RFR: 8255397: x86: coalesce reference and int entry points into vtos bytecodes

[Claes Redestad]

On x86 - both 32- and 64-bit - the code laid out for transitionining into a vtos bytecode when having a reference and int top-of-stack state is semantically identical, and can be coalesced.

This patch removes a short jump on some cases which is marginally beneficial when interpreting, while measurably reducing overhead of generating the interpreter itself.

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Commit messages:
 - x86: coalesce some ptr and int entry points

Changes: https://git.openjdk.java.net/jdk/pull/865/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=865&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255397
  Stats: 4 lines in 1 file changed: 0 ins; 3 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/865.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/865/head:pull/865

PR: https://git.openjdk.java.net/jdk/pull/865