| // Copyright 2014 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/simplified-lowering.h" | 
 |  | 
 | #include <limits> | 
 |  | 
 | #include "src/base/bits.h" | 
 | #include "src/code-factory.h" | 
 | #include "src/compiler/common-operator.h" | 
 | #include "src/compiler/graph-inl.h" | 
 | #include "src/compiler/node-matchers.h" | 
 | #include "src/compiler/node-properties-inl.h" | 
 | #include "src/compiler/representation-change.h" | 
 | #include "src/compiler/simplified-lowering.h" | 
 | #include "src/compiler/simplified-operator.h" | 
 | #include "src/objects.h" | 
 |  | 
 | namespace v8 { | 
 | namespace internal { | 
 | namespace compiler { | 
 |  | 
 | // Macro for outputting trace information from representation inference. | 
 | #define TRACE(x) \ | 
 |   if (FLAG_trace_representation) PrintF x | 
 |  | 
 | // Representation selection and lowering of {Simplified} operators to machine | 
 | // operators are interwined. We use a fixpoint calculation to compute both the | 
 | // output representation and the best possible lowering for {Simplified} nodes. | 
 | // Representation change insertion ensures that all values are in the correct | 
 | // machine representation after this phase, as dictated by the machine | 
 | // operators themselves. | 
 | enum Phase { | 
 |   // 1.) PROPAGATE: Traverse the graph from the end, pushing usage information | 
 |   //     backwards from uses to definitions, around cycles in phis, according | 
 |   //     to local rules for each operator. | 
 |   //     During this phase, the usage information for a node determines the best | 
 |   //     possible lowering for each operator so far, and that in turn determines | 
 |   //     the output representation. | 
 |   //     Therefore, to be correct, this phase must iterate to a fixpoint before | 
 |   //     the next phase can begin. | 
 |   PROPAGATE, | 
 |  | 
 |   // 2.) LOWER: perform lowering for all {Simplified} nodes by replacing some | 
 |   //     operators for some nodes, expanding some nodes to multiple nodes, or | 
 |   //     removing some (redundant) nodes. | 
 |   //     During this phase, use the {RepresentationChanger} to insert | 
 |   //     representation changes between uses that demand a particular | 
 |   //     representation and nodes that produce a different representation. | 
 |   LOWER | 
 | }; | 
 |  | 
 |  | 
 | class RepresentationSelector { | 
 |  public: | 
 |   // Information for each node tracked during the fixpoint. | 
 |   struct NodeInfo { | 
 |     MachineTypeUnion use : 15;     // Union of all usages for the node. | 
 |     bool queued : 1;           // Bookkeeping for the traversal. | 
 |     bool visited : 1;          // Bookkeeping for the traversal. | 
 |     MachineTypeUnion output : 15;  // Output type of the node. | 
 |   }; | 
 |  | 
 |   RepresentationSelector(JSGraph* jsgraph, Zone* zone, | 
 |                          RepresentationChanger* changer) | 
 |       : jsgraph_(jsgraph), | 
 |         count_(jsgraph->graph()->NodeCount()), | 
 |         info_(zone->NewArray<NodeInfo>(count_)), | 
 |         nodes_(zone), | 
 |         replacements_(zone), | 
 |         contains_js_nodes_(false), | 
 |         phase_(PROPAGATE), | 
 |         changer_(changer), | 
 |         queue_(zone) { | 
 |     memset(info_, 0, sizeof(NodeInfo) * count_); | 
 |  | 
 |     Factory* f = zone->isolate()->factory(); | 
 |     safe_int_additive_range_ = | 
 |         Type::Range(f->NewNumber(-std::pow(2.0, 52.0)), | 
 |                     f->NewNumber(std::pow(2.0, 52.0)), zone); | 
 |   } | 
 |  | 
 |   void Run(SimplifiedLowering* lowering) { | 
 |     // Run propagation phase to a fixpoint. | 
 |     TRACE(("--{Propagation phase}--\n")); | 
 |     phase_ = PROPAGATE; | 
 |     Enqueue(jsgraph_->graph()->end()); | 
 |     // Process nodes from the queue until it is empty. | 
 |     while (!queue_.empty()) { | 
 |       Node* node = queue_.front(); | 
 |       NodeInfo* info = GetInfo(node); | 
 |       queue_.pop(); | 
 |       info->queued = false; | 
 |       TRACE((" visit #%d: %s\n", node->id(), node->op()->mnemonic())); | 
 |       VisitNode(node, info->use, NULL); | 
 |       TRACE(("  ==> output ")); | 
 |       PrintInfo(info->output); | 
 |       TRACE(("\n")); | 
 |     } | 
 |  | 
 |     // Run lowering and change insertion phase. | 
 |     TRACE(("--{Simplified lowering phase}--\n")); | 
 |     phase_ = LOWER; | 
 |     // Process nodes from the collected {nodes_} vector. | 
 |     for (NodeVector::iterator i = nodes_.begin(); i != nodes_.end(); ++i) { | 
 |       Node* node = *i; | 
 |       TRACE((" visit #%d: %s\n", node->id(), node->op()->mnemonic())); | 
 |       // Reuse {VisitNode()} so the representation rules are in one place. | 
 |       VisitNode(node, GetUseInfo(node), lowering); | 
 |     } | 
 |  | 
 |     // Perform the final replacements. | 
 |     for (NodeVector::iterator i = replacements_.begin(); | 
 |          i != replacements_.end(); ++i) { | 
 |       Node* node = *i; | 
 |       Node* replacement = *(++i); | 
 |       node->ReplaceUses(replacement); | 
 |     } | 
 |   } | 
 |  | 
 |   // Enqueue {node} if the {use} contains new information for that node. | 
 |   // Add {node} to {nodes_} if this is the first time it's been visited. | 
 |   void Enqueue(Node* node, MachineTypeUnion use = 0) { | 
 |     if (phase_ != PROPAGATE) return; | 
 |     NodeInfo* info = GetInfo(node); | 
 |     if (!info->visited) { | 
 |       // First visit of this node. | 
 |       info->visited = true; | 
 |       info->queued = true; | 
 |       nodes_.push_back(node); | 
 |       queue_.push(node); | 
 |       TRACE(("  initial: ")); | 
 |       info->use |= use; | 
 |       PrintUseInfo(node); | 
 |       return; | 
 |     } | 
 |     TRACE(("   queue?: ")); | 
 |     PrintUseInfo(node); | 
 |     if ((info->use & use) != use) { | 
 |       // New usage information for the node is available. | 
 |       if (!info->queued) { | 
 |         queue_.push(node); | 
 |         info->queued = true; | 
 |         TRACE(("   added: ")); | 
 |       } else { | 
 |         TRACE((" inqueue: ")); | 
 |       } | 
 |       info->use |= use; | 
 |       PrintUseInfo(node); | 
 |     } | 
 |   } | 
 |  | 
 |   bool lower() { return phase_ == LOWER; } | 
 |  | 
 |   void Enqueue(Node* node, MachineType use) { | 
 |     Enqueue(node, static_cast<MachineTypeUnion>(use)); | 
 |   } | 
 |  | 
 |   void SetOutput(Node* node, MachineTypeUnion output) { | 
 |     // Every node should have at most one output representation. Note that | 
 |     // phis can have 0, if they have not been used in a representation-inducing | 
 |     // instruction. | 
 |     DCHECK((output & kRepMask) == 0 || | 
 |            base::bits::IsPowerOfTwo32(output & kRepMask)); | 
 |     GetInfo(node)->output = output; | 
 |   } | 
 |  | 
 |   bool BothInputsAre(Node* node, Type* type) { | 
 |     DCHECK_EQ(2, node->InputCount()); | 
 |     return NodeProperties::GetBounds(node->InputAt(0)).upper->Is(type) && | 
 |            NodeProperties::GetBounds(node->InputAt(1)).upper->Is(type); | 
 |   } | 
 |  | 
 |   void ProcessTruncateWord32Input(Node* node, int index, MachineTypeUnion use) { | 
 |     Node* input = node->InputAt(index); | 
 |     if (phase_ == PROPAGATE) { | 
 |       // In the propagate phase, propagate the usage information backward. | 
 |       Enqueue(input, use); | 
 |     } else { | 
 |       // In the change phase, insert a change before the use if necessary. | 
 |       MachineTypeUnion output = GetInfo(input)->output; | 
 |       if ((output & kRepWord32) == 0) { | 
 |         // Output representation doesn't match usage. | 
 |         TRACE(("  truncate-to-int32: #%d:%s(@%d #%d:%s) ", node->id(), | 
 |                node->op()->mnemonic(), index, input->id(), | 
 |                input->op()->mnemonic())); | 
 |         TRACE((" from ")); | 
 |         PrintInfo(output); | 
 |         TRACE((" to ")); | 
 |         PrintInfo(use); | 
 |         TRACE(("\n")); | 
 |         Node* n = changer_->GetTruncatedWord32For(input, output); | 
 |         node->ReplaceInput(index, n); | 
 |       } | 
 |     } | 
 |   } | 
 |  | 
 |   void ProcessInput(Node* node, int index, MachineTypeUnion use) { | 
 |     Node* input = node->InputAt(index); | 
 |     if (phase_ == PROPAGATE) { | 
 |       // In the propagate phase, propagate the usage information backward. | 
 |       Enqueue(input, use); | 
 |     } else { | 
 |       // In the change phase, insert a change before the use if necessary. | 
 |       if ((use & kRepMask) == 0) return;  // No input requirement on the use. | 
 |       MachineTypeUnion output = GetInfo(input)->output; | 
 |       if ((output & kRepMask & use) == 0) { | 
 |         // Output representation doesn't match usage. | 
 |         TRACE(("  change: #%d:%s(@%d #%d:%s) ", node->id(), | 
 |                node->op()->mnemonic(), index, input->id(), | 
 |                input->op()->mnemonic())); | 
 |         TRACE((" from ")); | 
 |         PrintInfo(output); | 
 |         TRACE((" to ")); | 
 |         PrintInfo(use); | 
 |         TRACE(("\n")); | 
 |         Node* n = changer_->GetRepresentationFor(input, output, use); | 
 |         node->ReplaceInput(index, n); | 
 |       } | 
 |     } | 
 |   } | 
 |  | 
 |   void ProcessRemainingInputs(Node* node, int index) { | 
 |     DCHECK_GE(index, NodeProperties::PastValueIndex(node)); | 
 |     DCHECK_GE(index, NodeProperties::PastContextIndex(node)); | 
 |     for (int i = std::max(index, NodeProperties::FirstEffectIndex(node)); | 
 |          i < NodeProperties::PastEffectIndex(node); ++i) { | 
 |       Enqueue(node->InputAt(i));  // Effect inputs: just visit | 
 |     } | 
 |     for (int i = std::max(index, NodeProperties::FirstControlIndex(node)); | 
 |          i < NodeProperties::PastControlIndex(node); ++i) { | 
 |       Enqueue(node->InputAt(i));  // Control inputs: just visit | 
 |     } | 
 |   } | 
 |  | 
 |   // The default, most general visitation case. For {node}, process all value, | 
 |   // context, effect, and control inputs, assuming that value inputs should have | 
 |   // {kRepTagged} representation and can observe all output values {kTypeAny}. | 
 |   void VisitInputs(Node* node) { | 
 |     InputIter i = node->inputs().begin(); | 
 |     for (int j = node->op()->ValueInputCount(); j > 0; ++i, j--) { | 
 |       ProcessInput(node, i.index(), kMachAnyTagged);  // Value inputs | 
 |     } | 
 |     for (int j = OperatorProperties::GetContextInputCount(node->op()); j > 0; | 
 |          ++i, j--) { | 
 |       ProcessInput(node, i.index(), kMachAnyTagged);  // Context inputs | 
 |     } | 
 |     for (int j = node->op()->EffectInputCount(); j > 0; ++i, j--) { | 
 |       Enqueue(*i);  // Effect inputs: just visit | 
 |     } | 
 |     for (int j = node->op()->ControlInputCount(); j > 0; ++i, j--) { | 
 |       Enqueue(*i);  // Control inputs: just visit | 
 |     } | 
 |     SetOutput(node, kMachAnyTagged); | 
 |   } | 
 |  | 
 |   // Helper for binops of the I x I -> O variety. | 
 |   void VisitBinop(Node* node, MachineTypeUnion input_use, | 
 |                   MachineTypeUnion output) { | 
 |     DCHECK_EQ(2, node->InputCount()); | 
 |     ProcessInput(node, 0, input_use); | 
 |     ProcessInput(node, 1, input_use); | 
 |     SetOutput(node, output); | 
 |   } | 
 |  | 
 |   // Helper for unops of the I -> O variety. | 
 |   void VisitUnop(Node* node, MachineTypeUnion input_use, | 
 |                  MachineTypeUnion output) { | 
 |     DCHECK_EQ(1, node->InputCount()); | 
 |     ProcessInput(node, 0, input_use); | 
 |     SetOutput(node, output); | 
 |   } | 
 |  | 
 |   // Helper for leaf nodes. | 
 |   void VisitLeaf(Node* node, MachineTypeUnion output) { | 
 |     DCHECK_EQ(0, node->InputCount()); | 
 |     SetOutput(node, output); | 
 |   } | 
 |  | 
 |   // Helpers for specific types of binops. | 
 |   void VisitFloat64Binop(Node* node) { | 
 |     VisitBinop(node, kMachFloat64, kMachFloat64); | 
 |   } | 
 |   void VisitInt32Binop(Node* node) { VisitBinop(node, kMachInt32, kMachInt32); } | 
 |   void VisitUint32Binop(Node* node) { | 
 |     VisitBinop(node, kMachUint32, kMachUint32); | 
 |   } | 
 |   void VisitInt64Binop(Node* node) { VisitBinop(node, kMachInt64, kMachInt64); } | 
 |   void VisitUint64Binop(Node* node) { | 
 |     VisitBinop(node, kMachUint64, kMachUint64); | 
 |   } | 
 |   void VisitFloat64Cmp(Node* node) { VisitBinop(node, kMachFloat64, kRepBit); } | 
 |   void VisitInt32Cmp(Node* node) { VisitBinop(node, kMachInt32, kRepBit); } | 
 |   void VisitUint32Cmp(Node* node) { VisitBinop(node, kMachUint32, kRepBit); } | 
 |   void VisitInt64Cmp(Node* node) { VisitBinop(node, kMachInt64, kRepBit); } | 
 |   void VisitUint64Cmp(Node* node) { VisitBinop(node, kMachUint64, kRepBit); } | 
 |  | 
 |   // Helper for handling selects. | 
 |   // TODO(turbofan): Share some code with VisitPhi() below? | 
 |   void VisitSelect(Node* node, MachineTypeUnion use, | 
 |                    SimplifiedLowering* lowering) { | 
 |     ProcessInput(node, 0, kRepBit); | 
 |  | 
 |     // Selects adapt to the output representation their uses demand, pushing | 
 |     // representation changes to their inputs. | 
 |     Type* upper = NodeProperties::GetBounds(node).upper; | 
 |     MachineType output = kMachNone; | 
 |     MachineType propagate = kMachNone; | 
 |  | 
 |     if (upper->Is(Type::Signed32()) || upper->Is(Type::Unsigned32())) { | 
 |       // legal = kRepTagged | kRepFloat64 | kRepWord32; | 
 |       if ((use & kRepMask) == kRepTagged) { | 
 |         // only tagged uses. | 
 |         output = kRepTagged; | 
 |         propagate = kRepTagged; | 
 |       } else if ((use & kRepMask) == kRepFloat64) { | 
 |         // only float64 uses. | 
 |         output = kRepFloat64; | 
 |         propagate = kRepFloat64; | 
 |       } else { | 
 |         // multiple uses. | 
 |         output = kRepWord32; | 
 |         propagate = kRepWord32; | 
 |       } | 
 |     } else if (upper->Is(Type::Boolean())) { | 
 |       // legal = kRepTagged | kRepBit; | 
 |       if ((use & kRepMask) == kRepTagged) { | 
 |         // only tagged uses. | 
 |         output = kRepTagged; | 
 |         propagate = kRepTagged; | 
 |       } else { | 
 |         // multiple uses. | 
 |         output = kRepBit; | 
 |         propagate = kRepBit; | 
 |       } | 
 |     } else if (upper->Is(Type::Number())) { | 
 |       // legal = kRepTagged | kRepFloat64; | 
 |       if ((use & kRepMask) == kRepTagged) { | 
 |         // only tagged uses. | 
 |         output = kRepTagged; | 
 |         propagate = kRepTagged; | 
 |       } else { | 
 |         // multiple uses. | 
 |         output = kRepFloat64; | 
 |         propagate = kRepFloat64; | 
 |       } | 
 |     } else { | 
 |       // legal = kRepTagged; | 
 |       output = kRepTagged; | 
 |       propagate = kRepTagged; | 
 |     } | 
 |  | 
 |     MachineType output_type = | 
 |         static_cast<MachineType>(changer_->TypeFromUpperBound(upper) | output); | 
 |     SetOutput(node, output_type); | 
 |  | 
 |     if (lower()) { | 
 |       // Update the select operator. | 
 |       SelectParameters p = SelectParametersOf(node->op()); | 
 |       MachineType type = static_cast<MachineType>(output_type); | 
 |       if (type != p.type()) { | 
 |         node->set_op(lowering->common()->Select(type, p.hint())); | 
 |       } | 
 |  | 
 |       // Convert inputs to the output representation of this select. | 
 |       ProcessInput(node, 1, output_type); | 
 |       ProcessInput(node, 2, output_type); | 
 |     } else { | 
 |       // Propagate {use} of the select to value inputs. | 
 |       MachineType use_type = | 
 |           static_cast<MachineType>((use & kTypeMask) | propagate); | 
 |       ProcessInput(node, 1, use_type); | 
 |       ProcessInput(node, 2, use_type); | 
 |     } | 
 |   } | 
 |  | 
 |   // Helper for handling phis. | 
 |   void VisitPhi(Node* node, MachineTypeUnion use, | 
 |                 SimplifiedLowering* lowering) { | 
 |     // Phis adapt to the output representation their uses demand, pushing | 
 |     // representation changes to their inputs. | 
 |     Type* upper = NodeProperties::GetBounds(node).upper; | 
 |     MachineType output = kMachNone; | 
 |     MachineType propagate = kMachNone; | 
 |  | 
 |     if (upper->Is(Type::Signed32()) || upper->Is(Type::Unsigned32())) { | 
 |       // legal = kRepTagged | kRepFloat64 | kRepWord32; | 
 |       if ((use & kRepMask) == kRepTagged) { | 
 |         // only tagged uses. | 
 |         output = kRepTagged; | 
 |         propagate = kRepTagged; | 
 |       } else if ((use & kRepMask) == kRepFloat64) { | 
 |         // only float64 uses. | 
 |         output = kRepFloat64; | 
 |         propagate = kRepFloat64; | 
 |       } else { | 
 |         // multiple uses. | 
 |         output = kRepWord32; | 
 |         propagate = kRepWord32; | 
 |       } | 
 |     } else if (upper->Is(Type::Boolean())) { | 
 |       // legal = kRepTagged | kRepBit; | 
 |       if ((use & kRepMask) == kRepTagged) { | 
 |         // only tagged uses. | 
 |         output = kRepTagged; | 
 |         propagate = kRepTagged; | 
 |       } else { | 
 |         // multiple uses. | 
 |         output = kRepBit; | 
 |         propagate = kRepBit; | 
 |       } | 
 |     } else if (upper->Is(Type::Number())) { | 
 |       // legal = kRepTagged | kRepFloat64; | 
 |       if ((use & kRepMask) == kRepTagged) { | 
 |         // only tagged uses. | 
 |         output = kRepTagged; | 
 |         propagate = kRepTagged; | 
 |       } else { | 
 |         // multiple uses. | 
 |         output = kRepFloat64; | 
 |         propagate = kRepFloat64; | 
 |       } | 
 |     } else { | 
 |       // legal = kRepTagged; | 
 |       output = kRepTagged; | 
 |       propagate = kRepTagged; | 
 |     } | 
 |  | 
 |     MachineType output_type = | 
 |         static_cast<MachineType>(changer_->TypeFromUpperBound(upper) | output); | 
 |     SetOutput(node, output_type); | 
 |  | 
 |     int values = node->op()->ValueInputCount(); | 
 |  | 
 |     if (lower()) { | 
 |       // Update the phi operator. | 
 |       MachineType type = static_cast<MachineType>(output_type); | 
 |       if (type != OpParameter<MachineType>(node)) { | 
 |         node->set_op(lowering->common()->Phi(type, values)); | 
 |       } | 
 |  | 
 |       // Convert inputs to the output representation of this phi. | 
 |       Node::Inputs inputs = node->inputs(); | 
 |       for (Node::Inputs::iterator iter(inputs.begin()); iter != inputs.end(); | 
 |            ++iter, --values) { | 
 |         // TODO(titzer): it'd be nice to have distinguished edge kinds here. | 
 |         ProcessInput(node, iter.index(), values > 0 ? output_type : 0); | 
 |       } | 
 |     } else { | 
 |       // Propagate {use} of the phi to value inputs, and 0 to control. | 
 |       Node::Inputs inputs = node->inputs(); | 
 |       MachineType use_type = | 
 |           static_cast<MachineType>((use & kTypeMask) | propagate); | 
 |       for (Node::Inputs::iterator iter(inputs.begin()); iter != inputs.end(); | 
 |            ++iter, --values) { | 
 |         // TODO(titzer): it'd be nice to have distinguished edge kinds here. | 
 |         ProcessInput(node, iter.index(), values > 0 ? use_type : 0); | 
 |       } | 
 |     } | 
 |   } | 
 |  | 
 |   const Operator* Int32Op(Node* node) { | 
 |     return changer_->Int32OperatorFor(node->opcode()); | 
 |   } | 
 |  | 
 |   const Operator* Uint32Op(Node* node) { | 
 |     return changer_->Uint32OperatorFor(node->opcode()); | 
 |   } | 
 |  | 
 |   const Operator* Float64Op(Node* node) { | 
 |     return changer_->Float64OperatorFor(node->opcode()); | 
 |   } | 
 |  | 
 |   bool CanLowerToInt32Binop(Node* node, MachineTypeUnion use) { | 
 |     return BothInputsAre(node, Type::Signed32()) && !CanObserveNonInt32(use); | 
 |   } | 
 |  | 
 |   bool IsSafeIntAdditiveOperand(Node* node) { | 
 |     Type* type = NodeProperties::GetBounds(node).upper; | 
 |     // TODO(jarin): Unfortunately, bitset types are not subtypes of larger | 
 |     // range types, so we have to explicitly check for Integral32 here | 
 |     // (in addition to the safe integer range). Once we fix subtyping for | 
 |     // ranges, we should simplify this. | 
 |     return type->Is(safe_int_additive_range_) || type->Is(Type::Integral32()); | 
 |   } | 
 |  | 
 |   bool CanLowerToInt32AdditiveBinop(Node* node, MachineTypeUnion use) { | 
 |     return IsSafeIntAdditiveOperand(node->InputAt(0)) && | 
 |            IsSafeIntAdditiveOperand(node->InputAt(1)) && | 
 |            !CanObserveNonInt32(use); | 
 |   } | 
 |  | 
 |   bool CanLowerToUint32Binop(Node* node, MachineTypeUnion use) { | 
 |     return BothInputsAre(node, Type::Unsigned32()) && !CanObserveNonUint32(use); | 
 |   } | 
 |  | 
 |   bool CanLowerToUint32AdditiveBinop(Node* node, MachineTypeUnion use) { | 
 |     return IsSafeIntAdditiveOperand(node->InputAt(0)) && | 
 |            IsSafeIntAdditiveOperand(node->InputAt(1)) && | 
 |            !CanObserveNonUint32(use); | 
 |   } | 
 |  | 
 |   bool CanObserveNonInt32(MachineTypeUnion use) { | 
 |     return (use & (kTypeUint32 | kTypeNumber | kTypeAny)) != 0; | 
 |   } | 
 |  | 
 |   bool CanObserveMinusZero(MachineTypeUnion use) { | 
 |     // TODO(turbofan): technically Uint32 cannot observe minus zero either. | 
 |     return (use & (kTypeUint32 | kTypeNumber | kTypeAny)) != 0; | 
 |   } | 
 |  | 
 |   bool CanObserveNaN(MachineTypeUnion use) { | 
 |     return (use & (kTypeNumber | kTypeAny)) != 0; | 
 |   } | 
 |  | 
 |   bool CanObserveNonUint32(MachineTypeUnion use) { | 
 |     return (use & (kTypeInt32 | kTypeNumber | kTypeAny)) != 0; | 
 |   } | 
 |  | 
 |   // Dispatching routine for visiting the node {node} with the usage {use}. | 
 |   // Depending on the operator, propagate new usage info to the inputs. | 
 |   void VisitNode(Node* node, MachineTypeUnion use, | 
 |                  SimplifiedLowering* lowering) { | 
 |     switch (node->opcode()) { | 
 |       //------------------------------------------------------------------ | 
 |       // Common operators. | 
 |       //------------------------------------------------------------------ | 
 |       case IrOpcode::kStart: | 
 |       case IrOpcode::kDead: | 
 |         return VisitLeaf(node, 0); | 
 |       case IrOpcode::kParameter: { | 
 |         // TODO(titzer): use representation from linkage. | 
 |         Type* upper = NodeProperties::GetBounds(node).upper; | 
 |         ProcessInput(node, 0, 0); | 
 |         SetOutput(node, kRepTagged | changer_->TypeFromUpperBound(upper)); | 
 |         return; | 
 |       } | 
 |       case IrOpcode::kInt32Constant: | 
 |         return VisitLeaf(node, kRepWord32); | 
 |       case IrOpcode::kInt64Constant: | 
 |         return VisitLeaf(node, kRepWord64); | 
 |       case IrOpcode::kFloat64Constant: | 
 |         return VisitLeaf(node, kRepFloat64); | 
 |       case IrOpcode::kExternalConstant: | 
 |         return VisitLeaf(node, kMachPtr); | 
 |       case IrOpcode::kNumberConstant: | 
 |         return VisitLeaf(node, kRepTagged); | 
 |       case IrOpcode::kHeapConstant: | 
 |         return VisitLeaf(node, kRepTagged); | 
 |  | 
 |       case IrOpcode::kEnd: | 
 |       case IrOpcode::kIfTrue: | 
 |       case IrOpcode::kIfFalse: | 
 |       case IrOpcode::kReturn: | 
 |       case IrOpcode::kMerge: | 
 |       case IrOpcode::kThrow: | 
 |         return VisitInputs(node);  // default visit for all node inputs. | 
 |  | 
 |       case IrOpcode::kBranch: | 
 |         ProcessInput(node, 0, kRepBit); | 
 |         Enqueue(NodeProperties::GetControlInput(node, 0)); | 
 |         break; | 
 |       case IrOpcode::kSelect: | 
 |         return VisitSelect(node, use, lowering); | 
 |       case IrOpcode::kPhi: | 
 |         return VisitPhi(node, use, lowering); | 
 |  | 
 | //------------------------------------------------------------------ | 
 | // JavaScript operators. | 
 | //------------------------------------------------------------------ | 
 | // For now, we assume that all JS operators were too complex to lower | 
 | // to Simplified and that they will always require tagged value inputs | 
 | // and produce tagged value outputs. | 
 | // TODO(turbofan): it might be possible to lower some JSOperators here, | 
 | // but that responsibility really lies in the typed lowering phase. | 
 | #define DEFINE_JS_CASE(x) case IrOpcode::k##x: | 
 |         JS_OP_LIST(DEFINE_JS_CASE) | 
 | #undef DEFINE_JS_CASE | 
 |         contains_js_nodes_ = true; | 
 |         VisitInputs(node); | 
 |         return SetOutput(node, kRepTagged); | 
 |  | 
 |       //------------------------------------------------------------------ | 
 |       // Simplified operators. | 
 |       //------------------------------------------------------------------ | 
 |       case IrOpcode::kBooleanNot: { | 
 |         if (lower()) { | 
 |           MachineTypeUnion input = GetInfo(node->InputAt(0))->output; | 
 |           if (input & kRepBit) { | 
 |             // BooleanNot(x: kRepBit) => Word32Equal(x, #0) | 
 |             node->set_op(lowering->machine()->Word32Equal()); | 
 |             node->AppendInput(jsgraph_->zone(), jsgraph_->Int32Constant(0)); | 
 |           } else { | 
 |             // BooleanNot(x: kRepTagged) => WordEqual(x, #false) | 
 |             node->set_op(lowering->machine()->WordEqual()); | 
 |             node->AppendInput(jsgraph_->zone(), jsgraph_->FalseConstant()); | 
 |           } | 
 |         } else { | 
 |           // No input representation requirement; adapt during lowering. | 
 |           ProcessInput(node, 0, kTypeBool); | 
 |           SetOutput(node, kRepBit); | 
 |         } | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kBooleanToNumber: { | 
 |         if (lower()) { | 
 |           MachineTypeUnion input = GetInfo(node->InputAt(0))->output; | 
 |           if (input & kRepBit) { | 
 |             // BooleanToNumber(x: kRepBit) => x | 
 |             DeferReplacement(node, node->InputAt(0)); | 
 |           } else { | 
 |             // BooleanToNumber(x: kRepTagged) => WordEqual(x, #true) | 
 |             node->set_op(lowering->machine()->WordEqual()); | 
 |             node->AppendInput(jsgraph_->zone(), jsgraph_->TrueConstant()); | 
 |           } | 
 |         } else { | 
 |           // No input representation requirement; adapt during lowering. | 
 |           ProcessInput(node, 0, kTypeBool); | 
 |           SetOutput(node, kMachInt32); | 
 |         } | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kNumberEqual: | 
 |       case IrOpcode::kNumberLessThan: | 
 |       case IrOpcode::kNumberLessThanOrEqual: { | 
 |         // Number comparisons reduce to integer comparisons for integer inputs. | 
 |         if (BothInputsAre(node, Type::Signed32())) { | 
 |           // => signed Int32Cmp | 
 |           VisitInt32Cmp(node); | 
 |           if (lower()) node->set_op(Int32Op(node)); | 
 |         } else if (BothInputsAre(node, Type::Unsigned32())) { | 
 |           // => unsigned Int32Cmp | 
 |           VisitUint32Cmp(node); | 
 |           if (lower()) node->set_op(Uint32Op(node)); | 
 |         } else { | 
 |           // => Float64Cmp | 
 |           VisitFloat64Cmp(node); | 
 |           if (lower()) node->set_op(Float64Op(node)); | 
 |         } | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kNumberAdd: | 
 |       case IrOpcode::kNumberSubtract: { | 
 |         // Add and subtract reduce to Int32Add/Sub if the inputs | 
 |         // are already integers and all uses are truncating. | 
 |         if (CanLowerToInt32Binop(node, use)) { | 
 |           // => signed Int32Add/Sub | 
 |           VisitInt32Binop(node); | 
 |           if (lower()) node->set_op(Int32Op(node)); | 
 |         } else if (CanLowerToInt32AdditiveBinop(node, use)) { | 
 |           // => signed Int32Add/Sub, truncating inputs | 
 |           ProcessTruncateWord32Input(node, 0, kTypeInt32); | 
 |           ProcessTruncateWord32Input(node, 1, kTypeInt32); | 
 |           SetOutput(node, kMachInt32); | 
 |           if (lower()) node->set_op(Int32Op(node)); | 
 |         } else if (CanLowerToUint32Binop(node, use)) { | 
 |           // => unsigned Int32Add/Sub | 
 |           VisitUint32Binop(node); | 
 |           if (lower()) node->set_op(Uint32Op(node)); | 
 |         } else if (CanLowerToUint32AdditiveBinop(node, use)) { | 
 |           // => signed Int32Add/Sub, truncating inputs | 
 |           ProcessTruncateWord32Input(node, 0, kTypeUint32); | 
 |           ProcessTruncateWord32Input(node, 1, kTypeUint32); | 
 |           SetOutput(node, kMachUint32); | 
 |           if (lower()) node->set_op(Uint32Op(node)); | 
 |         } else { | 
 |           // => Float64Add/Sub | 
 |           VisitFloat64Binop(node); | 
 |           if (lower()) node->set_op(Float64Op(node)); | 
 |         } | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kNumberMultiply: { | 
 |         NumberMatcher right(node->InputAt(1)); | 
 |         if (right.IsInRange(-1048576, 1048576)) {  // must fit double mantissa. | 
 |           if (CanLowerToInt32Binop(node, use)) { | 
 |             // => signed Int32Mul | 
 |             VisitInt32Binop(node); | 
 |             if (lower()) node->set_op(Int32Op(node)); | 
 |             break; | 
 |           } | 
 |         } | 
 |         // => Float64Mul | 
 |         VisitFloat64Binop(node); | 
 |         if (lower()) node->set_op(Float64Op(node)); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kNumberDivide: { | 
 |         if (CanLowerToInt32Binop(node, use)) { | 
 |           // => signed Int32Div | 
 |           VisitInt32Binop(node); | 
 |           if (lower()) DeferReplacement(node, lowering->Int32Div(node)); | 
 |           break; | 
 |         } | 
 |         if (CanLowerToUint32Binop(node, use)) { | 
 |           // => unsigned Uint32Div | 
 |           VisitUint32Binop(node); | 
 |           if (lower()) DeferReplacement(node, lowering->Uint32Div(node)); | 
 |           break; | 
 |         } | 
 |         // => Float64Div | 
 |         VisitFloat64Binop(node); | 
 |         if (lower()) node->set_op(Float64Op(node)); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kNumberModulus: { | 
 |         if (CanLowerToInt32Binop(node, use)) { | 
 |           // => signed Int32Mod | 
 |           VisitInt32Binop(node); | 
 |           if (lower()) DeferReplacement(node, lowering->Int32Mod(node)); | 
 |           break; | 
 |         } | 
 |         if (BothInputsAre(node, Type::Unsigned32()) && !CanObserveNaN(use)) { | 
 |           // => unsigned Uint32Mod | 
 |           VisitUint32Binop(node); | 
 |           if (lower()) DeferReplacement(node, lowering->Uint32Mod(node)); | 
 |           break; | 
 |         } | 
 |         // => Float64Mod | 
 |         VisitFloat64Binop(node); | 
 |         if (lower()) node->set_op(Float64Op(node)); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kNumberToInt32: { | 
 |         MachineTypeUnion use_rep = use & kRepMask; | 
 |         Node* input = node->InputAt(0); | 
 |         MachineTypeUnion in = GetInfo(input)->output; | 
 |         if (NodeProperties::GetBounds(input).upper->Is(Type::Signed32())) { | 
 |           // If the input has type int32, pass through representation. | 
 |           VisitUnop(node, kTypeInt32 | use_rep, kTypeInt32 | use_rep); | 
 |           if (lower()) DeferReplacement(node, node->InputAt(0)); | 
 |         } else if ((in & kTypeMask) == kTypeUint32 || | 
 |                    (in & kTypeMask) == kTypeInt32 || | 
 |                    (in & kRepMask) == kRepWord32) { | 
 |           // Just change representation if necessary. | 
 |           VisitUnop(node, kTypeInt32 | kRepWord32, kTypeInt32 | kRepWord32); | 
 |           if (lower()) DeferReplacement(node, node->InputAt(0)); | 
 |         } else { | 
 |           // Require the input in float64 format and perform truncation. | 
 |           // TODO(turbofan): avoid a truncation with a smi check. | 
 |           VisitUnop(node, kTypeInt32 | kRepFloat64, kTypeInt32 | kRepWord32); | 
 |           if (lower()) | 
 |             node->set_op(lowering->machine()->TruncateFloat64ToInt32()); | 
 |         } | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kNumberToUint32: { | 
 |         MachineTypeUnion use_rep = use & kRepMask; | 
 |         Node* input = node->InputAt(0); | 
 |         MachineTypeUnion in = GetInfo(input)->output; | 
 |         if (NodeProperties::GetBounds(input).upper->Is(Type::Unsigned32())) { | 
 |           // If the input has type uint32, pass through representation. | 
 |           VisitUnop(node, kTypeUint32 | use_rep, kTypeUint32 | use_rep); | 
 |           if (lower()) DeferReplacement(node, node->InputAt(0)); | 
 |         } else if ((in & kTypeMask) == kTypeUint32 || | 
 |                    (in & kTypeMask) == kTypeInt32 || | 
 |                    (in & kRepMask) == kRepWord32) { | 
 |           // Just change representation if necessary. | 
 |           VisitUnop(node, kTypeUint32 | kRepWord32, kTypeUint32 | kRepWord32); | 
 |           if (lower()) DeferReplacement(node, node->InputAt(0)); | 
 |         } else { | 
 |           // Require the input in float64 format and perform truncation. | 
 |           // TODO(turbofan): avoid a truncation with a smi check. | 
 |           VisitUnop(node, kTypeUint32 | kRepFloat64, kTypeUint32 | kRepWord32); | 
 |           if (lower()) | 
 |             node->set_op(lowering->machine()->TruncateFloat64ToInt32()); | 
 |         } | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kReferenceEqual: { | 
 |         VisitBinop(node, kMachAnyTagged, kRepBit); | 
 |         if (lower()) node->set_op(lowering->machine()->WordEqual()); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kStringEqual: { | 
 |         VisitBinop(node, kMachAnyTagged, kRepBit); | 
 |         if (lower()) lowering->DoStringEqual(node); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kStringLessThan: { | 
 |         VisitBinop(node, kMachAnyTagged, kRepBit); | 
 |         if (lower()) lowering->DoStringLessThan(node); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kStringLessThanOrEqual: { | 
 |         VisitBinop(node, kMachAnyTagged, kRepBit); | 
 |         if (lower()) lowering->DoStringLessThanOrEqual(node); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kStringAdd: { | 
 |         VisitBinop(node, kMachAnyTagged, kMachAnyTagged); | 
 |         if (lower()) lowering->DoStringAdd(node); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kLoadField: { | 
 |         FieldAccess access = FieldAccessOf(node->op()); | 
 |         ProcessInput(node, 0, changer_->TypeForBasePointer(access)); | 
 |         ProcessRemainingInputs(node, 1); | 
 |         SetOutput(node, access.machine_type); | 
 |         if (lower()) lowering->DoLoadField(node); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kStoreField: { | 
 |         FieldAccess access = FieldAccessOf(node->op()); | 
 |         ProcessInput(node, 0, changer_->TypeForBasePointer(access)); | 
 |         ProcessInput(node, 1, access.machine_type); | 
 |         ProcessRemainingInputs(node, 2); | 
 |         SetOutput(node, 0); | 
 |         if (lower()) lowering->DoStoreField(node); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kLoadElement: { | 
 |         ElementAccess access = ElementAccessOf(node->op()); | 
 |         ProcessInput(node, 0, changer_->TypeForBasePointer(access)); | 
 |         ProcessInput(node, 1, kMachInt32);  // element index | 
 |         ProcessInput(node, 2, kMachInt32);  // length | 
 |         ProcessRemainingInputs(node, 3); | 
 |         // Tagged overrides everything if we have to do a typed array bounds | 
 |         // check, because we may need to return undefined then. | 
 |         MachineType output_type = | 
 |             (access.bounds_check == kTypedArrayBoundsCheck && | 
 |              (use & kRepTagged)) | 
 |                 ? kMachAnyTagged | 
 |                 : access.machine_type; | 
 |         SetOutput(node, output_type); | 
 |         if (lower()) lowering->DoLoadElement(node, output_type); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kStoreElement: { | 
 |         ElementAccess access = ElementAccessOf(node->op()); | 
 |         ProcessInput(node, 0, changer_->TypeForBasePointer(access)); | 
 |         ProcessInput(node, 1, kMachInt32);  // element index | 
 |         ProcessInput(node, 2, kMachInt32);  // length | 
 |         ProcessInput(node, 3, access.machine_type); | 
 |         ProcessRemainingInputs(node, 4); | 
 |         SetOutput(node, 0); | 
 |         if (lower()) lowering->DoStoreElement(node); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kObjectIsSmi: { | 
 |         ProcessInput(node, 0, kMachAnyTagged); | 
 |         SetOutput(node, kRepBit | kTypeBool); | 
 |         if (lower()) { | 
 |           Node* is_tagged = jsgraph_->graph()->NewNode( | 
 |               jsgraph_->machine()->WordAnd(), node->InputAt(0), | 
 |               jsgraph_->Int32Constant(static_cast<int>(kSmiTagMask))); | 
 |           Node* is_smi = jsgraph_->graph()->NewNode( | 
 |               jsgraph_->machine()->WordEqual(), is_tagged, | 
 |               jsgraph_->Int32Constant(kSmiTag)); | 
 |           DeferReplacement(node, is_smi); | 
 |         } | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kObjectIsNonNegativeSmi: { | 
 |         ProcessInput(node, 0, kMachAnyTagged); | 
 |         SetOutput(node, kRepBit | kTypeBool); | 
 |         if (lower()) { | 
 |           Node* is_tagged = jsgraph_->graph()->NewNode( | 
 |               jsgraph_->machine()->WordAnd(), node->InputAt(0), | 
 |               jsgraph_->Int32Constant(static_cast<int>(kSmiTagMask))); | 
 |           Node* is_smi = jsgraph_->graph()->NewNode( | 
 |               jsgraph_->machine()->WordEqual(), is_tagged, | 
 |               jsgraph_->Int32Constant(kSmiTag)); | 
 |           Node* is_non_neg = jsgraph_->graph()->NewNode( | 
 |               jsgraph_->machine()->IntLessThanOrEqual(), | 
 |               jsgraph_->Int32Constant(0), node->InputAt(0)); | 
 |           Node* is_non_neg_smi = jsgraph_->graph()->NewNode( | 
 |               jsgraph_->machine()->Word32And(), is_smi, is_non_neg); | 
 |           DeferReplacement(node, is_non_neg_smi); | 
 |         } | 
 |         break; | 
 |       } | 
 |  | 
 |       //------------------------------------------------------------------ | 
 |       // Machine-level operators. | 
 |       //------------------------------------------------------------------ | 
 |       case IrOpcode::kLoad: { | 
 |         // TODO(titzer): machine loads/stores need to know BaseTaggedness!? | 
 |         MachineTypeUnion tBase = kRepTagged | kMachPtr; | 
 |         LoadRepresentation rep = OpParameter<LoadRepresentation>(node); | 
 |         ProcessInput(node, 0, tBase);   // pointer or object | 
 |         ProcessInput(node, 1, kMachInt32);  // index | 
 |         ProcessRemainingInputs(node, 2); | 
 |         SetOutput(node, rep); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kStore: { | 
 |         // TODO(titzer): machine loads/stores need to know BaseTaggedness!? | 
 |         MachineTypeUnion tBase = kRepTagged | kMachPtr; | 
 |         StoreRepresentation rep = OpParameter<StoreRepresentation>(node); | 
 |         ProcessInput(node, 0, tBase);   // pointer or object | 
 |         ProcessInput(node, 1, kMachInt32);  // index | 
 |         ProcessInput(node, 2, rep.machine_type()); | 
 |         ProcessRemainingInputs(node, 3); | 
 |         SetOutput(node, 0); | 
 |         break; | 
 |       } | 
 |       case IrOpcode::kWord32Shr: | 
 |         // We output unsigned int32 for shift right because JavaScript. | 
 |         return VisitBinop(node, kMachUint32, kMachUint32); | 
 |       case IrOpcode::kWord32And: | 
 |       case IrOpcode::kWord32Or: | 
 |       case IrOpcode::kWord32Xor: | 
 |       case IrOpcode::kWord32Shl: | 
 |       case IrOpcode::kWord32Sar: | 
 |         // We use signed int32 as the output type for these word32 operations, | 
 |         // though the machine bits are the same for either signed or unsigned, | 
 |         // because JavaScript considers the result from these operations signed. | 
 |         return VisitBinop(node, kRepWord32, kRepWord32 | kTypeInt32); | 
 |       case IrOpcode::kWord32Equal: | 
 |         return VisitBinop(node, kRepWord32, kRepBit); | 
 |  | 
 |       case IrOpcode::kInt32Add: | 
 |       case IrOpcode::kInt32Sub: | 
 |       case IrOpcode::kInt32Mul: | 
 |       case IrOpcode::kInt32Div: | 
 |       case IrOpcode::kInt32Mod: | 
 |         return VisitInt32Binop(node); | 
 |       case IrOpcode::kUint32Div: | 
 |       case IrOpcode::kUint32Mod: | 
 |         return VisitUint32Binop(node); | 
 |       case IrOpcode::kInt32LessThan: | 
 |       case IrOpcode::kInt32LessThanOrEqual: | 
 |         return VisitInt32Cmp(node); | 
 |  | 
 |       case IrOpcode::kUint32LessThan: | 
 |       case IrOpcode::kUint32LessThanOrEqual: | 
 |         return VisitUint32Cmp(node); | 
 |  | 
 |       case IrOpcode::kInt64Add: | 
 |       case IrOpcode::kInt64Sub: | 
 |       case IrOpcode::kInt64Mul: | 
 |       case IrOpcode::kInt64Div: | 
 |       case IrOpcode::kInt64Mod: | 
 |         return VisitInt64Binop(node); | 
 |       case IrOpcode::kInt64LessThan: | 
 |       case IrOpcode::kInt64LessThanOrEqual: | 
 |         return VisitInt64Cmp(node); | 
 |  | 
 |       case IrOpcode::kUint64LessThan: | 
 |         return VisitUint64Cmp(node); | 
 |  | 
 |       case IrOpcode::kUint64Div: | 
 |       case IrOpcode::kUint64Mod: | 
 |         return VisitUint64Binop(node); | 
 |  | 
 |       case IrOpcode::kWord64And: | 
 |       case IrOpcode::kWord64Or: | 
 |       case IrOpcode::kWord64Xor: | 
 |       case IrOpcode::kWord64Shl: | 
 |       case IrOpcode::kWord64Shr: | 
 |       case IrOpcode::kWord64Sar: | 
 |         return VisitBinop(node, kRepWord64, kRepWord64); | 
 |       case IrOpcode::kWord64Equal: | 
 |         return VisitBinop(node, kRepWord64, kRepBit); | 
 |  | 
 |       case IrOpcode::kChangeInt32ToInt64: | 
 |         return VisitUnop(node, kTypeInt32 | kRepWord32, | 
 |                          kTypeInt32 | kRepWord64); | 
 |       case IrOpcode::kChangeUint32ToUint64: | 
 |         return VisitUnop(node, kTypeUint32 | kRepWord32, | 
 |                          kTypeUint32 | kRepWord64); | 
 |       case IrOpcode::kTruncateFloat64ToFloat32: | 
 |         return VisitUnop(node, kTypeNumber | kRepFloat64, | 
 |                          kTypeNumber | kRepFloat32); | 
 |       case IrOpcode::kTruncateInt64ToInt32: | 
 |         // TODO(titzer): Is kTypeInt32 correct here? | 
 |         return VisitUnop(node, kTypeInt32 | kRepWord64, | 
 |                          kTypeInt32 | kRepWord32); | 
 |  | 
 |       case IrOpcode::kChangeFloat32ToFloat64: | 
 |         return VisitUnop(node, kTypeNumber | kRepFloat32, | 
 |                          kTypeNumber | kRepFloat64); | 
 |       case IrOpcode::kChangeInt32ToFloat64: | 
 |         return VisitUnop(node, kTypeInt32 | kRepWord32, | 
 |                          kTypeInt32 | kRepFloat64); | 
 |       case IrOpcode::kChangeUint32ToFloat64: | 
 |         return VisitUnop(node, kTypeUint32 | kRepWord32, | 
 |                          kTypeUint32 | kRepFloat64); | 
 |       case IrOpcode::kChangeFloat64ToInt32: | 
 |         return VisitUnop(node, kTypeInt32 | kRepFloat64, | 
 |                          kTypeInt32 | kRepWord32); | 
 |       case IrOpcode::kChangeFloat64ToUint32: | 
 |         return VisitUnop(node, kTypeUint32 | kRepFloat64, | 
 |                          kTypeUint32 | kRepWord32); | 
 |  | 
 |       case IrOpcode::kFloat64Add: | 
 |       case IrOpcode::kFloat64Sub: | 
 |       case IrOpcode::kFloat64Mul: | 
 |       case IrOpcode::kFloat64Div: | 
 |       case IrOpcode::kFloat64Mod: | 
 |         return VisitFloat64Binop(node); | 
 |       case IrOpcode::kFloat64Sqrt: | 
 |       case IrOpcode::kFloat64Floor: | 
 |       case IrOpcode::kFloat64Ceil: | 
 |       case IrOpcode::kFloat64RoundTruncate: | 
 |       case IrOpcode::kFloat64RoundTiesAway: | 
 |         return VisitUnop(node, kMachFloat64, kMachFloat64); | 
 |       case IrOpcode::kFloat64Equal: | 
 |       case IrOpcode::kFloat64LessThan: | 
 |       case IrOpcode::kFloat64LessThanOrEqual: | 
 |         return VisitFloat64Cmp(node); | 
 |       case IrOpcode::kLoadStackPointer: | 
 |         return VisitLeaf(node, kMachPtr); | 
 |       case IrOpcode::kStateValues: | 
 |         for (int i = 0; i < node->InputCount(); i++) { | 
 |           ProcessInput(node, i, kTypeAny); | 
 |         } | 
 |         SetOutput(node, kMachAnyTagged); | 
 |         break; | 
 |       default: | 
 |         VisitInputs(node); | 
 |         break; | 
 |     } | 
 |   } | 
 |  | 
 |   void DeferReplacement(Node* node, Node* replacement) { | 
 |     if (FLAG_trace_representation) { | 
 |       TRACE(("defer replacement #%d:%s with #%d:%s\n", node->id(), | 
 |              node->op()->mnemonic(), replacement->id(), | 
 |              replacement->op()->mnemonic())); | 
 |     } | 
 |     if (replacement->id() < count_) { | 
 |       // Replace with a previously existing node eagerly. | 
 |       node->ReplaceUses(replacement); | 
 |     } else { | 
 |       // Otherwise, we are replacing a node with a representation change. | 
 |       // Such a substitution must be done after all lowering is done, because | 
 |       // new nodes do not have {NodeInfo} entries, and that would confuse | 
 |       // the representation change insertion for uses of it. | 
 |       replacements_.push_back(node); | 
 |       replacements_.push_back(replacement); | 
 |     } | 
 |     // TODO(titzer) node->RemoveAllInputs();  // Node is now dead. | 
 |   } | 
 |  | 
 |   void PrintUseInfo(Node* node) { | 
 |     TRACE(("#%d:%-20s ", node->id(), node->op()->mnemonic())); | 
 |     PrintInfo(GetUseInfo(node)); | 
 |     TRACE(("\n")); | 
 |   } | 
 |  | 
 |   void PrintInfo(MachineTypeUnion info) { | 
 |     if (FLAG_trace_representation) { | 
 |       OFStream os(stdout); | 
 |       os << static_cast<MachineType>(info); | 
 |     } | 
 |   } | 
 |  | 
 |  private: | 
 |   JSGraph* jsgraph_; | 
 |   int count_;                       // number of nodes in the graph | 
 |   NodeInfo* info_;                  // node id -> usage information | 
 |   NodeVector nodes_;                // collected nodes | 
 |   NodeVector replacements_;         // replacements to be done after lowering | 
 |   bool contains_js_nodes_;          // {true} if a JS operator was seen | 
 |   Phase phase_;                     // current phase of algorithm | 
 |   RepresentationChanger* changer_;  // for inserting representation changes | 
 |   ZoneQueue<Node*> queue_;          // queue for traversing the graph | 
 |   Type* safe_int_additive_range_; | 
 |  | 
 |   NodeInfo* GetInfo(Node* node) { | 
 |     DCHECK(node->id() >= 0); | 
 |     DCHECK(node->id() < count_); | 
 |     return &info_[node->id()]; | 
 |   } | 
 |  | 
 |   MachineTypeUnion GetUseInfo(Node* node) { return GetInfo(node)->use; } | 
 | }; | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::IsTagged(Node* node) { | 
 |   // TODO(titzer): factor this out to a TaggingScheme abstraction. | 
 |   STATIC_ASSERT(kSmiTagMask == 1);  // Only works if tag is the low bit. | 
 |   return graph()->NewNode(machine()->WordAnd(), node, | 
 |                           jsgraph()->Int32Constant(kSmiTagMask)); | 
 | } | 
 |  | 
 |  | 
 | void SimplifiedLowering::LowerAllNodes() { | 
 |   SimplifiedOperatorBuilder simplified(graph()->zone()); | 
 |   RepresentationChanger changer(jsgraph(), &simplified, | 
 |                                 graph()->zone()->isolate()); | 
 |   RepresentationSelector selector(jsgraph(), zone(), &changer); | 
 |   selector.Run(this); | 
 | } | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::Untag(Node* node) { | 
 |   // TODO(titzer): factor this out to a TaggingScheme abstraction. | 
 |   Node* shift_amount = jsgraph()->Int32Constant(kSmiTagSize + kSmiShiftSize); | 
 |   return graph()->NewNode(machine()->WordSar(), node, shift_amount); | 
 | } | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::SmiTag(Node* node) { | 
 |   // TODO(titzer): factor this out to a TaggingScheme abstraction. | 
 |   Node* shift_amount = jsgraph()->Int32Constant(kSmiTagSize + kSmiShiftSize); | 
 |   return graph()->NewNode(machine()->WordShl(), node, shift_amount); | 
 | } | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::OffsetMinusTagConstant(int32_t offset) { | 
 |   return jsgraph()->Int32Constant(offset - kHeapObjectTag); | 
 | } | 
 |  | 
 |  | 
 | static WriteBarrierKind ComputeWriteBarrierKind(BaseTaggedness base_is_tagged, | 
 |                                                 MachineType representation, | 
 |                                                 Type* type) { | 
 |   // TODO(turbofan): skip write barriers for Smis, etc. | 
 |   if (base_is_tagged == kTaggedBase && | 
 |       RepresentationOf(representation) == kRepTagged) { | 
 |     // Write barriers are only for writes into heap objects (i.e. tagged base). | 
 |     return kFullWriteBarrier; | 
 |   } | 
 |   return kNoWriteBarrier; | 
 | } | 
 |  | 
 |  | 
 | void SimplifiedLowering::DoLoadField(Node* node) { | 
 |   const FieldAccess& access = FieldAccessOf(node->op()); | 
 |   node->set_op(machine()->Load(access.machine_type)); | 
 |   Node* offset = jsgraph()->IntPtrConstant(access.offset - access.tag()); | 
 |   node->InsertInput(graph()->zone(), 1, offset); | 
 | } | 
 |  | 
 |  | 
 | void SimplifiedLowering::DoStoreField(Node* node) { | 
 |   const FieldAccess& access = FieldAccessOf(node->op()); | 
 |   WriteBarrierKind kind = ComputeWriteBarrierKind( | 
 |       access.base_is_tagged, access.machine_type, access.type); | 
 |   node->set_op( | 
 |       machine()->Store(StoreRepresentation(access.machine_type, kind))); | 
 |   Node* offset = jsgraph()->IntPtrConstant(access.offset - access.tag()); | 
 |   node->InsertInput(graph()->zone(), 1, offset); | 
 | } | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::ComputeIndex(const ElementAccess& access, | 
 |                                        Node* const key) { | 
 |   Node* index = key; | 
 |   const int element_size_shift = ElementSizeLog2Of(access.machine_type); | 
 |   if (element_size_shift) { | 
 |     index = graph()->NewNode(machine()->Word32Shl(), index, | 
 |                              jsgraph()->Int32Constant(element_size_shift)); | 
 |   } | 
 |   const int fixed_offset = access.header_size - access.tag(); | 
 |   if (fixed_offset) { | 
 |     index = graph()->NewNode(machine()->Int32Add(), index, | 
 |                              jsgraph()->Int32Constant(fixed_offset)); | 
 |   } | 
 |   if (machine()->Is64()) { | 
 |     // TODO(turbofan): This is probably only correct for typed arrays, and only | 
 |     // if the typed arrays are at most 2GiB in size, which happens to match | 
 |     // exactly our current situation. | 
 |     index = graph()->NewNode(machine()->ChangeUint32ToUint64(), index); | 
 |   } | 
 |   return index; | 
 | } | 
 |  | 
 |  | 
 | namespace { | 
 |  | 
 | intptr_t AddressForOutOfBoundsLoad(MachineType type) { | 
 |   switch (RepresentationOf(type)) { | 
 |     case kRepFloat32: { | 
 |       static const float dummy = std::numeric_limits<float>::quiet_NaN(); | 
 |       return bit_cast<intptr_t>(&dummy); | 
 |     } | 
 |     case kRepFloat64: { | 
 |       static const double dummy = std::numeric_limits<double>::quiet_NaN(); | 
 |       return bit_cast<intptr_t>(&dummy); | 
 |     } | 
 |     case kRepBit: | 
 |     case kRepWord8: | 
 |     case kRepWord16: | 
 |     case kRepWord32: { | 
 |       static const int32_t dummy = 0; | 
 |       return bit_cast<intptr_t>(&dummy); | 
 |     } | 
 |     default: | 
 |       break; | 
 |   } | 
 |   UNREACHABLE(); | 
 |   return 0; | 
 | } | 
 |  | 
 |  | 
 | intptr_t AddressForOutOfBoundsStore() { | 
 |   static volatile double dummy = 0; | 
 |   return bit_cast<intptr_t>(&dummy); | 
 | } | 
 |  | 
 | }  // namespace | 
 |  | 
 |  | 
 | void SimplifiedLowering::DoLoadElement(Node* node, MachineType output_type) { | 
 |   const ElementAccess& access = ElementAccessOf(node->op()); | 
 |   const Operator* op = machine()->Load(access.machine_type); | 
 |   Node* key = node->InputAt(1); | 
 |   Node* index = ComputeIndex(access, key); | 
 |   Node* effect = node->InputAt(3); | 
 |   if (access.bounds_check == kNoBoundsCheck) { | 
 |     DCHECK_EQ(access.machine_type, output_type); | 
 |     node->set_op(op); | 
 |     node->ReplaceInput(1, index); | 
 |     node->ReplaceInput(2, effect); | 
 |     node->ReplaceInput(3, graph()->start()); | 
 |   } else { | 
 |     DCHECK_EQ(kTypedArrayBoundsCheck, access.bounds_check); | 
 |  | 
 |     Node* base = node->InputAt(0); | 
 |     Node* length = node->InputAt(2); | 
 |     Node* check = graph()->NewNode(machine()->Uint32LessThan(), key, length); | 
 |  | 
 |     IntPtrMatcher mbase(base); | 
 |     if (mbase.HasValue() && (output_type & kRepTagged) == 0) { | 
 |       Node* select = graph()->NewNode( | 
 |           common()->Select(kMachIntPtr, BranchHint::kTrue), check, index, | 
 |           jsgraph()->IntPtrConstant(AddressForOutOfBoundsLoad(output_type) - | 
 |                                     mbase.Value())); | 
 |  | 
 |       node->set_op(op); | 
 |       node->ReplaceInput(1, select); | 
 |       node->ReplaceInput(2, effect); | 
 |       node->ReplaceInput(3, graph()->start()); | 
 |     } else { | 
 |       Node* branch = graph()->NewNode(common()->Branch(BranchHint::kTrue), | 
 |                                       check, graph()->start()); | 
 |  | 
 |       Node* if_true = graph()->NewNode(common()->IfTrue(), branch); | 
 |       Node* load = graph()->NewNode(op, base, index, effect, if_true); | 
 |       Node* result = load; | 
 |       if (output_type & kRepTagged) { | 
 |         // TODO(turbofan): This is ugly as hell! | 
 |         SimplifiedOperatorBuilder simplified(graph()->zone()); | 
 |         RepresentationChanger changer(jsgraph(), &simplified, | 
 |                                       graph()->zone()->isolate()); | 
 |         result = | 
 |             changer.GetTaggedRepresentationFor(result, access.machine_type); | 
 |       } | 
 |  | 
 |       Node* if_false = graph()->NewNode(common()->IfFalse(), branch); | 
 |       Node* undefined; | 
 |       if (output_type & kRepTagged) { | 
 |         DCHECK_EQ(0, access.machine_type & kRepTagged); | 
 |         undefined = jsgraph()->UndefinedConstant(); | 
 |       } else if (output_type & kRepFloat32) { | 
 |         undefined = | 
 |             jsgraph()->Float32Constant(std::numeric_limits<float>::quiet_NaN()); | 
 |       } else if (output_type & kRepFloat64) { | 
 |         undefined = jsgraph()->Float64Constant( | 
 |             std::numeric_limits<double>::quiet_NaN()); | 
 |       } else { | 
 |         undefined = jsgraph()->Int32Constant(0); | 
 |       } | 
 |  | 
 |       Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false); | 
 |       Node* phi = graph()->NewNode(common()->EffectPhi(2), load, effect, merge); | 
 |  | 
 |       // Replace effect uses of node with the effect phi. | 
 |       for (UseIter i = node->uses().begin(); i != node->uses().end();) { | 
 |         if (NodeProperties::IsEffectEdge(i.edge())) { | 
 |           i = i.UpdateToAndIncrement(phi); | 
 |         } else { | 
 |           ++i; | 
 |         } | 
 |       } | 
 |  | 
 |       node->set_op(common()->Phi(output_type, 2)); | 
 |       node->ReplaceInput(0, result); | 
 |       node->ReplaceInput(1, undefined); | 
 |       node->ReplaceInput(2, merge); | 
 |       node->TrimInputCount(3); | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 |  | 
 | void SimplifiedLowering::DoStoreElement(Node* node) { | 
 |   const ElementAccess& access = ElementAccessOf(node->op()); | 
 |   const Operator* op = machine()->Store(StoreRepresentation( | 
 |       access.machine_type, | 
 |       ComputeWriteBarrierKind(access.base_is_tagged, access.machine_type, | 
 |                               access.type))); | 
 |   Node* key = node->InputAt(1); | 
 |   Node* index = ComputeIndex(access, key); | 
 |   if (access.bounds_check == kNoBoundsCheck) { | 
 |     node->set_op(op); | 
 |     node->ReplaceInput(1, index); | 
 |     node->RemoveInput(2); | 
 |   } else { | 
 |     DCHECK_EQ(kTypedArrayBoundsCheck, access.bounds_check); | 
 |  | 
 |     Node* base = node->InputAt(0); | 
 |     Node* length = node->InputAt(2); | 
 |     Node* value = node->InputAt(3); | 
 |     Node* effect = node->InputAt(4); | 
 |     Node* control = node->InputAt(5); | 
 |     Node* check = graph()->NewNode(machine()->Uint32LessThan(), key, length); | 
 |  | 
 |     IntPtrMatcher mbase(base); | 
 |     if (mbase.HasValue()) { | 
 |       Node* select = graph()->NewNode( | 
 |           common()->Select(kMachIntPtr, BranchHint::kTrue), check, index, | 
 |           jsgraph()->IntPtrConstant(AddressForOutOfBoundsStore() - | 
 |                                     mbase.Value())); | 
 |  | 
 |       node->set_op(op); | 
 |       node->ReplaceInput(1, select); | 
 |       node->RemoveInput(2); | 
 |     } else { | 
 |       Node* branch = | 
 |           graph()->NewNode(common()->Branch(BranchHint::kTrue), check, control); | 
 |  | 
 |       Node* if_true = graph()->NewNode(common()->IfTrue(), branch); | 
 |       Node* store = graph()->NewNode(op, base, index, value, effect, if_true); | 
 |  | 
 |       Node* if_false = graph()->NewNode(common()->IfFalse(), branch); | 
 |  | 
 |       Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false); | 
 |  | 
 |       node->set_op(common()->EffectPhi(2)); | 
 |       node->ReplaceInput(0, store); | 
 |       node->ReplaceInput(1, effect); | 
 |       node->ReplaceInput(2, merge); | 
 |       node->TrimInputCount(3); | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 |  | 
 | void SimplifiedLowering::DoStringAdd(Node* node) { | 
 |   Callable callable = CodeFactory::StringAdd( | 
 |       zone()->isolate(), STRING_ADD_CHECK_NONE, NOT_TENURED); | 
 |   CallDescriptor::Flags flags = CallDescriptor::kNoFlags; | 
 |   CallDescriptor* desc = | 
 |       Linkage::GetStubCallDescriptor(callable.descriptor(), 0, flags, zone()); | 
 |   node->set_op(common()->Call(desc)); | 
 |   node->InsertInput(graph()->zone(), 0, | 
 |                     jsgraph()->HeapConstant(callable.code())); | 
 |   node->AppendInput(graph()->zone(), jsgraph()->UndefinedConstant()); | 
 |   node->AppendInput(graph()->zone(), graph()->start()); | 
 |   node->AppendInput(graph()->zone(), graph()->start()); | 
 | } | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::StringComparison(Node* node, bool requires_ordering) { | 
 |   CEntryStub stub(zone()->isolate(), 1); | 
 |   Runtime::FunctionId f = | 
 |       requires_ordering ? Runtime::kStringCompare : Runtime::kStringEquals; | 
 |   ExternalReference ref(f, zone()->isolate()); | 
 |   Operator::Properties props = node->op()->properties(); | 
 |   // TODO(mstarzinger): We should call StringCompareStub here instead, once an | 
 |   // interface descriptor is available for it. | 
 |   CallDescriptor* desc = Linkage::GetRuntimeCallDescriptor(f, 2, props, zone()); | 
 |   return graph()->NewNode(common()->Call(desc), | 
 |                           jsgraph()->HeapConstant(stub.GetCode()), | 
 |                           NodeProperties::GetValueInput(node, 0), | 
 |                           NodeProperties::GetValueInput(node, 1), | 
 |                           jsgraph()->ExternalConstant(ref), | 
 |                           jsgraph()->Int32Constant(2), | 
 |                           jsgraph()->UndefinedConstant()); | 
 | } | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::Int32Div(Node* const node) { | 
 |   Int32BinopMatcher m(node); | 
 |   Node* const zero = jsgraph()->Int32Constant(0); | 
 |   Node* const lhs = m.left().node(); | 
 |   Node* const rhs = m.right().node(); | 
 |  | 
 |   if (m.right().Is(-1)) { | 
 |     return graph()->NewNode(machine()->Int32Sub(), zero, lhs); | 
 |   } else if (m.right().Is(0)) { | 
 |     return rhs; | 
 |   } else if (machine()->Int32DivIsSafe() || m.right().HasValue()) { | 
 |     return graph()->NewNode(machine()->Int32Div(), lhs, rhs, graph()->start()); | 
 |   } | 
 |  | 
 |   Node* check0 = graph()->NewNode(machine()->Word32Equal(), rhs, zero); | 
 |   Node* branch0 = graph()->NewNode(common()->Branch(BranchHint::kFalse), check0, | 
 |                                    graph()->start()); | 
 |  | 
 |   Node* if_true0 = graph()->NewNode(common()->IfTrue(), branch0); | 
 |   Node* true0 = zero; | 
 |  | 
 |   Node* if_false0 = graph()->NewNode(common()->IfFalse(), branch0); | 
 |   Node* false0 = nullptr; | 
 |   { | 
 |     Node* check1 = graph()->NewNode(machine()->Word32Equal(), rhs, | 
 |                                     jsgraph()->Int32Constant(-1)); | 
 |     Node* branch1 = graph()->NewNode(common()->Branch(BranchHint::kFalse), | 
 |                                      check1, if_false0); | 
 |  | 
 |     Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1); | 
 |     Node* true1 = graph()->NewNode(machine()->Int32Sub(), zero, lhs); | 
 |  | 
 |     Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1); | 
 |     Node* false1 = graph()->NewNode(machine()->Int32Div(), lhs, rhs, if_false1); | 
 |  | 
 |     if_false0 = graph()->NewNode(common()->Merge(2), if_true1, if_false1); | 
 |     false0 = graph()->NewNode(common()->Phi(kMachInt32, 2), true1, false1, | 
 |                               if_false0); | 
 |   } | 
 |  | 
 |   Node* merge0 = graph()->NewNode(common()->Merge(2), if_true0, if_false0); | 
 |   return graph()->NewNode(common()->Phi(kMachInt32, 2), true0, false0, merge0); | 
 | } | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::Int32Mod(Node* const node) { | 
 |   Int32BinopMatcher m(node); | 
 |   Node* const zero = jsgraph()->Int32Constant(0); | 
 |   Node* const lhs = m.left().node(); | 
 |   Node* const rhs = m.right().node(); | 
 |  | 
 |   if (m.right().Is(-1) || m.right().Is(0)) { | 
 |     return zero; | 
 |   } else if (machine()->Int32ModIsSafe() || m.right().HasValue()) { | 
 |     return graph()->NewNode(machine()->Int32Mod(), lhs, rhs, graph()->start()); | 
 |   } | 
 |  | 
 |   Node* check0 = graph()->NewNode(machine()->Word32Equal(), rhs, zero); | 
 |   Node* branch0 = graph()->NewNode(common()->Branch(BranchHint::kFalse), check0, | 
 |                                    graph()->start()); | 
 |  | 
 |   Node* if_true0 = graph()->NewNode(common()->IfTrue(), branch0); | 
 |   Node* true0 = zero; | 
 |  | 
 |   Node* if_false0 = graph()->NewNode(common()->IfFalse(), branch0); | 
 |   Node* false0 = nullptr; | 
 |   { | 
 |     Node* check1 = graph()->NewNode(machine()->Word32Equal(), rhs, | 
 |                                     jsgraph()->Int32Constant(-1)); | 
 |     Node* branch1 = graph()->NewNode(common()->Branch(BranchHint::kFalse), | 
 |                                      check1, if_false0); | 
 |  | 
 |     Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1); | 
 |     Node* true1 = zero; | 
 |  | 
 |     Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1); | 
 |     Node* false1 = graph()->NewNode(machine()->Int32Mod(), lhs, rhs, if_false1); | 
 |  | 
 |     if_false0 = graph()->NewNode(common()->Merge(2), if_true1, if_false1); | 
 |     false0 = graph()->NewNode(common()->Phi(kMachInt32, 2), true1, false1, | 
 |                               if_false0); | 
 |   } | 
 |  | 
 |   Node* merge0 = graph()->NewNode(common()->Merge(2), if_true0, if_false0); | 
 |   return graph()->NewNode(common()->Phi(kMachInt32, 2), true0, false0, merge0); | 
 | } | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::Uint32Div(Node* const node) { | 
 |   Uint32BinopMatcher m(node); | 
 |   Node* const zero = jsgraph()->Uint32Constant(0); | 
 |   Node* const lhs = m.left().node(); | 
 |   Node* const rhs = m.right().node(); | 
 |  | 
 |   if (m.right().Is(0)) { | 
 |     return zero; | 
 |   } else if (machine()->Uint32DivIsSafe() || m.right().HasValue()) { | 
 |     return graph()->NewNode(machine()->Uint32Div(), lhs, rhs, graph()->start()); | 
 |   } | 
 |  | 
 |   Node* check = graph()->NewNode(machine()->Word32Equal(), rhs, zero); | 
 |   Node* branch = graph()->NewNode(common()->Branch(BranchHint::kFalse), check, | 
 |                                   graph()->start()); | 
 |  | 
 |   Node* if_true = graph()->NewNode(common()->IfTrue(), branch); | 
 |   Node* vtrue = zero; | 
 |  | 
 |   Node* if_false = graph()->NewNode(common()->IfFalse(), branch); | 
 |   Node* vfalse = graph()->NewNode(machine()->Uint32Div(), lhs, rhs, if_false); | 
 |  | 
 |   Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false); | 
 |   return graph()->NewNode(common()->Phi(kMachUint32, 2), vtrue, vfalse, merge); | 
 | } | 
 |  | 
 |  | 
 | Node* SimplifiedLowering::Uint32Mod(Node* const node) { | 
 |   Uint32BinopMatcher m(node); | 
 |   Node* const zero = jsgraph()->Uint32Constant(0); | 
 |   Node* const lhs = m.left().node(); | 
 |   Node* const rhs = m.right().node(); | 
 |  | 
 |   if (m.right().Is(0)) { | 
 |     return zero; | 
 |   } else if (machine()->Uint32ModIsSafe() || m.right().HasValue()) { | 
 |     return graph()->NewNode(machine()->Uint32Mod(), lhs, rhs, graph()->start()); | 
 |   } | 
 |  | 
 |   Node* check = graph()->NewNode(machine()->Word32Equal(), rhs, zero); | 
 |   Node* branch = graph()->NewNode(common()->Branch(BranchHint::kFalse), check, | 
 |                                   graph()->start()); | 
 |  | 
 |   Node* if_true = graph()->NewNode(common()->IfTrue(), branch); | 
 |   Node* vtrue = zero; | 
 |  | 
 |   Node* if_false = graph()->NewNode(common()->IfFalse(), branch); | 
 |   Node* vfalse = graph()->NewNode(machine()->Uint32Mod(), lhs, rhs, if_false); | 
 |  | 
 |   Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false); | 
 |   return graph()->NewNode(common()->Phi(kMachUint32, 2), vtrue, vfalse, merge); | 
 | } | 
 |  | 
 |  | 
 | void SimplifiedLowering::DoStringEqual(Node* node) { | 
 |   node->set_op(machine()->WordEqual()); | 
 |   node->ReplaceInput(0, StringComparison(node, false)); | 
 |   node->ReplaceInput(1, jsgraph()->SmiConstant(EQUAL)); | 
 | } | 
 |  | 
 |  | 
 | void SimplifiedLowering::DoStringLessThan(Node* node) { | 
 |   node->set_op(machine()->IntLessThan()); | 
 |   node->ReplaceInput(0, StringComparison(node, true)); | 
 |   node->ReplaceInput(1, jsgraph()->SmiConstant(EQUAL)); | 
 | } | 
 |  | 
 |  | 
 | void SimplifiedLowering::DoStringLessThanOrEqual(Node* node) { | 
 |   node->set_op(machine()->IntLessThanOrEqual()); | 
 |   node->ReplaceInput(0, StringComparison(node, true)); | 
 |   node->ReplaceInput(1, jsgraph()->SmiConstant(EQUAL)); | 
 | } | 
 |  | 
 | }  // namespace compiler | 
 | }  // namespace internal | 
 | }  // namespace v8 |