Fix another bailout problem where not all blocks were visiting when propagating bailout information…

sdk/lib/_internal/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.
 
 part of ssa;
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBailoutTarget(HBailoutTarget node);
   R visitBitAnd(HBitAnd node);
@@ skipping 1839 matching lines @@
 
   final int kind;
   HLoopBranch(HInstruction condition, [this.kind = CONDITION_FIRST_LOOP])
       : super(<HInstruction>[condition]);
   toString() => 'loop-branch';
   accept(HVisitor visitor) => visitor.visitLoopBranch(this);
 
   bool isDoWhile() {
     return identical(kind, DO_WHILE_LOOP);
   }
+
+  HBasicBlock computeLoopHeader() {
+    HBasicBlock result;
+    if (isDoWhile()) {
+      // In case of a do/while, the successor is a block that avoids
+      // a critical edge and branchs to the loop header.
+      result = block.successors[0].successors[0];
+    } else {
+      // For other loops, the loop header might be up the dominator
+      // tree if the loop condition has control flow.
+      result = block;
+      while (!result.isLoopHeader()) result = result.dominator;
+    }
+
+    assert(result.isLoopHeader());
+    return result;
+  }
 }
 
 class HConstant extends HInstruction {
   final Constant constant;
   final HType constantType;
   HConstant.internal(this.constant, HType this.constantType)
       : super(<HInstruction>[]);
 
   toString() => 'literal: $constant';
   accept(HVisitor visitor) => visitor.visitConstant(this);
@@ skipping 741 matching lines @@
     if (kind == DO_WHILE_LOOP && condition != null) {
       return condition.end;
     }
     return body.end;
   }
 
   static int loopType(Node node) {
     return node.accept(const LoopTypeVisitor());
   }
 
+  bool isDoWhile() => kind == DO_WHILE_LOOP;
+
   bool accept(HStatementInformationVisitor visitor) =>
     visitor.visitLoopInfo(this);
 }
 
 class HIfBlockInformation implements HStatementInformation {
   final HExpressionInformation condition;
   final HStatementInformation thenGraph;
   final HStatementInformation elseGraph;
   HIfBlockInformation(this.condition,
                       this.thenGraph,
@@ skipping 65 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);
 }