Consider lowering JIT_MAXSIZE #9861

Currently, JIT_MAXSIZE (org.jruby.util.cli.Options.JIT_MAXSIZE, configured by property jruby.jit.maxsize) is set to 3000 IR instructions. This limit appears to be larger than all but 2 code bodies in the .rb sources included in a JRuby dev environment.

During the update of ASM to 9.11.1 (#9858) we discovered that 11 large bodies would be compiled by JRuby under our max size limit, but ultimately fail ASM's new bytecode size and count limits:

• lib/ruby/stdlib/date/format.rb:196 (method _parse_ddd)
• lib/ruby/stdlib/mkmf.rb:2180 (method create_makefile)
• spec/ruby/core/string/undump_spec.rb:5 (block)
• spec/ruby/core/string/undump_spec.rb:158 (block)
• spec/ruby/library/uri/plus_spec.rb:5 (block)
• spec/ruby/library/uri/plus_spec.rb:43 (block)
• test/mri/openssl/test_asn1.rb:7 (method test_decode_x509_certificate)
• test/mri/ruby/test_call.rb:510 (method test_call_cfunc_splat_large_array_bug_4040)
• test/mri/ruby/test_complex.rb:786 (method test_parse)
• test/mri/ruby/test_keyword.rb:292 (method test_keyword_splat_new)
• test/mri/ruby/test_keyword.rb:2477 (method test_ruby2_keywords)

Note that most of these are test bodies, which are frequently large and normally won't JIT, but the __parse_ddd method in date.rb is more likely to be used by real-world applications.

The create_makefile method also likely only runs a few times, during installation of gems that include C libraries (rare on JRuby).

Some of these bodies, such as the spec block for spec/ruby/library/uri/plus_spec.rb, also exceed the 10MB size limit in ASM. Such large methods will certainly never be JIT compiled by the JVM, and as a result they will probably be more efficient (and use less memory) if they remain in the interpreter.

I believe we should reexamine the max JIT method size and probably drop it down from the current 3000 IR instructions to a more reasonable 1000 instructions or lower.