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sdk/runtime
Alexander Aprelev 5b0285866d Revert "Reland "[vm] Recognize int.trailingZeroBitCount/oneBitCount as graph-inlinable""
This reverts commit 415b040d6f.

Reason for revert: breaks riscv https://github.com/dart-lang/sdk/issues/63479

Original change's description:
> 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 754239b077). 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>

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
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Iaf11d03d394fa615098bed8fcdea38ba40c7e45f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/507520
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Kevin Moore <kevmoo@google.com>
2026-05-29 10:29:33 -07:00
..
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2026-05-18 11:35:03 -07:00
2026-05-18 11:35:03 -07:00
2026-05-26 14:38:25 -07:00