Add ArrayVec and AccumulateVec to reduce heap allocations during interning of slices
Updates `mk_tup`, `mk_type_list`, and `mk_substs` to allow interning directly from iterators. The previous PR, #37220, changed some of the calls to pass a borrowed slice from `Vec` instead of directly passing the iterator, and these changes further optimize that to avoid the allocation entirely.
This change yields 50% less malloc calls in [some cases](https://pastebin.mozilla.org/8921686). It also yields decent, though not amazing, performance improvements:
```
futures-rs-test 4.091s vs 4.021s --> 1.017x faster (variance: 1.004x, 1.004x)
helloworld 0.219s vs 0.220s --> 0.993x faster (variance: 1.010x, 1.018x)
html5ever-2016- 3.805s vs 3.736s --> 1.018x faster (variance: 1.003x, 1.009x)
hyper.0.5.0 4.609s vs 4.571s --> 1.008x faster (variance: 1.015x, 1.017x)
inflate-0.1.0 3.864s vs 3.883s --> 0.995x faster (variance: 1.232x, 1.005x)
issue-32062-equ 0.309s vs 0.299s --> 1.033x faster (variance: 1.014x, 1.003x)
issue-32278-big 1.614s vs 1.594s --> 1.013x faster (variance: 1.007x, 1.004x)
jld-day15-parse 1.390s vs 1.326s --> 1.049x faster (variance: 1.006x, 1.009x)
piston-image-0. 10.930s vs 10.675s --> 1.024x faster (variance: 1.006x, 1.010x)
reddit-stress 2.302s vs 2.261s --> 1.019x faster (variance: 1.010x, 1.026x)
regex.0.1.30 2.250s vs 2.240s --> 1.005x faster (variance: 1.087x, 1.011x)
rust-encoding-0 1.895s vs 1.887s --> 1.005x faster (variance: 1.005x, 1.018x)
syntex-0.42.2 29.045s vs 28.663s --> 1.013x faster (variance: 1.004x, 1.006x)
syntex-0.42.2-i 13.925s vs 13.868s --> 1.004x faster (variance: 1.022x, 1.007x)
```
We implement a small-size optimized vector, intended to be used primarily for collection of presumed to be short iterators. This vector cannot be "upsized/reallocated" into a heap-allocated vector, since that would require (slow) branching logic, but during the initial collection from an iterator heap-allocation is possible.
We make the new `AccumulateVec` and `ArrayVec` generic over implementors of the `Array` trait, of which there is currently one, `[T; 8]`. In the future, this is likely to expand to other values of N.
Huge thanks to @nnethercote for collecting the performance and other statistics mentioned above.
check target abi support
This PR checks for each extern function / block whether the ABI / calling convention used is supported by the current target.
This was achieved by adding an `abi_blacklist` field to the target specifications, listing the calling conventions unsupported for that target.
Disallow Unsized Enums
Fixes#16812.
This PR is a potential fix for #16812, an issue which is reported [again](https://github.com/rust-lang/rust/issues/36801) and [again](https://github.com/rust-lang/rust/issues/36975), with over a dozen duplicates by now.
This PR is mainly meant to promoted discussion about the issue and the correct way to fix it.
This is a [breaking-change] since the error is now reported during wfchecking, so that even the definition of a (potentially) unsized enum will cause an error (whereas it would previously cause an ICE at trans time if the enum was used in an unsized manner).
Link to PathBuf from the Path docs
I got stuck trying to use `Path` when `PathBuf` was what I needed. Hopefully this makes `PathBuf` and the module docs a bit easier to find for others.
r? @steveklabnik
debuginfo: Use TypeIdHasher for generating global debuginfo type IDs.
The only requirement for debuginfo type IDs is that they are globally unique. The `TypeIdHasher` (which is used for `std::intrinsic::type_id()` provides that, so we can get rid of some redundancy by re-using it for debuginfo. Values produced by the `TypeIdHasher` are also more stable than the current `UniqueTypeId` generation algorithm produces -- these incorporate the `NodeId`s, which is not good for incremental compilation.
@alexcrichton @eddyb : Could you take a look at the endianess adaptations that I made to the `TypeIdHasher`?
Also, are we sure that a 64 bit hash is wide enough for something that is supposed to be globally unique? For debuginfo I'm using 160 bits to make sure that we don't run into conflicts there.
trans: Make names of internal symbols independent of CGU translation order
Every codegen unit gets its own local counter for generating new symbol names. This makes bitcode and object files reproducible at the binary level even when incremental compilation is used.
The PR also solves a rare ICE resulting from a naming conflict between a user defined name and a generated one. E.g. try compiling the following program with 1.12.1 stable:
```rust
pub fn str7233() -> &'static str { "foo" }
```
This results in:
> error: internal compiler error: ../src/librustc_trans/common.rs:979: symbol `str7233` is already defined
Running into this is not very likely but it's also easily avoidable.
Fix a error of 'book/deref-coercions.html'
The original sentence is:
> This example has two conversions: `Rc<String>` to `String` and then `String` to `&str`.
But it should be
> This example has two conversions: `Rc<String>` to `String` and then `String` to `str`.
or
> This example has two conversions: `&Rc<String>` to `&String` and then `&String` to `&str`.
I think the latter is more clearly.
r? @steveklabnik
Use `SmallVector` in `CombineFields::instantiate`.
This avoids 4% of malloc calls when compiling
rustc-benchmarks/issue-32278-big-array-of-strings, and 1--2% for other
benchmarks. A small win, but an easy one.
This avoids 4% of malloc calls when compiling
rustc-benchmarks/issue-32278-big-array-of-strings, and 1--2% for other
benchmarks. A small win, but an easy one.
Fix typo that resulted in comparison-to-self
This line was introduced in commit 843db01bd9, rebased from eddyb's c5f6f84d59b853b6a3485380721b71b479ece337.
I don't know whether this fixes anything in practice, but it seems like the changed version was what was intended originally.
r? @eddyb
libcore documentation for builtin macros
Fixes: #36272
Additionally I've edited docstring for `include!` a bit. (related PR #36404)
Unfortunately it seems there is no sane way to reexport empty macros definitions for their docstrings. To avoid copying the whole documentation for builtin macros I've only copied description and added links to `std` macro pages.
Implement `From<Cow<str>> for String` and `From<Cow<[T]>> for Vec<T>`.
Motivation: the `selectors` crate is generic over a string type, in order to support all of `String`, `string_cache::Atom`, and `gecko_string_cache::Atom`. Multiple trait bounds are used for the various operations done with these strings. One of these operations is creating a string (as efficiently as possible, re-using an existing memory allocation if possible) from `Cow<str>`.
The `std::convert::From` trait seems natural for this, but the relevant implementation was missing before this PR. To work around this I’ve added a `FromCowStr` trait in `selectors`, but with trait coherence that means one of `selectors` or `string_cache` needs to depend on the other to implement this trait. Using a trait from `std` would solve this.
The `Vec<T>` implementation is just added for consistency. I also tried a more general `impl<'a, O, B: ?Sized + ToOwned<Owned=O>> From<Cow<'a, B>> for O`, but (the compiler thinks?) it conflicts with `From<T> for T` the impl (after moving all of `collections::borrow` into `core::borrow` to work around trait coherence).
Ariel Ben-Yehuda
bors
Mark-Simulacrum
Jeffrey Seyfried
Tim Neumann
Jonathan Turner
Michael Woerister
Duncan
Nicholas Nethercote
Alex Crichton
Srinivas Reddy Thatiparthy