Revert of revert r25736 (patchset #2 id:20001 of https://codereview.chromium.org/803493002/)

Reason for revert:
performance bots were unchanged by the original revert

Original issue's description:
> revert r25736
>
> R=bmeurer@chromium.org
>
> BUG=

TBR=bmeurer@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/787183003

Cr-Commit-Position: refs/heads/master@{#25801}

src/compiler/graph-visualizer.cc

@@ -725,7 +725,7 @@ void GraphC1Visualizer::PrintLiveRange(LiveRange* range, const char* type) {
       }
     } else if (range->IsSpilled()) {
       int index = -1;
-      if (range->TopLevel()->GetSpillRange() != nullptr) {
+      if (range->TopLevel()->HasSpillRange()) {
         index = kMaxInt;  // This hasn't been set yet.
       } else {
         index = range->TopLevel()->GetSpillOperand()->index();

src/compiler/instruction.cc

@@ -15,8 +15,6 @@ std::ostream& operator<<(std::ostream& os,
   const InstructionOperand& op = *printable.op_;
   const RegisterConfiguration* conf = printable.register_configuration_;
   switch (op.kind()) {
-    case InstructionOperand::INVALID:
-      return os << "(0)";
     case InstructionOperand::UNALLOCATED: {
       const UnallocatedOperand* unalloc = UnallocatedOperand::cast(&op);
       os << "v" << unalloc->virtual_register();

src/compiler/instruction.h

@@ -39,7 +39,6 @@ const InstructionCode kSourcePositionInstruction = -3;
 class InstructionOperand : public ZoneObject {
  public:
   enum Kind {
-    INVALID,
     UNALLOCATED,
     CONSTANT,
     IMMEDIATE,
@@ -49,7 +48,6 @@ class InstructionOperand : public ZoneObject {
     DOUBLE_REGISTER
   };
 
-  InstructionOperand() : value_(KindField::encode(INVALID)) {}
   InstructionOperand(Kind kind, int index) { ConvertTo(kind, index); }
 
   Kind kind() const { return KindField::decode(value_); }
@@ -58,7 +56,6 @@ class InstructionOperand : public ZoneObject {
   bool Is##name() const { return kind() == type; }
   INSTRUCTION_OPERAND_LIST(INSTRUCTION_OPERAND_PREDICATE)
   INSTRUCTION_OPERAND_PREDICATE(Unallocated, UNALLOCATED, 0)
-  INSTRUCTION_OPERAND_PREDICATE(Ignored, INVALID, 0)
 #undef INSTRUCTION_OPERAND_PREDICATE
   bool Equals(const InstructionOperand* other) const {
     return value_ == other->value_;
@@ -291,16 +288,12 @@ class MoveOperands FINAL {
   }
 
   // A move is redundant if it's been eliminated, if its source and
-  // destination are the same, or if its destination is unneeded or constant.
+  // destination are the same, or if its destination is  constant.
   bool IsRedundant() const {
-    return IsEliminated() || source_->Equals(destination_) || IsIgnored() ||
+    return IsEliminated() || source_->Equals(destination_) ||
            (destination_ != NULL && destination_->IsConstant());
   }
 
-  bool IsIgnored() const {
-    return destination_ != NULL && destination_->IsIgnored();
-  }
-
   // We clear both operands to indicate move that's been eliminated.
   void Eliminate() { source_ = destination_ = NULL; }
   bool IsEliminated() const {
@@ -348,7 +341,7 @@ class SubKindOperand FINAL : public InstructionOperand {
  private:
   static SubKindOperand* cache;
 
-  SubKindOperand() : InstructionOperand() {}
+  SubKindOperand() : InstructionOperand(kOperandKind, 0) {}  // For the caches.
   explicit SubKindOperand(int index)
       : InstructionOperand(kOperandKind, index) {}
 };

src/compiler/pipeline.cc

@@ -585,6 +585,15 @@ struct ReuseSpillSlotsPhase {
 };
 
 
+struct CommitAssignmentPhase {
+  static const char* phase_name() { return "commit assignment"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
+    data->register_allocator()->CommitAssignment();
+  }
+};
+
+
 struct PopulatePointerMapsPhase {
   static const char* phase_name() { return "populate pointer maps"; }
 
@@ -1036,6 +1045,7 @@ void Pipeline::AllocateRegisters(const RegisterConfiguration* config,
   if (FLAG_turbo_reuse_spill_slots) {
     Run<ReuseSpillSlotsPhase>();
   }
+  Run<CommitAssignmentPhase>();
   Run<PopulatePointerMapsPhase>();
   Run<ConnectRangesPhase>();
   Run<ResolveControlFlowPhase>();

src/compiler/register-allocator-verifier.cc

@@ -276,10 +276,8 @@ class RegisterAllocatorVerifier::OutgoingMapping : public ZoneObject {
     auto* moves = move->move_operands();
     for (auto i = moves->begin(); i != moves->end(); ++i) {
       if (i->IsEliminated()) continue;
-      CHECK(i->source()->kind() != InstructionOperand::INVALID);
       auto cur = locations()->find(i->source());
       CHECK(cur != locations()->end());
-      if (i->destination()->kind() == InstructionOperand::INVALID) continue;
       to_insert.insert(std::make_pair(i->destination(), cur->second));
     }
     // Drop current mappings.

src/compiler/register-allocator.h

@@ -197,7 +197,7 @@ class LiveRange FINAL : public ZoneObject {
   int assigned_register() const { return assigned_register_; }
   int spill_start_index() const { return spill_start_index_; }
   void set_assigned_register(int reg, Zone* zone);
-  void MakeSpilled(Zone* zone);
+  void MakeSpilled();
   bool is_phi() const { return is_phi_; }
   void set_is_phi(bool is_phi) { is_phi_ = is_phi; }
   bool is_non_loop_phi() const { return is_non_loop_phi_; }
@@ -260,13 +260,27 @@ class LiveRange FINAL : public ZoneObject {
     return last_interval_->end();
   }
 
-  bool HasAllocatedSpillOperand() const;
-  InstructionOperand* GetSpillOperand() const { return spill_operand_; }
-  void SetSpillOperand(InstructionOperand* operand);
+  enum class SpillType { kNoSpillType, kSpillOperand, kSpillRange };
+  SpillType spill_type() const { return spill_type_; }
+  InstructionOperand* GetSpillOperand() const {
+    return spill_type_ == SpillType::kSpillOperand ? spill_operand_ : nullptr;
+  }
+  SpillRange* GetSpillRange() const {
+    return spill_type_ == SpillType::kSpillRange ? spill_range_ : nullptr;
+  }
+  bool HasNoSpillType() const { return spill_type_ == SpillType::kNoSpillType; }
+  bool HasSpillOperand() const {
+    return spill_type_ == SpillType::kSpillOperand;
+  }
+  bool HasSpillRange() const { return spill_type_ == SpillType::kSpillRange; }
 
-  void SetSpillRange(SpillRange* spill_range) { spill_range_ = spill_range; }
-  SpillRange* GetSpillRange() const { return spill_range_; }
+  void SpillAtDefinition(Zone* zone, int gap_index,
+                         InstructionOperand* operand);
+  void SetSpillOperand(InstructionOperand* operand);
+  void SetSpillRange(SpillRange* spill_range);
   void CommitSpillOperand(InstructionOperand* operand);
+  void CommitSpillsAtDefinition(InstructionSequence* sequence,
+                                InstructionOperand* operand);
 
   void SetSpillStartIndex(int start) {
     spill_start_index_ = Min(start, spill_start_index_);
@@ -293,12 +307,14 @@ class LiveRange FINAL : public ZoneObject {
 #endif
 
  private:
-  void ConvertOperands(Zone* zone);
+  struct SpillAtDefinitionList;
+
   void ConvertUsesToOperand(InstructionOperand* op);
   UseInterval* FirstSearchIntervalForPosition(LifetimePosition position) const;
   void AdvanceLastProcessedMarker(UseInterval* to_start_of,
                                   LifetimePosition but_not_past) const;
 
+  // TODO(dcarney): pack this structure better.
   int id_;
   bool spilled_;
   bool is_phi_;
@@ -315,9 +331,13 @@ class LiveRange FINAL : public ZoneObject {
   UsePosition* last_processed_use_;
   // This is used as a cache, it's invalid outside of BuildLiveRanges.
   InstructionOperand* current_hint_operand_;
-  InstructionOperand* spill_operand_;
   int spill_start_index_;
-  SpillRange* spill_range_;
+  SpillType spill_type_;
+  union {
+    InstructionOperand* spill_operand_;
+    SpillRange* spill_range_;
+  };
+  SpillAtDefinitionList* spills_at_definition_;
 
   friend class RegisterAllocator;  // Assigns to kind_.
 
@@ -388,13 +408,16 @@ class RegisterAllocator FINAL : public ZoneObject {
   // Phase 5: reassign spill splots for maximal reuse.
   void ReuseSpillSlots();
 
-  // Phase 6: compute values for pointer maps.
+  // Phase 6: commit assignment.
+  void CommitAssignment();
+
+  // Phase 7: compute values for pointer maps.
   void PopulatePointerMaps();  // TODO(titzer): rename to PopulateReferenceMaps.
 
-  // Phase 7: reconnect split ranges with moves.
+  // Phase 8: reconnect split ranges with moves.
   void ConnectRanges();
 
-  // Phase 8: insert moves to connect ranges across basic blocks.
+  // Phase 9: insert moves to connect ranges across basic blocks.
   void ResolveControlFlow();
 
  private: