On Mon, 22 Sep 2025 08:02:57 GMT, Johan Sjölen <[email protected]> wrote:
>> Hi,
>>
>> This is a refactoring of the way that we store the Bootstrap method
>> attribute in the ConstantPool class. We used to have a single `Array<u2>`
>> which was divided into a section of `u4` offsets and a section which was the
>> actual data. In this refactoring we make this split more clear, by actually
>> allocating an `Array<u4>` to store the offsets in and an `Array<u2>` to
>> store the data in. These arrays are then put into a `BSMAttributeEntries`
>> class, which allows us to separate out the API from that of the rest of the
>> `ConstantPool`.
>>
>> We had multiple instances of the code knowing the layout of the operands
>> array and using this to do 'clever' ways of copying and inserting data into
>> it. See `ConstantPool::copy_operands` and `ConstantPool::resize_operands`. I
>> felt like we could do things in a simpler way, so I added the
>> `start_/end_extension` protocol and added the `InsertionIterator` for this.
>> See `ClassFileParser::parse_classfile_bootstrap_methods_attribute` for how
>> this works. I put several relevant definitions into the inline file in hopes
>> of encouraging the compiler to optimize these appropriately.
>>
>> For the Java SA code, I had to add a `U4Array` class. I also had to fix the
>> vmstructs definitions, etc.
>>
>> On the whole, while this code is a bit less terse, I think it's a good API
>> improvement and the underlying implementation of splitting up the operands
>> array is also an improvement.
>>
>> Testing: Oracle Tier1-Tier5 has been run succesfully multiple times. Before
>> integration, I will merge with master and run these tiers again.
>
> Johan Sjölen has updated the pull request incrementally with two additional
> commits since the last revision:
>
> - Merge remote-tracking branch 'origin/operands-again' into operands-again
> - Fix BSM naming
src/hotspot/share/oops/constantPool.hpp line 116:
> 114: return _argument_count;
> 115: }
> 116: int argument(int n) const {
Q: Why was the function name changed?
src/hotspot/share/oops/constantPool.hpp line 139:
> 137: int _cur_offset;
> 138: // Current unused offset into BSMAEs bsm-data array
> 139: int _cur_array;
Nit: I'd suggest to rename this to something like `_cur_bsm_entry`.
src/hotspot/share/prims/jvmtiRedefineClasses.hpp line 440:
> 438: int append_bsm_entry(const constantPoolHandle& scratch_cp, int
> scratch_bootstrap_spec_index,
> 439: constantPoolHandle *merge_cp_p, int *merge_cp_length_p);
> 440: void finalize_bsmentries_merge(const constantPoolHandle& merge_cp,
> TRAPS);
Nit: A suggestion to rename: `finalize_bsmentries_merge` =>
`finalize_bsm_entries_merge`
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/ConstantPool.java line
95:
> 93: Type bsmaetype = db.lookupType("BSMAttributeEntries");
> 94: bsmaentries_offsets = bsmaetype.getAddressField("_offsets");
> 95: bsmaentries_bootstrap_methods =
> bsmaetype.getAddressField("_bootstrap_methods");
Nit: A suggestion to rename:
`bsmaentries` => `bsma_entries` or `bsm_entries`
`bsmaetype` => `bsma_type` or `bsm_type`
`bsmaentries_offsets` => `bsma_entries_offsets` or `bsm_entries_offsets`
`bsmaentries_bootstrap_methods` => `bsma_entries_bootstrap_methods` or
`bsm_entries_bootstrap_methods`
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/ConstantPool.java line
122:
> 120: private static long bsmaentries; // Offset in the constantpool where
> the BSMAEntries are found
> 121: private static AddressField bsmaentries_offsets;
> 122: private static AddressField bsmaentries_bootstrap_methods;
Nit: Same renaming suggestion as above.
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/ConstantPool.java line
482:
> 480: int basePos = offs.at(bsmIndex);
> 481: int argv = basePos + INDY_ARGV_OFFSET;
> 482: int argc = getBootstrapMethodArgsCount(bsmIndex);
Nit: Consider to make it shorter:
`getBootstrapMethods` => `getBSMs`
`getBootstrapMethodArgsCount` => `getBSMArgsCount`
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/27198#discussion_r2371074352
PR Review Comment: https://git.openjdk.org/jdk/pull/27198#discussion_r2371075707
PR Review Comment: https://git.openjdk.org/jdk/pull/27198#discussion_r2371078749
PR Review Comment: https://git.openjdk.org/jdk/pull/27198#discussion_r2371084318
PR Review Comment: https://git.openjdk.org/jdk/pull/27198#discussion_r2371084929
PR Review Comment: https://git.openjdk.org/jdk/pull/27198#discussion_r2371087738
