[perf] Skip phpdoc path in RenameClassRector for nodes without a docblock

[TomasVotruba]

Why

RenameClassRector is one of the heaviest rules. It subscribes to FullyQualified, Name, Property, FunctionLike, Expression, ClassLike and If_, and for every non-name node it built a PhpDocInfo and ran the phpdoc rename, regardless of whether the node had a docblock.

A phpdoc type rename can only ever change a node that carries a real docblock. Plain line comments or no comment never match.

Measurement

Single-process run over this repo's src/ + rules/ with a 600-entry rename map, counting the phpdoc path:

• createFromNode was called 28258 times (every Expression/If_/FunctionLike/Property/ClassLike node)
• only 3983 of those nodes actually had a docblock
• 1576 had plain comments only - these still ran the full refactorPhpDoc, which cannot change anything
• 22699 had no comment at all

The phpdoc path (createFromNode + refactorPhpDoc) accounted for ~92% of the rule's own time.

Change

1. Guard the phpdoc branch behind a cheap getDocComment() !== null check. The expensive path now runs on ~4k nodes instead of ~28k. Behaviour is identical: nodes without a docblock produced an empty/typeless PhpDocInfo that refactorPhpDoc always left unchanged.
2. Drop the per-call serialize() + hash in createOldToNewTypes. The rename map is constant during a run, so memoize on the identical array and remove the now unused FileHasher dependency.

Tests

• rules-tests/Renaming - 105 tests green
• ECS + PHPStan level 8 clean on the changed file