Update til::bitmap to use dynamic_bitset<> + libpopcnt (#5092)
This commit replaces `std::vector<bool>` with `dynamic_bitset<>` by
@pinam45 (https://github.com/pinam45/dynamic_bitset) and with
`libpopcnt` for high-performance bit counting by @kimwalisch
(https://github.com/kimwalisch/libpopcnt).
* [x] In support of performance, incremental rendering, and Terminal
"not speed enough" as well as my sanity relative to
`std::vector<bool>`
* [x] Tests updated and passed.
* [x] `LICENSE`, `NOTICE`, and provenance files updated.
* [x] I'm a core contributor. I discussed it with @DHowett-MSFT and
cleared the licensing checks before pulling this in.
## Details `std::vector<bool>` provided by the Microsoft VC Runtime is
incapable of a great many things. Many of the methods you come to expect
off of `std::vector<T>` that are dutifully presented through the `bool`
variant will spontaneously fail at some future date because it decides
you allocated, resized, or manipulated the `vector<bool>` specialization
in an unsupported manner. Half of the methods will straight up not work
for filling/resizing in bulk. And you will tear your hair out as it will
somehow magically forget the assignment of half the bits you gave it
part way through an iteration then assert out and die.
As such, to preserve my sanity, I searched for an alternative. I came
across the self-contained header-only library `dynamic_bitset` by
@pinam45 which appears to do as much of `boost::dynamic_bitset` as I
wanted, but without including 400kg of boost libraries. It also has a
nifty optional dependency on `libpopcnt` by @kimwalisch that will use
processor-specific extensions for rapidly counting bits. @DHowett-MSFT
and I briefly discussed how nice `popcnt` would have been on
`std::vector<bool>` last week... and now we can have it. (To be fair, I
don't believe I'm using it yet... but we'll be able to easily dial in
`til::bitmap` soon and not worry about a performance hit if we do have
to walk bits and count them thanks to `libpopcnt`.)
This PR specifically focuses on swapping the dependencies out and
ingesting the new libraries. We'll further tune `til::bitmap` in future
pulls as necessary.
## Validation
* [x] Ran the automated tests for bitmap.
* [x] Ran the terminal manually and it looks fine still.
2020-03-25 03:41:10 +01:00
### Notes for Future Maintainers
This was originally imported by @miniksa in March 2020.
The provenance information (where it came from and which commit) is stored in the file `cgmanifest.json` in the same directory as this readme.
Please update the provenance information in that file when ingesting an updated version of the dependent library.
2021-08-26 23:40:26 +02:00
That provenance file is automatically read and inventoried by Microsoft systems to ensure compliance with appropriate governance standards.
Update til::bitmap to use dynamic_bitset<> + libpopcnt (#5092)
This commit replaces `std::vector<bool>` with `dynamic_bitset<>` by
@pinam45 (https://github.com/pinam45/dynamic_bitset) and with
`libpopcnt` for high-performance bit counting by @kimwalisch
(https://github.com/kimwalisch/libpopcnt).
* [x] In support of performance, incremental rendering, and Terminal
"not speed enough" as well as my sanity relative to
`std::vector<bool>`
* [x] Tests updated and passed.
* [x] `LICENSE`, `NOTICE`, and provenance files updated.
* [x] I'm a core contributor. I discussed it with @DHowett-MSFT and
cleared the licensing checks before pulling this in.
## Details `std::vector<bool>` provided by the Microsoft VC Runtime is
incapable of a great many things. Many of the methods you come to expect
off of `std::vector<T>` that are dutifully presented through the `bool`
variant will spontaneously fail at some future date because it decides
you allocated, resized, or manipulated the `vector<bool>` specialization
in an unsupported manner. Half of the methods will straight up not work
for filling/resizing in bulk. And you will tear your hair out as it will
somehow magically forget the assignment of half the bits you gave it
part way through an iteration then assert out and die.
As such, to preserve my sanity, I searched for an alternative. I came
across the self-contained header-only library `dynamic_bitset` by
@pinam45 which appears to do as much of `boost::dynamic_bitset` as I
wanted, but without including 400kg of boost libraries. It also has a
nifty optional dependency on `libpopcnt` by @kimwalisch that will use
processor-specific extensions for rapidly counting bits. @DHowett-MSFT
and I briefly discussed how nice `popcnt` would have been on
`std::vector<bool>` last week... and now we can have it. (To be fair, I
don't believe I'm using it yet... but we'll be able to easily dial in
`til::bitmap` soon and not worry about a performance hit if we do have
to walk bits and count them thanks to `libpopcnt`.)
This PR specifically focuses on swapping the dependencies out and
ingesting the new libraries. We'll further tune `til::bitmap` in future
pulls as necessary.
## Validation
* [x] Ran the automated tests for bitmap.
* [x] Ran the terminal manually and it looks fine still.
2020-03-25 03:41:10 +01:00
## What should be done to update this in the future?
1. Go to pinam45/dynamic_bitset repository on GitHub.
2. Take the entire contents of the include directory wholesale and drop it in the root directory here.
3. Don't change anything about it.
4. Validate that the license in the root of the repository didn't change and update it if so. It is sitting in the same directory as this readme.
If it changed dramatically, ensure that it is still compatible with our license scheme. Also update the NOTICE file in the root of our repository to declare the third-party usage.
5. Submit the pull.
