[PATCH] D115798: Provide SmallAttrBuilder as a lightweight alternative to AttrBuilder

[Reid Kleckner via Phabricator via llvm-commits]

rnk added a comment.

I would really prefer to avoid adding a new variant of AttrBuilder. What is the main blocker to making AttrBuilder more efficient? It just needs an `LLVMContext`, right? Would that be feasible instead? Most AttrBuilders are constructed from existing AttributeLists, which have a context.

> Internally it maintains two SmallVector of sorted Attributes, which turns out to
> be more efficient than temporary hashmap and bitfields as used by AttrBuilder.

Surely the bitset is more efficient than a vector of attributes. I think it's the `std::map<SmallString, SmallString>` that's slow. I think replacing that with a sorted vector of hashed string attributes would be just as efficient.


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  https://reviews.llvm.org/D115798/new/

https://reviews.llvm.org/D115798