Files
sdk/pkg
Modestas Valauskas 754239b077 [core] Add trailingZeroBitCount and oneBitCount to int
Adds two new getters to int for bit-counting: trailingZeroBitCount
(ctz) and oneBitCount (popcount). On native platforms they operate
on the full 64-bit two's-complement representation; on the web they
operate on the least-significant 32 bits.

Implementations:
- VM: unified C++ natives Integer_trailingZeroBitCount /
  Integer_oneBitCount on _IntegerImplementation, using
  Utils::CountTrailingZeros64 and Utils::CountOneBits64. The receiver
  may be _Smi or _Mint at runtime.
- dart2js / DDC: clz32-based ctz and a SWAR popcount.
- dart2wasm: inlined i64.ctz and i64.popcnt intrinsics.

leadingZeroBitCount (clz) is intentionally excluded from this CL: its
result depends on the platform integer width (e.g. 1.leadingZeroBitCount
is 31 on web, 63 on native), and the same value can be derived from
the existing bitLength getter when needed.

Asm intrinsification on native architectures is intentionally left for
a separate follow-up CL.

Work towards https://github.com/dart-lang/sdk/issues/6486 (this CL
covers popcount and ctz from the bit-twiddling list; clz, rotate,
reverse, and others remain).

Work towards https://github.com/dart-lang/sdk/issues/1053 (efficient
BitSet implementation).

Bug: https://github.com/dart-lang/sdk/issues/52673
Bug: https://github.com/dart-lang/sdk/issues/38346
TEST=tests/corelib/int_bit_count_test

Change-Id: I8a5cdb5c91360478f47bbd6b9c84ca1c477aa8c7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/498041
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Stephen Adams <sra@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Auto-Submit: Modestas Valauskas <valauskasmodestas@gmail.com>
Reviewed-by: Lasse Nielsen <lrn@google.com>
2026-05-12 05:49:31 -07:00
..
2026-05-12 00:24:55 -07:00
2026-05-01 11:29:56 -07:00
2026-05-01 11:29:56 -07:00
2026-05-06 16:14:04 -07:00
2026-05-05 14:04:00 -07:00

Package validation

The packages in pkg/ are automatically validated on the LUCI CI bots. The validation is largely done by the tools/package_deps package; it can be tested locally via:

dart tools/package_deps/bin/package_deps.dart

Packages which are published

There are several packages developed in pkg/ which are published to pub. Validation of these packages is particularly important because the pub tools are not used for these packages during development; we get our dependency versions from the DEPS file. It's very easy for the dependencies specified in a package's pubspec file to get out of date wrt the packages and versions actually used.

In order to better ensure we're publishing correct packages, we validate some properties of the pubspec files on our CI system. These validations include:

  • that the dependencies listed in the pubspec are used in the package
  • that all the packages used by the source are listed in the pubspec
  • that we don't use relative path deps to pkg/ or third_party/ packages

Packages which are not published

For packages in pkg/ which we do not intend to be published, we put the following comment in the pubspec.yaml file:

# This package is not intended for consumption on pub.dev. DO NOT publish.
publish_to: none

These pubspecs are still validated by the package validation tool. The contents are more informational as the pubspecs for these packages are not consumed by the pub tool or ecosystem.

We validate:

  • that the dependencies listed in the pubspec are used in the package
  • that all the packages used by the source are listed in the pubspec
  • that a reference to a pkg/ package is done via a relative path dependency

Adding new packages

Run gclient sync to re-generate .dart_tool/package_config.json after adding a new package.

Testing packages

Currently dart test can't be used to run the tests, use test.py as usual. E.g. the command ./tools/test.py -n...<path> runs all tests with prefix <path>.