[Turbofan] Add concept of FP register aliasing on ARM 32.

src/compiler/register-allocator.cc

 // 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/base/adapters.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/register-allocator.h"
 #include "src/string-stream.h"
 
 namespace v8 {
@@ skipping 15 matching lines @@
 }
 
 int GetRegisterCount(const RegisterConfiguration* cfg, RegisterKind kind) {
   return kind == FP_REGISTERS ? cfg->num_double_registers()
                               : cfg->num_general_registers();
 }
 
 
 int GetAllocatableRegisterCount(const RegisterConfiguration* cfg,
                                 RegisterKind kind) {
-  return kind == FP_REGISTERS ? cfg->num_allocatable_aliased_double_registers()
+  return kind == FP_REGISTERS ? cfg->num_allocatable_double_registers()
                               : cfg->num_allocatable_general_registers();
 }
 
 
 const int* GetAllocatableRegisterCodes(const RegisterConfiguration* cfg,
                                        RegisterKind kind) {
   return kind == FP_REGISTERS ? cfg->allocatable_double_codes()
                               : cfg->allocatable_general_codes();
 }
 
@@ skipping 20 matching lines @@
 // TODO(dcarney): fix frame to allow frame accesses to half size location.
 int GetByteWidth(MachineRepresentation rep) {
   switch (rep) {
     case MachineRepresentation::kBit:
     case MachineRepresentation::kWord8:
     case MachineRepresentation::kWord16:
     case MachineRepresentation::kWord32:
     case MachineRepresentation::kTaggedSigned:
     case MachineRepresentation::kTaggedPointer:
     case MachineRepresentation::kTagged:
+    case MachineRepresentation::kFloat32:
       return kPointerSize;
-    case MachineRepresentation::kFloat32:
-// TODO(bbudge) Eliminate this when FP register aliasing works.
-#if V8_TARGET_ARCH_ARM
-      return kDoubleSize;
-#else
-      return kPointerSize;
-#endif
     case MachineRepresentation::kWord64:
     case MachineRepresentation::kFloat64:
-      return kDoubleSize;
+      return 8;

[Mircea Trofin, 2016/10/12 21:09:26]

here and below, don't we have a constant somewhere, like in globals.h? If not,
should we?

[bbudge, 2016/10/12 23:07:18]

Indeed. Done.

     case MachineRepresentation::kSimd128:
-      return kSimd128Size;
+      return 16;
     case MachineRepresentation::kNone:
       break;
   }
   UNREACHABLE();
   return 0;
 }
 
 }  // namespace
 
 class LiveRangeBound {
@@ skipping 1253 matching lines @@
       code_(code),
       debug_name_(debug_name),
       config_(config),
       phi_map_(allocation_zone()),
       live_in_sets_(code->InstructionBlockCount(), nullptr, allocation_zone()),
       live_out_sets_(code->InstructionBlockCount(), nullptr, allocation_zone()),
       live_ranges_(code->VirtualRegisterCount() * 2, nullptr,
                    allocation_zone()),
       fixed_live_ranges_(this->config()->num_general_registers(), nullptr,
                          allocation_zone()),
+      fixed_float_live_ranges_(this->config()->num_float_registers(), nullptr,
+                               allocation_zone()),
       fixed_double_live_ranges_(this->config()->num_double_registers(), nullptr,
                                 allocation_zone()),
+      fixed_simd128_live_ranges_(this->config()->num_simd128_registers(),
+                                 nullptr, allocation_zone()),
       spill_ranges_(code->VirtualRegisterCount(), nullptr, allocation_zone()),
       delayed_references_(allocation_zone()),
       assigned_registers_(nullptr),
       assigned_double_registers_(nullptr),
       virtual_register_count_(code->VirtualRegisterCount()),
       preassigned_slot_ranges_(zone) {
   assigned_registers_ = new (code_zone())
       BitVector(this->config()->num_general_registers(), code_zone());
   assigned_double_registers_ = new (code_zone())
       BitVector(this->config()->num_double_registers(), code_zone());
@@ skipping 157 matching lines @@
   DCHECK(!range->IsSplinter());
   SpillRange* spill_range =
       new (allocation_zone()) SpillRange(range, allocation_zone());
   return spill_range;
 }
 
 void RegisterAllocationData::MarkAllocated(MachineRepresentation rep,
                                            int index) {
   switch (rep) {
     case MachineRepresentation::kFloat32:
+    case MachineRepresentation::kSimd128:
+      if (kSimpleFPAliasing) {
+        assigned_double_registers_->Add(index);
+      } else {
+        int alias_base_index = -1;
+        int aliases = config()->GetAliases(
+            rep, index, MachineRepresentation::kFloat64, &alias_base_index);
+        DCHECK(aliases > 0 || (aliases == 0 && alias_base_index == -1));
+        while (aliases--) {
+          int aliased_reg = alias_base_index + aliases;
+          assigned_double_registers_->Add(aliased_reg);
+        }
+      }
+      break;
     case MachineRepresentation::kFloat64:
-    case MachineRepresentation::kSimd128:
       assigned_double_registers_->Add(index);
       break;
     default:
       DCHECK(!IsFloatingPoint(rep));
       assigned_registers_->Add(index);
       break;
   }
 }
 
 bool RegisterAllocationData::IsBlockBoundary(LifetimePosition pos) const {
@@ skipping 306 matching lines @@
     TopLevelLiveRange* range = data()->GetOrCreateLiveRangeFor(operand_index);
     range->AddUseInterval(start, end, allocation_zone());
     iterator.Advance();
   }
 }
 
 int LiveRangeBuilder::FixedFPLiveRangeID(int index, MachineRepresentation rep) {
   int result = -index - 1;
   switch (rep) {
     case MachineRepresentation::kSimd128:
+      result -= config()->num_float_registers();
+    // Fall through.
     case MachineRepresentation::kFloat32:
+      result -= config()->num_double_registers();
+    // Fall through.
     case MachineRepresentation::kFloat64:
       result -= config()->num_general_registers();
       break;
     default:
       UNREACHABLE();
       break;
   }
   return result;
 }
 
 TopLevelLiveRange* LiveRangeBuilder::FixedLiveRangeFor(int index) {
   DCHECK(index < config()->num_general_registers());
   TopLevelLiveRange* result = data()->fixed_live_ranges()[index];
   if (result == nullptr) {
     MachineRepresentation rep = InstructionSequence::DefaultRepresentation();
     result = data()->NewLiveRange(FixedLiveRangeID(index), rep);
     DCHECK(result->IsFixed());
     result->set_assigned_register(index);
     data()->MarkAllocated(rep, index);
     data()->fixed_live_ranges()[index] = result;
   }
   return result;
 }
 
 TopLevelLiveRange* LiveRangeBuilder::FixedFPLiveRangeFor(
     int index, MachineRepresentation rep) {
-  TopLevelLiveRange* result = nullptr;
+  int num_regs = -1;
+  ZoneVector<TopLevelLiveRange*>* live_ranges = nullptr;
   switch (rep) {
     case MachineRepresentation::kFloat32:
+      num_regs = config()->num_float_registers();
+      live_ranges = &data()->fixed_float_live_ranges();
+      break;
     case MachineRepresentation::kFloat64:
+      num_regs = config()->num_double_registers();
+      live_ranges = &data()->fixed_double_live_ranges();
+      break;
     case MachineRepresentation::kSimd128:
-      DCHECK(index < config()->num_double_registers());
-      result = data()->fixed_double_live_ranges()[index];
-      if (result == nullptr) {
-        result = data()->NewLiveRange(FixedFPLiveRangeID(index, rep), rep);
-        DCHECK(result->IsFixed());
-        result->set_assigned_register(index);
-        data()->MarkAllocated(rep, index);
-        data()->fixed_double_live_ranges()[index] = result;
-      }
+      num_regs = config()->num_simd128_registers();
+      live_ranges = &data()->fixed_simd128_live_ranges();
       break;
     default:
       UNREACHABLE();
       break;
   }
+
+  DCHECK(index < num_regs);
+  TopLevelLiveRange* result = (*live_ranges)[index];
+  if (result == nullptr) {
+    result = data()->NewLiveRange(FixedFPLiveRangeID(index, rep), rep);
+    DCHECK(result->IsFixed());
+    result->set_assigned_register(index);
+    data()->MarkAllocated(rep, index);
+    (*live_ranges)[index] = result;
+  }
   return result;
 }
 
 TopLevelLiveRange* LiveRangeBuilder::LiveRangeFor(InstructionOperand* operand) {
   if (operand->IsUnallocated()) {
     return data()->GetOrCreateLiveRangeFor(
         UnallocatedOperand::cast(operand)->virtual_register());
   } else if (operand->IsConstant()) {
     return data()->GetOrCreateLiveRangeFor(
         ConstantOperand::cast(operand)->virtual_register());
@@ skipping 102 matching lines @@
         // is OK because AddUseInterval will just merge it with the existing
         // one at the end of the range.
         int code = config()->GetAllocatableGeneralCode(i);
         TopLevelLiveRange* range = FixedLiveRangeFor(code);
         range->AddUseInterval(curr_position, curr_position.End(),
                               allocation_zone());
       }
     }
 
     if (instr->ClobbersDoubleRegisters()) {
-      for (int i = 0; i < config()->num_allocatable_aliased_double_registers();
-           ++i) {
+      for (int i = 0; i < config()->num_allocatable_double_registers(); ++i) {
         // Add a UseInterval for all DoubleRegisters. See comment above for
         // general registers.
         int code = config()->GetAllocatableDoubleCode(i);
         TopLevelLiveRange* range =
             FixedFPLiveRangeFor(code, MachineRepresentation::kFloat64);
         range->AddUseInterval(curr_position, curr_position.End(),
                               allocation_zone());
       }
+      // Preserve fixed float registers on archs with non-simple aliasing.
+      if (!kSimpleFPAliasing) {
+        for (int i = 0; i < config()->num_allocatable_float_registers(); ++i) {
+          // Add a UseInterval for all FloatRegisters. See comment above for
+          // general registers.
+          int code = config()->GetAllocatableFloatCode(i);
+          TopLevelLiveRange* range =
+              FixedFPLiveRangeFor(code, MachineRepresentation::kFloat32);
+          range->AddUseInterval(curr_position, curr_position.End(),
+                                allocation_zone());
+        }
+        for (int i = 0; i < config()->num_allocatable_simd128_registers();
+             ++i) {
+          int code = config()->GetAllocatableSimd128Code(i);
+          TopLevelLiveRange* range =
+              FixedFPLiveRangeFor(code, MachineRepresentation::kSimd128);
+          range->AddUseInterval(curr_position, curr_position.End(),
+                                allocation_zone());
+        }
+      }
     }
 
     for (size_t i = 0; i < instr->InputCount(); i++) {
       InstructionOperand* input = instr->InputAt(i);
       if (input->IsImmediate() || input->IsExplicit()) {
         continue;  // Ignore immediates and explicitly reserved registers.
       }
       LifetimePosition use_pos;
       if (input->IsUnallocated() &&
           UnallocatedOperand::cast(input)->IsUsedAtStart()) {
@@ skipping 546 matching lines @@
     }
   }
   SortUnhandled();
   DCHECK(UnhandledIsSorted());
 
   if (mode() == GENERAL_REGISTERS) {
     for (TopLevelLiveRange* current : data()->fixed_live_ranges()) {
       if (current != nullptr) AddToInactive(current);
     }
   } else {
+    for (TopLevelLiveRange* current : data()->fixed_float_live_ranges()) {
+      if (current != nullptr) AddToInactive(current);
+    }
     for (TopLevelLiveRange* current : data()->fixed_double_live_ranges()) {
       if (current != nullptr) AddToInactive(current);
     }
+    for (TopLevelLiveRange* current : data()->fixed_simd128_live_ranges()) {
+      if (current != nullptr) AddToInactive(current);
+    }
   }
 
   while (!unhandled_live_ranges().empty()) {
     DCHECK(UnhandledIsSorted());
     LiveRange* current = unhandled_live_ranges().back();
     unhandled_live_ranges().pop_back();
     DCHECK(UnhandledIsSorted());
     LifetimePosition position = current->Start();
 #ifdef DEBUG
     allocation_finger_ = position;
@@ skipping 160 matching lines @@
 
 void LinearScanAllocator::InactiveToActive(LiveRange* range) {
   RemoveElement(&inactive_live_ranges(), range);
   active_live_ranges().push_back(range);
   TRACE("Moving live range %d:%d from inactive to active\n",
         range->TopLevel()->vreg(), range->relative_id());
 }
 
 void LinearScanAllocator::FindFreeRegistersForRange(
     LiveRange* range, Vector<LifetimePosition> positions) {
+  MachineRepresentation rep = range->representation();
   int num_regs = num_registers();
+  int num_codes = num_allocatable_registers();
+  const int* codes = allocatable_register_codes();
+  if (!kSimpleFPAliasing) {
+    if (rep == MachineRepresentation::kFloat32) {
+      num_regs = data()->config()->num_float_registers();
+      num_codes = data()->config()->num_allocatable_float_registers();
+      codes = data()->config()->allocatable_float_codes();

[Mircea Trofin, 2016/10/12 21:09:26]

would it make sense to move this logic to num_registers() and
num_allocatable_registers()?

[bbudge, 2016/10/12 23:07:17]

I'd like to avoid the procedure call for non-ARM and for non-FP and kFloat64
representations. I added a GetFPRegisterSet method to extract the logic for
kFloat32 and kSimd128 though.

Done.

+    } else if (rep == MachineRepresentation::kSimd128) {
+      num_regs = data()->config()->num_simd128_registers();
+      num_codes = data()->config()->num_allocatable_simd128_registers();
+      codes = data()->config()->allocatable_simd128_codes();
+    }
+  }
   DCHECK_GE(positions.length(), num_regs);
 
   for (int i = 0; i < num_regs; i++) {
     positions[i] = LifetimePosition::MaxPosition();
   }
 
   for (LiveRange* cur_active : active_live_ranges()) {
     int cur_reg = cur_active->assigned_register();
-    positions[cur_reg] = LifetimePosition::GapFromInstructionIndex(0);
-    TRACE("Register %s is free until pos %d (1)\n", RegisterName(cur_reg),
-          LifetimePosition::GapFromInstructionIndex(0).value());
+    if (kSimpleFPAliasing || mode() == GENERAL_REGISTERS) {
+      positions[cur_reg] = LifetimePosition::GapFromInstructionIndex(0);
+      TRACE("Register %s is free until pos %d (1)\n", RegisterName(cur_reg),
+            LifetimePosition::GapFromInstructionIndex(0).value());
+    } else {
+      int alias_base_index = -1;
+      int aliases = data()->config()->GetAliases(
+          cur_active->representation(), cur_reg, rep, &alias_base_index);
+      DCHECK(aliases > 0 || (aliases == 0 && alias_base_index == -1));
+      while (aliases--) {
+        int aliased_reg = alias_base_index + aliases;
+        positions[aliased_reg] = LifetimePosition::GapFromInstructionIndex(0);
+      }
+    }
   }
 
   for (LiveRange* cur_inactive : inactive_live_ranges()) {
     DCHECK(cur_inactive->End() > range->Start());
     LifetimePosition next_intersection = cur_inactive->FirstIntersection(range);
     if (!next_intersection.IsValid()) continue;
     int cur_reg = cur_inactive->assigned_register();
-    positions[cur_reg] = Min(positions[cur_reg], next_intersection);
-    TRACE("Register %s is free until pos %d (2)\n", RegisterName(cur_reg),
-          Min(positions[cur_reg], next_intersection).value());
+    if (kSimpleFPAliasing || mode() == GENERAL_REGISTERS) {
+      positions[cur_reg] = Min(positions[cur_reg], next_intersection);
+      TRACE("Register %s is free until pos %d (2)\n", RegisterName(cur_reg),
+            Min(positions[cur_reg], next_intersection).value());
+    } else {
+      int alias_base_index = -1;
+      int aliases = data()->config()->GetAliases(
+          cur_inactive->representation(), cur_reg, rep, &alias_base_index);
+      DCHECK(aliases > 0 || (aliases == 0 && alias_base_index == -1));
+      while (aliases--) {
+        int aliased_reg = alias_base_index + aliases;
+        positions[aliased_reg] = Min(positions[aliased_reg], next_intersection);
+      }
+    }
   }
 }
 
 // High-level register allocation summary:
 //
 // For regular, or hot (i.e. not splinter) ranges, we attempt to first
 // allocate first the preferred (hint) register. If that is not possible,
 // we find a register that's free, and allocate that. If that's not possible,
 // we search for a register to steal from a range that was allocated. The
 // goal is to optimize for throughput by avoiding register-to-memory
@@ skipping 60 matching lines @@
             current->relative_id());
       SetLiveRangeAssignedRegister(current, hint_register);
       return true;
     }
   }
   return false;
 }
 
 bool LinearScanAllocator::TryAllocateFreeReg(
     LiveRange* current, const Vector<LifetimePosition>& free_until_pos) {
+  MachineRepresentation rep = current->representation();
   int num_codes = num_allocatable_registers();
   const int* codes = allocatable_register_codes();
+  if (!kSimpleFPAliasing) {
+    if (rep == MachineRepresentation::kFloat32) {
+      num_codes = data()->config()->num_allocatable_float_registers();
+      codes = data()->config()->allocatable_float_codes();
+    } else if (rep == MachineRepresentation::kSimd128) {
+      num_codes = data()->config()->num_allocatable_simd128_registers();
+      codes = data()->config()->allocatable_simd128_codes();

[Mircea Trofin, 2016/10/12 21:09:26]

see factoring comment above about the num_allocatable_registers()

[bbudge, 2016/10/12 23:07:18]

Done.

+    }
+  }
   DCHECK_GE(free_until_pos.length(), num_codes);
 
   // Find the register which stays free for the longest time.
   int reg = codes[0];
   for (int i = 1; i < num_codes; ++i) {
     int code = codes[i];
     if (free_until_pos[code] > free_until_pos[reg]) {
       reg = code;
     }
   }
@@ skipping 24 matching lines @@
 
 void LinearScanAllocator::AllocateBlockedReg(LiveRange* current) {
   UsePosition* register_use = current->NextRegisterPosition(current->Start());
   if (register_use == nullptr) {
     // There is no use in the current live range that requires a register.
     // We can just spill it.
     Spill(current);
     return;
   }
 
+  MachineRepresentation rep = current->representation();
   int num_regs = num_registers();
   int num_codes = num_allocatable_registers();
   const int* codes = allocatable_register_codes();
+  if (!kSimpleFPAliasing) {
+    if (rep == MachineRepresentation::kFloat32) {
+      num_regs = data()->config()->num_float_registers();
+      num_codes = data()->config()->num_allocatable_float_registers();
+      codes = data()->config()->allocatable_float_codes();
+    } else if (rep == MachineRepresentation::kSimd128) {
+      num_regs = data()->config()->num_simd128_registers();
+      num_codes = data()->config()->num_allocatable_simd128_registers();
+      codes = data()->config()->allocatable_simd128_codes();

[Mircea Trofin, 2016/10/12 21:09:26]

factoring comment above

[bbudge, 2016/10/12 23:07:17]

Done.

+    }
+  }
 
   LifetimePosition use_pos[RegisterConfiguration::kMaxFPRegisters];
   LifetimePosition block_pos[RegisterConfiguration::kMaxFPRegisters];
   for (int i = 0; i < num_regs; i++) {
     use_pos[i] = block_pos[i] = LifetimePosition::MaxPosition();
   }
 
   for (LiveRange* range : active_live_ranges()) {
     int cur_reg = range->assigned_register();
     bool is_fixed_or_cant_spill =
         range->TopLevel()->IsFixed() || !range->CanBeSpilled(current->Start());
-    if (is_fixed_or_cant_spill) {
-      block_pos[cur_reg] = use_pos[cur_reg] =
-          LifetimePosition::GapFromInstructionIndex(0);
+    if (kSimpleFPAliasing || mode() == GENERAL_REGISTERS) {
+      if (is_fixed_or_cant_spill) {
+        block_pos[cur_reg] = use_pos[cur_reg] =
+            LifetimePosition::GapFromInstructionIndex(0);
+      } else {
+        UsePosition* next_use =
+            range->NextUsePositionRegisterIsBeneficial(current->Start());
+        if (next_use == nullptr) {
+          use_pos[cur_reg] = range->End();

[Mircea Trofin, 2016/10/12 21:09:26]

this logic around next_use appears below, too. Could you factor it out?

[bbudge, 2016/10/12 23:07:17]

I added a LiveRange;:NextLifetimePositionRegisterIsBeneficial convenience
function.

Done.

+        } else {
+          use_pos[cur_reg] = next_use->pos();
+        }
+      }
     } else {
-      UsePosition* next_use =
-          range->NextUsePositionRegisterIsBeneficial(current->Start());
-      if (next_use == nullptr) {
-        use_pos[cur_reg] = range->End();
-      } else {
-        use_pos[cur_reg] = next_use->pos();
+      int alias_base_index = -1;
+      int aliases = data()->config()->GetAliases(
+          range->representation(), cur_reg, rep, &alias_base_index);
+      DCHECK(aliases > 0 || (aliases == 0 && alias_base_index == -1));
+      while (aliases--) {
+        int aliased_reg = alias_base_index + aliases;
+        if (is_fixed_or_cant_spill) {
+          block_pos[aliased_reg] = use_pos[aliased_reg] =
+              LifetimePosition::GapFromInstructionIndex(0);
+        } else {
+          UsePosition* next_use =
+              range->NextUsePositionRegisterIsBeneficial(current->Start());
+          if (next_use == nullptr) {
+            use_pos[aliased_reg] = range->End();
+          } else {
+            use_pos[aliased_reg] = next_use->pos();
+          }
+        }
       }
     }
   }
 
   for (LiveRange* range : inactive_live_ranges()) {
     DCHECK(range->End() > current->Start());
     LifetimePosition next_intersection = range->FirstIntersection(current);
     if (!next_intersection.IsValid()) continue;
     int cur_reg = range->assigned_register();
     bool is_fixed = range->TopLevel()->IsFixed();
-    if (is_fixed) {
-      block_pos[cur_reg] = Min(block_pos[cur_reg], next_intersection);
-      use_pos[cur_reg] = Min(block_pos[cur_reg], use_pos[cur_reg]);
+    if (kSimpleFPAliasing || mode() == GENERAL_REGISTERS) {
+      if (is_fixed) {
+        block_pos[cur_reg] = Min(block_pos[cur_reg], next_intersection);
+        use_pos[cur_reg] = Min(block_pos[cur_reg], use_pos[cur_reg]);
+      } else {
+        use_pos[cur_reg] = Min(use_pos[cur_reg], next_intersection);
+      }
     } else {
-      use_pos[cur_reg] = Min(use_pos[cur_reg], next_intersection);
+      int alias_base_index = -1;
+      int aliases = data()->config()->GetAliases(
+          range->representation(), cur_reg, rep, &alias_base_index);
+      DCHECK(aliases > 0 || (aliases == 0 && alias_base_index == -1));
+      while (aliases--) {
+        int aliased_reg = alias_base_index + aliases;
+        if (is_fixed) {
+          block_pos[aliased_reg] =
+              Min(block_pos[aliased_reg], next_intersection);
+          use_pos[aliased_reg] =
+              Min(block_pos[aliased_reg], use_pos[aliased_reg]);
+        } else {
+          use_pos[aliased_reg] = Min(use_pos[aliased_reg], next_intersection);
+        }
+      }
     }
   }
 
   int reg = codes[0];
   for (int i = 1; i < num_codes; ++i) {
     int code = codes[i];
     if (use_pos[code] > use_pos[reg]) {
       reg = code;
     }
   }
@@ skipping 31 matching lines @@
   SplitAndSpillIntersecting(current);
 }
 
 
 void LinearScanAllocator::SplitAndSpillIntersecting(LiveRange* current) {
   DCHECK(current->HasRegisterAssigned());
   int reg = current->assigned_register();
   LifetimePosition split_pos = current->Start();
   for (size_t i = 0; i < active_live_ranges().size(); ++i) {
     LiveRange* range = active_live_ranges()[i];
-    if (range->assigned_register() != reg) continue;
+    if (kSimpleFPAliasing || mode() == GENERAL_REGISTERS) {
+      if (range->assigned_register() != reg) continue;
+    } else {
+      if (!data()->config()->AreAliases(current->representation(), reg,
+                                        range->representation(),
+                                        range->assigned_register())) {
+        continue;
+      }
+    }
 
     UsePosition* next_pos = range->NextRegisterPosition(current->Start());
     LifetimePosition spill_pos = FindOptimalSpillingPos(range, split_pos);
     if (next_pos == nullptr) {
       SpillAfter(range, spill_pos);
     } else {
       // When spilling between spill_pos and next_pos ensure that the range
       // remains spilled at least until the start of the current live range.
       // This guarantees that we will not introduce new unhandled ranges that
       // start before the current range as this violates allocation invariants
       // and will lead to an inconsistent state of active and inactive
       // live-ranges: ranges are allocated in order of their start positions,
       // ranges are retired from active/inactive when the start of the
       // current live-range is larger than their end.
       DCHECK(LifetimePosition::ExistsGapPositionBetween(current->Start(),
                                                         next_pos->pos()));
       SpillBetweenUntil(range, spill_pos, current->Start(), next_pos->pos());
     }
     ActiveToHandled(range);
     --i;
   }
 
   for (size_t i = 0; i < inactive_live_ranges().size(); ++i) {
     LiveRange* range = inactive_live_ranges()[i];
     DCHECK(range->End() > current->Start());
     if (range->TopLevel()->IsFixed()) continue;
-    if (range->assigned_register() != reg) continue;
+    if (kSimpleFPAliasing || mode() == GENERAL_REGISTERS) {
+      if (range->assigned_register() != reg) continue;
+    } else {
+      if (!data()->config()->AreAliases(current->representation(), reg,
+                                        range->representation(),
+                                        range->assigned_register()))
+        continue;
+    }
 
     LifetimePosition next_intersection = range->FirstIntersection(current);
     if (next_intersection.IsValid()) {
       UsePosition* next_pos = range->NextRegisterPosition(current->Start());
       if (next_pos == nullptr) {
         SpillAfter(range, split_pos);
       } else {
         next_intersection = Min(next_intersection, next_pos->pos());
         SpillBetween(range, split_pos, next_intersection);
       }
@@ skipping 470 matching lines @@
     DCHECK(!code()
                 ->InstructionAt(pred->last_instruction_index())
                 ->HasReferenceMap());
     gap_index = pred->last_instruction_index();
     position = Instruction::END;
   }
   data()->AddGapMove(gap_index, position, pred_op, cur_op);
   return gap_index;
 }
 
-
 void LiveRangeConnector::ConnectRanges(Zone* local_zone) {
   DelayedInsertionMap delayed_insertion_map(local_zone);
   for (TopLevelLiveRange* top_range : data()->live_ranges()) {
     if (top_range == nullptr) continue;
     bool connect_spilled = top_range->IsSpilledOnlyInDeferredBlocks();
     LiveRange* first_range = top_range;
     for (LiveRange *second_range = first_range->next(); second_range != nullptr;
          first_range = second_range, second_range = second_range->next()) {
       LifetimePosition pos = second_range->Start();
       // Add gap move if the two live ranges touch and there is no block
@@ skipping 67 matching lines @@
       }
       if (done) break;
       // Reset state.
       to_eliminate.clear();
       to_insert.clear();
       moves = it->first.first;
     }
     // Gather all MoveOperands for a single ParallelMove.
     MoveOperands* move =
         new (code_zone()) MoveOperands(it->first.second, it->second);
-    MoveOperands* eliminate = moves->PrepareInsertAfter(move);
+    moves->PrepareInsertAfter(move, &to_eliminate);
     to_insert.push_back(move);
-    if (eliminate != nullptr) to_eliminate.push_back(eliminate);
   }
 }
 
 
 void LiveRangeConnector::CommitSpillsInDeferredBlocks(
     TopLevelLiveRange* range, LiveRangeBoundArray* array, Zone* temp_zone) {
   DCHECK(range->IsSpilledOnlyInDeferredBlocks());
   DCHECK(!range->spilled());
 
   InstructionSequence* code = data()->code();
@@ skipping 61 matching lines @@
         }
       }
     }
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8