RFR: 8283327: Add methods to save/restore registers when calling into the VM from C1/interpreter barrier code [v2]

[Thomas Schatzl]

> Hi all,
> 
>   can I have reviews for this change that adds an API to save/restore caller-saved registers for VM upcalls for C1/interpreter.
> 
> Currently, for x86, this is done in a very ad-hoc (copy&pasty) way, which starts to fall apart. Additionally this fixes some problems with wrong stack alignment.
> 
> There is some cleanup to do separately to remove that copy&paste code in another CR. At the moment the API (`push_call_clobbered_registers/pop_call_clobbered_registers`) is only used for g1.
> 
> It's based on `RegSet` from AArch64.
> 
> Testing: tier1-5, tier1 testing with x64 and x86, with some at this point obscure combinations (like x86 UseSSE=0/1).
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  dean comments

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7867/files
  - new: https://git.openjdk.java.net/jdk/pull/7867/files/1be201b1..2d04da02

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7867&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7867&range=00-01

  Stats: 4 lines in 1 file changed: 0 ins; 4 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7867.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7867/head:pull/7867

PR: https://git.openjdk.java.net/jdk/pull/7867