rustc: Improve type size assertions
Now they
- Tell what the new size is, when it changes
- Do not require passing an identifier
```
::: src\libsyntax\parse\token.rs:223:1
|
223 | static_assert_size!(Token, 123);
| -------------------------------- in this macro invocation
|
= note: expected type `[(); 123]`
found type `[(); 16]`
```
Refactor passes and pass execution to be more parallel
For `syntex_syntax` (with 16 threads and 8 cores):
- Cuts `misc checking 1` from `0.096s` to `0.08325s`.
- Cuts `misc checking 2` from `0.3575s` to `0.2545s`.
- Cuts `misc checking 3` from `0.34625s` to `0.21375s`.
- Cuts `wf checking` from `0.3085s` to `0.05025s`.
Reduces overall execution time for `syntex_syntax` (with 8 threads and cores) from `4.92s` to `4.34s`.
Subsumes https://github.com/rust-lang/rust/pull/58494
Blocked on https://github.com/rust-lang/rust/pull/58250
r? @michaelwoerister
Cosmetic improvements to doc comments
This has been factored out from https://github.com/rust-lang/rust/pull/58036 to only include changes to documentation comments (throughout the rustc codebase).
r? @steveklabnik
Once you're happy with this, maybe we could get it through with r=1, so it doesn't constantly get invalidated? (I'm not sure this will be an issue, but just in case...) Anyway, thanks for your advice so far!
This commit changes `syntax::fold::Folder` from a functional style
(where most methods take a `T` and produce a new `T`) to a more
imperative style (where most methods take and modify a `&mut T`), and
renames it `syntax::mut_visit::MutVisitor`.
The first benefit is speed. The functional style does not require any
reallocations, due to the use of `P::map` and
`MoveMap::move_{,flat_}map`. However, every field in the AST must be
overwritten; even those fields that are unchanged are overwritten with
the same value. This causes a lot of unnecessary memory writes. The
imperative style reduces instruction counts by 1--3% across a wide range
of workloads, particularly incremental workloads.
The second benefit is conciseness; the imperative style is usually more
concise. E.g. compare the old functional style:
```
fn fold_abc(&mut self, abc: ABC) {
ABC {
a: fold_a(abc.a),
b: fold_b(abc.b),
c: abc.c,
}
}
```
with the imperative style:
```
fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
visit_a(a);
visit_b(b);
}
```
(The reductions get larger in more complex examples.)
Overall, the patch removes over 200 lines of code -- even though the new
code has more comments -- and a lot of the remaining lines have fewer
characters.
Some notes:
- The old style used methods called `fold_*`. The new style mostly uses
methods called `visit_*`, but there are a few methods that map a `T`
to something other than a `T`, which are called `flat_map_*` (`T` maps
to multiple `T`s) or `filter_map_*` (`T` maps to 0 or 1 `T`s).
- `move_map.rs`/`MoveMap`/`move_map`/`move_flat_map` are renamed
`map_in_place.rs`/`MapInPlace`/`map_in_place`/`flat_map_in_place` to
reflect their slightly changed signatures.
- Although this commit renames the `fold` module as `mut_visit`, it
keeps it in the `fold.rs` file, so as not to confuse git. The next
commit will rename the file.
