Make num_unroll a compile time constant

Author: Raghuveer Devulapalli

src/avx512-32bit-qsort.hpp

@@ -648,7 +648,7 @@ qsort_32bit_(type_t *arr, int64_t left, int64_t right, int64_t max_iters)
     type_t pivot = get_pivot_32bit<vtype>(arr, left, right);
     type_t smallest = vtype::type_max();
     type_t biggest = vtype::type_min();
-    int64_t pivot_index = partition_avx512_unrolled<vtype>(
+    int64_t pivot_index = partition_avx512_unrolled<vtype,2>(
             arr, left, right + 1, pivot, &smallest, &biggest);
     if (pivot != smallest)
         qsort_32bit_<vtype>(arr, left, pivot_index - 1, max_iters - 1);
@@ -680,7 +680,7 @@ qselect_32bit_(type_t *arr, int64_t pos,
     type_t pivot = get_pivot_32bit<vtype>(arr, left, right);
     type_t smallest = vtype::type_max();
     type_t biggest = vtype::type_min();
-    int64_t pivot_index = partition_avx512<vtype>(
+    int64_t pivot_index = partition_avx512_unrolled<vtype,2>(
             arr, left, right + 1, pivot, &smallest, &biggest);
     if ((pivot != smallest) && (pos < pivot_index))
         qselect_32bit_<vtype>(arr, pos, left, pivot_index - 1, max_iters - 1);

src/avx512-64bit-qsort.hpp

@@ -742,7 +742,7 @@ qsort_64bit_(type_t *arr, int64_t left, int64_t right, int64_t max_iters)
     type_t pivot = get_pivot_64bit<vtype>(arr, left, right);
     type_t smallest = vtype::type_max();
     type_t biggest = vtype::type_min();
-    int64_t pivot_index = partition_avx512_unrolled<vtype>(
+    int64_t pivot_index = partition_avx512_unrolled<vtype, 8>(
             arr, left, right + 1, pivot, &smallest, &biggest);
     if (pivot != smallest)
         qsort_64bit_<vtype>(arr, left, pivot_index - 1, max_iters - 1);
@@ -774,7 +774,7 @@ qselect_64bit_(type_t *arr, int64_t pos,
     type_t pivot = get_pivot_64bit<vtype>(arr, left, right);
     type_t smallest = vtype::type_max();
     type_t biggest = vtype::type_min();
-    int64_t pivot_index = partition_avx512<vtype>(
+    int64_t pivot_index = partition_avx512_unrolled<vtype, 8>(
             arr, left, right + 1, pivot, &smallest, &biggest);
     if ((pivot != smallest) && (pos < pivot_index))
         qselect_64bit_<vtype>(arr, pos, left, pivot_index - 1, max_iters - 1);

src/avx512-common-qsort.h

@@ -260,15 +260,16 @@ static inline int64_t partition_avx512(type_t *arr,
     return l_store;
 }
 
-template <typename vtype, typename type_t>
+template <typename vtype,
+          int num_unroll,
+          typename type_t = typename vtype::type_t>
 static inline int64_t partition_avx512_unrolled(type_t *arr,
                                                 int64_t left,
                                                 int64_t right,
                                                 type_t pivot,
                                                 type_t *smallest,
                                                 type_t *biggest)
 {
-    const int num_unroll = 8;
     if (right - left <= 2 * num_unroll * vtype::numlanes) {
         return partition_avx512<vtype>(
                 arr, left, right, pivot, smallest, biggest);