Subroutine exit knows when it's an error

compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/JetControlFlowInstructionsGenerator.java

@@ -219,9 +219,9 @@ public class JetControlFlowInstructionsGenerator extends JetControlFlowBuilderAd
         @Override
         public Pseudocode exitSubroutine(@NotNull JetElement subroutine) {
             bindLabel(getExitPoint(subroutine));
-            pseudocode.addExitInstruction(new SubroutineExitInstruction(subroutine, "<END>"));
+            pseudocode.addExitInstruction(new SubroutineExitInstruction(subroutine, false));
             bindLabel(error);
-            pseudocode.addErrorInstruction(new SubroutineExitInstruction(subroutine, "<ERROR>"));
+            pseudocode.addErrorInstruction(new SubroutineExitInstruction(subroutine, true));
             bindLabel(sink);
             pseudocode.addSinkInstruction(new SubroutineSinkInstruction(subroutine, "<SINK>"));
             elementToBlockInfo.remove(subroutine);

compiler/frontend/src/org/jetbrains/jet/lang/cfg/pseudocode/SubroutineExitInstruction.java

@@ -24,18 +24,22 @@ import java.util.Collections;
 
 public class SubroutineExitInstruction extends InstructionImpl {
     private final JetElement subroutine;
-    private final String debugLabel;
+    private final boolean isError;
     private SubroutineSinkInstruction sinkInstruction;
 
-    public SubroutineExitInstruction(@NotNull JetElement subroutine, @NotNull String debugLabel) {
+    public SubroutineExitInstruction(@NotNull JetElement subroutine, boolean isError) {
         this.subroutine = subroutine;
-        this.debugLabel = debugLabel;
+        this.isError = isError;
     }
 
     public JetElement getSubroutine() {
         return subroutine;
     }
 
+    public boolean isError() {
+        return isError;
+    }
+
     public void setSink(SubroutineSinkInstruction instruction) {
         sinkInstruction = (SubroutineSinkInstruction) outgoingEdgeTo(instruction);
     }
@@ -59,12 +63,12 @@ public class SubroutineExitInstruction extends InstructionImpl {
 
     @Override
     public String toString() {
-        return debugLabel;
+        return isError ? "<ERROR>" : "<END>";
     }
 
     @NotNull
     @Override
     protected Instruction createCopy() {
-        return new SubroutineExitInstruction(subroutine, debugLabel);
+        return new SubroutineExitInstruction(subroutine, isError);
     }
 }