[TypeFeedbackVector] Root literal arrays in function literals slots

src/objects.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 12521 matching lines @@
       isolate->builtins()->builtin(Builtins::kCompileOptimizedConcurrent));
   // No write barrier required, since the builtin is part of the root set.
   if (FLAG_mark_shared_functions_for_tier_up) {
     // TODO(leszeks): The compilation isn't concurrent if we trigger it using
     // this bit.
     shared()->set_marked_for_tier_up(true);
   }
 }
 
 // static
-Handle<LiteralsArray> SharedFunctionInfo::FindOrCreateLiterals(
-    Handle<SharedFunctionInfo> shared, Handle<Context> native_context) {
-  Isolate* isolate = shared->GetIsolate();
-  CodeAndLiterals result =
-      shared->SearchOptimizedCodeMap(*native_context, BailoutId::None());
-  if (result.literals != nullptr) {
-    DCHECK(shared->feedback_metadata()->is_empty() ||
-           !result.literals->feedback_vector()->is_empty());
-    return handle(result.literals, isolate);
-  }
-
-  Handle<TypeFeedbackVector> feedback_vector =
-      TypeFeedbackVector::New(isolate, handle(shared->feedback_metadata()));
-  Handle<LiteralsArray> literals =
-      LiteralsArray::New(isolate, feedback_vector, shared->num_literals());
-  Handle<Code> code;
-  if (result.code != nullptr) {
-    code = Handle<Code>(result.code, isolate);
-  }
-  AddToOptimizedCodeMap(shared, native_context, code, literals,
-                        BailoutId::None());
-  return literals;
-}
-
-// static
 void SharedFunctionInfo::AddToOptimizedCodeMap(
     Handle<SharedFunctionInfo> shared, Handle<Context> native_context,
-    MaybeHandle<Code> code, Handle<LiteralsArray> literals,
-    BailoutId osr_ast_id) {
+    Handle<Code> code, BailoutId osr_ast_id) {
   Isolate* isolate = shared->GetIsolate();
   if (isolate->serializer_enabled()) return;
-  DCHECK(code.is_null() ||
-         code.ToHandleChecked()->kind() == Code::OPTIMIZED_FUNCTION);
+  DCHECK(code.is_null() || code->kind() == Code::OPTIMIZED_FUNCTION);

[Michael Starzinger, 2017/01/11 13:22:44]

nit: First half of the predicate should always hold now AFAICT.

[mvstanton, 2017/01/11 14:52:06]

Done.

   DCHECK(native_context->IsNativeContext());
-  STATIC_ASSERT(kEntryLength == 3);
+  STATIC_ASSERT(kEntryLength == 2);
   Handle<FixedArray> new_code_map;
   int entry;
 
   if (!osr_ast_id.IsNone()) {
-    Context::AddToOptimizedCodeMap(
-        native_context, shared, code.ToHandleChecked(), literals, osr_ast_id);
+    Context::AddToOptimizedCodeMap(native_context, shared, code, osr_ast_id);
     return;
   }
 
   DCHECK(osr_ast_id.IsNone());
   if (shared->OptimizedCodeMapIsCleared()) {
     new_code_map = isolate->factory()->NewFixedArray(kInitialLength, TENURED);
     entry = kEntriesStart;
   } else {
     Handle<FixedArray> old_code_map(shared->optimized_code_map(), isolate);
     entry = shared->SearchOptimizedCodeMapEntry(*native_context);
     if (entry >= kEntriesStart) {
-      // Just set the code and literals of the entry.
+      // Just set the code of the entry.
       if (!code.is_null()) {

[Michael Starzinger, 2017/01/11 13:22:44]

nit: Should always hold now AFAICT.

[mvstanton, 2017/01/11 14:52:06]

Done.

-        Handle<WeakCell> code_cell =
-            isolate->factory()->NewWeakCell(code.ToHandleChecked());
+        Handle<WeakCell> code_cell = isolate->factory()->NewWeakCell(code);
         old_code_map->set(entry + kCachedCodeOffset, *code_cell);
       }
-      Handle<WeakCell> literals_cell =
-          isolate->factory()->NewWeakCell(literals);
-      old_code_map->set(entry + kLiteralsOffset, *literals_cell);
       return;
     }
 
     // Can we reuse an entry?
     DCHECK(entry < kEntriesStart);
     int length = old_code_map->length();
     for (int i = kEntriesStart; i < length; i += kEntryLength) {
       if (WeakCell::cast(old_code_map->get(i + kContextOffset))->cleared()) {
         new_code_map = old_code_map;
         entry = i;
         break;
       }
     }
 
     if (entry < kEntriesStart) {
       // Copy old optimized code map and append one new entry.
       new_code_map = isolate->factory()->CopyFixedArrayAndGrow(
           old_code_map, kEntryLength, TENURED);
       // TODO(mstarzinger): Temporary workaround. The allocation above might
       // have flushed the optimized code map and the copy we created is full of
       // holes. For now we just give up on adding the entry and pretend it got
       // flushed.
       if (shared->OptimizedCodeMapIsCleared()) return;
       entry = old_code_map->length();
     }
   }
 
-  Handle<WeakCell> code_cell =
-      code.is_null() ? isolate->factory()->empty_weak_cell()
-                     : isolate->factory()->NewWeakCell(code.ToHandleChecked());
-  Handle<WeakCell> literals_cell = isolate->factory()->NewWeakCell(literals);
+  Handle<WeakCell> code_cell = code.is_null()

[Michael Starzinger, 2017/01/11 13:22:44]

nit: Should always hold now AFAICT.

[mvstanton, 2017/01/11 14:52:06]

Done.

+                                   ? isolate->factory()->empty_weak_cell()
+                                   : isolate->factory()->NewWeakCell(code);
   WeakCell* context_cell = native_context->self_weak_cell();
 
   new_code_map->set(entry + kContextOffset, context_cell);
   new_code_map->set(entry + kCachedCodeOffset, *code_cell);
-  new_code_map->set(entry + kLiteralsOffset, *literals_cell);
 
 #ifdef DEBUG
   for (int i = kEntriesStart; i < new_code_map->length(); i += kEntryLength) {
     WeakCell* cell = WeakCell::cast(new_code_map->get(i + kContextOffset));
     DCHECK(cell->cleared() || cell->value()->IsNativeContext());
     cell = WeakCell::cast(new_code_map->get(i + kCachedCodeOffset));
     DCHECK(cell->cleared() ||
            (cell->value()->IsCode() &&
             Code::cast(cell->value())->kind() == Code::OPTIMIZED_FUNCTION));
-    cell = WeakCell::cast(new_code_map->get(i + kLiteralsOffset));
-    DCHECK(cell->cleared() || cell->value()->IsFixedArray());
   }
 #endif
 
   FixedArray* old_code_map = shared->optimized_code_map();
   if (old_code_map != *new_code_map) {
     shared->set_optimized_code_map(*new_code_map);
   }
 }
 
 
@@ skipping 17 matching lines @@
       DCHECK(WeakCell::cast(code_map->get(src))->cleared() ||
              WeakCell::cast(code_map->get(src))->value()->IsNativeContext());
       found = WeakCell::cast(code_map->get(src + kCachedCodeOffset))->value() ==
               optimized_code;
       if (found) {
         if (FLAG_trace_opt) {
           PrintF("[evicting entry from optimizing code map (%s) for ", reason);
           ShortPrint();
           PrintF("]\n");
         }
-        // Just clear the code in order to continue sharing literals.
+        // Just clear the code.
         code_map->set(src + kCachedCodeOffset, heap->empty_weak_cell(),
                       SKIP_WRITE_BARRIER);
       }
     }
   }
 
   if (!found) {
     // We didn't find the code in here. It must be osr'd code.
     isolate->EvictOSROptimizedCode(optimized_code, reason);
   }
 }
 
 // static
 void JSFunction::EnsureLiterals(Handle<JSFunction> function) {
   Handle<SharedFunctionInfo> shared(function->shared());
   Handle<Context> native_context(function->context()->native_context());
-  if (function->literals() ==
-      function->GetIsolate()->heap()->empty_literals_array()) {
-    Handle<LiteralsArray> literals =
-        SharedFunctionInfo::FindOrCreateLiterals(shared, native_context);
-    function->set_literals(*literals);
+  Isolate* isolate = shared->GetIsolate();
+
+  if (!function->has_literals_array()) {
+    if (FLAG_trace_strong_rooted_literals) {
+      PrintF("EnsureLiterals: Installing literals array in %s %p\n",
+             shared->DebugName()->ToCString().get(),
+             reinterpret_cast<void*>(*function));
+    }
+    // Top level code didn't get it's literals installed.
+    Handle<TypeFeedbackVector> feedback_vector =
+        TypeFeedbackVector::New(isolate, handle(shared->feedback_metadata()));
+    Handle<LiteralsArray> new_literals =
+        LiteralsArray::New(isolate, feedback_vector, shared->num_literals());
+    function->set_literals(*new_literals);
+  } else if (!function->literals()->has_feedback_vector()) {
+    if (FLAG_trace_strong_rooted_literals) {
+      PrintF("EnsureLiterals: Installing feedback vector in %s %p\n",
+             shared->DebugName()->ToCString().get(),
+             reinterpret_cast<void*>(*function));
+    }
+    // If the feedback vector hasn't been installed, do that.
+    Handle<TypeFeedbackVector> feedback_vector = TypeFeedbackVector::New(
+        shared->GetIsolate(), handle(shared->feedback_metadata()));
+    function->literals()->set_feedback_vector(*feedback_vector);
+  } else {
+    if (FLAG_trace_strong_rooted_literals) {
+      PrintF("EnsureLiterals: did nothing for %s %p\n",
+             shared->DebugName()->ToCString().get(),
+             reinterpret_cast<void*>(*function));
+    }
   }
+
+  // No matter what, ensure some post-conditions.
+  DCHECK(shared->feedback_metadata()->slot_count() != 0 ||
+         function->feedback_vector() ==
+             shared->GetIsolate()->heap()->empty_type_feedback_vector());
+  DCHECK(shared->num_literals() == 0 ||
+         function->literals() !=
+             shared->GetIsolate()->heap()->empty_literals_array());
 }
 
 static void GetMinInobjectSlack(Map* map, void* data) {
   int slack = map->unused_property_fields();
   if (*reinterpret_cast<int*>(data) > slack) {
     *reinterpret_cast<int*>(data) = slack;
   }
 }
 
 
@@ skipping 1549 matching lines @@
     FixedArray* optimized_code_map = this->optimized_code_map();
     int length = optimized_code_map->length();
     WeakCell* empty_weak_cell = GetHeap()->empty_weak_cell();
     for (int i = kEntriesStart; i < length; i += kEntryLength) {
       optimized_code_map->set(i + kCachedCodeOffset, empty_weak_cell,
                               SKIP_WRITE_BARRIER);
     }
   }
 }
 
-CodeAndLiterals SharedFunctionInfo::SearchOptimizedCodeMap(
-    Context* native_context, BailoutId osr_ast_id) {
-  CodeAndLiterals result = {nullptr, nullptr};
+Code* SharedFunctionInfo::SearchOptimizedCodeMap(Context* native_context,
+                                                 BailoutId osr_ast_id) {
+  Code* result = nullptr;
   if (!osr_ast_id.IsNone()) {
-    Code* code;
-    LiteralsArray* literals;
-    native_context->SearchOptimizedCodeMap(this, osr_ast_id, &code, &literals);
-    result = {code, literals};
-    return result;
+    return native_context->SearchOptimizedCodeMap(this, osr_ast_id);
   }
 
   DCHECK(osr_ast_id.IsNone());
   int entry = SearchOptimizedCodeMapEntry(native_context);
   if (entry != kNotFound) {
     FixedArray* code_map = optimized_code_map();
     DCHECK_LE(entry + kEntryLength, code_map->length());
     WeakCell* cell = WeakCell::cast(code_map->get(entry + kCachedCodeOffset));
-    WeakCell* literals_cell =
-        WeakCell::cast(code_map->get(entry + kLiteralsOffset));
 
-    result = {cell->cleared() ? nullptr : Code::cast(cell->value()),
-              literals_cell->cleared() ? nullptr : LiteralsArray::cast(
-                                                       literals_cell->value())};
+    result = cell->cleared() ? nullptr : Code::cast(cell->value());
   }
   return result;
 }
 
 
 #define DECLARE_TAG(ignore1, name, ignore2) name,
 const char* const VisitorSynchronization::kTags[
     VisitorSynchronization::kNumberOfSyncTags] = {
   VISITOR_SYNCHRONIZATION_TAGS_LIST(DECLARE_TAG)
 };
@@ skipping 6179 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8