RFR: 8327283: RISC-V: Minimal build failed after JDK-8319716

[Gui Cao]

Hi, please review this patch that fix the minimal build failed for riscv.

Error log for minimal build:

Creating support/modules_libs/java.base/minimal/libjvm.so from 591 file(s)
^@/home/zifeihan/jdk/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp: In member function ‘u_char* StubGenerator::Sha2Generator::generate_sha2_implCompress(Assembler::SEW, bool)’:
/home/zifeihan/jdk/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp:3938:41: error: ‘MaxVectorSize’ was not declared in this scope; did you mean ‘MaxNewSize’?
 3938 |       if (vset_sew == Assembler::e64 && MaxVectorSize == 16) { // SHA512 and VLEN = 128
      |                                         ^~~~~~~~~~~~~
      |                                         MaxNewSize
gmake[3]: *** [lib/CompileJvm.gmk:165: /home/zifeihan/jdk/build/linux-riscv64-minimal-fastdebug/hotspot/variant-minimal/libjvm/objs/stubGenerator_riscv.o] Error 1
gmake[3]: *** Waiting for unfinished jobs....
^@gmake[2]: *** [make/Main.gmk:253: hotspot-minimal-libs] Error 2
gmake[2]: *** Waiting for unfinished jobs....
^@
ERROR: Build failed for target 'images' in configuration 'linux-riscv64-minimal-fastdebug' (exit code 2)

=== Output from failing command(s) repeated here ===
* For target hotspot_variant-minimal_libjvm_objs_stubGenerator_riscv.o:
/home/zifeihan/jdk/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp: In member function ‘u_char* StubGenerator::Sha2Generator::generate_sha2_implCompress(Assembler::SEW, bool)’:
/home/zifeihan/jdk/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp:3938:41: error: ‘MaxVectorSize’ was not declared in this scope; did you mean ‘MaxNewSize’?
 3938 |       if (vset_sew == Assembler::e64 && MaxVectorSize == 16) { // SHA512 and VLEN = 128
      |                                         ^~~~~~~~~~~~~
      |                                         MaxNewSize

* All command lines available in /home/zifeihan/jdk/build/linux-riscv64-minimal-fastdebug/make-support/failure-logs.
=== End of repeated output ===

No indication of failed target found.
HELP: Try searching the build log for '] Error'.
HELP: Run 'make doctor' to diagnose build problems.

make[1]: *** [/home/zifeihan/jdk/make/Init.gmk:323: main] Error 2
make: *** [/home/zifeihan/jdk/make/Init.gmk:189: images] Error 2


The root cause is that MaxVectorSize defined under COMPILER2 , We should use VM_Version::_initial_vector_length instead of MaxVectorSize. 

Testing:

- [x] linux-riscv minimal fastdebug native build

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

Commit messages:
 - 8327283: RISC-V: Minimal build failed after JDK-8319716

Changes: https://git.openjdk.org/jdk/pull/18114/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18114&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327283
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18114.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18114/head:pull/18114

PR: https://git.openjdk.org/jdk/pull/18114