Merge libv1.

sdk/lib/_internal/compiler/implementation/ssa/nodes.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart b/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
index e29a7aa9871beccf9e3e6c81bae1ddf04dacf301..ac51d423f860b53af33943595fc1496386bb17cb 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
@@ -19,6 +19,7 @@ abstract class HVisitor<R> {
   R visitDivide(HDivide node);
   R visitEquals(HEquals node);
   R visitExit(HExit node);
+  R visitExitTry(HExitTry node);
   R visitFieldGet(HFieldGet node);
   R visitFieldSet(HFieldSet node);
   R visitForeign(HForeign node);
@@ -220,7 +221,6 @@ class HGraph {
       HBasicBlock block = blocks[i];
       List<HBasicBlock> predecessors = block.predecessors;
       if (block.isLoopHeader()) {
-        assert(predecessors.length >= 2);
         block.assignCommonDominator(predecessors[0]);
       } else {
         for (int j = predecessors.length - 1; j >= 0; j--) {
@@ -279,6 +279,7 @@ class HBaseVisitor extends HGraphVisitor implements HVisitor {
   visitDivide(HDivide node) => visitBinaryArithmetic(node);
   visitEquals(HEquals node) => visitRelational(node);
   visitExit(HExit node) => visitControlFlow(node);
+  visitExitTry(HExitTry node) => visitControlFlow(node);
   visitFieldGet(HFieldGet node) => visitFieldAccess(node);
   visitFieldSet(HFieldSet node) => visitFieldAccess(node);
   visitForeign(HForeign node) => visitInstruction(node);
@@ -2033,6 +2034,18 @@ class HTry extends HControlFlow {
   HBasicBlock get joinBlock => this.block.successors.last;
 }
 
+// An [HExitTry] control flow node is used when the body of a try or
+// the body of a catch contains a return, break or continue. To build
+// the control flow graph, we explicitely mark the body that
+// leads to one of this instruction a predecessor of catch and
+// finally.
+class HExitTry extends HControlFlow {
+  HExitTry() : super(const <HInstruction>[]);
+  toString() => 'exit try';
+  accept(HVisitor visitor) => visitor.visitExitTry(this);
+  HBasicBlock get bodyTrySuccessor => block.successors[0];
+}
+
 class HIf extends HConditionalBranch {
   HBlockFlow blockInformation = null;
   HIf(HInstruction condition) : super(<HInstruction>[condition]);
@@ -2914,7 +2927,7 @@ class HLoopBlockInformation implements HStatementInformation {
 
   HBasicBlock get end {
     if (updates != null) return updates.end;
-    if (kind == DO_WHILE_LOOP) {
+    if (kind == DO_WHILE_LOOP && condition != null) {
       return condition.end;
     }
     return body.end;