Remove hack around aborting loop body in the case of for loops and while loops.

sdk/lib/_internal/compiler/implementation/ssa/variable_allocator.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.
 
 part of ssa;
 
 /**
  * The [LiveRange] class covers a range where an instruction is live.
  */
 class LiveRange {
@@ skipping 277 matching lines @@
     // If the block is a loop header, we can remove the loop marker,
     // because it will just recompute the loop phis.
     if (block.isLoopHeader()) {
       updateLoopMarker(block);
     }
   }
 
   void updateLoopMarker(HBasicBlock header) {
     LiveEnvironment env = liveInstructions[header];
     int lastId = env.loopMarkers[header];
+    if (lastId == null) {
+      assert(header.predecessors.length == 1);

[floitsch, 2012/11/05 17:36:09]

add comment what happened.

[ngeoffray, 2012/11/06 08:55:27]

I changed the code to not enter updateLoopMarker in case the loop header does
not have back edge. And added a comment there.

+      return;
+    }
+
     // Update all instructions that are liveIns in [header] to have a
     // range that covers the loop.
     env.liveInstructions.forEach((HInstruction instruction, int id) {
       LiveInterval range = env.liveIntervals.putIfAbsent(
           instruction, () => new LiveInterval());
       range.loopUpdate(env.startId, lastId);
       env.liveInstructions[instruction] = lastId;
     });
 
     env.removeLoopMarker(header);
@@ skipping 363 matching lines @@
       if (!needsName(input)) {
         names.addAssignment(predecessor, input, phi);
       } else {
         names.addCopy(predecessor, input, phi);
       }
     }
 
     namer.allocateName(phi);
   }
 }