Land the Fan (disabled)

src/compiler/graph-builder.cc

+// Copyright 2013 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/graph-builder.h"
+
+#include "src/compiler.h"
+#include "src/compiler/generic-graph.h"
+#include "src/compiler/generic-node.h"
+#include "src/compiler/generic-node-inl.h"
+#include "src/compiler/graph-visualizer.h"
+#include "src/compiler/node-properties.h"
+#include "src/compiler/node-properties-inl.h"
+#include "src/compiler/operator-properties.h"
+#include "src/compiler/operator-properties-inl.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+
+StructuredGraphBuilder::StructuredGraphBuilder(Graph* graph,
+                                               CommonOperatorBuilder* common)
+    : GraphBuilder(graph),
+      common_(common),
+      environment_(NULL),
+      current_context_(NULL),
+      exit_control_(NULL) {}
+
+
+Node* StructuredGraphBuilder::MakeNode(Operator* op, int value_input_count,
+                                       Node** value_inputs) {
+  bool has_context = OperatorProperties::HasContextInput(op);
+  bool has_control = OperatorProperties::GetControlInputCount(op) == 1;
+  bool has_effect = OperatorProperties::GetEffectInputCount(op) == 1;
+
+  ASSERT(OperatorProperties::GetControlInputCount(op) < 2);
+  ASSERT(OperatorProperties::GetEffectInputCount(op) < 2);
+
+  Node* result = NULL;
+  if (!has_context && !has_control && !has_effect) {
+    result = graph()->NewNode(op, value_input_count, value_inputs);
+  } else {
+    int input_count_with_deps = value_input_count;
+    if (has_context) ++input_count_with_deps;
+    if (has_control) ++input_count_with_deps;
+    if (has_effect) ++input_count_with_deps;
+    void* raw_buffer = alloca(kPointerSize * input_count_with_deps);
+    Node** buffer = reinterpret_cast<Node**>(raw_buffer);
+    memcpy(buffer, value_inputs, kPointerSize * value_input_count);
+    Node** current_input = buffer + value_input_count;
+    if (has_context) {
+      *current_input++ = current_context();
+    }
+    if (has_effect) {
+      *current_input++ = environment_->GetEffectDependency();
+    }
+    if (has_control) {
+      *current_input++ = GetControlDependency();
+    }
+    result = graph()->NewNode(op, input_count_with_deps, buffer);
+    if (has_effect) {
+      environment_->UpdateEffectDependency(result);
+    }
+    if (NodeProperties::HasControlOutput(result) &&
+        !environment_internal()->IsMarkedAsUnreachable()) {
+      UpdateControlDependency(result);
+    }
+  }
+
+  return result;
+}
+
+
+Node* StructuredGraphBuilder::GetControlDependency() {
+  return environment_->GetControlDependency();
+}
+
+
+void StructuredGraphBuilder::UpdateControlDependency(Node* new_control) {
+  environment_->UpdateControlDependency(new_control);
+}
+
+
+void StructuredGraphBuilder::UpdateControlDependencyToLeaveFunction(
+    Node* exit) {
+  if (environment_internal()->IsMarkedAsUnreachable()) return;
+  if (exit_control() != NULL) {
+    exit = MergeControl(exit_control(), exit);
+  }
+  environment_internal()->MarkAsUnreachable();
+  set_exit_control(exit);
+}
+
+
+StructuredGraphBuilder::Environment* StructuredGraphBuilder::CopyEnvironment(
+    Environment* env) {
+  return new (zone()) Environment(*env);
+}
+
+
+StructuredGraphBuilder::Environment::Environment(
+    StructuredGraphBuilder* builder, Node* control_dependency)
+    : builder_(builder),
+      control_dependency_(control_dependency),
+      effect_dependency_(control_dependency),
+      values_(NodeVector::allocator_type(zone())) {}
+
+
+StructuredGraphBuilder::Environment::Environment(const Environment& copy)
+    : builder_(copy.builder()),
+      control_dependency_(copy.control_dependency_),
+      effect_dependency_(copy.effect_dependency_),
+      values_(copy.values_) {}
+
+
+void StructuredGraphBuilder::Environment::Merge(Environment* other) {
+  ASSERT(values_.size() == other->values_.size());
+
+  // Nothing to do if the other environment is dead.
+  if (other->IsMarkedAsUnreachable()) return;
+
+  // Resurrect a dead environment by copying the contents of the other one and
+  // placing a singleton merge as the new control dependency.
+  if (this->IsMarkedAsUnreachable()) {
+    Node* other_control = other->control_dependency_;
+    control_dependency_ = graph()->NewNode(common()->Merge(1), other_control);
+    effect_dependency_ = other->effect_dependency_;
+    values_ = other->values_;
+    return;
+  }
+
+  // Create a merge of the control dependencies of both environments and update
+  // the current environment's control dependency accordingly.
+  Node* control = builder_->MergeControl(this->GetControlDependency(),
+                                         other->GetControlDependency());
+  UpdateControlDependency(control);
+
+  // Create a merge of the effect dependencies of both environments and update
+  // the current environment's effect dependency accordingly.
+  Node* effect = builder_->MergeEffect(this->GetEffectDependency(),
+                                       other->GetEffectDependency(), control);
+  UpdateEffectDependency(effect);
+
+  // Introduce Phi nodes for values that have differing input at merge points,
+  // potentially extending an existing Phi node if possible.
+  for (int i = 0; i < static_cast<int>(values_.size()); ++i) {
+    if (values_[i] == NULL) continue;
+    values_[i] = builder_->MergeValue(values_[i], other->values_[i], control);
+  }
+}
+
+
+void StructuredGraphBuilder::Environment::PrepareForLoop() {
+  Node* control = GetControlDependency();
+  for (int i = 0; i < static_cast<int>(values()->size()); ++i) {
+    if (values()->at(i) == NULL) continue;
+    Node* phi = builder_->NewPhi(1, values()->at(i), control);
+    values()->at(i) = phi;
+  }
+  Node* effect = builder_->NewEffectPhi(1, GetEffectDependency(), control);
+  UpdateEffectDependency(effect);
+}
+
+
+Node* StructuredGraphBuilder::NewPhi(int count, Node* input, Node* control) {
+  Operator* phi_op = common()->Phi(count);
+  void* raw_buffer = alloca(kPointerSize * (count + 1));
+  Node** buffer = reinterpret_cast<Node**>(raw_buffer);
+  MemsetPointer(buffer, input, count);
+  buffer[count] = control;
+  return graph()->NewNode(phi_op, count + 1, buffer);
+}
+
+
+// TODO(mstarzinger): Revisit this once we have proper effect states.
+Node* StructuredGraphBuilder::NewEffectPhi(int count, Node* input,
+                                           Node* control) {
+  Operator* phi_op = common()->EffectPhi(count);
+  void* raw_buffer = alloca(kPointerSize * (count + 1));
+  Node** buffer = reinterpret_cast<Node**>(raw_buffer);
+  MemsetPointer(buffer, input, count);
+  buffer[count] = control;
+  return graph()->NewNode(phi_op, count + 1, buffer);
+}
+
+
+Node* StructuredGraphBuilder::MergeControl(Node* control, Node* other) {
+  int inputs = NodeProperties::GetControlInputCount(control) + 1;
+  if (control->opcode() == IrOpcode::kLoop) {
+    // Control node for loop exists, add input.
+    Operator* op = common()->Loop(inputs);
+    control->AppendInput(zone(), other);
+    control->set_op(op);
+  } else if (control->opcode() == IrOpcode::kMerge) {
+    // Control node for merge exists, add input.
+    Operator* op = common()->Merge(inputs);
+    control->AppendInput(zone(), other);
+    control->set_op(op);
+  } else {
+    // Control node is a singleton, introduce a merge.
+    Operator* op = common()->Merge(inputs);
+    control = graph()->NewNode(op, control, other);
+  }
+  return control;
+}
+
+
+Node* StructuredGraphBuilder::MergeEffect(Node* value, Node* other,
+                                          Node* control) {
+  int inputs = NodeProperties::GetControlInputCount(control);
+  if (value->opcode() == IrOpcode::kEffectPhi &&
+      NodeProperties::GetControlInput(value) == control) {
+    // Phi already exists, add input.
+    value->set_op(common()->EffectPhi(inputs));
+    value->InsertInput(zone(), inputs - 1, other);
+  } else if (value != other) {
+    // Phi does not exist yet, introduce one.
+    value = NewEffectPhi(inputs, value, control);
+    value->ReplaceInput(inputs - 1, other);
+  }
+  return value;
+}
+
+
+Node* StructuredGraphBuilder::MergeValue(Node* value, Node* other,
+                                         Node* control) {
+  int inputs = NodeProperties::GetControlInputCount(control);
+  if (value->opcode() == IrOpcode::kPhi &&
+      NodeProperties::GetControlInput(value) == control) {
+    // Phi already exists, add input.
+    value->set_op(common()->Phi(inputs));
+    value->InsertInput(zone(), inputs - 1, other);
+  } else if (value != other) {
+    // Phi does not exist yet, introduce one.
+    value = NewPhi(inputs, value, control);
+    value->ReplaceInput(inputs - 1, other);
+  }
+  return value;
+}
+
+
+Node* StructuredGraphBuilder::dead_control() {
+  if (!dead_control_.is_set()) {
+    Node* dead_node = graph()->NewNode(common_->Dead());
+    dead_control_.set(dead_node);
+    return dead_node;
+  }
+  return dead_control_.get();
+}
+}
+}
+}  // namespace v8::internal::compiler