RFR: 8291459: JVM crash with GenerateOopMap::error_work(char const*, __va_list_tag*)

[Harold Seigel]

The JVM fails when generating oop maps for method getAlphanumericCode(int) in bug_file/com/google/zxing/qrcode/encoder/Encoder.javap because the last bytecode in the method is an unreachable conditional branch at byecode index 11131:

      11124: ireturn
      11125: iinc          41, 1
      11128: iload         41
      11130: iconst_2
      11131: if_icmple     291

The class file (Encoder.class) containing getAlphanumericCode(int) has a class file version of 49.  So it is verified by the old verifier, which allows methods to end in a conditional branch provided that the conditional branch is unreachable during method execution.

This fix changes GenerateOopMap::jump_targets_do() to handle such methods.

The fix was tested by running the user's failing program, the new regression test, Mach5 tiers 1-2 on Linux, Mac OS, and Windows, Mach5 tiers 3-5 on Linu x64, and the JC Lang,VM, and API tests locally on Linux x64.

Please review.
Thanks, Harold

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Commit messages:
 - 8291459: JVM crash with GenerateOopMap::error_work(char const*, __va_list_tag*)

Changes: https://git.openjdk.org/jdk/pull/9745/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9745&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291459
  Stats: 118 lines in 3 files changed: 117 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9745.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9745/head:pull/9745

PR: https://git.openjdk.org/jdk/pull/9745