[master] RFR: Load Klass from header, C1/x86 implementation [v7]

[Roman Kennke]

> This implements loading the Klass* from object header (instead of dedicated Klass* field) in C1 generated code. It introduces a new C1 LIR opcode (LoadKlass) and related CodeStub for the slow-path runtime-call.
> 
> The original implementation was brittle in that it emits the decode_klass() whenever it encounters a load that is T_ADDRESS and from klass_offset_in_bytes() (e.g. 4 or 8). Lucky that we did not seem to emit any unrelated such loads. This new implementation uses a dedicated C1 op instead, and expands this to the corresponding load of the header word, and call into slow-path upon fast-path-failure, in the LIR assembler.
> 
> Testing:
>  - [x] tier1 (x86_64,x86_32)
>  - [x] tier2 (x86_64,x86_32)
>  - [x] tier3 (x86_64,x86_32)
>  - [ ] tier4 (x86_64,x86_32)

Roman Kennke has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 36 commits:

 - Merge remote-tracking branch 'origin/klass-from-header-c1' into klass-from-header-c1
 - Merge remote-tracking branch 'upstream/master' into klass-from-header-c1
 - Increase code size estimate
 - Merge branch 'master' into klass-from-header-c1
 - Merge remote-tracking branch 'jdk-upstream/master' into klass-from-header-c1
 - Merge remote-tracking branch 'upstream/master' into klass-from-header-c1
 - Basic arm implementation
 - Basic s390 implementation
 - Basic ppc implementation
 - Use long jump
 - ... and 26 more: https://git.openjdk.java.net/lilliput/compare/4390f5f0...6b24f6c6

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

Changes: https://git.openjdk.java.net/lilliput/pull/20/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lilliput&pr=20&range=06
  Stats: 102 lines in 15 files changed: 87 ins; 6 del; 9 mod
  Patch: https://git.openjdk.java.net/lilliput/pull/20.diff
  Fetch: git fetch https://git.openjdk.java.net/lilliput pull/20/head:pull/20

PR: https://git.openjdk.java.net/lilliput/pull/20