Line data    Source code

       1             : // Copyright 2018 the V8 project authors. All rights reserved.
       2             : // Use of this source code is governed by a BSD-style license that can be
       3             : // found in the LICENSE file.
       4             : 
       5             : #include "src/compiler/constant-folding-reducer.h"
       6             : 
       7             : #include "src/compiler/js-graph.h"
       8             : #include "src/objects-inl.h"
       9             : 
      10             : namespace v8 {
      11             : namespace internal {
      12             : namespace compiler {
      13             : 
      14      928279 : ConstantFoldingReducer::ConstantFoldingReducer(Editor* editor, JSGraph* jsgraph,
      15             :                                                JSHeapBroker* broker)
      16      928279 :     : AdvancedReducer(editor), jsgraph_(jsgraph), broker_(broker) {}
      17             : 
      18             : ConstantFoldingReducer::~ConstantFoldingReducer() = default;
      19             : 
      20    70101349 : Reduction ConstantFoldingReducer::Reduce(Node* node) {
      21             :   DisallowHeapAccess no_heap_access;
      22             :   // Check if the output type is a singleton.  In that case we already know the
      23             :   // result value and can simply replace the node if it's eliminable.
      24   109390448 :   if (!NodeProperties::IsConstant(node) && NodeProperties::IsTyped(node) &&
      25             :       node->op()->HasProperty(Operator::kEliminatable)) {
      26             :     // TODO(v8:5303): We must not eliminate FinishRegion here. This special
      27             :     // case can be removed once we have separate operators for value and
      28             :     // effect regions.
      29    32120600 :     if (node->opcode() == IrOpcode::kFinishRegion) return NoChange();
      30             :     // We can only constant-fold nodes here, that are known to not cause any
      31             :     // side-effect, may it be a JavaScript observable side-effect or a possible
      32             :     // eager deoptimization exit (i.e. {node} has an operator that doesn't have
      33             :     // the Operator::kNoDeopt property).
      34    30987519 :     Type upper = NodeProperties::GetType(node);
      35    30987519 :     if (!upper.IsNone()) {
      36             :       Node* replacement = nullptr;
      37    30951465 :       if (upper.IsHeapConstant()) {
      38      192586 :         replacement = jsgraph()->Constant(upper.AsHeapConstant()->Ref());
      39    30759461 :       } else if (upper.Is(Type::MinusZero())) {
      40             :         Factory* factory = jsgraph()->isolate()->factory();
      41          24 :         ObjectRef minus_zero(broker(), factory->minus_zero_value());
      42          24 :         replacement = jsgraph()->Constant(minus_zero);
      43    30759345 :       } else if (upper.Is(Type::NaN())) {
      44         397 :         replacement = jsgraph()->NaNConstant();
      45    30758945 :       } else if (upper.Is(Type::Null())) {
      46           1 :         replacement = jsgraph()->NullConstant();
      47    30758852 :       } else if (upper.Is(Type::PlainNumber()) && upper.Min() == upper.Max()) {
      48       35762 :         replacement = jsgraph()->Constant(upper.Min());
      49    30723116 :       } else if (upper.Is(Type::Undefined())) {
      50           1 :         replacement = jsgraph()->UndefinedConstant();
      51             :       }
      52    30952184 :       if (replacement) {
      53             :         // Make sure the node has a type.
      54      228769 :         if (!NodeProperties::IsTyped(replacement)) {
      55             :           NodeProperties::SetType(replacement, upper);
      56             :         }
      57             :         ReplaceWithValue(node, replacement);
      58             :         return Changed(replacement);
      59             :       }
      60             :     }
      61             :   }
      62             :   return NoChange();
      63             : }
      64             : 
      65             : }  // namespace compiler
      66             : }  // namespace internal
      67      121996 : }  // namespace v8