Haiku: work around the lack of setrlimit
The default Unix codepath fails, because Haiku does not implement
setrlimit for stack size. Thus we create an additional path.
By default, Haiku has the desired 16 MB stack, therefore in general
we do not have to spawn a new thread. The code has been written in
such a way that any changes in Haiku or in Rust will be adapted to.
By default, Haiku has the desired 16 MB stack, therefore in general
we do not have to spawn a new thread. The code has been written in
such a way that any changes in Haiku or in Rust will be adapted to.
This is gated on edition 2018 & the `async_await` feature gate.
The parser will accept `async fn` and `async unsafe fn` as fn
items. Along the same lines as `const fn`, only `async unsafe fn`
is permitted, not `unsafe async fn`.The parser will not accept
`async` functions as trait methods.
To do a little code clean up, four fields of the function type
struct have been merged into the new `FnHeader` struct: constness,
asyncness, unsafety, and ABI.
Also, a small bug in HIR printing is fixed: it previously printed
`const unsafe fn` as `unsafe const fn`, which is grammatically
incorrect.
Add existential type definitions
Note: this does not allow creating named existential types, it just desugars `impl Trait` to a less (but still very) hacky version of actual `existential type` items.
r? @nikomatsakis
Use scope tree depths to speed up `nearest_common_ancestor`.
This patch adds depth markings to all entries in the `ScopeTree`'s
`parent_map`. This change increases memory usage somewhat, but permits a
much faster algorithm to be used:
- If one scope has a greater depth than the other, the deeper scope is
moved upward until they are at equal depths.
- Then we move the two scopes upward in lockstep until they match.
This avoids the need to keep track of which scopes have already been
seen, which was the major part of the cost of the old algorithm. It also
reduces the number of child-to-parent moves (which are hash table
lookups) when the scopes start at different levels, because it never
goes past the nearest common ancestor the way the old algorithm did.
Finally, the case where one of the scopes is the root is now handled in
advance, because that is moderately common and lets us skip everything.
This change speeds up runs of several rust-perf benchmarks, the best by
6%.
A selection of the bigger improvements:
```
clap-rs-check
avg: -2.6% min: -6.6% max: 0.0%
syn-check
avg: -2.2% min: -5.0% max: 0.0%
style-servo-check
avg: -2.9%? min: -4.8%? max: 0.0%?
cargo-check
avg: -1.3% min: -2.8% max: 0.0%
sentry-cli-check
avg: -1.0% min: -2.1% max: 0.0%
webrender-check
avg: -0.9% min: -2.0% max: 0.0%
style-servo
avg: -0.9%? min: -1.8%? max: -0.0%?
ripgrep-check
avg: -0.7% min: -1.8% max: 0.1%
clap-rs
avg: -0.9% min: -1.6% max: -0.2%
regex-check
avg: -0.2% min: -1.3% max: 0.1%
syn
avg: -0.6% min: -1.3% max: 0.1%
hyper-check
avg: -0.5% min: -1.1% max: 0.0%
```
The idea came from multiple commenters on my blog and on Reddit. Thank you!
r? @nikomatsakis
This patch adds depth markings to all entries in the `ScopeTree`'s
`parent_map`. This change increases memory usage somewhat, but permits a
much faster algorithm to be used:
- If one scope has a greater depth than the other, the deeper scope is
moved upward until they are at equal depths.
- Then we move the two scopes upward in lockstep until they match.
This avoids the need to keep track of which scopes have already been
seen, which was the major part of the cost of the old algorithm. It also
reduces the number of child-to-parent moves (which are hash table
lookups) when the scopes start at different levels, because it never
goes past the nearest common ancestor the way the old algorithm did.
Finally, the case where one of the scopes is the root is now handled in
advance, because that is moderately common and lets us skip everything.
This change speeds up runs of several rust-perf benchmarks, the best by
6%.
This leads to a lot of simplifications, as most code doesn't actually need to know about the specific lifetime/type data; rather, it's concerned with properties like name, index and def_id.
