RFR: 8330388: Remove invokedynamic cache index encoding

[Dean Long]

On Wed, 17 Apr 2024 15:26:52 GMT, Matias Saavedra Silva <matsaave at openjdk.org> wrote:

> Before [JDK-8307190](https://bugs.openjdk.org/browse/JDK-8307190), [JDK-8309673](https://bugs.openjdk.org/browse/JDK-8309673), and [JDK-8301995](https://bugs.openjdk.org/browse/JDK-8301995), invokedynamic operands needed to be rewritten to encoded values to better distinguish indy entries from other cp cache entries. The above changes now distinguish between entries with `to_cp_index()` using the bytecode, which is now propagated by the callers.
> 
> The encoding flips the bits of the index so the encoded index is always negative, leading to access errors if there is no matching decode call. These calls are removed with some methods adjusted to distinguish between indices with the bytecode. Verified with tier 1-5 tests.

src/hotspot/share/ci/ciEnv.cpp line 1513:

> 1511:     // process the BSM
> 1512:     int pool_index = indy_info->constant_pool_index();
> 1513:     BootstrapInfo bootstrap_specifier(cp, pool_index, indy_index);

Why not just change the incoming parameter name to `index`?

src/hotspot/share/classfile/resolutionErrors.hpp line 60:

> 58: 
> 59:   // This function is used to encode an invokedynamic index to differentiate it from a
> 60:   // constant pool index.  It assumes it is being called with a index that is less than 0

Is this comment still correct?

src/hotspot/share/interpreter/bootstrapInfo.cpp line 77:

> 75:     return true;
> 76:   } else if (indy_entry->resolution_failed()) {
> 77:     int encoded_index = ResolutionErrorTable::encode_indy_index(_indy_index);

That's an improvement, from two levels of encoding to only one!

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PR Review Comment: https://git.openjdk.org/jdk/pull/18819#discussion_r1569625123
PR Review Comment: https://git.openjdk.org/jdk/pull/18819#discussion_r1569626519
PR Review Comment: https://git.openjdk.org/jdk/pull/18819#discussion_r1569627219