~35 tests in the jdk repo are failing with VerifyError. It appears to have crept in with the recent nasgen changes, specifically this change:
   http://hg.openjdk.java.net/jigsaw/jake/nashorn/rev/64016e0013ca


Here's one example:

TEST: tools/jjs/jjs-cpTest.sh
java version "9-internal"
Java(TM) SE Runtime Environment (build 9-internal+0-2016-03-05-164535.albatem.jake)
Java HotSpot(TM) 64-Bit Server VM (build 9-internal+0-2016-03-05-164535.albatem.jake, mixed mode)


ACTION: shell -- Failed. Execution failed: exit code 1
REASON: User specified action: run shell jjs-cpTest.sh Tests -cp/-classpath option to set the classpath for jjs
TIME: 1.14 seconds
messages:
command: shell jjs-cpTest.sh Tests -cp/-classpath option to set the classpath for jjs
reason: User specified action: run shell jjs-cpTest.sh Tests -cp/-classpath option to set the classpath for jjs
elapsed time (seconds): 1.14
STDOUT:
STDERR:
Exception in thread "main" java.lang.VerifyError: Bad return type
Exception Details:
  Location:
    jdk/nashorn/internal/objects/Global.newObject()Ljdk/nashorn/internal/runtime/ScriptObject; @32: areturn
  Reason:
    Type 'java/lang/Object' (current frame, stack[0]) is not assignable to 'jdk/nashorn/internal/runtime/ScriptObject' (from method signature)
  Current Frame:
    bci: @32
    flags: { }
    locals: { 'jdk/nashorn/internal/objects/Global' }
    stack: { 'java/lang/Object' }
  Bytecode:
    0000000: 2ab6 0271 9900 11bb 0273 592a b602 76b7
    0000010: 0279 a700 0ebb 027b 592a b602 76b7 027c
    0000020: b0
  Stackmap Table:
    same_frame(@21)
    same_locals_1_stack_item_frame(@32,Object[#638])

at jdk.nashorn.internal.runtime.Context.newGlobal(jdk.scripting.nashorn@9-internal/Context.java:1198)
at jdk.nashorn.internal.runtime.Context.createGlobal(jdk.scripting.nashorn@9-internal/Context.java:1189)
at jdk.nashorn.tools.Shell.run(jdk.scripting.nashorn@9-internal/Shell.java:171)
at jdk.nashorn.tools.jjs.Main.main(jdk.scripting.nashorn.shell@9-internal/Main.java:102)
at jdk.nashorn.tools.jjs.Main.main(jdk.scripting.nashorn.shell@9-internal/Main.java:78)