[turbofan] extend escape analysis to reduce CheckMaps

src/compiler/escape-analysis-reducer.cc

Index: src/compiler/escape-analysis-reducer.cc
diff --git a/src/compiler/escape-analysis-reducer.cc b/src/compiler/escape-analysis-reducer.cc
index c05092e06ea95f71ef958c121990df06254834e6..0054ef15832c939dcc164176210faa2e843041cc 100644
--- a/src/compiler/escape-analysis-reducer.cc
+++ b/src/compiler/escape-analysis-reducer.cc
@@ -44,6 +44,8 @@ Reduction EscapeAnalysisReducer::ReduceNode(Node* node) {
     case IrOpcode::kStoreField:
     case IrOpcode::kStoreElement:
       return ReduceStore(node);
+    case IrOpcode::kCheckMaps:
+      return ReduceCheckMaps(node);
     case IrOpcode::kAllocate:
       return ReduceAllocate(node);
     case IrOpcode::kFinishRegion:
@@ -166,12 +168,29 @@ Reduction EscapeAnalysisReducer::ReduceStore(Node* node) {
   return NoChange();
 }
 
+Reduction EscapeAnalysisReducer::ReduceCheckMaps(Node* node) {
+  DCHECK(node->opcode() == IrOpcode::kCheckMaps);
+  if (node->id() < static_cast<NodeId>(fully_reduced_.length())) {
+    fully_reduced_.Add(node->id());
+  }
+  if (!escape_analysis()->IsEscaped(node)) {
+    TRACE("Removed #%d (%s) from effect chain\n", node->id(),
+          node->op()->mnemonic());
+    RelaxEffectsAndControls(node);
+    return Changed(node);
+  }
+  return NoChange();
+}
 
 Reduction EscapeAnalysisReducer::ReduceAllocate(Node* node) {
   DCHECK_EQ(node->opcode(), IrOpcode::kAllocate);
   if (node->id() < static_cast<NodeId>(fully_reduced_.length())) {
     fully_reduced_.Add(node->id());
   }
+  Node* object = NodeProperties::GetValueInput(node, 0);

[Benedikt Meurer, 2017/02/13 15:02:01]

This looks wrong. Input 0 is the size.

+  if (escape_analysis_->IsEscaped(object)) {
+    return NoChange();
+  }
   if (escape_analysis()->IsVirtual(node)) {
     RelaxEffectsAndControls(node);
     TRACE("Removed allocate #%d from effect chain\n", node->id());