Reland "[vm] Recognize int.trailingZeroBitCount/oneBitCount as graph-inlinable"
The previous attempt was reverted because it broke unoptimized JIT
on ARM 32. This reland force-optimizes the two getters.
Stacks on top of the int.{trailingZeroBitCount,oneBitCount} API CL
(commit 754239b077e). Both getters route through OTHER_RECOGNIZED_LIST
when a hardware fast path is available; otherwise the newly added
Dart bodies inline at call sites via vm:prefer-inline. The C++
natives are removed.
Backend codegen
---------------
ARM64: NEON CNT + UADDLV (popcount); RBIT + CLZ (ctz).
ARM: NEON CNT + VPADDL chain (popcount); RBIT + CLZ on the
register pair (ctz).
x64: popcntq when TargetCPUFeatures::popcnt_supported();
LoadImmediate(64) + rep_bsfq for ctz (decodes as tzcnt
on BMI1+, preserves dest on zero otherwise).
RISC-V 64: cpop / ctz when RV_baseline includes Zbb.
Per-arch availability is encapsulated in
UnaryInt64OpInstr::IsSupported(Token::Kind).
Apple M-series ARM64, AOT (us/iter, lower is better):
cardinality.swar 371
cardinality.accelerated 154 (2.4x)
forEachSetBit.swar 19031
forEachSetBit.accelerated 4988 (3.8x)
select.swar 199
select.accelerated 77 (2.6x)
complementCardinality.swar 399
complementCardinality.accel 152 (2.6x)
Work towards https://github.com/dart-lang/sdk/issues/6486 (popcount
and ctz intrinsification).
Work towards https://github.com/dart-lang/sdk/issues/1053 (efficient
BitSet implementation).
Fixes https://github.com/dart-lang/sdk/issues/52673
Fixes https://github.com/dart-lang/sdk/issues/38346
Fixes https://github.com/dart-lang/sdk/issues/63436
Issue https://github.com/dart-lang/sdk/issues/10212
Issue https://github.com/dart-lang/sdk/issues/5798
TEST=tests/corelib/int_bit_count_test
Cq-Include-Trybots: luci.dart.try:vm-linux-release-simarm-try,vm-ffi-qemu-linux-release-arm-try,vm-aot-linux-release-simarm_x64-try,vm-aot-linux-debug-simarm_x64-try,dart-sdk-linux-riscv64-try
Change-Id: Ib812cbaec6e371b9720df7a543411f78e524cac1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/506060
Reviewed-by: Martin Kustermann <kustermann@google.com>
Auto-Submit: Modestas Valauskas <valauskasmodestas@gmail.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
Dart is:
Approachable: Develop with a strongly typed programming language that is consistent, concise, and offers modern language features like null safety and patterns.
Portable: Compile to ARM, x64, or RISC-V machine code for mobile, desktop, and backend. Compile to JavaScript or WebAssembly for the web.
Productive: Make changes iteratively: use hot reload to see the result instantly in your running app. Diagnose app issues using DevTools.
Dart's flexible compiler technology lets you run Dart code in different ways, depending on your target platform and goals:
Dart Native: For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.
Dart Web: For programs targeting the web, Dart Web includes both a development time compiler (dartdevc) and a production time compiler (dart2js).
Dart is free and open source.
See LICENSE and PATENT_GRANT.
Visit dart.dev to learn more about the language, tools, and to find codelabs.
Browse pub.dev for more packages and libraries contributed by the community and the Dart team.
Our API reference documentation is published at api.dart.dev, based on the stable release. (We also publish docs from our beta and dev channels, as well as from the primary development branch).
If you want to build Dart yourself, here is a guide to getting the source, preparing your machine to build the SDK, and building.
There are more documents in our repo at docs.
The easiest way to contribute to Dart is to file issues.
You can also contribute patches, as described in Contributing.
Future plans for Dart are included in the combined Dart and Flutter roadmap on the Flutter wiki.