rustc_metadata: replace Entry table with one table for each of its fields (AoS -> SoA).
In https://github.com/rust-lang/rust/pull/59789#issuecomment-481958212 I noticed that for many cross-crate queries (e.g. `predicates_of(def_id)`), we were deserializing the `rustc_metadata::schema::Entry` for `def_id` *only* to read one field (i.e. `predicates`).
But there are several such queries, and `Entry` is not particularly small (in terms of number of fields, the encoding itself is quite compact), so there is a large (and unnecessary) constant factor.
This PR replaces the (random-access) array¹ of `Entry` structures ("AoS"), with many separate arrays¹, one for each field that used to be in `Entry` ("SoA"), resulting in the ability to read individual fields separately, with negligible time overhead (in thoery), and some size overhead (as these arrays are not sparse).
In a way, the new approach is closer to incremental on-disk caches, which store each query's cached results separately, but it would take significantly more work to unify the two.
For stage1 `libcore`'s metadata blob, the size overhead is `8.44%`, and I have another commit (~~not initially included because I want to do perf runs with both~~ **EDIT**: added it now) that brings it down to `5.88%`.
¹(in the source, these arrays are called "tables", but perhaps they could use a better name)
Upgrade Emscripten targets to use upstream LLVM backend
- Compatible with Emscripten 1.38.46-upstream or later upstream.
- Refactors the Emscripten target spec to share code with other wasm
targets.
- Replaces the old incorrect wasm32 C call ABI with the correct one,
preserving the old one as wasm32_bindgen_compat for wasm-bindgen
compatibility.
- Updates the varargs ABI used by Emscripten and deletes the old one.
- Removes the obsolete wasm32-experimental-emscripten target.
- Uses EMCC_CFLAGS on CI to avoid the timeout problems with #63649.
r? @alexcrichton
- Compatible with Emscripten 1.38.46-upstream or later upstream.
- Refactors the Emscripten target spec to share code with other wasm
targets.
- Replaces the old incorrect wasm32 C call ABI with the correct one,
preserving the old one as wasm32_bindgen_compat for wasm-bindgen
compatibility.
- Updates the varargs ABI used by Emscripten and deletes the old one.
- Removes the obsolete wasm32-experimental-emscripten target.
- Uses EMCC_CFLAGS on CI to avoid the timeout problems with #63649.
Update cargo, books
## nomicon
3 commits in 4374786f0b4bf0606b35d5c30a9681f342e5707b..5004ad30d69f93553ceef74439fea2159d1f769e
2019-09-17 18:33:21 +0200 to 2019-10-12 19:52:40 +0200
- further clarify C11 and C/C++11 terminology (rust-lang-nursery/nomicon#169)
- atomics: C11 -> C++20 (rust-lang-nursery/nomicon#168)
- use sound/unsound terminology
## cargo
12 commits in a429e8cc4614a46a86322a0777a477e2baa83f1c..3a9abe3f065554a7fbc59f440df2baba4a6e47ee
2019-10-04 17:36:12 +0000 to 2019-10-15 15:55:35 +0000
- Fix typo in git index initialization error path (rust-lang/cargo#7512)
- Reject feature flags in a virtual workspace. (rust-lang/cargo#7507)
- Rename `overrides` to `package` in profiles. (rust-lang/cargo#7504)
- Allow publishing with dev-dependencies without a version. (rust-lang/cargo#7333)
- Stabilize cache-messages (rust-lang/cargo#7450)
- don't lock the package cache when cleaning target dir. (rust-lang/cargo#7502)
- Document rustc wrapper (rust-lang/cargo#7499)
- Migrate towards exclusively using serde for `Config` (rust-lang/cargo#7456)
- Re-enable some MSVC tests. (rust-lang/cargo#7492)
- when -Z unstable-options not specified, don't validate --profile (rust-lang/cargo#7489)
- Improve error message for cyclic dependencies (rust-lang/cargo#7470)
- Some minor clippy fixes. (rust-lang/cargo#7484)
## book
7 commits in 04806c80be0f54b1290287e3f85e84bdfc0b6ec7..9bb8b161963fcebc9d9ccd732ba26f42108016d5
2019-10-01 20:20:22 -0400 to 2019-10-14 18:42:55 -0500
- Make a portion of text less ambiguous (rust-lang/book#2092)
- fix heading level (rust-lang/book#2117)
- Add missing "of" before `"duck typing"`. (rust-lang/book#1951)
- ch18-03: no need to debug print destructured int (rust-lang/book#1991)
- Subtle fix to introduce ? on Option in Chapter 9.2 (rust-lang/book#2047)
- make wording clearer (rust-lang/book#1976)
- Update the version of rand we use
## rust-by-example
5 commits in a6288e7407a6c4c19ea29de6d43f40c803883f21..0b111eaae36cc4b4997684be853882a59e2c7ca7
2019-10-01 10:09:14 -0300 to 2019-10-14 18:34:25 -0300
- Some fix to three files (rust-lang/rust-by-example#1280)
- Add reference to Generics (rust-lang/rust-by-example#1281)
- Confusing and long sentence (rust-lang/rust-by-example#1282)
- Explicit mention of slice range meaning (rust-lang/rust-by-example#1277)
- Updated aliasing for nll (rust-lang/rust-by-example#1276)
use precalculated dominators in explain_borrow
This looks like the only place calculating dominators from the MIR body every time instead of using the ones stored on the `MirBorrowckCtxt`. For example, in rust-lang/rust#65131 a big generated function with a number of borrowck errors takes a few hours(!) recalculating the dominators while explaining the errors.
I don't know enough about this part of rustc codebase to know for sure that this change is correct, but no tests seem to fail as a result of this change in local testing.
Rollup of 14 pull requests
Successful merges:
- #64603 (Reducing spurious unused lifetime warnings.)
- #64623 (Remove last uses of gensyms)
- #65235 (don't assume we can *always* find a return type hint in async fn)
- #65242 (Fix suggestion to constrain trait for method to be found)
- #65265 (Cleanup librustc mir err codes)
- #65293 (Optimize `try_expand_impl_trait_type`)
- #65307 (Try fix incorrect "explicit lifetime name needed")
- #65308 (Add long error explanation for E0574)
- #65353 (save-analysis: Don't ICE when resolving qualified type paths in struct members)
- #65389 (Return `false` from `needs_drop` for all zero-sized arrays.)
- #65402 (Add troubleshooting section to PGO chapter in rustc book.)
- #65425 (Optimize `BitIter`)
- #65438 (Organize `never_type` tests)
- #65444 (Implement AsRef<[T]> for List<T>)
Failed merges:
- #65390 (Add long error explanation for E0576)
r? @ghost
Add troubleshooting section to PGO chapter in rustc book.
- Adds a note about using `-pgo-warn-missing-function` in order to spot mistakes in PGO setup.
- Mentions cargo symbol name issue fixed in 1.39.
Nominating for backport.
r? @alexcrichton
Return `false` from `needs_drop` for all zero-sized arrays.
Resolves#65348.
This changes the result of the `needs_drop` query from `true` to `false` for types such as `[Box<i32>; 0]`. I believe this change to be sound because a zero-sized array can never actually hold a value. This is an elegant way of resolving #65348 and #64945, but obviously it has much broader implications.
save-analysis: Don't ICE when resolving qualified type paths in struct members
Previously, we failed since we use `qpath_res` via typeck tables - when using those we need to pass in a HirId that's local to the definition path the tables are rooted at (otherwise we risk frame of reference mismatch and an assertion against invalid lookup).
In this case we can't get typeck tables for struct definition because it has no body, however the struct member type node is rooted under the struct definition and so we can't really do anything about it in terms of traversal.
Instead, we try to "nest" the tables as always but change the default behaviour to use empty typeck tables rather than silently trying to use the current ones. This does work as we expect and for prior art, we use the same approach in the [privacy](7bc94cc3c2/src/librustc_privacy/lib.rs (L332-L341)) [pass](7bc94cc3c2/src/librustc_privacy/lib.rs (L1007-L1028)).
Fixes#64659.
Fixes#64821.
r? @nikomatsakis (since this changes the default behaviour introduced in d7d3f197f6)
Optimize `try_expand_impl_trait_type`
A lot of time was being spent expanding some large `impl Future` types in fuchsia. This PR takes the number of types being visited in one expansion from >3 billion to about a thousand, and eliminates the compile time regression in https://github.com/rust-lang/rust/issues/65147 (in fact, compile times are better than they were before).
Thanks to @Mark-Simulacrum for helping identify the issue and to @matthewjasper for suggesting this change.
Fixes#65147.
r? @matthewjasper,@nikomatsakis
Cleanup librustc mir err codes
Three things are done in this PR:
* Sort error codes
* Uncomment an error code long error explanation (they should **never** be commented)
* Unify explanations
don't assume we can *always* find a return type hint in async fn
In particular, we sometimes cannot if there is an earlier error.
Fixes#65159
r? @cramertj, who reviewed the original PR
Remove last uses of gensyms
Underscore bindings now use unique `SyntaxContext`s to avoid collisions. This was the last use of gensyms in the compiler, so this PR also removes them.
closes#49300
cc #60869
r? @petrochenkov
This commit removes an `Option` check in `BitIter::next()`, avoids
calling `trailing_zeros()` when it's not necessary, and avoids the need
for `enumerate()`. This gives a tiny (0.2%) instruction count win on a
couple of benchmarks.
The commit also adds some comments, which is good because this iteration
code is moderately complex.
