Rollup of 8 pull requests
Successful merges:
- #67585 (Improve `char::is_ascii_*` codegen)
- #68914 (Speed up `SipHasher128`.)
- #68994 (rustbuild: include channel in sanitizers installed name)
- #69032 (ICE in nightly-2020-02-08: handle TerminatorKind::Yield in librustc_mir::transform::promote_consts::Validator method)
- #69034 (parser: Remove `Parser::prev_token_kind`)
- #69042 (Remove backtrace header text)
- #69059 (Remove a few unused objects)
- #69089 (Properly use the darwin archive format on Apple targets)
Failed merges:
r? @ghost
Remove a few unused objects
As far as I can tell, these won't be missed:
- `infer::region_constraints::ConstraintInfo`
- `driver::DefaultCallbacks`
- ~~`hir::intravisit::ParDeepVisitor`~~
ICE in nightly-2020-02-08: handle TerminatorKind::Yield in librustc_mir::transform::promote_consts::Validator method
IR: https://github.com/rust-lang/rust/issues/69017
regressed commit: f8fd462447
Source: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=55e65a869e1f5fef64cc4462b1a5a087
Addresses ICE reported in #69017 by handling `TerminatorKind::Yield` in 4d1241f515/src/librustc_mir/transform/promote_consts.rs (L465-L468).
<details><summary>Nightly build</summary>
<p>
```
$ cargo +nightly build
Compiling yielder v0.1.0 (/Users/chris/Desktop/tests/rustlang-tests/yielder)
error: internal compiler error: src/librustc_mir/transform/promote_consts.rs:467: _1 = suspend(move _21) -> [resume: bb2, drop: bb3] not promotable
--> src/main.rs:8:27
|
8 | println!("-> {}", yield);
| ^^^^^
thread 'rustc' panicked at 'Box<Any>', <::std::macros::panic macros>:2:4
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: rustc 1.43.0-nightly (71c7e149e 2020-02-09) running on x86_64-apple-darwin
note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin
note: some of the compiler flags provided by cargo are hidden
error: aborting due to previous error
error: could not compile `yielder`.
To learn more, run the command again with --verbose.
```
</p>
</details>
<details><summary>Stage 1 dev build</summary>
<p>
```
$ cargo +stage1 build
Compiling yielder v0.1.0 (/Users/chris/Desktop/tests/rustlang-tests/yielder)
warning: function is never used: `gen`
--> src/main.rs:6:4
|
6 | fn gen() -> impl Generator<usize> {
| ^^^
|
= note: `#[warn(dead_code)]` on by default
Finished dev [unoptimized + debuginfo] target(s) in 0.53s
```
</p>
</details>
@jonas-schievink @oli-obk
rustbuild: include channel in sanitizers installed name
Allows parallel install of different rust channels.
I'm not sure if the channel is the right thing to use there, but currently both beta and nightly try to install e.g. `/usr/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_rt.asan.a` when before (and in current stable) it used to be `/usr/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_asan-45a4390180e83d28.rlib` which contained a hash, making it unique.
With this patch, `/usr/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc-nightly_rt.asan.a` gets installed
Speed up `SipHasher128`.
The current code in `SipHasher128::short_write` is inefficient. It uses
`u8to64_le` (which is complex and slow) to extract just the right number of
bytes of the input into a u64 and pad the result with zeroes. It then
left-shifts that value in order to bitwise-OR it with `self.tail`.
For example, imagine we have a u32 input `0xIIHH_GGFF` and only need three bytes
to fill up `self.tail`. The current code uses `u8to64_le` to construct
`0x0000_0000_00HH_GGFF`, which is just `0xIIHH_GGFF` with the `0xII` removed and
zero-extended to a u64. The code then left-shifts that value by five bytes --
discarding the `0x00` byte that replaced the `0xII` byte! -- to give
`0xHHGG_FF00_0000_0000`. It then then ORs that value with `self.tail`.
There's a much simpler way to do it: zero-extend to u64 first, then left shift.
E.g. `0xIIHH_GGFF` is zero-extended to `0x0000_0000_IIHH_GGFF`, and then
left-shifted to `0xHHGG_FF00_0000_0000`. We don't have to take time to exclude
the unneeded `0xII` byte, because it just gets shifted out anyway! It also avoids
multiple occurrences of `unsafe`.
There's a similar story with the setting of `self.tail` at the method's end.
The current code uses `u8to64_le` to extract the remaining part of the input,
but the same effect can be achieved more quickly with a right shift on the
zero-extended input.
This commit changes `SipHasher128` to use the simpler shift-based approach. The
code is also smaller, which means that `short_write` is now inlined where
previously it wasn't, which makes things faster again. This gives big
speed-ups for all incremental builds, especially "baseline" incremental
builds.
r? @michaelwoerister
Improve `char::is_ascii_*` codegen
This PR is an attempt to fix https://github.com/rust-lang/rust/issues/65127
A couple of warnings:
1. the generated code might be further improved (in LLVM and/or MIR) by emitting better comparison sequences; in particular, this would improve the performance of "complex" checks such as those in `is_ascii_punctuation`
2. the second commit is currently marked "DO NOT MERGE", because it regresses SIMD on `u8` slices; this could likely be fixed by improving the computation/usage of demanded bits in LLVM
An alternative approach to remove the code duplication might be the use of macros, but currently most of the duplication is actually in the doc comments, so maybe just keeping the redundancy could be ok
Migrate borrowck dataflow impls to new framework
This uses #65672 to implement the dataflow analyses needed by borrowck. These include all the `InitializedPlaces` analyses as well as `Borrows`. Additionally, this PR contains several independent changes around the dataflow API which improve performance and make it more ergonomic.
* An optimization that inhibits the caching of block transfer functions for acyclic MIR (~0.3% I-CNT savings).
* A `ResultsVisitor` for dataflow results that is more efficient than `ResultsCursor` when we have to visit every statement unconditionally (~0.3% I-CNT savings).
* An `into_engine` method on `Analysis` that selects the appropriate `Engine` constructor.
* A `contains` method for `ResultsCursor` as a shorthand for `.get().contains()`.
* A `find_descendants` helper on `MovePath` that replaces `has_any_child_of` on the old `FlowsAtLocation`
These changes made porting the dataflow analyses much easier. Finally, this PR removes some now-unused code in `dataflow/at_location.rs` and elsewhere.
You can view the perf results for the final version of this PR [here](https://perf.rust-lang.org/compare.html?start=29b854fb741809c29764e33fc17c32ba9c6523ba&end=6e516c1410c18cfe4eb6d030a39fdb73c8d8a4fe). Here's an example of the graphviz diagrams that are generated for the `MaybeInitializedPlaces` analysis.
Preparation for allocator aware `Box`
This cleans up the `Box` code a bit, and uses `Box::from_raw(ptr)` instead of `Box(ptr)`.
Additionally, `box_free` and `exchange_malloc` now uses the `AllocRef` trait and a comment was added on how `box_free` is tied to `Box`.
This a preparation for an upcoming PR, which makes `Box` aware of an allocator.
r? @Amanieu
Add missing `_zeroed` varants to `AllocRef`
The majority of the allocator wg has decided to add the missing `_zeroed` variants to `AllocRef`:
> these should be added since they can be efficiently implemented with the `mremap` system call on Linux. `mremap` allows you to move/grow/shrink a memory mapping, and any new pages added for growth are guaranteed to be zeroed.
>
> If `AllocRef` does not have these methods then the user will have to manually write zeroes to the added memory since the API makes no guarantees on their contents.
For the full discussion please see https://github.com/rust-lang/wg-allocators/issues/14.
This PR provides default implementations for `realloc_zeroed`, `alloc_excess_zeroed`, `realloc_excess_zeroed`, and `grow_in_place_zeroed`.
r? @Amanieu
Remove common usage pattern from `AllocRef`
This removes the common usage patterns from `AllocRef`:
- `alloc_one`
- `dealloc_one`
- `alloc_array`
- `realloc_array`
- `dealloc_array`
Actually, they add nothing to `AllocRef` except a [convenience wrapper around `Layout` and other methods in this trait](https://doc.rust-lang.org/1.41.0/src/core/alloc.rs.html#1076-1240) but have a major flaw: The documentation of `AllocRefs` notes, that
> some higher-level allocation methods (`alloc_one`, `alloc_array`) are well-defined on zero-sized types and can optionally support them: it is left up to the implementor whether to return `Err`, or to return `Ok` with some pointer.
With the current API, `GlobalAlloc` does not have those methods, so they cannot be overridden for `liballoc::Global`, which means that even if the global allocator would support zero-sized allocations, `alloc_one`, `alloc_array`, and `realloc_array` for `liballoc::Global` will error, while calling `alloc` with a zeroed-size `Layout` could succeed. Even worse: allocating with `alloc` and deallocating with `dealloc_{one,array}` could end up with not calling `dealloc` at all!
For the full discussion please see https://github.com/rust-lang/wg-allocators/issues/18
r? @Amanieu
Python script PEP8 style guide space formatting and minor Python source cleanup
This PR includes the following changes in the Python sources based on a flake8 3.7.9 (mccabe: 0.6.1, pycodestyle: 2.5.0, pyflakes: 2.1.1) CPython 3.7.6 on Darwin lint:
- PEP8 style guide spacing updates *without* line length changes
- removal of unused local variable assignments in context managers and exception handling
- removal of unused Python import statements
- removal of unnecessary semicolons
Test failure of unchecked arithmetic intrinsics in const eval
Test that the unchecked arithmetic intrinsics that were made unstably const in #68809 emit an error during const-eval if given invalid input.
Addresses [this comment](https://github.com/rust-lang/rust/pull/68809#discussion_r375753066).
r? @RalfJung
[experiment] Support linking from a .rlink file
Flag `-Z no-link` was previously introduced, which allows creating an `.rlink` file to perform compilation without linking. This change enables linking from an `.rlink` file.
Part of Issue #64191
This makes it faster and also changes it to a safe function. (Thanks to
Michael Woerister for the suggestion.) `load_int_le!` is also no longer
necessary.
