[turbofan] Initial support for escape analysis.

src/compiler/escape-analysis-reducer.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/compiler/escape-analysis-reducer.h"
+
+#include "src/compiler/js-graph.h"
+#include "src/compiler/js-operator.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+EscapeAnalysisReducer::EscapeAnalysisReducer(
+    Editor* editor, JSGraph* jsgraph, EscapeStatusAnalysis* escape_status,
+    EscapeObjectAnalysis* escape_analysis, Zone* zone)
+    : AdvancedReducer(editor),
+      jsgraph_(jsgraph),
+      escape_status_(escape_status),
+      escape_analysis_(escape_analysis),
+      zone_(zone) {}
+
+
+Reduction EscapeAnalysisReducer::Reduce(Node* node) {
+  switch (node->opcode()) {
+    case IrOpcode::kLoadField:
+      return ReduceLoadField(node);
+    case IrOpcode::kStoreField:
+      return ReduceStoreField(node);
+    case IrOpcode::kAllocate:
+      return ReduceAllocate(node);
+    case IrOpcode::kFinishRegion:
+      return ReduceFinishRegion(node);
+    case IrOpcode::kReferenceEqual:
+      return ReduceReferenceEqual(node);
+    case IrOpcode::kStateValues:
+    case IrOpcode::kFrameState:
+      return ReplaceWithDeoptDummy(node);
+    default:
+      break;
+  }
+  return NoChange();
+}
+
+
+Reduction EscapeAnalysisReducer::ReduceLoadField(Node* node) {
+  DCHECK(node->opcode() == IrOpcode::kLoadField);

[Michael Starzinger, 2015/11/30 10:05:38]

nit: DCHECK_EQ, here and throughout the file.

[sigurds, 2015/11/30 13:50:23]

Done.

+  if (Node* rep = escape_analysis()->representation(node, node->id())) {

[Michael Starzinger, 2015/11/30 10:05:38]

The term "representation" is already pretty overloaded in V8, I would vote for
using a different name for this method. How would you feel about calling this
"replacement" instead?

[sigurds, 2015/11/30 13:50:23]

Done.

+    if (FLAG_trace_turbo_escape) {
+      PrintF("Replaced #%d with #%d\n", node->id(), rep->id());
+    }
+    ReplaceWithValue(node, rep);
+    return Changed(rep);
+  }
+  return NoChange();
+}
+
+
+Reduction EscapeAnalysisReducer::ReduceStoreField(Node* node) {
+  DCHECK(node->opcode() == IrOpcode::kStoreField);
+  if (escape_status()->IsVirtual(NodeProperties::GetValueInput(node, 0))) {
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Removed store field #%d from effect chain\n", node->id());
+    }
+    RemoveFromEffectChain(node);
+    return Changed(node);
+  }
+  return NoChange();
+}
+
+
+void EscapeAnalysisReducer::RemoveFromEffectChain(Node* node) {

[Michael Starzinger, 2015/11/30 10:05:38]

This should be equivalent with calling AdvancedReducer::RelaxEffectsAndControls
on the affected node. This helper would become obsolete and we could drop it.

[sigurds, 2015/11/30 13:50:23]

Done.

+  Node* effect = NodeProperties::GetEffectInput(node);
+  for (Edge edge : node->use_edges()) {
+    if (NodeProperties::IsEffectEdge(edge)) {
+      DCHECK_NOT_NULL(effect);
+      edge.UpdateTo(effect);
+      Revisit(node);
+    }
+  }
+}
+
+
+Reduction EscapeAnalysisReducer::ReduceAllocate(Node* node) {
+  DCHECK(node->opcode() == IrOpcode::kAllocate);
+  if (escape_status()->IsVirtual(node)) {
+    RemoveFromEffectChain(node);
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Removed allocate #%d from effect chain\n", node->id());
+    }
+    return Changed(node);
+  }
+  return NoChange();
+}
+
+
+Reduction EscapeAnalysisReducer::ReduceFinishRegion(Node* node) {
+  DCHECK(node->opcode() == IrOpcode::kFinishRegion);
+  Node* effect = NodeProperties::GetEffectInput(node, 0);
+  if (effect->opcode() == IrOpcode::kBeginRegion) {
+    RemoveFromEffectChain(effect);
+    Revisit(effect);
+    RemoveFromEffectChain(node);
+    Revisit(node);
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Removed region #%d / #%d from effect chain,", effect->id(),
+             node->id());
+      PrintF("%d user(s) of #%d remain(s):", node->UseCount(), node->id());
+      for (Edge edge : node->use_edges()) {
+        PrintF(" #%d", edge.from()->id());
+      }
+      PrintF("\n");
+    }
+    return Changed(node);
+  }
+  return NoChange();
+}
+
+
+Reduction EscapeAnalysisReducer::ReduceReferenceEqual(Node* node) {
+  DCHECK(node->opcode() == IrOpcode::kReferenceEqual);
+  Node* left = NodeProperties::GetValueInput(node, 0);
+  Node* right = NodeProperties::GetValueInput(node, 1);
+  if (escape_status()->IsVirtual(left)) {
+    if (escape_status()->IsVirtual(right)) {
+      if (Node* rep = escape_analysis()->representation(node, left->id())) {
+        left = rep;
+      }
+      if (Node* rep = escape_analysis()->representation(node, right->id())) {
+        right = rep;
+      }
+      // TODO(sigurds): What to do if either is a PHI?
+      if (left == right) {
+        ReplaceWithValue(node, jsgraph()->TrueConstant());
+        if (FLAG_trace_turbo_escape) {
+          PrintF("Replaced ref eq #%d with true\n", node->id());
+        }
+        return Replace(node);
+      }
+    }
+    // Right-hand side is either not virtual, or a different node.
+    ReplaceWithValue(node, jsgraph()->FalseConstant());
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Replaced ref eq #%d with false\n", node->id());
+    }
+    return Replace(node);
+  } else if (escape_status()->IsVirtual(right)) {
+    // Left-hand side is not a virtual object.
+    ReplaceWithValue(node, jsgraph()->FalseConstant());
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Replaced ref eq #%d with false\n", node->id());
+    }
+  }
+  return NoChange();
+}
+
+
+Reduction EscapeAnalysisReducer::ReplaceWithDeoptDummy(Node* node) {

[Michael Starzinger, 2015/11/30 10:05:38]

nit: Let's add a TODO comment here, saying that this is temporary until
materialization during deoptimization is handled.

[sigurds, 2015/11/30 13:50:23]

Done.

+  DCHECK(node->opcode() == IrOpcode::kStateValues ||
+         node->opcode() == IrOpcode::kFrameState);
+  Reduction r = NoChange();
+  for (int i = 0; i < node->op()->ValueInputCount(); ++i) {
+    Node* input = NodeProperties::GetValueInput(node, i);
+    if (input->opcode() == IrOpcode::kFinishRegion ||
+        input->opcode() == IrOpcode::kAllocate ||
+        input->opcode() == IrOpcode::kPhi) {
+      if (escape_status()->IsVirtual(input)) {
+        NodeProperties::ReplaceValueInput(node, jsgraph()->UndefinedConstant(),
+                                          i);
+        if (FLAG_trace_turbo_escape) {
+          PrintF("Replaced state value (#%d) input with dummy\n", node->id());
+        }
+        r = Changed(node);
+      }
+    }
+  }
+  return r;
+}
+
+
+Graph* EscapeAnalysisReducer::graph() const { return jsgraph()->graph(); }

[Michael Starzinger, 2015/11/30 10:05:38]

nit: Method seems to be unused, can we drop it?

[sigurds, 2015/11/30 13:50:23]

Done.

+
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8