[turbofan] extend escape analysis to reduce CheckMaps

src/compiler/escape-analysis.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.h"
 
 #include <limits>
 
 #include "src/base/flags.h"
 #include "src/bootstrapper.h"
@@ skipping 789 matching lines @@
         }
       // Fallthrough.
       case IrOpcode::kStoreField:
       case IrOpcode::kLoadField:
       case IrOpcode::kStoreElement:
       case IrOpcode::kLoadElement:
       case IrOpcode::kFrameState:
       case IrOpcode::kStateValues:
       case IrOpcode::kReferenceEqual:
       case IrOpcode::kFinishRegion:
+      case IrOpcode::kCheckMaps:
         if (IsEscaped(use) && SetEscaped(rep)) {
           TRACE(
               "Setting #%d (%s) to escaped because of use by escaping node "
               "#%d (%s)\n",
               rep->id(), rep->op()->mnemonic(), use->id(),
               use->op()->mnemonic());
           return true;
         }
         break;
       case IrOpcode::kObjectIsSmi:
@@ skipping 297 matching lines @@
       break;
     case IrOpcode::kLoadField:
       ProcessLoadField(node);
       break;
     case IrOpcode::kStoreElement:
       ProcessStoreElement(node);
       break;
     case IrOpcode::kLoadElement:
       ProcessLoadElement(node);
       break;
+    case IrOpcode::kCheckMaps:
+      ProcessCheckMaps(node);
+      break;
     case IrOpcode::kStart:
       ProcessStart(node);
       break;
     case IrOpcode::kEffectPhi:
       return ProcessEffectPhi(node);
       break;
     default:
       if (node->op()->EffectInputCount() > 0) {
         ForwardVirtualState(node);
       }
@@ skipping 17 matching lines @@
       case IrOpcode::kStoreField:
       case IrOpcode::kLoadField:
       case IrOpcode::kStoreElement:
       case IrOpcode::kLoadElement:
       case IrOpcode::kFrameState:
       case IrOpcode::kStateValues:
       case IrOpcode::kReferenceEqual:
       case IrOpcode::kFinishRegion:
       case IrOpcode::kObjectIsSmi:
         break;
+      case IrOpcode::kCheckMaps: {
+        CheckMapsParameters params = CheckMapsParametersOf(node->op());
+        if (params.flags() == CheckMapsFlag::kNone) break;
+      }  // Fallthrough.
       default:
         VirtualState* state = virtual_states_[node->id()];
         if (VirtualObject* obj =
                 GetVirtualObject(state, ResolveReplacement(input))) {
           if (!obj->AllFieldsClear()) {
             obj = CopyForModificationAt(obj, state, node);
             obj->ClearAllFields();
             TRACE("Cleared all fields of @%d:#%d\n",
                   status_analysis_->GetAlias(obj->id()), obj->id());
           }
@@ skipping 333 matching lines @@
   } else if (from->opcode() == IrOpcode::kPhi &&
              IsOffsetForFieldAccessCorrect(FieldAccessOf(node->op()))) {
     int offset = OffsetForFieldAccess(node);
     // Only binary phis are supported for now.
     ProcessLoadFromPhi(offset, from, node, state);
   } else {
     UpdateReplacement(state, node, nullptr);
   }
 }
 
+void EscapeAnalysis::ProcessCheckMaps(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kCheckMaps);
+  ForwardVirtualState(node);
+  Node* checked = ResolveReplacement(NodeProperties::GetValueInput(node, 0));
+  if (FLAG_turbo_experimental) {
+    VirtualState* state = virtual_states_[node->id()];
+    if (VirtualObject* object = GetVirtualObject(state, checked)) {
+      if (!object->IsTracked()) {
+        if (status_analysis_->SetEscaped(node)) {
+          TRACE(
+              "Setting #%d (%s) to escaped because checked object #%i is not "
+              "tracked\n",
+              node->id(), node->op()->mnemonic(), object->id());
+        }
+        return;
+      }
+      CheckMapsParameters params = CheckMapsParametersOf(node->op());
+
+      Node* value = object->GetField(HeapObject::kMapOffset / kPointerSize);
+      if (value) {
+        value = ResolveReplacement(value);
+        // TODO(tebbi): We want to extend this beyond constant folding with a
+        // CheckMapsValue operator that takes the load-eliminated map value as
+        // input.
+        if (value->opcode() == IrOpcode::kHeapConstant &&
+            params.maps().contains(ZoneHandleSet<Map>(
+                Handle<Map>::cast(OpParameter<Handle<HeapObject>>(value))))) {
+          TRACE("CheckMaps #%i seems to be redundant (until now).\n",
+                node->id());
+          return;
+        }
+      }
+    }
+  }
+  if (status_analysis_->SetEscaped(node)) {
+    TRACE("Setting #%d (%s) to escaped (checking #%i)\n", node->id(),
+          node->op()->mnemonic(), checked->id());
+  }
+}
+
 void EscapeAnalysis::ProcessLoadElement(Node* node) {
   DCHECK_EQ(node->opcode(), IrOpcode::kLoadElement);
   ForwardVirtualState(node);
   Node* from = ResolveReplacement(NodeProperties::GetValueInput(node, 0));
   VirtualState* state = virtual_states_[node->id()];
   Node* index_node = node->InputAt(1);
   NumberMatcher index(index_node);
   DCHECK(index_node->opcode() != IrOpcode::kInt32Constant &&
          index_node->opcode() != IrOpcode::kInt64Constant &&
          index_node->opcode() != IrOpcode::kFloat32Constant &&
@@ skipping 221 matching lines @@
     }
   }
   return false;
 }
 
 Graph* EscapeAnalysis::graph() const { return status_analysis_->graph(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8