true);
+  AllocationSiteUsageScope site_scope(&site_context, site, boilerplate);
+  Handle<JSObject> copy = JSObject::DeepCopy(boilerplate, &site_context);
   RETURN_IF_EMPTY_HANDLE(isolate, copy);
   return *copy;
 }
@@ -566,9 +588,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_CreateArrayLiteralShallow) {
     isolate->counters()->cow_arrays_created_runtime()->Increment();
   }
 
-  AllocationSiteMode mode = AllocationSite::GetMode(
-      boilerplate->GetElementsKind());
-  if (mode == TRACK_ALLOCATION_SITE) {
+  if (AllocationSite::GetMode(boilerplate->GetElementsKind()) ==
+      TRACK_ALLOCATION_SITE) {
     return isolate->heap()->CopyJSObject(boilerplate, *site);
   }