diff --git a/include/rabitqlib/fastscan/detail/qg_estimator.hpp b/include/rabitqlib/fastscan/detail/qg_estimator.hpp
new file mode 100644
index 00000000..b761eda5
--- /dev/null
+++ b/include/rabitqlib/fastscan/detail/qg_estimator.hpp
@@ -0,0 +1,42 @@
+#pragma once
+
+#include <array>
+#include <cstddef>
+#include <cstdint>
+
+#include "rabitqlib/core/detail/eigen.hpp"
+#include "rabitqlib/fastscan/data_layout.hpp"
+#include "rabitqlib/fastscan/pack_codes.hpp"
+#include "rabitqlib/fastscan/query.hpp"
+
+namespace rabitqlib::fastscan::detail {
+// Share QG accumulation and correction while callers select the accumulator.
+// TU-local linkage keeps each ISA's Eigen expression compiled with its own flags.
+template <typename T, auto Accumulate>
+static inline void qg_batch_estdist_impl(
+    const char* batch_data,
+    const BatchQuery<T>& query_wrapper,
+    size_t padded_dim,
+    T* estimated_distances
+) {
+    ConstQGBatchDataMap<T> cur_batch(batch_data, padded_dim);
+    std::array<int32_t, fastscan::kBatchSize> accu_values{};
+    Accumulate(cur_batch.bin_code(), query_wrapper.lut(), accu_values.data(), padded_dim);
+
+    ConstRowMajorArrayMap<int32_t> ip_arr(accu_values.data(), 1, fastscan::kBatchSize);
+    std::array<T, fastscan::kBatchSize> f_add_values;
+    std::array<T, fastscan::kBatchSize> f_rescale_values;
+    cur_batch.f_add().copy_to(f_add_values.data(), f_add_values.size());
+    cur_batch.f_rescale().copy_to(f_rescale_values.data(), f_rescale_values.size());
+    ConstRowMajorArrayMap<T> f_add_arr(f_add_values.data(), 1, fastscan::kBatchSize);
+    ConstRowMajorArrayMap<T> f_rescale_arr(
+        f_rescale_values.data(), 1, fastscan::kBatchSize
+    );
+
+    RowMajorArrayMap<T> est_dist_arr(estimated_distances, 1, fastscan::kBatchSize);
+
+    est_dist_arr = f_add_arr + query_wrapper.g_add() +
+                   (f_rescale_arr * (query_wrapper.delta() * (ip_arr.template cast<T>()) +
+                                     query_wrapper.sum_vl_lut() + query_wrapper.k1xsumq()));
+}
+}  // namespace rabitqlib::fastscan::detail
diff --git a/include/rabitqlib/fastscan/estimator.hpp b/include/rabitqlib/fastscan/estimator.hpp
index 9d96d3ce..e6c7ff10 100644
--- a/include/rabitqlib/fastscan/estimator.hpp
+++ b/include/rabitqlib/fastscan/estimator.hpp
@@ -1,16 +1,13 @@
 #pragma once
 
-#include <array>
 #include <cstddef>
 #include <cstdint>
 #include <stdexcept>
 #include <type_traits>
 
-#include "rabitqlib/core/detail/eigen.hpp"
-#include "rabitqlib/fastscan/data_layout.hpp"
 #include "rabitqlib/fastscan/detail/estimator_dispatch.hpp"
+#include "rabitqlib/fastscan/detail/qg_estimator.hpp"
 #include "rabitqlib/fastscan/fastscan.hpp"
-#include "rabitqlib/fastscan/pack_codes.hpp"
 #include "rabitqlib/fastscan/query.hpp"
 
 namespace rabitqlib {
@@ -81,26 +78,9 @@ inline void qg_batch_estdist(
         return;
     }
 
-    ConstQGBatchDataMap<T> cur_batch(batch_data, padded_dim);
-    std::array<TA, fastscan::kBatchSize> accumulated_values{};
-    fastscan::accumulate(
-        cur_batch.bin_code(), query_wrapper.lut(), accumulated_values.data(), padded_dim
+    fastscan::detail::qg_batch_estdist_impl<T, fastscan::accumulate>(
+        batch_data, query_wrapper, padded_dim, estimated_distances
     );
-    ConstRowMajorArrayMap<TA> ip_arr(accumulated_values.data(), 1, fastscan::kBatchSize);
-    std::array<T, fastscan::kBatchSize> f_add_values;
-    std::array<T, fastscan::kBatchSize> f_rescale_values;
-    cur_batch.f_add().copy_to(f_add_values.data(), f_add_values.size());
-    cur_batch.f_rescale().copy_to(f_rescale_values.data(), f_rescale_values.size());
-    ConstRowMajorArrayMap<T> f_add_arr(f_add_values.data(), 1, fastscan::kBatchSize);
-    ConstRowMajorArrayMap<T> f_rescale_arr(
-        f_rescale_values.data(), 1, fastscan::kBatchSize
-    );
-
-    RowMajorArrayMap<T> est_dist_arr(estimated_distances, 1, fastscan::kBatchSize);
-
-    est_dist_arr = f_add_arr + query_wrapper.g_add() +
-                   (f_rescale_arr * (query_wrapper.delta() * (ip_arr.template cast<T>()) +
-                                     query_wrapper.sum_vl_lut() + query_wrapper.k1xsumq()));
 }
 
 }  // namespace rabitqlib
diff --git a/include/rabitqlib/index/detail/visited_set_hash.hpp b/include/rabitqlib/index/detail/visited_set_hash.hpp
index a79478f1..7fdb39f2 100644
--- a/include/rabitqlib/index/detail/visited_set_hash.hpp
+++ b/include/rabitqlib/index/detail/visited_set_hash.hpp
@@ -34,7 +34,6 @@ class HashBasedVisitedSet {
     static constexpr size_t kNoSizeHint = std::numeric_limits<size_t>::max();
 
    private:
-    size_t table_size_ = 0;
     PID mask_ = 0;
     std::vector<PID, memory::AlignedAllocator<PID>> table_;
     std::unordered_set<PID> stl_hash_;
@@ -44,8 +43,7 @@ class HashBasedVisitedSet {
     void initialize_table(const size_t table_size) {
         // Allocate before changing the mask so failure preserves the previous table.
         table_ = std::vector<PID, memory::AlignedAllocator<PID>>(table_size);
-        table_size_ = table_size;
-        mask_ = static_cast<PID>(table_size_ - 1);
+        mask_ = static_cast<PID>(table_size - 1);
         assert(hash1(static_cast<PID>(table_size)) == 0);
 
         std::fill(table_.begin(), table_.end(), kPidMax);
diff --git a/include/rabitqlib/index/hnsw/hnsw.hpp b/include/rabitqlib/index/hnsw/hnsw.hpp
index 3b7a3de4..5c0ed5c5 100644
--- a/include/rabitqlib/index/hnsw/hnsw.hpp
+++ b/include/rabitqlib/index/hnsw/hnsw.hpp
@@ -432,7 +432,6 @@ class HierarchicalNSW {
         size_t k,
         const SplitSingleQuery<float>& query_wrapper,
         const std::vector<float>& q_to_centroids,
-        const float* query,
         BoundedKNN& nearest_candidates
     ) const;
 
diff --git a/include/rabitqlib/utils/space.hpp b/include/rabitqlib/utils/space.hpp
index af064813..8c6ec87b 100644
--- a/include/rabitqlib/utils/space.hpp
+++ b/include/rabitqlib/utils/space.hpp
@@ -15,6 +15,7 @@
 #include "rabitqlib/utils/bitops.hpp"
 #include "rabitqlib/utils/openmp.hpp"  // IWYU pragma: keep (configuration macros)
 #include "rabitqlib/utils/tools.hpp"
+#include "rabitqlib/utils/warmup_space.hpp"
 
 #if RABITQ_USE_OPENMP
 #include <limits>
@@ -319,35 +320,7 @@ inline float ip_x0_q(
     size_t padded_dim,
     size_t b_query
 ) {
-    auto num_blk = padded_dim / 64;
-    const auto* it_data = reinterpret_cast<const uint8_t*>(data);
-    const auto* it_query = query;
-
-    size_t ip = 0;
-    size_t ppc = 0;
-
-    for (size_t i = 0; i < num_blk; ++i) {
-        const uint64_t x = rabitqlib::bitops::load_word(it_data, sizeof(uint64_t));
-        ppc += bitops::popcount64(x);
-
-        for (size_t j = 0; j < b_query; ++j) {
-            uint64_t y = *static_cast<const uint64_t*>(it_query);
-            ip += (bitops::popcount64(x & y) << j);
-            it_query++;
-        }
-        it_data += sizeof(uint64_t);
-    }
-
-    if (padded_dim % 64 != 0) {
-        const uint64_t x = rabitqlib::bitops::load_word(it_data, (padded_dim % 64) / 8);
-        ppc += bitops::popcount64(x);
-        for (size_t j = 0; j < b_query; ++j) {
-            ip += (bitops::popcount64(x & *it_query) << j);
-            ++it_query;
-        }
-    }
-
-    return (delta * static_cast<float>(ip)) + (vl * static_cast<float>(ppc));
+    return detail::ip_x0_q_impl(data, query, delta, vl, padded_dim, b_query);
 }
 
 static inline uint32_t ip_bin_bin(const uint64_t* q, const uint64_t* d, size_t padded_dim) {
diff --git a/include/rabitqlib/utils/warmup_space.hpp b/include/rabitqlib/utils/warmup_space.hpp
index 30544ec3..050581b3 100644
--- a/include/rabitqlib/utils/warmup_space.hpp
+++ b/include/rabitqlib/utils/warmup_space.hpp
@@ -25,14 +25,16 @@ float warmup_ip_x0_q_512(
     size_t b_query
 );
 
-template <uint32_t b_query>
-inline float warmup_ip_x0_q(
+namespace detail {
+// Scalar word-interleaved query planes; distinct from the 512-coordinate layout.
+// Keep the shared loop local to each translation unit's ISA configuration.
+static inline float ip_x0_q_impl(
     const uint64_t* data,
     const uint64_t* query,
     float delta,
     float vl,
     size_t padded_dim,
-    [[maybe_unused]] size_t unused_query_bits = 0  // not used
+    size_t b_query
 ) {
     auto num_blk = padded_dim / 64;
     const auto* it_data = reinterpret_cast<const uint8_t*>(data);
@@ -64,5 +66,18 @@ inline float warmup_ip_x0_q(
 
     return (delta * static_cast<float>(ip)) + (vl * static_cast<float>(ppc));
 }
+}  // namespace detail
+
+template <uint32_t b_query>
+inline float warmup_ip_x0_q(
+    const uint64_t* data,
+    const uint64_t* query,
+    float delta,
+    float vl,
+    size_t padded_dim,
+    [[maybe_unused]] size_t unused_query_bits = 0  // not used
+) {
+    return detail::ip_x0_q_impl(data, query, delta, vl, padded_dim, b_query);
+}
 
 }  // namespace rabitqlib
diff --git a/src/fastscan/estimator_avx2.cpp b/src/fastscan/estimator_avx2.cpp
index f41a28ed..4050fd4c 100644
--- a/src/fastscan/estimator_avx2.cpp
+++ b/src/fastscan/estimator_avx2.cpp
@@ -5,6 +5,7 @@
 
 #include "estimator_kernels.hpp"
 #include "rabitqlib/fastscan/detail/estimator_dispatch.hpp"
+#include "rabitqlib/fastscan/detail/qg_estimator.hpp"
 #include "rabitqlib/fastscan/fastscan.hpp"
 #include "rabitqlib/fastscan/highacc_fastscan.hpp"
 
@@ -50,7 +51,7 @@ void qg_batch_estdist_avx2(
     size_t padded_dim,
     float* estimated_distances
 ) {
-    qg_batch_estdist_impl<fastscan::accumulate>(
+    fastscan::detail::qg_batch_estdist_impl<float, fastscan::accumulate>(
         batch_data, query_wrapper, padded_dim, estimated_distances
     );
 }
@@ -66,7 +67,7 @@ uint32_t qg_batch_estdist_mask_avx2(
     float* estimated_distances,
     float threshold
 ) {
-    qg_batch_estdist_impl<fastscan::accumulate>(
+    fastscan::detail::qg_batch_estdist_impl<float, fastscan::accumulate>(
         batch_data, query_wrapper, padded_dim, estimated_distances
     );
     return candidate_mask_impl(estimated_distances, threshold);
diff --git a/src/fastscan/estimator_avx512.cpp b/src/fastscan/estimator_avx512.cpp
index a7e8a092..1536b4cc 100644
--- a/src/fastscan/estimator_avx512.cpp
+++ b/src/fastscan/estimator_avx512.cpp
@@ -3,6 +3,7 @@
 
 #include "estimator_kernels.hpp"
 #include "rabitqlib/fastscan/detail/estimator_dispatch.hpp"
+#include "rabitqlib/fastscan/detail/qg_estimator.hpp"
 #include "rabitqlib/fastscan/detail/simd.hpp"
 
 namespace rabitqlib::simd {
@@ -45,7 +46,7 @@ void qg_batch_estdist_avx512(
     if (padded_dim == 0 || padded_dim % 16 != 0) {
         throw std::invalid_argument("FastScan dimension must be a positive multiple of 16");
     }
-    qg_batch_estdist_impl<fastscan::simd::accumulate_avx512>(
+    fastscan::detail::qg_batch_estdist_impl<float, fastscan::simd::accumulate_avx512>(
         batch_data, query_wrapper, padded_dim, estimated_distances
     );
 }
diff --git a/src/fastscan/estimator_generic.cpp b/src/fastscan/estimator_generic.cpp
index 5601ecde..d0d3e325 100644
--- a/src/fastscan/estimator_generic.cpp
+++ b/src/fastscan/estimator_generic.cpp
@@ -3,6 +3,7 @@
 
 #include "estimator_kernels.hpp"
 #include "rabitqlib/fastscan/detail/estimator_dispatch.hpp"
+#include "rabitqlib/fastscan/detail/qg_estimator.hpp"
 #include "rabitqlib/fastscan/fastscan.hpp"
 #include "rabitqlib/fastscan/highacc_fastscan.hpp"
 
@@ -45,7 +46,7 @@ void qg_batch_estdist_generic(
     size_t padded_dim,
     float* estimated_distances
 ) {
-    qg_batch_estdist_impl<fastscan::accumulate>(
+    fastscan::detail::qg_batch_estdist_impl<float, fastscan::accumulate>(
         batch_data, query_wrapper, padded_dim, estimated_distances
     );
 }
@@ -61,7 +62,7 @@ uint32_t qg_batch_estdist_mask_generic(
     float* estimated_distances,
     float threshold
 ) {
-    qg_batch_estdist_impl<fastscan::accumulate>(
+    fastscan::detail::qg_batch_estdist_impl<float, fastscan::accumulate>(
         batch_data, query_wrapper, padded_dim, estimated_distances
     );
     return candidate_mask_impl(estimated_distances, threshold);
diff --git a/src/fastscan/estimator_kernels.hpp b/src/fastscan/estimator_kernels.hpp
index 8d3cedae..2454ec26 100644
--- a/src/fastscan/estimator_kernels.hpp
+++ b/src/fastscan/estimator_kernels.hpp
@@ -63,34 +63,5 @@ inline void split_batch_estdist_impl(
     low_dist_arr = est_dist_arr - f_error_arr * query_wrapper.g_error();
 }
 
-template <auto Accumulate>
-inline void qg_batch_estdist_impl(
-    const char* batch_data,
-    const BatchQuery<float>& query_wrapper,
-    size_t padded_dim,
-    float* estimated_distances
-) {
-    using T = float;
-    ConstQGBatchDataMap<T> cur_batch(batch_data, padded_dim);
-    std::array<int32_t, fastscan::kBatchSize> accu_values{};
-    Accumulate(cur_batch.bin_code(), query_wrapper.lut(), accu_values.data(), padded_dim);
-
-    ConstRowMajorArrayMap<int32_t> ip_arr(accu_values.data(), 1, fastscan::kBatchSize);
-    std::array<T, fastscan::kBatchSize> f_add_values;
-    std::array<T, fastscan::kBatchSize> f_rescale_values;
-    cur_batch.f_add().copy_to(f_add_values.data(), f_add_values.size());
-    cur_batch.f_rescale().copy_to(f_rescale_values.data(), f_rescale_values.size());
-    ConstRowMajorArrayMap<T> f_add_arr(f_add_values.data(), 1, fastscan::kBatchSize);
-    ConstRowMajorArrayMap<T> f_rescale_arr(
-        f_rescale_values.data(), 1, fastscan::kBatchSize
-    );
-
-    RowMajorArrayMap<T> est_dist_arr(estimated_distances, 1, fastscan::kBatchSize);
-
-    est_dist_arr = f_add_arr + query_wrapper.g_add() +
-                   (f_rescale_arr * (query_wrapper.delta() * (ip_arr.template cast<T>()) +
-                                     query_wrapper.sum_vl_lut() + query_wrapper.k1xsumq()));
-}
-
 }  // namespace
 }  // namespace rabitqlib::simd
diff --git a/src/index/hnsw_search_impl.hpp b/src/index/hnsw_search_impl.hpp
index 48f85f34..fc6759dd 100644
--- a/src/index/hnsw_search_impl.hpp
+++ b/src/index/hnsw_search_impl.hpp
@@ -177,7 +177,6 @@ inline std::vector<std::pair<float, PID>> HierarchicalNSW::search_knn_sorted_dir
         k,
         query_wrapper,
         q_to_centroids,
-        rotated_query,
         nearest_candidates
     );
     result.reserve(nearest_candidates.size());
@@ -204,7 +203,6 @@ inline void HierarchicalNSW::search_base_layer_direct(
     size_t k,
     const SplitSingleQuery<float>& query_wrapper,
     const std::vector<float>& q_to_centroids,
-    [[maybe_unused]] const float* query,
     BoundedKNN& nearest_candidates
 ) const {
     auto visited = visited_list_pool_->get_free_vislist();