Optimize insertion sort
This change slightly changes the main iteration loop so that LLVM can optimize it more efficiently.
Benchmark:
```
name before ns/iter after ns/iter diff ns/iter diff %
slice::sort_unstable_small_ascending 39 (2051 MB/s) 38 (2105 MB/s) -1 -2.56%
slice::sort_unstable_small_big_random 579 (2210 MB/s) 575 (2226 MB/s) -4 -0.69%
slice::sort_unstable_small_descending 80 (1000 MB/s) 70 (1142 MB/s) -10 -12.50%
slice::sort_unstable_small_random 396 (202 MB/s) 386 -10 -2.53%
```
The benchmark is not a fluke. I can see that performance on `small_descending` is consistently better after this change. I'm not 100% sure why this makes things faster, but my guess would be that `v.len()+1` to the compiler looks like it could in theory overflow.
Fix doc error for ExactSizeIterator
The code example in the trait documentation of ExactSizeIterator
has an incorrect implementation of the len method that does not return
the number of times the example iterator 'Counter' will iterate. This
may confuse readers of the docs as the example code will compile but
doesn't uphold the trait's contract.
This is easily fixed by modifying the implementation of len and changing
the assert statement to actually assert the correct behaviour. I also
slightly modified a code comment to better reflect what the method
returns.
str: Make docs consistently punctuated
Every so slightly pointless one character PR, but this was driving me nuts while reading the docs a moment ago (all the [other public structs](https://doc.rust-lang.org/std/str/index.html#structs) have descriptions that end in a full-stop).
The code example in the trait documentation of ExactSizeIterator
has an incorrect implementation of the len method that does not return
the number of times the example iterator 'Counter' will iterate. This
may confuse readers of the docs as the example code will compile but
doesn't uphold the trait's contract.
This is easily fixed by modifying the implementation of len and changing
the assert statement to actually assert the correct behaviour. I also
slightly modified a code comment to better reflect what the method
returns.
Extract book into a submodule
Part of https://github.com/rust-lang/rust/issues/39588
We probably don't want to land this till after the beta branches on friday, but would still ❤️ a review from @alexcrichton , since I am a rustbuild noob.
This pr:
1. removes the book
2. adds it back in as a submodule
3. the submodule includes both the old book and the new book
4. it also includes an index page explaining the difference in editions
5. it also includes redirect pages for the old book URLs.
6. so we build all that stuff too.
r? @alexcrichton
Rename TryFrom's associated type and implement str::parse using TryFrom.
Per discussion on the tracking issue, naming `TryFrom`'s associated type `Error` is generally more consistent with similar traits in the Rust ecosystem, and what people seem to assume it should be called. It also helps disambiguate from `Result::Err`, the most common "Err".
See https://github.com/rust-lang/rust/issues/33417#issuecomment-269108968.
`TryFrom<&str>` and `FromStr` are equivalent, so have the latter provide the former to ensure that. Using `TryFrom` in the implementation of `str::parse` means types that implement either trait can use it. When we're ready to stabilize `TryFrom`, we should update `FromStr` to
suggest implementing `TryFrom<&str>` instead for new code.
See https://github.com/rust-lang/rust/issues/33417#issuecomment-277175994
and https://github.com/rust-lang/rust/issues/33417#issuecomment-277253827.
Refs #33417.
Implemente overflowing_sh* with new unchecked_sh* intrinsics
Also update some 128 bit builtins to not rely on the constant evaluator to avoid checked operations.
Fixes#40508.
cc @nagisa, @alexcrichton
Note: I still have a build running to see if the 128 bit changes worked (unoptimized builds take *forever* to compile), however at least the overflowing builtins no longer reference `core::panicking::panic`.
Rename TryFrom's associated type and implement str::parse using TryFrom.
Per discussion on the tracking issue, naming `TryFrom`'s associated type `Error` is generally more consistent with similar traits in the Rust ecosystem, and what people seem to assume it should be called. It also helps disambiguate from `Result::Err`, the most common "Err".
See https://github.com/rust-lang/rust/issues/33417#issuecomment-269108968.
`TryFrom<&str>` and `FromStr` are equivalent, so have the latter provide the former to ensure that. Using `TryFrom` in the implementation of `str::parse` means types that implement either trait can use it. When we're ready to stabilize `TryFrom`, we should update `FromStr` to
suggest implementing `TryFrom<&str>` instead for new code.
See https://github.com/rust-lang/rust/issues/33417#issuecomment-277175994
and https://github.com/rust-lang/rust/issues/33417#issuecomment-277253827.
Refs #33417.
Change how the `0` flag works in format!
Now it always implies right-alignment, so that padding zeroes are placed after the sign (if any) and before the digits. In other words, it always takes precedence over explicitly specified `[[fill]align]`. This also affects the '#' flag: zeroes are placed after the prefix (0b, 0o, 0x) and before the digits.
Here's a short summary of how similar format strings work in Python and Rust:
```
:05 :<05 :>05 :^05
Python 3.6 |-0001| |-1000| |000-1| |0-100|
Rust before |-0001| |-1000| |-0001| |-0100|
Rust after |-0001| |-0001| |-0001| |-0001|
:#05x :<#05x :>#05x :^#05x
Python 3.6 |0x001| |0x100| |000x1| |00x10|
Rust before |0x001| |0x100| |000x1| |0x010|
Rust after |0x001| |0x001| |0x001| |0x001|
```
Fixes#39997 [breaking-change]
Drop of arrays is now translated in trans::block in an ugly way that I
should clean up in a later PR, and does not handle panics in the middle
of an array drop, but this commit & PR are growing too big.
Inline functions Ordering::{then, then_with}
@jongiddy noticed bad performance due to the lack of inlining on `then`
and `then_with`. I confirmed that inlining really is the culprit by
creating a custom `then` function and repeating his benchmark on my
machine with and without the `#[inline]` attribute.
The numbers were exactly the same on my machine without the attribute.
With `#[inline]` I got the same performance as I did with manually
inlined implementation.
The problem was reported in #37053.
A few improvements to the `core::hash` top-level docs.
Primarily opened to address the concerns brought up in
https://github.com/rust-lang/rust/issues/40498.
* run rustfmt on code blocks
* use `DefaultHasher` instead of deprecated `SipHasher`
* rename `hash` to `calculate_hash` to prevent confusion with the `hash`
method
Now it always implies right-alignment, so that padding zeroes are placed after the sign (if any) and before the digits. In other words, it always takes precedence over explicitly specified `[[fill]align]`.
:06 :<06 :>06 :^06
before |-001.2| |-1.200| |-001.2| |-01.20|
after |-001.2| |-001.2| |-001.2| |-001.2|
Now it always implies right-alignment, so that padding zeroes are placed after the sign (if any) and before the digits. In other words, it always takes precedence over explicitly specified `[[fill]align]`. This also affects the '#' flag: zeroes are placed after the prefix (0b, 0o, 0x) and before the digits.
:05 :<05 :>05 :^05
before |-0001| |-1000| |-0001| |-0100|
after |-0001| |-0001| |-0001| |-0001|
:#05x :<#05x :>#05x :^#05x
before |0x001| |0x100| |000x1| |0x010|
after |0x001| |0x001| |0x001| |0x001|
Fixes#39997 [breaking-change]
@jongiddy noticed bad performance due to the lack of inlining on `then`
and `then_with`. I confirmed that inlining really is the culprit by
creating a custom `then` function and repeating his benchmark on my
machine with and without the `#[inline]` attribute.
The numbers were exactly the same on my machine without the attribute.
With `#[inline]` I got the same performance as I did with manually
inlined implementation.
