[turbofan] extend escape analysis to reduce CheckMaps

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/all-nodes.h"
 #include "src/compiler/js-graph.h"
 #include "src/counters.h"
 
@@ skipping 26 matching lines @@
     return NoChange();
   }
 
   switch (node->opcode()) {
     case IrOpcode::kLoadField:
     case IrOpcode::kLoadElement:
       return ReduceLoad(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:
       return ReduceFinishRegion(node);
     case IrOpcode::kReferenceEqual:
       return ReduceReferenceEqual(node);
     case IrOpcode::kObjectIsSmi:
       return ReduceObjectIsSmi(node);
     // FrameStates and Value nodes are preprocessed here,
     // and visited via ReduceFrameStateUses from their user nodes.
@@ skipping 102 matching lines @@
   if (escape_analysis()->IsVirtual(
           SkipTypeGuards(NodeProperties::GetValueInput(node, 0)))) {
     TRACE("Removed #%d (%s) from effect chain\n", node->id(),
           node->op()->mnemonic());
     RelaxEffectsAndControls(node);
     return Changed(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());
     return Changed(node);
   }
   return NoChange();
 }
 
 
 Reduction EscapeAnalysisReducer::ReduceFinishRegion(Node* node) {
@@ skipping 191 matching lines @@
     if (node->opcode() == IrOpcode::kAllocate) {
       CHECK(!escape_analysis_->IsVirtual(node));
     }
   }
 #endif  // DEBUG
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8