perf(fastlanes): fuse bit-packed compare into a transposed mask + untranspose#8239
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joseph-isaacs wants to merge 8 commits into
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perf(fastlanes): fuse bit-packed compare into a transposed mask + untranspose#8239joseph-isaacs wants to merge 8 commits into
joseph-isaacs wants to merge 8 commits into
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Add `bitpack_compare_sweep`, which exercises the public `array.binary(rhs, op)` compare-against-constant path over all eight integer types and every valid bit width (64Ki in-range elements per case, no patches). It isolates the `<BitPacked as CompareKernel>` unpack + per-element compare kernel so a kernel change shows up as a CodSpeed diff. Signed-off-by: Joe Isaacs <joe.isaacs@live.co.uk>
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Merging this PR will not alter performance
|
| Mode | Benchmark | BASE |
HEAD |
Efficiency | |
|---|---|---|---|---|---|
| ❌ | Simulation | chunked_varbinview_canonical_into[(100, 100)] |
269.9 µs | 304.9 µs | -11.47% |
| ❌ | Simulation | baseline_lt[16, 65536] |
216.1 µs | 244.1 µs | -11.44% |
| ⚡ | Simulation | chunked_varbinview_canonical_into[(1000, 10)] |
197.1 µs | 160.7 µs | +22.59% |
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Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.
Comparing claude/confident-hamilton-mZIEo (211903c) with develop (4e6e9ed)
…ranspose Replace the unpack-then-compare streaming kernel for compare-against-constant with the FastLanes fused `unpack_cmp`: compare each value as it is unpacked, accumulating results straight into a transposed 1024-bit mask (`[u64; 16]`, one register-resident word per lane - no `[bool; 1024]`/`[T; 1024]` scratch), then a single SIMD `untranspose_bits` per block rotates the mask into logical row order, copied directly into the output bit buffer. Inline patches are spliced in afterwards; sliced (offset != 0) arrays fall back to the scalar streaming predicate. This requires the in-development FastLanes (PR #141 fused mask + PR #145 width-generic BMI2/VBMI untranspose), pinned via a git patch until released. Benchmarked end-to-end through the public compare path (`bitpack_compare_sweep`, 64Ki elements, all integer types and bit widths): fused beats the streaming baseline for every type and width - i8/u8 ~6.2-7.7x i16/u16 ~4.5-6.0x i32/u32 ~1.9-4.3x i64/u64 ~1.2-1.9x Signed-off-by: Joe Isaacs <joe.isaacs@live.co.uk>
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| [patch.crates-io] | ||
| fastlanes = { git = "https://github.com/spiraldb/fastlanes", rev = "6c10ea72cf693a17e994aa6401604ebedbeda453" } |
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We will remove this before we merge this PR
…space wasm-test is excluded from the workspace, so it does not inherit the root [patch.crates-io] and was building vortex-fastlanes against published fastlanes 0.5.0 (old `[bool;1024]` unpack_cmp, no `untranspose_bits`) -> compile error in compare_fused.rs. Add the matching git `rev` pin here. Temporary, like the root pin: both are removed when a FastLanes release is cut and the version is bumped. Signed-off-by: Joe Isaacs <joe.isaacs@live.co.uk>
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Summary
Stacked on #8238 (the benchmark) so the change lands as a CodSpeed diff.
Replaces the unpack-then-compare streaming kernel for compare-against-constant with the FastLanes fused
unpack_cmp:[u64; 16], one register-resident word per lane — no[bool; 1024]/[T; 1024]scratch),untranspose_bitsper block rotates the mask into logical row order, copied directly into the output bit buffer,offset != 0) arrays fall back to the scalar streaming predicate.