RFR: 8241503: C2: Share MacroAssembler between mach nodes during code emission [v4]

[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 incrementally with one additional commit since the last revision:

  fix merge

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9074/files
  - new: https://git.openjdk.org/jdk/pull/9074/files/fbb8cb1c..8ebb3dca

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=9074&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=9074&range=02-03

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 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