RFR: 8241503: C2: Share MacroAssembler between mach nodes during code emission [v3]

[Cesar Soares]

> Hi there, can I please get some reviews on this change? The patch is to make the code reuse the same C2_MacroAssembler object during the emission of CPU instructions of a given compilation.
> 
> As you'll see the change affects all backends. I've done my best to keep the changes minimal/simple.
> 
> I tested this locally on Linux x86_64, x86_32 and MacOS Arm32, and ARM64.
> 
> **I need help testing the changes on PPC, S390, and RISCV**. I cross-compiled the JVM locally and the builds are all succeeding, but I couldn't use an emulator (yet) or any real hardware (no access to one) to test the changes on these platforms. I see that GitHub actions do some tests on S390 and PPC but the tests seem to not be extensive.
> 
> Thanks in advance,
> Cesar

Cesar Soares has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 23 commits:

 - update with master
 - fix last minute typo
 - work
 - work
 - work
 - work
 - work
 - work
 - work
 - work
 - ... and 13 more: https://git.openjdk.org/jdk/compare/a9c2ab67...fbb8cb1c

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Changes: https://git.openjdk.org/jdk/pull/9074/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=9074&range=02
  Stats: 2392 lines in 48 files changed: 117 ins; 331 del; 1944 mod
  Patch: https://git.openjdk.org/jdk/pull/9074.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9074/head:pull/9074

PR: https://git.openjdk.org/jdk/pull/9074