Revert of [turbofan] Remove redundant code.

src/compiler/register-allocator.cc

Index: src/compiler/register-allocator.cc
diff --git a/src/compiler/register-allocator.cc b/src/compiler/register-allocator.cc
index 8de847e1a75211c779dfc8ee4d7237cd83100929..0410b417f84136a52c80b1a5940cd1651d99c2f2 100644
--- a/src/compiler/register-allocator.cc
+++ b/src/compiler/register-allocator.cc
@@ -2443,6 +2443,28 @@
     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;