[turbofan] Add inlined Array.prototype.pop support.

src/compiler/js-builtin-reducer.cc

Index: src/compiler/js-builtin-reducer.cc
diff --git a/src/compiler/js-builtin-reducer.cc b/src/compiler/js-builtin-reducer.cc
index 868ae7b0b3cb0411e35084c6bad2f9325dc39c90..94946a5279e9e6b8cc938239719886f70713871f 100644
--- a/src/compiler/js-builtin-reducer.cc
+++ b/src/compiler/js-builtin-reducer.cc
@@ -4,6 +4,7 @@
 
 #include "src/compiler/js-builtin-reducer.h"
 
+#include "src/compilation-dependencies.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-matchers.h"
@@ -93,11 +94,157 @@ class JSCallReduction {
   Node* node_;
 };
 
-JSBuiltinReducer::JSBuiltinReducer(Editor* editor, JSGraph* jsgraph)
+JSBuiltinReducer::JSBuiltinReducer(Editor* editor, JSGraph* jsgraph,
+                                   Flags flags,
+                                   CompilationDependencies* dependencies)
     : AdvancedReducer(editor),
+      dependencies_(dependencies),
+      flags_(flags),
       jsgraph_(jsgraph),
       type_cache_(TypeCache::Get()) {}
 
+namespace {
+
+MaybeHandle<Map> GetMapWitness(Node* node) {
+  Node* receiver = NodeProperties::GetValueInput(node, 1);
+  Node* effect = NodeProperties::GetEffectInput(node);
+  // Check if the {node} is dominated by a CheckMaps with a single map
+  // for the {receiver}, and if so use that map for the lowering below.
+  for (Node* dominator = effect;;) {
+    if (dominator->opcode() == IrOpcode::kCheckMaps &&
+        dominator->InputAt(0) == receiver) {
+      if (dominator->op()->ValueInputCount() == 2) {
+        HeapObjectMatcher m(dominator->InputAt(1));
+        if (m.HasValue()) return Handle<Map>::cast(m.Value());
+      }
+      return MaybeHandle<Map>();
+    }
+    if (dominator->op()->EffectInputCount() != 1) {
+      // Didn't find any appropriate CheckMaps node.
+      return MaybeHandle<Map>();
+    }
+    dominator = NodeProperties::GetEffectInput(dominator);
+  }
+}
+
+// TODO(turbofan): This was copied from Crankshaft, might be too restrictive.
+bool IsReadOnlyLengthDescriptor(Handle<Map> jsarray_map) {
+  DCHECK(!jsarray_map->is_dictionary_map());
+  Isolate* isolate = jsarray_map->GetIsolate();
+  Handle<Name> length_string = isolate->factory()->length_string();
+  DescriptorArray* descriptors = jsarray_map->instance_descriptors();
+  int number =
+      descriptors->SearchWithCache(isolate, *length_string, *jsarray_map);
+  DCHECK_NE(DescriptorArray::kNotFound, number);
+  return descriptors->GetDetails(number).IsReadOnly();
+}
+
+// TODO(turbofan): This was copied from Crankshaft, might be too restrictive.
+bool CanInlineArrayResizeOperation(Handle<Map> receiver_map) {
+  Isolate* const isolate = receiver_map->GetIsolate();
+  if (!receiver_map->prototype()->IsJSArray()) return false;
+  Handle<JSArray> receiver_prototype(JSArray::cast(receiver_map->prototype()),
+                                     isolate);
+  return receiver_map->instance_type() == JS_ARRAY_TYPE &&
+         IsFastElementsKind(receiver_map->elements_kind()) &&
+         !receiver_map->is_dictionary_map() && receiver_map->is_extensible() &&
+         (!receiver_map->is_prototype_map() || receiver_map->is_stable()) &&
+         receiver_prototype->map()->is_stable() &&
+         isolate->IsFastArrayConstructorPrototypeChainIntact() &&
+         isolate->IsAnyInitialArrayPrototype(receiver_prototype) &&
+         !IsReadOnlyLengthDescriptor(receiver_map);
+}
+
+}  // namespace
+
+// ES6 section 22.1.3.17 Array.prototype.pop ( )
+Reduction JSBuiltinReducer::ReduceArrayPop(Node* node) {
+  Handle<Map> receiver_map;
+  Node* receiver = NodeProperties::GetValueInput(node, 1);
+  Node* effect = NodeProperties::GetEffectInput(node);
+  Node* control = NodeProperties::GetControlInput(node);
+  // TODO(turbofan): Extend this to also handle fast (holey) double elements
+  // once we got the hole NaN mess sorted out in TurboFan/V8.
+  if (GetMapWitness(node).ToHandle(&receiver_map) &&
+      CanInlineArrayResizeOperation(receiver_map) &&
+      IsFastSmiOrObjectElementsKind(receiver_map->elements_kind())) {
+    // Install code dependencies on the {receiver} prototype maps and the
+    // global array protector cell.
+    dependencies()->AssumePropertyCell(factory()->array_protector());
+    dependencies()->AssumePrototypeMapsStable(receiver_map);
+
+    // Load the "length" property of the {receiver}.
+    Node* length = effect = graph()->NewNode(
+        simplified()->LoadField(
+            AccessBuilder::ForJSArrayLength(receiver_map->elements_kind())),
+        receiver, effect, control);
+
+    // Check if the {receiver} has any elements.
+    Node* check = graph()->NewNode(simplified()->NumberEqual(), length,
+                                   jsgraph()->ZeroConstant());
+    Node* branch =
+        graph()->NewNode(common()->Branch(BranchHint::kFalse), check, control);
+
+    Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
+    Node* etrue = effect;
+    Node* vtrue = jsgraph()->UndefinedConstant();
+
+    Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
+    Node* efalse = effect;
+    Node* vfalse;
+    {
+      // Load the elements backing store from the {receiver}.
+      Node* elements = efalse = graph()->NewNode(
+          simplified()->LoadField(AccessBuilder::ForJSObjectElements()),
+          receiver, efalse, if_false);
+
+      // Ensure that we aren't popping from a copy-on-write backing store.
+      elements = efalse =
+          graph()->NewNode(simplified()->EnsureWritableFastElements(), receiver,
+                           elements, efalse, if_false);
+
+      // Compute the new {length}.
+      length = graph()->NewNode(simplified()->NumberSubtract(), length,
+                                jsgraph()->OneConstant());
+
+      // Store the new {length} to the {receiver}.
+      efalse = graph()->NewNode(
+          simplified()->StoreField(
+              AccessBuilder::ForJSArrayLength(receiver_map->elements_kind())),
+          receiver, length, efalse, if_false);
+
+      // Load the last entry from the {elements}.
+      vfalse = efalse = graph()->NewNode(
+          simplified()->LoadElement(AccessBuilder::ForFixedArrayElement(
+              receiver_map->elements_kind())),
+          elements, length, efalse, if_false);
+
+      // Store a hole to the element we just removed from the {receiver}.
+      efalse = graph()->NewNode(
+          simplified()->StoreElement(AccessBuilder::ForFixedArrayElement(
+              GetHoleyElementsKind(receiver_map->elements_kind()))),
+          elements, length, jsgraph()->TheHoleConstant(), efalse, if_false);
+    }
+
+    control = graph()->NewNode(common()->Merge(2), if_true, if_false);
+    effect = graph()->NewNode(common()->EffectPhi(2), etrue, efalse, control);
+    Node* value =
+        graph()->NewNode(common()->Phi(MachineRepresentation::kTagged, 2),
+                         vtrue, vfalse, control);
+
+    // Convert the hole to undefined. Do this last, so that we can optimize
+    // conversion operator via some smart strength reduction in many cases.
+    if (IsFastHoleyElementsKind(receiver_map->elements_kind())) {
+      value =
+          graph()->NewNode(simplified()->ConvertTaggedHoleToUndefined(), value);
+    }
+
+    ReplaceWithValue(node, value, effect, control);
+    return Replace(value);
+  }
+  return NoChange();
+}
+
 // ES6 section 20.2.2.1 Math.abs ( x )
 Reduction JSBuiltinReducer::ReduceMathAbs(Node* node) {
   JSCallReduction r(node);
@@ -749,6 +896,8 @@ Reduction JSBuiltinReducer::Reduce(Node* node) {
   // Dispatch according to the BuiltinFunctionId if present.
   if (!r.HasBuiltinFunctionId()) return NoChange();
   switch (r.GetBuiltinFunctionId()) {
+    case kArrayPop:
+      return ReduceArrayPop(node);
     case kMathAbs:
       reduction = ReduceMathAbs(node);
       break;
@@ -903,6 +1052,7 @@ Node* JSBuiltinReducer::ToUint32(Node* input) {
 
 Graph* JSBuiltinReducer::graph() const { return jsgraph()->graph(); }
 
+Factory* JSBuiltinReducer::factory() const { return isolate()->factory(); }
 
 Isolate* JSBuiltinReducer::isolate() const { return jsgraph()->isolate(); }