RFR: 8262368: wrong verifier message for bogus return type

[Harold Seigel]

Please review this small change to fix some verifier error messages.  If a method's descriptor has a void return signature, but contains a bytecode such as 'ireturn' or 'areturn'. then it will get a VerifyError exception with the message "Method descriptor has a void return type".   Conversely, if a method's descriptor has a non-void return signature, but contains a 'return' bytecode then it will get a VerifyError exception with the message "Method descriptor has a non-void return type".

A sample error message looks like:
Error: Unable to initialize main class Hi
Caused by: java.lang.VerifyError: Method descriptor has a void return type
Exception Details:
  Location:
    Hi.noRet(I)V @1: ireturn
  Reason:
    Type integer (current frame, stack[0]) is not assignable to top (from method signature)
  Current Frame:
    bci: @1
    flags: { }
    locals: { integer }
    stack: { integer }
  Bytecode:
    0000000: 08ac

The fix was tested with Mach5 tiers 1 and 2 on Linux, Mac OS, and Windows, tiers 3-5 on Linux x64. and the JCK Lang and VM tests on Linux x64.

Thanks, Harold

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Commit messages:
 - 8262368: wrong verifier message for bogus return type

Changes: https://git.openjdk.java.net/jdk/pull/2757/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2757&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262368
  Stats: 128 lines in 3 files changed: 126 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2757.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2757/head:pull/2757

PR: https://git.openjdk.java.net/jdk/pull/2757