Integrated: 8309811: BytecodePrinter cannot handle unlinked classes

[Ioi Lam]

On Fri, 23 Jun 2023 05:18:36 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> `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.

This pull request has now been integrated.

Changeset: ded13707
Author:    Ioi Lam <iklam at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/ded137073ac1b2086a577508172626898999e275
Stats:     672 lines in 6 files changed: 395 ins; 184 del; 93 mod

8309811: BytecodePrinter cannot handle unlinked classes

Reviewed-by: coleenp, fparain

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