This uses quite a bit of unsafe code for speed and failure safety, and allocates `2*n` temporary storage.
[Performance](https://gist.github.com/huonw/5547f2478380288a28c2):
| n | new | priority_queue | quick3 |
|-------:|---------:|---------------:|---------:|
| 5 | 200 | 155 | 106 |
| 100 | 6490 | 8750 | 5810 |
| 10000 | 1300000 | 1790000 | 1060000 |
| 100000 | 16700000 | 23600000 | 12700000 |
| sorted | 520000 | 1380000 | 53900000 |
| trend | 1310000 | 1690000 | 1100000 |
(The times are in nanoseconds, having subtracted the set-up time (i.e. the `just_generate` bench target).)
I imagine that there is still significant room for improvement, particularly because both priority_queue and quick3 are doing a static call via `Ord` or `TotalOrd` for the comparisons, while this is using a (boxed) closure.
Also, this code does not `clone`, unlike `quick_sort3`; and is stable, unlike both of the others.
Now that the metadata is an owned value with a lifetime of a borrowed byte
slice, it's possible to have future optimizations where the metadata doesn't
need to be copied around (very expensive operation).
Now that the metadata is an owned value with a lifetime of a borrowed byte
slice, it's possible to have future optimizations where the metadata doesn't
need to be copied around (very expensive operation).
`[1e20, 1.0, -1e20].sum()` returns `0.0`. This happens because during
the summation, `1.0` is too small relative to `1e20`, making it
negligible.
I have tried Kahan summation but it hasn't fixed the problem.
Therefore, I've used Python's `fsum()` implementation.
For more details, read:
www.cs.cmu.edu/~quake-papers/robust-arithmetic.ps
https://github.com/mozilla/rust/issues/10851
Python's fsum (msum)
http://code.activestate.com/recipes/393090/
@huonw, your feedback is more than welcome.
It looks unpolished; Do you have suggestions how to make it more beautiful and elegant?
Thanks in advance,
For `str.as_mut_buf`, un-closure-ification is achieved by outright removal (see commit message). The others are replaced by `.as_ptr`, `.as_mut_ptr` and `.len`
`[1e20, 1.0, -1e20].sum()` returns `0.0`. This happens because during
the summation, `1.0` is too small relative to `1e20`, making it
negligible.
I have tried Kahan summation but it hasn't fixed the problem.
Therefore, I've used Python's `fsum()` implementation with some
help from Jason Fager and Huon Wilson.
For more details, read:
www.cs.cmu.edu/~quake-papers/robust-arithmetic.ps
Moreover, benchmark and unit tests were added.
Note: `Status.sum` is still not fully fixed. It doesn't handle
NaNs, infinities and overflow correctly. See issue 11059:
https://github.com/mozilla/rust/issues/11059
This code in resolve accidentally forced all types with an impl to become
public. This fixes it by default inheriting the privacy of what was previously
there and then becoming `true` if nothing else exits.
Closes#10545
The removal of the aliasing &mut[] and &[] from `shift_opt` also comes with its simplification.
The above also allows the use of `copy_nonoverlapping_memory` in `[].copy_memory` (I did an audit of each use of `.copy_memory` and `std::vec::bytes::copy_memory`, and I believe none of them are called with arguments can ever alias). This changes requires that `unsafe` code using `copy_memory` **needs** to respect the aliasing rules of `&mut[]`.
Understand 'pkgid' in stage0. As a bonus, the snapshot now contains now metadata
(now that those changes have landed), and the snapshot download is half as large
as it used to be!
This makes sure we always run benchmarks even if they are predicted to
take a long time, so that we have some non-zero time to display
(although the error bars may be huge for particularly slow benchmarks).
Fixes#9532.
This makes sure we always run benchmarks even if they are predicted to
take a long time, so that we have some non-zero time to display
(although the error bars may be huge for particularly slow benchmarks).
Fixes#9532.
This replaces the link meta attributes with a pkgid attribute and uses a hash
of this as the crate hash. This makes the crate hash computable by things
other than the Rust compiler. It also switches the hash function ot SHA1 since
that is much more likely to be available in shell, Python, etc than SipHash.
Fixes#10188, #8523.
This reverts commit c54427ddfb.
Leave the #[ignores] in that were added to rustpkg tests.
Conflicts:
src/librustc/driver/driver.rs
src/librustc/metadata/creader.rs
