Rollup of 11 pull requests #52588
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Rollup of 11 pull requests #52588
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Deemphasize the secondary messages so that all other highlights stand out more.
LLVM isn't able to remove the alloca for the unaligned block in the SIMD tail in some cases, so doing this helps SRoA work in cases where it currently doesn't. Found in the `replace_with` RFC discussion.
… values The documentation of Unique::empty() and NonNull::dangling() could potentially suggest that they work as sentinel values indicating a not-yet-initialized pointer. However, they both declare a non-null pointer equal to the alignment of the type, which could potentially reference a valid value of that type (specifically, the first such valid value in memory). Explicitly document that the return value of these functions does not work as a sentinel value.
Due to a change in how mdbook generates section anchors, headers with non-alphabetic characters now start with "a".
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@bors r+ p=8 |
…excrichton Deprecation of str::slice_unchecked(_mut) Closes rust-lang#51715 I am not sure if 1.28.0 or 1.29.0 should be used for deprecation version, for now it's 1.28.0. Additionally I've replaced `slice_unchecked` uses with `get_unchecked`. The only places where this method is still used are `src/liballoc/tests/str.rs` and `src/liballoc/tests/str.rs`.
mem::swap the obvious way for types smaller than the SIMD optimization's block size
LLVM isn't able to remove the alloca for the unaligned block in the post-SIMD tail in some cases, so doing this helps SRoA work in cases where it currently doesn't. Found in the `replace_with` RFC discussion.
Examples of the improvements:
<details>
<summary>swapping `[u16; 3]` takes 1/3 fewer instructions and no stackalloc</summary>
```rust
type Demo = [u16; 3];
pub fn swap_demo(x: &mut Demo, y: &mut Demo) {
std::mem::swap(x, y);
}
```
nightly:
```asm
_ZN4blah9swap_demo17ha1732a9b71393a7eE:
.seh_proc _ZN4blah9swap_demo17ha1732a9b71393a7eE
sub rsp, 32
.seh_stackalloc 32
.seh_endprologue
movzx eax, word ptr [rcx + 4]
mov word ptr [rsp + 4], ax
mov eax, dword ptr [rcx]
mov dword ptr [rsp], eax
movzx eax, word ptr [rdx + 4]
mov word ptr [rcx + 4], ax
mov eax, dword ptr [rdx]
mov dword ptr [rcx], eax
movzx eax, word ptr [rsp + 4]
mov word ptr [rdx + 4], ax
mov eax, dword ptr [rsp]
mov dword ptr [rdx], eax
add rsp, 32
ret
.seh_handlerdata
.section .text,"xr",one_only,_ZN4blah9swap_demo17ha1732a9b71393a7eE
.seh_endproc
```
this PR:
```asm
_ZN4blah9swap_demo17ha1732a9b71393a7eE:
mov r8d, dword ptr [rcx]
movzx r9d, word ptr [rcx + 4]
movzx eax, word ptr [rdx + 4]
mov word ptr [rcx + 4], ax
mov eax, dword ptr [rdx]
mov dword ptr [rcx], eax
mov word ptr [rdx + 4], r9w
mov dword ptr [rdx], r8d
ret
```
</details>
<details>
<summary>`replace_with` optimizes down much better</summary>
Inspired by rust-lang/rfcs#2490,
```rust
fn replace_with<T, F>(x: &mut Option<T>, f: F)
where F: FnOnce(Option<T>) -> Option<T>
{
*x = f(x.take());
}
pub fn inc_opt(mut x: &mut Option<i32>) {
replace_with(&mut x, |i| i.map(|j| j + 1));
}
```
Rust 1.26.0:
```asm
_ZN4blah7inc_opt17heb0acb64c51777cfE:
mov rax, qword ptr [rcx]
movabs r8, 4294967296
add r8, rax
shl rax, 32
movabs rdx, -4294967296
and rdx, r8
xor r8d, r8d
test rax, rax
cmove rdx, rax
setne r8b
or rdx, r8
mov qword ptr [rcx], rdx
ret
```
Nightly (better thanks to ScalarPair, maybe?):
```asm
_ZN4blah7inc_opt17h66df690be0b5899dE:
mov r8, qword ptr [rcx]
mov rdx, r8
shr rdx, 32
xor eax, eax
test r8d, r8d
setne al
add edx, 1
mov dword ptr [rcx], eax
mov dword ptr [rcx + 4], edx
ret
```
This PR:
```asm
_ZN4blah7inc_opt17h1426dc215ecbdb19E:
xor eax, eax
cmp dword ptr [rcx], 0
setne al
mov dword ptr [rcx], eax
add dword ptr [rcx + 4], 1
ret
```
Where that add is beautiful -- using an addressing mode to not even need to explicitly go through a register -- and the remaining imperfection is well-known (rust-lang#49420 (comment)).
</details>
Reword when `_` couldn't be inferred r? @nikomatsakis
Add tests for ICEs which no longer repro Adds tests for some ICEs which no longer repro and closes the associated issues.
Avoid using `#[macro_export]` for documenting builtin macros Use a special `rustc_*` attribute instead. cc rust-lang#52234
Fix links in rustdoc book. Due to a change in how mdbook generates section anchors, headers with non-alphabetic characters now start with "a".
Add missing backtick in UniversalRegions doc comment
Add CI test harness for `thumb*` targets. [IRR-2018-embedded] This pull request will do the following (rather trivial) changes: - Fix rust-lang#52163. In other words, we enabled `./x.py test src/test/run-make` for `no_std` targets. - Modify `dist-various-1` Dockerfile. - CI now performs `run-make` test run on the targets below: - `thumbv6m-none-eabi` - `thumbv7m-none-eabi` - `thumbv7em-none-eabi` - `thumbv7em-none-eabihf`. - ~~Add `thumb-none` Dockerfile.~~ - ~~Initially, `thumbv7m-none-eabi`, `thumbv7em-none-eabi` and `thumbv7em-none-eabihf` are included as the tested target. `thumbv6m-none-eabi` is disabled for now because LLVM support is not certain.~~ - ~~Add `thumb-none` to .travis.yml~~ Note: - `run-make` tests are not implemented yet. This PR is test harness only. The amount of change is very small, but I'd like to open the pull request while the change is trivial. Because I'm not very used to pull request process, I want to make a small progress first. This PR will be a foundation for later additions.
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📌 Commit f79284a has been approved by |
bors
added
S-waiting-on-bors
…, r=GuillaumeGomez Remove highlighting from secondary messages Deemphasize the secondary messages so that all other highlights stand out more. <img width="684" alt="" src="https://user-images.githubusercontent.com/1606434/41261199-7b4fe96e-6d8f-11e8-8619-04d170617df2.png">
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📌 Commit 51f50ad has been approved by |
… r=Mark-Simulacrum Document that Unique::empty() and NonNull::dangling() aren't sentinel values The documentation of Unique::empty() and NonNull::dangling() could potentially suggest that they work as sentinel values indicating a not-yet-initialized pointer. However, they both declare a non-null pointer equal to the alignment of the type, which could potentially reference a valid value of that type (specifically, the first such valid value in memory). Explicitly document that the return value of these functions does not work as a sentinel value.
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📌 Commit 3c66e8b has been approved by |
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⌛ Testing commit 3c66e8b with merge 84454cc2a7ff990ee18efefd122d055e434a4053... |
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💔 Test failed - status-appveyor |
bors
added
S-waiting-on-review
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Successful merges:
thumb*targets. [IRR-2018-embedded] #52465 (Add CI test harness forthumb*targets. [IRR-2018-embedded])_couldn't be inferred #52507 (Reword when_couldn't be inferred)#[macro_export]for documenting builtin macros #52581 (Avoid using#[macro_export]for documenting builtin macros)Failed merges:
r? @ghost