bors 4cbda829c0 Auto merge of #74967 - Aaron1011:feature/incr-def-path-table, r=pnkfelix ... Implement lazy decoding of DefPathTable during incremental compilation PR https://github.com/rust-lang/rust/pull/75813 implemented lazy decoding of the `DefPathTable` from crate metadata. However, it requires decoding the entire `DefPathTable` when incremental compilation is active, so that we can map a decoded `DefPathHash` to a `DefId` from an arbitrary crate. This PR adds support for lazy decoding of dependency `DefPathTable`s when incremental compilation si active. When we load the incremental cache and dep graph, we need the ability to map a `DefPathHash` to a `DefId` in the current compilation session (if the corresponding definition still exists). This is accomplished by storing the old `DefId` (that is, the `DefId` from the previous compilation session) for each `DefPathHash` we need to remap. Since a `DefPathHash` includes the owning crate, the old crate is guaranteed to be the right one (if the definition still exists). We then use the old `DefIndex` as an initial guess, which we validate by comparing the expected and actual `DefPathHash`es. In most cases, foreign crates will be completely unchanged, which means that we our guess will be correct. If our guess is wrong, we fall back to decoding the entire `DefPathTable` for the foreign crate. This still represents an improvement over the status quo, since we can skip decoding the entire `DefPathTable` for other crates (where all of our guesses were correct).		2020-12-01 14:30:02 +00:00
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src	Auto merge of #74967 - Aaron1011:feature/incr-def-path-table, r=pnkfelix	2020-12-01 14:30:02 +00:00
Cargo.toml	mv compiler to compiler/	2020-08-30 18:45:07 +03:00