Convert binary index Hamming callers to dynamic dispatch (#5071)#5071
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Convert binary index Hamming callers to dynamic dispatch (#5071)#5071algoriddle wants to merge 2 commits intofacebookresearch:mainfrom
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…earch#5071) Summary: Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT converted: IndexIVFPQ.cpp polysemous path — deeply interleaved with PQ distance computation inside IVFPQScannerT, niche (off by default, polysemous_ht=0). See ~/ivfpq_polysemous_dd.md for analysis. Differential Revision: D100020358
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…earch#5071) Summary: Pull Request resolved: facebookresearch#5071 Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT yet converted: IndexIVFPQ.cpp polysemous path Differential Revision: D100020358
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…earch#5071) Summary: Pull Request resolved: facebookresearch#5071 Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT yet converted: IndexIVFPQ.cpp polysemous path Differential Revision: D100020358
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…earch#5071) Summary: Pull Request resolved: facebookresearch#5071 Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT yet converted: IndexIVFPQ.cpp polysemous path Differential Revision: D100020358
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…earch#5071) Summary: Pull Request resolved: facebookresearch#5071 Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT yet converted: IndexIVFPQ.cpp polysemous path Differential Revision: D100020358
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…earch#5071) Summary: Pull Request resolved: facebookresearch#5071 Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT converted: IndexIVFPQ.cpp polysemous path — deeply interleaved with PQ distance computation inside IVFPQScannerT, niche (off by default, polysemous_ht=0). See ~/ivfpq_polysemous_dd.md for analysis. Differential Revision: D100020358
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…earch#5071) Summary: Pull Request resolved: facebookresearch#5071 Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT converted: IndexIVFPQ.cpp polysemous path — deeply interleaved with PQ distance computation inside IVFPQScannerT, niche (off by default, polysemous_ht=0). See ~/ivfpq_polysemous_dd.md for analysis. Differential Revision: D100020358
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Summary: Convert all 8 public Hamming distance functions in `hamming.cpp` to dynamic dispatch so they use the best available SIMD implementation at runtime instead of always running at scalar speed in DD mode. This integrates Matthijs's refactor (D100004339): deduplicates the HammingComputer code across the 4 per-ISA backend files into a shared `common.h`. It is Phase 1 of the Hamming DD conversion; Phase 2 (future diff) will migrate external callers that use `dispatch_HammingComputer` directly. Key changes: - **DD dispatch**: the 8 public hamming.cpp functions now dispatch via `with_simd_level` (mask A0: NONE/AVX2/AVX512/ARM_NEON) to SL-templated `*_fixSL<SL>` entry points. - **`_fixSL` suffix** on SL-templated entry points (per Matthijs's D100020358 convention), distinguishing them from the non-templated DD entry points that share the same base name. Avoids silent-dispatch-vs- pinned-specialization confusion at call sites. - **New `hamming_avx512.cpp` TU** — makes the pre-existing AVX-512 HammingComputer specializations in `avx512-inl.h` reachable from Buck DD builds (previously reachable only from OSS CMake `faiss_avx512` / `faiss_avx512_spr` targets). The AVX-512 TU gives SKX/CLX/Ice Lake clients ZMM auto-vectorization of the hamming kernels; the `_mm512_popcnt_epi64` fast path remains gated on VPOPCNTDQ (active in OSS `faiss_avx512_spr` CMake target only, per pre-existing design). - **ODR fix via SIMDLevel templatization**: the 9 ISA-varying `HammingComputer*` / `GenHammingComputer*` structs are now primary templates `*_tpl<SIMDLevel>` with scalar bodies in `common.h`, and per-ISA specializations in the respective `-inl.h` files. Each TU picks its specialization via a `using`-alias in hamdis-inl.h keyed on `FAISS_HAMMING_SL`. Distinct mangled names per SL eliminate the latent ODR hazard where multiple DD TUs with different flags saw differently-laid-out structs sharing the `faiss::HammingComputer*` name. Verified by disassembly: distinct `<SIMDLevel)0|1|2>` suffixes per TU. - **Silent OOB fix in `HammingComputer20::set`** (inherited from D100004339): pre-diff `uint64_t a[2]` read 8 bytes on a 20-byte code (past-end read, tripped by ASan); post-diff `uint32_t a32[4]` reads exactly 4 bytes. - **`faiss_hamming_sl_collapse()` constexpr** in hamdis-inl.h makes the AVX512_SPR→AVX512 / ARM_SVE→ARM_NEON collapse explicit at the alias level, rather than relying on the raw arch-macro ladder happening to match. Applies only to HammingComputer aliases; does not change the dispatcher. - **popcount.h extraction**: moved `popcount32` / `popcount64` out of `common.h` into a standalone `faiss/utils/popcount.h` so callers outside the hamming subtree (rabitq_simd.h, rabitq_avx2/512.cpp, partitioning_simdlib256.h, PolysemousTraining.cpp) have a clean include. Migrated all `__builtin_popcount*` call sites. Silent Windows correctness improvement: pre-diff `__builtin_popcountl` on `uint64_t` truncated to 32 bits on MSVC (LLP64, `long` is 32-bit); post-diff `popcount64` always dispatches to `__popcnt64`. The pre-diff `__builtin_popcount → __popcnt` macro shim in `platform_macros.h` is removed — no longer needed now that all call sites use the helpers. - **`FAISS_MAYBE_UNUSED` on Windows**: previously defined only in the Linux/OSX branch of platform_macros.h; added to the MSVC branch so the templated HammingComputer `set(..., int code_size)` ctors compile cleanly on Windows under `-Wunused-parameter` + NDEBUG. Differential Revision: D99994593
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…earch#5071) Summary: Pull Request resolved: facebookresearch#5071 Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT converted: IndexIVFPQ.cpp polysemous path — deeply interleaved with PQ distance computation inside IVFPQScannerT, niche (off by default, polysemous_ht=0). See ~/ivfpq_polysemous_dd.md for analysis. Differential Revision: D100020358
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…earch#5071) Summary: Pull Request resolved: facebookresearch#5071 Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT converted: IndexIVFPQ.cpp polysemous path — deeply interleaved with PQ distance computation inside IVFPQScannerT, niche (off by default, polysemous_ht=0). See ~/ivfpq_polysemous_dd.md for analysis. Differential Revision: D100020358
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…earch#5071) Summary: Pull Request resolved: facebookresearch#5071 Phase 2 of the Hamming DD conversion. Converts 5 external callers of dispatch_HammingComputer to use per-ISA TUs so the correct HammingComputer structs (AVX2/NEON/generic) are used at runtime. Previously, these files compiled as common TUs with no ISA flags, causing hamdis-inl.h to fall through to generic-inl.h — scalar HammingComputer structs even on AVX2-capable machines in DD mode. Converted files: - IndexBinaryHNSW.cpp: get_distance_computer() factory - IndexBinaryIVF.cpp: get_InvertedListScanner() + search_preassigned() - IndexBinaryHash.cpp: 4 search entry points (knn+range × 2 index types) - IndexIVFSpectralHash.cpp: get_InvertedListScanner() factory - IndexPQ.cpp: polysemous_inner_loop dispatch NOT converted: IndexIVFPQ.cpp polysemous path — deeply interleaved with PQ distance computation inside IVFPQScannerT, niche (off by default, polysemous_ht=0). See ~/ivfpq_polysemous_dd.md for analysis. Differential Revision: D100020358
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Summary:
Phase 2 of the Hamming DD conversion. Converts 5 external callers of
dispatch_HammingComputer to use per-ISA TUs so the correct
HammingComputer structs (AVX2/NEON/generic) are used at runtime.
Previously, these files compiled as common TUs with no ISA flags,
causing hamdis-inl.h to fall through to generic-inl.h — scalar
HammingComputer structs even on AVX2-capable machines in DD mode.
Converted files:
NOT converted: IndexIVFPQ.cpp polysemous path — deeply interleaved
with PQ distance computation inside IVFPQScannerT, niche (off by
default, polysemous_ht=0). See ~/ivfpq_polysemous_dd.md for analysis.
Differential Revision: D100020358