Revert "Revert of [turbofan] Remove redundant code.[...]"

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 2210 matching lines @@
   LifetimePosition ret = LifetimePosition::Invalid();
 
   ret = LifetimePosition::GapFromInstructionIndex(instruction_index);
   if (range->Start() >= ret || ret >= range->End()) {
     return LifetimePosition::Invalid();
   }
   return ret;
 }
 
 
-void RegisterAllocator::SplitAndSpillRangesDefinedByMemoryOperand() {
+void RegisterAllocator::SplitAndSpillRangesDefinedByMemoryOperand(
+    bool operands_only) {
   size_t initial_range_count = data()->live_ranges().size();
   for (size_t i = 0; i < initial_range_count; ++i) {
     TopLevelLiveRange* range = data()->live_ranges()[i];
     if (!CanProcessRange(range)) continue;
-    if (!range->HasSpillOperand()) continue;
+    if (range->HasNoSpillType() || (operands_only && range->HasSpillRange())) {
+      continue;
+    }
 
     LifetimePosition start = range->Start();
     TRACE("Live range %d:%d is defined by a spill operand.\n",
           range->TopLevel()->vreg(), range->relative_id());
     LifetimePosition next_pos = start;
     if (next_pos.IsGapPosition()) {
       next_pos = next_pos.NextStart();
     }
     UsePosition* pos = range->NextUsePositionRegisterIsBeneficial(next_pos);
     // If the range already has a spill operand and it doesn't need a
@@ skipping 162 matching lines @@
   DCHECK(RegisterConfiguration::kMaxDoubleRegisters >=
          this->data()->config()->num_general_registers());
 }
 
 
 void LinearScanAllocator::AllocateRegisters() {
   DCHECK(unhandled_live_ranges().empty());
   DCHECK(active_live_ranges().empty());
   DCHECK(inactive_live_ranges().empty());
 
-  SplitAndSpillRangesDefinedByMemoryOperand();
+  SplitAndSpillRangesDefinedByMemoryOperand(false);
 
   for (TopLevelLiveRange* range : data()->live_ranges()) {
     if (!CanProcessRange(range)) continue;
     for (LiveRange* to_add = range; to_add != nullptr;
          to_add = to_add->next()) {
       if (!to_add->spilled()) {
         AddToUnhandledUnsorted(to_add);
       }
     }
   }
@@ skipping 13 matching lines @@
     auto current = unhandled_live_ranges().back();
     unhandled_live_ranges().pop_back();
     DCHECK(UnhandledIsSorted());
     auto position = current->Start();
 #ifdef DEBUG
     allocation_finger_ = position;
 #endif
     TRACE("Processing interval %d:%d start=%d\n", current->TopLevel()->vreg(),
           current->relative_id(), position.value());
 
-    if (current->IsTopLevel() && !current->TopLevel()->HasNoSpillType()) {
-      TRACE("Live range %d:%d already has a spill operand\n",
-            current->TopLevel()->vreg(), current->relative_id());
-      auto next_pos = position;
-      if (next_pos.IsGapPosition()) {
-        next_pos = next_pos.NextStart();
-      }
-      auto pos = current->NextUsePositionRegisterIsBeneficial(next_pos);
-      // If the range already has a spill operand and it doesn't need a
-      // register immediately, split it and spill the first part of the range.
-      if (pos == nullptr) {
-        Spill(current);
-        continue;
-      } else if (pos->pos() > current->Start().NextStart()) {
-        // Do not spill live range eagerly if use position that can benefit from
-        // the register is too close to the start of live range.
-        SpillBetween(current, current->Start(), pos->pos());
-        DCHECK(UnhandledIsSorted());
-        continue;
-      }
-    }
-
     if (current->IsTopLevel() && TryReuseSpillForPhi(current->TopLevel()))
       continue;
 
     for (size_t i = 0; i < active_live_ranges().size(); ++i) {
       auto cur_active = active_live_ranges()[i];
       if (cur_active->End() <= position) {
         ActiveToHandled(cur_active);
         --i;  // The live range was removed from the list of active live ranges.
       } else if (!cur_active->Covers(position)) {
         ActiveToInactive(cur_active);
@@ skipping 975 matching lines @@
     auto eliminate = moves->PrepareInsertAfter(move);
     to_insert.push_back(move);
     if (eliminate != nullptr) to_eliminate.push_back(eliminate);
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8