RFR: 8343415: RISC-V: Increase maximum size of C2EntryBarrierStub by one [v2]

[Fei Yang]

> Hi, please consider this small change.
> 
> There is one jump to continuation (after nmethod entry barriers) in C2EntryBarrierStub [1].
> The current max_size setting assumes the distance is within 1MB, which means a simple `jal` instruction [2].
> So I just count one for this jump in [JDK-8343121](https://bugs.openjdk.org/browse/JDK-8343121). This doesn't seem to break for various tests. But I don't think there is a good reason for that assumption to stand. Instead, we should remove this constraint assuming a `auipc+jalr` pair for this jump.
> 
> [1] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/riscv/c2_CodeStubs_riscv.cpp#L66
> [2] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/riscv/macroAssembler_riscv.cpp#L965
> 
> Testing on linux-riscv64:
> - [x] tier1 (fastdebug build)

Fei Yang has updated the pull request incrementally with one additional commit since the last revision:

  Comment typo

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21818/files
  - new: https://git.openjdk.org/jdk/pull/21818/files/b133d081..e07f6e37

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21818&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21818&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21818.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21818/head:pull/21818

PR: https://git.openjdk.org/jdk/pull/21818