Remove Hash cache in Node<T>
#872
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Hashing is much less important to apollo-compiler as it was when we were using Salsa. Many of the structs stored in `Node<_>` don’t even implement `Hash` since they contain `IndexMap` which doesn’t. We lose: potential CPU time if repeatedly hashing nodes. `ast::Definition` implements `PartialEq` and `Hash` by traversing the whole subtree, which can be expensive. We gain: 8 fewer bytes in the heap allocation of every `Node`, and slightly less code complexity.
goto-bus-stop
approved these changes
Jun 25, 2024
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Added a changelog entry, and the |
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Hashing is much less important to apollo-compiler as it was when we were using Salsa. Many of the structs stored in
Node<_>don’t even implementHashsince they containIndexMapwhich doesn’t.We lose: potential CPU time if repeatedly hashing nodes.
ast::DefinitionimplementsPartialEqandHashby traversing the whole subtree, which can be expensive. We gain: 8 fewer bytes in the heap allocation of everyNode, and slightly less code complexity.