rewrite the predecessors code to create a reduced graph
The old code created a flat listing of "HIR -> WorkProduct" edges.
While perfectly general, this could lead to a lot of repetition if the
same HIR nodes affect many work-products. This is set to be a problem
when we start to skip typeck, since we will be adding a lot more
"work-product"-like nodes.
The newer code uses an alternative strategy: it "reduces" the graph
instead. Basically we walk the dep-graph and convert it to a DAG, where
we only keep intermediate nodes if they are used by multiple
work-products.
This DAG does not contain the same set of nodes as the original graph,
but it is guaranteed that (a) every output node is included in the graph
and (b) the set of input nodes that can reach each output node is
unchanged.
(Input nodes are basically HIR nodes and foreign metadata; output nodes
are nodes that have assocaited state which we will persist to disk in
some way. These are assumed to be disjoint sets.)
r? @michaelwoerister
Fixes#39494
Miscellaneous refactors around how lints and typeck interact
This is preparation for making incr. comp. skip typeck. The main gist of is trying to rationalize the outputs from typeck that are not part of tables:
- one bit of output is the `used_trait_imports` set, which becomes something we track for dependencies
- the other big of output are various lints; we used to store these into a table on sess, but this work stores them into the`TypeckTables`, and then makes the lint pass consult that
- I think it probably makes sense to handle errors similarly, eventually, but that's not necessary now
r? @eddyb
Fixes#39495
std: Add ToString trait specialization for Cow<'a, str> and String
There is a specialized version of ToString for str type in std. I think there are other types can also benefit from specialization. `Cow` and `String` are the most obvious one.
r? @bluss
Bump version, upgrade bootstrap
This commit updates the version number to 1.17.0 as we're not on that version of
the nightly compiler, and at the same time this updates src/stage0.txt to
bootstrap from freshly minted beta compiler and beta Cargo.
This commit updates the version number to 1.17.0 as we're not on that version of
the nightly compiler, and at the same time this updates src/stage0.txt to
bootstrap from freshly minted beta compiler and beta Cargo.
Use `String::with_capacity` in `format!`
Add an `Arguments::estimated_capacity` to estimate the length of formatted text and use it in `std::fmt::format` as the initial capacity of the buffer.
The capacity is calculated based on the literal parts of format string, see the details in the implementation.
Some benches:
```rust
empty: format!("{}", black_box(""))
literal: format!("Literal")
long: format!("Hello Hello Hello Hello, {}!", black_box("world"))
long_rev: format!("{}, hello hello hello hello!", black_box("world"))
long_rev_2: format!("{}{}, hello hello hello hello!", 1, black_box("world"))
short: format!("Hello, {}!", black_box("world"))
short_rev: format!("{}, hello!", black_box("world"))
short_rev_2: format!("{}{}, hello!", 1, black_box("world"))
surround: format!("aaaaa{}ccccc{}eeeee", black_box("bbbbb"), black_box("eeeee"))
two_spaced: format!("{} {}", black_box("bbbbb"), black_box("eeeee"))
worst_case: format!("{} a long piece...", black_box("and even longer argument. not sure why it has to be so long"))
```
```
empty 25 28 3 12.00%
literal 35 29 -6 -17.14%
long 80 46 -34 -42.50%
long_rev 79 45 -34 -43.04%
long_rev_2 111 66 -45 -40.54%
short 73 46 -27 -36.99%
short_rev 74 76 2 2.70%
short_rev_2 107 108 1 0.93%
surround 142 65 -77 -54.23%
two_spaced 111 115 4 3.60%
worst_case 89 101 12 13.48%
```
rustbuild: Build jemalloc and libbacktrace only once (take 2)
This is a rebase of https://github.com/rust-lang/rust/pull/38583 without any additions, but with implemented @alexcrichton's suggestions.
~~This includes `exists(Makefile)` => `cfg(stage0)` suggestion... but it will break cross-compilation, no? Are `libstd/liballoc_jemalloc` cross-compiled for `target != host` built during `stage0`?~~
r? @alexcrichton
Extend Cell to work with non-Copy types
I'm not sure that I did this right but all of the tests pass.
I also had to move the `new()` function so that `Cell`s with non-`Copy` `T`s could be created. That wasn't in the RFC but I assume it needed to be done?
The previous way was not friendly to incremental compilation. The new
plan is to compute, for each body, a set of trait imports used in that
body (slightly subtle: for a closure, we assign the trait imports to the
enclosing fn). Then we walk all bodies and union these sets. The reason
we do this is that we can save the individual sets in the incremental
state, and then recompute only those sets that are needed. Before we
were planning to save only the final union, but in that case if some
components are invalidated we have to recompute *all* of them since we
don't have enough information to "partly" invalidate a result.
In truth, this set probably ought to be part of the `TypeckTables`;
however, I opted not to do that because I don't want to have to
save/restore the entire tables in the incremental state yet (since it
contains a lot of `NodeId` references, and removing those is a
significant refactoring).
