Store OSR'd optimized code on the native context.

src/contexts.cc

 // Copyright 2011 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/contexts.h"
 
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
 
@@ skipping 390 matching lines @@
                !context->IsNativeContext() && !context->IsWithContext());
     }
   } while (follow_context_chain);
 
   if (FLAG_trace_contexts) {
     PrintF("=> no property/slot found\n");
   }
   return Handle<Object>::null();
 }
 
+static const int kSharedOffset = 0;
+static const int kCachedCodeOffset = 1;
+static const int kLiteralsOffset = 2;
+static const int kOsrAstIdOffset = 3;
+static const int kEntryLength = 4;
+static const int kInitialLength = kEntryLength;
+
+int Context::SearchOptimizedCodeMapEntry(SharedFunctionInfo* shared,
+                                         BailoutId osr_ast_id) {
+  DisallowHeapAllocation no_gc;
+  DCHECK(this->IsNativeContext());
+  if (!OptimizedCodeMapIsCleared()) {
+    FixedArray* optimized_code_map = this->osrd_function_table();
+    int length = optimized_code_map->length();
+    Smi* osr_ast_id_smi = Smi::FromInt(osr_ast_id.ToInt());
+    for (int i = 0; i < length; i += kEntryLength) {
+      if (WeakCell::cast(optimized_code_map->get(i + kSharedOffset))->value() ==
+              shared &&
+          optimized_code_map->get(i + kOsrAstIdOffset) == osr_ast_id_smi) {
+        return i;
+      }
+    }
+  }
+  return -1;
+}
+
+void Context::SearchOptimizedCodeMap(SharedFunctionInfo* shared,
+                                     BailoutId osr_ast_id, Code** pcode,
+                                     LiteralsArray** pliterals) {
+  DCHECK(this->IsNativeContext());
+  int entry = SearchOptimizedCodeMapEntry(shared, osr_ast_id);
+  if (entry != -1) {
+    FixedArray* code_map = osrd_function_table();
+    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));
+
+    *pcode = cell->cleared() ? nullptr : Code::cast(cell->value());
+    *pliterals = literals_cell->cleared()
+                     ? nullptr
+                     : LiteralsArray::cast(literals_cell->value());
+  } else {
+    *pcode = nullptr;
+    *pliterals = nullptr;
+  }
+}
+
+void Context::AddToOptimizedCodeMap(Handle<Context> native_context,
+                                    Handle<SharedFunctionInfo> shared,
+                                    Handle<Code> code,
+                                    Handle<LiteralsArray> literals,
+                                    BailoutId osr_ast_id) {
+  DCHECK(native_context->IsNativeContext());
+  Isolate* isolate = native_context->GetIsolate();
+  if (isolate->serializer_enabled()) return;
+
+  STATIC_ASSERT(kEntryLength == 4);
+  Handle<FixedArray> new_code_map;
+  int entry;
+
+  if (native_context->OptimizedCodeMapIsCleared()) {
+    new_code_map = isolate->factory()->NewFixedArray(kInitialLength, TENURED);
+    entry = 0;
+  } else {
+    Handle<FixedArray> old_code_map(native_context->osrd_function_table(),
+                                    isolate);
+    entry = native_context->SearchOptimizedCodeMapEntry(*shared, osr_ast_id);
+    if (entry >= 0) {
+      // Just set the code and literals of the entry.
+      Handle<WeakCell> code_cell = isolate->factory()->NewWeakCell(code);

[ulan, 2016/12/07 14:54:57]

Since the code is optimized, Code::WeakCellFor(code) will return cached weak
cell, so we can save one allocation here.

+      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 < 0);
+    int length = old_code_map->length();
+    for (int i = 0; i < length; i += kEntryLength) {
+      if (WeakCell::cast(old_code_map->get(i + kSharedOffset))->cleared()) {
+        new_code_map = old_code_map;
+        entry = i;
+        break;
+      }
+    }
+
+    if (entry < 0) {
+      // 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

[Michael Starzinger, 2016/12/07 09:26:31]

This should no longer happen now that flushing has been removed from the GC. Can
we get by with not copying this workaround over?

[mvstanton, 2016/12/07 14:42:32]

Done.

+      // 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 (native_context->OptimizedCodeMapIsCleared()) return;
+      entry = old_code_map->length();
+    }
+  }
+
+  // TODO(mvstanton): isn't there a cached weak cell in the Code class?
+  Handle<WeakCell> code_cell = isolate->factory()->NewWeakCell(code);

[ulan, 2016/12/07 14:54:57]

Code::WeakCellFor(code)

+  Handle<WeakCell> literals_cell = isolate->factory()->NewWeakCell(literals);
+  // TODO(mvstanton): Should we cache a weak cell for a SharedFunctionInfo?
+  Handle<WeakCell> shared_cell = isolate->factory()->NewWeakCell(shared);
+
+  new_code_map->set(entry + kSharedOffset, *shared_cell);
+  new_code_map->set(entry + kCachedCodeOffset, *code_cell);
+  new_code_map->set(entry + kLiteralsOffset, *literals_cell);
+  new_code_map->set(entry + kOsrAstIdOffset, Smi::FromInt(osr_ast_id.ToInt()));
+
+#ifdef DEBUG
+  for (int i = 0; i < new_code_map->length(); i += kEntryLength) {
+    WeakCell* cell = WeakCell::cast(new_code_map->get(i + kSharedOffset));
+    DCHECK(cell->cleared() || cell->value()->IsSharedFunctionInfo());
+    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());
+    DCHECK(new_code_map->get(i + kOsrAstIdOffset)->IsSmi());
+  }
+#endif
+
+  FixedArray* old_code_map = native_context->osrd_function_table();
+  if (old_code_map != *new_code_map) {
+    native_context->set_osrd_function_table(*new_code_map);
+  }
+}
+
+void Context::EvictFromOptimizedCodeMap(Code* optimized_code,
+                                        const char* reason) {
+  DCHECK(IsNativeContext());
+  DisallowHeapAllocation no_gc;
+  if (OptimizedCodeMapIsCleared()) return;
+
+  Heap* heap = GetHeap();
+  FixedArray* code_map = osrd_function_table();
+  int dst = 0;
+  int length = code_map->length();
+  for (int src = 0; src < length; src += kEntryLength) {
+    if (WeakCell::cast(code_map->get(src + kCachedCodeOffset))->value() ==
+        optimized_code) {
+      BailoutId osr(Smi::cast(code_map->get(src + kOsrAstIdOffset))->value());
+      if (FLAG_trace_opt) {
+        PrintF(
+            "[evicting entry from native context optimizing code map (%s) for ",
+            reason);
+        ShortPrint();
+        DCHECK(!osr.IsNone());
+        PrintF(" (osr ast id %d)]\n", osr.ToInt());
+      }
+      // Evict the src entry by not copying it to the dst entry.
+      continue;
+    }
+    // Keep the src entry by copying it to the dst entry.
+    if (dst != src) {
+      code_map->set(dst + kSharedOffset, code_map->get(src + kSharedOffset));
+      code_map->set(dst + kCachedCodeOffset,
+                    code_map->get(src + kCachedCodeOffset));
+      code_map->set(dst + kLiteralsOffset,
+                    code_map->get(src + kLiteralsOffset));
+      code_map->set(dst + kOsrAstIdOffset,
+                    code_map->get(src + kOsrAstIdOffset));
+    }
+    dst += kEntryLength;
+  }
+  if (dst != length) {
+    // Always trim even when array is cleared because of heap verifier.
+    heap->RightTrimFixedArray(code_map, length - dst);
+    if (code_map->length() == 0) {
+      ClearOptimizedCodeMap();
+    }
+  }
+}
+
+void Context::ClearOptimizedCodeMap() {
+  DCHECK(IsNativeContext());
+  FixedArray* empty_fixed_array = GetHeap()->empty_fixed_array();
+  // TODO(mvstanton): we could skip the write barrier...
+  set_osrd_function_table(empty_fixed_array);
+}
 
 void Context::AddOptimizedFunction(JSFunction* function) {
   DCHECK(IsNativeContext());
   Isolate* isolate = GetIsolate();
 #ifdef ENABLE_SLOW_DCHECKS
   if (FLAG_enable_slow_asserts) {
     Object* element = get(OPTIMIZED_FUNCTIONS_LIST);
     while (!element->IsUndefined(isolate)) {
       CHECK(element != function);
       element = JSFunction::cast(element)->next_function_link();
@@ skipping 167 matching lines @@
 
   int previous_value = errors_thrown()->value();
   set_errors_thrown(Smi::FromInt(previous_value + 1));
 }
 
 
 int Context::GetErrorsThrown() { return errors_thrown()->value(); }
 
 }  // namespace internal
 }  // namespace v8