Stream the dep-graph to a file instead of storing it in-memory.
This is a reimplementation of #60035.
Instead of storing the dep-graph in-memory, the nodes are encoded as they come
into the a temporary file as they come. At the end of a successful the compilation,
this file is renamed to be the persistent dep-graph, to be decoded during the next
compilation session.
This two-files scheme avoids overwriting the dep-graph on unsuccessful or crashing compilations.
The structure of the file is modified to be the sequence of `(DepNode, Fingerprint, EdgesVec)`.
The deserialization is responsible for going to the more compressed representation.
The `node_count` and `edge_count` are stored in the last 16 bytes of the file,
in order to accurately reserve capacity for the vectors.
At the end of the compilation, the encoder is flushed and dropped.
The graph is not usable after this point: any creation of a node will ICE.
I had to retrofit the debugging options, which is not really pretty.
panic early when `TrustedLen` indicates a `length > usize::MAX`
Changes `TrustedLen` specializations to immediately panic when `size_hint().1 == None`.
As far as I can tell this is ~not a change~ a minimal change in observable behavior for anything except ZSTs because the fallback path would go through `extend_desugared()` which tries to `reserve(lower_bound)` which already is `usize::MAX` and that would also lead to a panic. Before it might have popped somewhere between zero and a few elements from the iterator before panicking while it now panics immediately.
Overall this should reduce codegen by eliminating the fallback paths.
While looking into the `with_capacity()` behavior I also noticed that its documentation didn't have a *Panics* section, so I added that.
Update cargo
5 commits in 1e8703890f285befb5e32627ad4e0a0454dde1fb..3c44c3c4b7900b8b13c85ead25ccaa8abb7d8989
2021-03-26 16:59:39 +0000 to 2021-03-31 21:21:15 +0000
- Fix semver docs for 1.51. (rust-lang/cargo#9316)
- Add `cargo config` subcommand. (rust-lang/cargo#9302)
- Give one more example for the --featuers CLI (rust-lang/cargo#9313)
- Bump to 0.54.0, update changelog (rust-lang/cargo#9308)
- Make the URL to the tracking issue for `--out-dir` into a link (rust-lang/cargo#9309)
Rollup of 5 pull requests
Successful merges:
- #83015 (Add regression tests for #79825 and #81555)
- #83699 (Add a regression test for issue-68830)
- #83700 (Fix documentation of conversion from String to OsString)
- #83711 (Clarify `--print target-list` is a rustc's option)
- #83712 (Update LLVM with another wasm simd fix)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Refactor `Binder` to track bound vars
c.c. `@rust-lang/wg-traits`
This is super early (and might just get closed at some point), but want to get at least an initial idea of the perf impact.
r? `@ghost`
