[turbofan] relative_id of splinters and their children.

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 853 matching lines @@
       UsePosition* pos = first_pos_;
       for (; pos->next() != nullptr; pos = pos->next()) {
       }
       pos->set_next(end_part.first_pos_);
     }
   }
   result->next_ = nullptr;
   result->top_level_ = result;
 
   result->SetSplinteredFrom(this);
+  // Ensure the result's relative ID is unique within the IDs used for this
+  // virtual register's children and splinters.
+  result->relative_id_ = GetNextChildId();
 }
 
 
 void TopLevelLiveRange::SetSplinteredFrom(TopLevelLiveRange* splinter_parent) {
   // The splinter parent is always the original "Top".
   DCHECK(splinter_parent->Start() < Start());
 
   splintered_from_ = splinter_parent;
   if (!HasSpillOperand() && splinter_parent->spill_range_ != nullptr) {
     SetSpillRange(splinter_parent->spill_range_);
@@ skipping 2432 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