More aggressive reuse of spill slots in the register allocator.

src/hydrogen.cc

 // Copyright 2013 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/hydrogen.h"
 
 #include <algorithm>
 
 #include "src/v8.h"
 
@@ skipping 12341 matching lines @@
       LOperand* op = range->CreateAssignedOperand(zone);
       int assigned_reg = op->index();
       if (op->IsDoubleRegister()) {
         trace_.Add(" \"%s\"",
                    DoubleRegister::AllocationIndexToString(assigned_reg));
       } else {
         DCHECK(op->IsRegister());
         trace_.Add(" \"%s\"", Register::AllocationIndexToString(assigned_reg));
       }
     } else if (range->IsSpilled()) {
-      LOperand* op = range->TopLevel()->GetSpillOperand();
-      if (op->IsDoubleStackSlot()) {
-        trace_.Add(" \"double_stack:%d\"", op->index());
+      int index = -1;
+      if (range->TopLevel()->GetSpillRange()->id() != -1) {
+        index = range->TopLevel()->GetSpillRange()->id();
       } else {
-        DCHECK(op->IsStackSlot());
-        trace_.Add(" \"stack:%d\"", op->index());
+        index = range->TopLevel()->GetSpillOperand()->index();
+      }
+      if (range->TopLevel()->Kind() == DOUBLE_REGISTERS) {
+        trace_.Add(" \"double_stack:%d\"", index);
+      } else {
+        DCHECK(range->TopLevel()->Kind() == GENERAL_REGISTERS);
+        trace_.Add(" \"stack:%d\"", index);
       }
     }
     int parent_index = -1;
     if (range->IsChild()) {
       parent_index = range->parent()->id();
     } else {
       parent_index = range->id();
     }
     LOperand* op = range->FirstHint();
     int hint_index = -1;
@@ skipping 110 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal