[turbofan] Introduce JSCallReducer to strength reduce JSCallFunction nodes.

src/compiler/js-call-reducer.cc

Index: src/compiler/js-call-reducer.cc
diff --git a/src/compiler/js-call-reducer.cc b/src/compiler/js-call-reducer.cc
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--- /dev/null
+++ b/src/compiler/js-call-reducer.cc
@@ -0,0 +1,187 @@
+// 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/compiler/js-call-reducer.h"
+
+#include "src/compiler/js-graph.h"
+#include "src/compiler/node-matchers.h"
+#include "src/objects-inl.h"
+#include "src/type-feedback-vector-inl.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+namespace {
+
+VectorSlotPair CallCountFeedback(VectorSlotPair p) {
+  // Extract call count from {p}.
+  if (!p.IsValid()) return VectorSlotPair();
+  CallICNexus n(p.vector(), p.slot());
+  int const call_count = n.ExtractCallCount();
+  if (call_count <= 0) return VectorSlotPair();
+
+  // Create megamorphic CallIC feedback with the given {call_count}.
+  StaticFeedbackVectorSpec spec;
+  FeedbackVectorSlot slot = spec.AddCallICSlot();
+  Handle<TypeFeedbackMetadata> metadata =
+      TypeFeedbackMetadata::New(n.GetIsolate(), &spec);
+  Handle<TypeFeedbackVector> vector =
+      TypeFeedbackVector::New(n.GetIsolate(), metadata);
+  CallICNexus nexus(vector, slot);
+  nexus.ConfigureMegamorphic(call_count);
+  return VectorSlotPair(vector, slot);
+}
+
+}  // namespace
+
+
+Reduction JSCallReducer::Reduce(Node* node) {
+  if (node->opcode() == IrOpcode::kJSCallFunction) {
+    HeapObjectMatcher m(node->InputAt(0));
+    if (m.HasValue() && m.Value()->IsJSFunction()) {
+      Handle<SharedFunctionInfo> shared(
+          Handle<JSFunction>::cast(m.Value())->shared(), isolate());
+      if (shared->HasBuiltinFunctionId()) {
+        switch (shared->builtin_function_id()) {
+          case kFunctionApply:
+            return ReduceFunctionPrototypeApply(node);
+          case kFunctionCall:
+            return ReduceFunctionPrototypeCall(node);
+          default:
+            break;
+        }
+      }
+    }
+  }
+  return NoChange();
+}
+
+
+// ES6 section 19.2.3.1 Function.prototype.apply ( thisArg, argArray )
+Reduction JSCallReducer::ReduceFunctionPrototypeApply(Node* node) {
+  DCHECK_EQ(IrOpcode::kJSCallFunction, node->opcode());
+  Node* target = NodeProperties::GetValueInput(node, 0);
+  CallFunctionParameters const& p = CallFunctionParametersOf(node->op());
+  Handle<JSFunction> apply =
+      Handle<JSFunction>::cast(HeapObjectMatcher(target).Value());
+  size_t arity = p.arity();
+  DCHECK_LE(2, arity);
+  ConvertReceiverMode convert_mode = ConvertReceiverMode::kAny;
+  if (arity == 2) {
+    // Neither thisArg nor argArray was provided.
+    convert_mode = ConvertReceiverMode::kNullOrUndefined;
+    node->ReplaceInput(0, node->InputAt(1));
+    node->ReplaceInput(1, jsgraph()->UndefinedConstant());
+  } else if (arity == 3) {
+    // The argArray was not provided, just remove the {target}.
+    node->RemoveInput(0);
+    --arity;
+  } else if (arity == 4) {
+    // Check if argArray is an arguments object, and {node} is the only value
+    // user of argArray (except for value uses in frame states).
+    Node* arg_array = NodeProperties::GetValueInput(node, 3);
+    if (arg_array->opcode() != IrOpcode::kJSCreateArguments) return NoChange();
+    for (Edge edge : arg_array->use_edges()) {
+      if (edge.from()->opcode() == IrOpcode::kStateValues) continue;
+      if (!NodeProperties::IsValueEdge(edge)) continue;
+      if (edge.from() == node) continue;
+      return NoChange();
+    }
+    // Get to the actual frame state from which to extract the arguments;
+    // we can only optimize this in case the {node} was already inlined into
+    // some other function (and same for the {arg_array}).
+    CreateArgumentsParameters const& p =
+        CreateArgumentsParametersOf(arg_array->op());
+    Node* frame_state = NodeProperties::GetFrameStateInput(arg_array, 0);
+    Node* outer_state = frame_state->InputAt(kFrameStateOuterStateInput);
+    if (outer_state->opcode() != IrOpcode::kFrameState) return NoChange();
+    FrameStateInfo outer_info = OpParameter<FrameStateInfo>(outer_state);
+    if (outer_info.type() == FrameStateType::kArgumentsAdaptor) {
+      // Need to take the parameters from the arguments adaptor.
+      frame_state = outer_state;
+    }
+    FrameStateInfo state_info = OpParameter<FrameStateInfo>(frame_state);
+    if (p.type() == CreateArgumentsParameters::kMappedArguments) {
+      // Mapped arguments (sloppy mode) cannot be handled if they are aliased.
+      Handle<SharedFunctionInfo> shared;
+      if (!state_info.shared_info().ToHandle(&shared)) return NoChange();
+      if (shared->internal_formal_parameter_count() != 0) return NoChange();
+    }
+    // Remove the argArray input from the {node}.
+    node->RemoveInput(static_cast<int>(--arity));
+    // Add the actual parameters to the {node}, skipping the receiver.
+    Node* const parameters = frame_state->InputAt(kFrameStateParametersInput);
+    for (int i = p.start_index() + 1; i < state_info.parameter_count(); ++i) {
+      node->InsertInput(graph()->zone(), static_cast<int>(arity),
+                        parameters->InputAt(i));
+      ++arity;
+    }
+    // Drop the {target} from the {node}.
+    node->RemoveInput(0);
+    --arity;
+  } else {
+    return NoChange();
+  }
+  // Change {node} to the new {JSCallFunction} operator.
+  NodeProperties::ChangeOp(
+      node, javascript()->CallFunction(arity, p.language_mode(),
+                                       CallCountFeedback(p.feedback()),
+                                       convert_mode, p.tail_call_mode()));
+  // Change context of {node} to the Function.prototype.apply context,
+  // to ensure any exception is thrown in the correct context.
+  NodeProperties::ReplaceContextInput(
+      node, jsgraph()->HeapConstant(handle(apply->context(), isolate())));
+  return Changed(node);
+}
+
+
+// ES6 section 19.2.3.3 Function.prototype.call (thisArg, ...args)
+Reduction JSCallReducer::ReduceFunctionPrototypeCall(Node* node) {
+  DCHECK_EQ(IrOpcode::kJSCallFunction, node->opcode());
+  CallFunctionParameters const& p = CallFunctionParametersOf(node->op());
+  Handle<JSFunction> call = Handle<JSFunction>::cast(
+      HeapObjectMatcher(NodeProperties::GetValueInput(node, 0)).Value());
+  // Change context of {node} to the Function.prototype.call context,
+  // to ensure any exception is thrown in the correct context.
+  NodeProperties::ReplaceContextInput(
+      node, jsgraph()->HeapConstant(handle(call->context(), isolate())));
+  // Remove the target from {node} and use the receiver as target instead, and
+  // the thisArg becomes the new target.  If thisArg was not provided, insert
+  // undefined instead.
+  size_t arity = p.arity();
+  DCHECK_LE(2u, arity);
+  ConvertReceiverMode convert_mode;
+  if (arity == 2) {
+    // The thisArg was not provided, use undefined as receiver.
+    convert_mode = ConvertReceiverMode::kNullOrUndefined;
+    node->ReplaceInput(0, node->InputAt(1));
+    node->ReplaceInput(1, jsgraph()->UndefinedConstant());
+  } else {
+    // Just remove the target, which is the first value input.
+    convert_mode = ConvertReceiverMode::kAny;
+    node->RemoveInput(0);
+    --arity;
+  }
+  NodeProperties::ChangeOp(
+      node, javascript()->CallFunction(arity, p.language_mode(),
+                                       CallCountFeedback(p.feedback()),
+                                       convert_mode, p.tail_call_mode()));
+  return Changed(node);
+}
+
+
+Graph* JSCallReducer::graph() const { return jsgraph()->graph(); }
+
+
+Isolate* JSCallReducer::isolate() const { return jsgraph()->isolate(); }
+
+
+JSOperatorBuilder* JSCallReducer::javascript() const {
+  return jsgraph()->javascript();
+}
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8