Use a hash-table when selecting impls #24965
Conversation
|
r? @pnkfelix (rust_highfive has picked a reviewer for you, use r? to override) |
The former stopped making sense when we started interning substs and made TraitRef a 2-word copy type, and I'm moving the latter into an arena as they live as long as the type context.
Puts implementations in bins hashed by the fast-reject key, and only looks up the relevant impls, reducing O(n^2)-ishness Before: 688.92user 5.08system 8:56.70elapsed 129%CPU (0avgtext+0avgdata 1208164maxresident)k, LLVM 379.142s After: 637.78user 5.11system 8:17.48elapsed 129%CPU (0avgtext+0avgdata 1201448maxresident)k LLVM 375.552s Performance increase is +7%-ish
arielb1
changed the title
I see that you chose to pick the smallest NodeId, which seems fine -- do you feel this resolves your concern here? (It's not clear to me that there is a "wrong" order, but it'd be easiest and best to stick with the same order as the previous code, I agree, and a consistent order is good for testing.) |
|
OK, so, r+ but I left a few nits and other questions. Nothing egregious, r=me when you've fixed them (or, if there are things you don't agree with, let me know). |
Out of interest, did you end up collecting some? |
|
@huonw: From the second commit message: |
This uses a (per-trait) hash-table to separate impls from different TraitDefs, and makes coherence go so much quicker. I will post performance numbers tomorrow. This is still WIP, as when there's an overlap error, impls can get printed in the wrong order, which causes a few issues. Should I pick the local impl with the smallest NodeId to print? Could you take a look at this @nikomatsakis?
This uses a (per-trait) hash-table to separate impls from different TraitDefs, and makes coherence go so much quicker. I will post performance numbers tomorrow.
This is still WIP, as when there's an overlap error, impls can get printed in the wrong order, which causes a few issues. Should I pick the local impl with the smallest NodeId to print?
Could you take a look at this @nikomatsakis?