RFR: JDK-8241503: C2: Share MacroAssembler between mach nodes during code emission [v12]

[Cesar Soares Lucas]

> # Description
> 
> Please review this PR with a patch to re-use the same C2_MacroAssembler object to emit all instructions in the same compilation unit.
> 
> Overall, the change is pretty simple. However, due to the renaming of the variable to access C2_MacroAssembler, from `_masm.` to `masm->`, and also some method prototype changes, the patch became quite large.
> 
> # Help Needed for Testing
> 
> I don't have access to all platforms necessary to test this. I hope some other folks can help with testing on `S390`, `RISC-V` and `PPC`.

Cesar Soares Lucas has updated the pull request incrementally with one additional commit since the last revision:

  Fix ARM32 AD file

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16484/files
  - new: https://git.openjdk.org/jdk/pull/16484/files/b4d73c98..693c7ef8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16484&range=11
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16484&range=10-11

  Stats: 21 lines in 1 file changed: 12 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/16484.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16484/head:pull/16484

PR: https://git.openjdk.org/jdk/pull/16484