RFR: 8309811: BytecodePrinter cannot handle unlinked classes [v2]

[Ioi Lam]

> `BytecodePrinter` assumes that it's printing a method from a linked class (e.g., it assumes that the two bytes following an `invokestatic` bytecode have been rewritten to be a `ConstantPoolCache` index.)
> 
> This works fine for `-XX:+TraceBytecodes`, which prints only code from linked classes. However, it doesn't work `Method::print_codes_on()` for a method from an unlinked class.
> 
> The old code in `BytecodePrinter` uses a very convoluted logic to go from the rewritten index back to the `cp_index`. It's also difficult to understand the type of the indices from the badly named variables like `i` and `orig_i`.
> 
> I had to rewrite all the logic for fetching the indices. Now they are in this form:
> 
> 
>     case Bytecodes::_putfield:
>     case Bytecodes::_getfield:
>       {
>         int cp_index;
>         if (is_linked()) {
>           int cpcache_index = get_native_index_u2();
>           cp_index = cpcache()->entry_at(cpcache_index)->constant_pool_index();
>         } else {
>           cp_index = get_Java_index_u2();
>         }
>         print_field_or_method(cp_index, st);
>       }
> 
> 
> The indices have names like `cp_index`, `cpcache_index`, `indy_index` so we know exactly what we are dealing with.
> 
> Other changes:
> - Added test cases to cover both linked/unlinked classes for the bytecodes modified by this PR
> - Fixed the printing of strings to escape unprintable characters (E.g., "\u0001" is very common used by indified string concat)
> - Added a test case for `-XX:+TraceBytecodes`
> - Added a develop flag `-XX:TraceBytecodesStopAt=` so the test cases won't produce excessive output.

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  @coleenp comments

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14623/files
  - new: https://git.openjdk.org/jdk/pull/14623/files/0108e6ba..17163f39

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14623&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14623&range=00-01

  Stats: 10 lines in 1 file changed: 2 ins; 1 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/14623.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14623/head:pull/14623

PR: https://git.openjdk.org/jdk/pull/14623