[RFC] Associate AST nodes with HIstructions when building HGraph.

lib/compiler/implementation/ssa/nodes.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 interface HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBitAnd(HBitAnd node);
   R visitBitNot(HBitNot node);
   R visitBitOr(HBitOr node);
   R visitBitXor(HBitXor node);
@@ skipping 686 matching lines @@
       if (this === other) return true;
       other = other.dominator;
     } while (other !== null && other.id >= id);
     return false;
   }
 }
 
 
 class HInstruction implements Hashable {
   Element sourceElement;
+  Token sourcePosition;
 
   final int id;
   static int idCounter;
 
   final List<HInstruction> inputs;
   final List<HInstruction> usedBy;
 
   HBasicBlock block;
   HInstruction previous = null;
   HInstruction next = null;
@@ skipping 1943 matching lines @@
   HBasicBlock get start() => expression.start;
   HBasicBlock get end() {
     // We don't create a switch block if there are no cases.
     assert(!statements.isEmpty());
     return statements.last().end;
   }
 
   bool accept(HStatementInformationVisitor visitor) =>
       visitor.visitSwitchInfo(this);
 }