RFR: 8255397: x86: coalesce reference and int entry points into vtos bytecodes [v3]

[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.

Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:

  Use push directly in push_i_or_ptr

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/865/files
  - new: https://git.openjdk.java.net/jdk/pull/865/files/6595372e..77bf4fcf

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=865&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=865&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 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