include/oneapi/dpl/pstl/hetero/dpcpp/parallel_backend_sycl_merge.h - …

…fix review comment: remove extra condition check from __find_start_point_in

Signed-off-by: Sergey Kopienko <[email protected]>

include/oneapi/dpl/pstl/hetero/dpcpp/parallel_backend_sycl_merge.h

@@ -107,7 +107,9 @@ __find_start_point_in(const _Rng1& __rng1, const _Index __rng1_from, _Index __rn
     if constexpr (!std::is_pointer_v<_Rng2>)
         assert(__rng2_to <= __rng2.size());
 
-    assert(__i_elem >= 0);
+    // We shouldn't call this function with __i_elem == 0 because we a priory know that
+    // split point for this case is {0, 0}
+    assert(__i_elem > 0);
 
     // ----------------------- EXAMPLE ------------------------
     // Let's consider the following input data:
@@ -150,76 +152,64 @@ __find_start_point_in(const _Rng1& __rng1, const _Index __rng1_from, _Index __rn
     //   - where for every comparing pairs idx(rng1) + idx(rng2) == i_diag - 1
 
     ////////////////////////////////////////////////////////////////////////////////////
-    // Process the corner case: for the first diagonal with the index 0 split point
-    // is equal to (0, 0) regardless of the size and content of the data.
-    if (__i_elem > 0)
-    {
-        ////////////////////////////////////////////////////////////////////////////////////
-        // Taking into account the specified constraints of the range of processed data
-        const auto __index_sum = __i_elem - 1;
+    // Taking into account the specified constraints of the range of processed data
+    const auto __index_sum = __i_elem - 1;
 
-        using _IndexSigned = std::make_signed_t<_Index>;
+    using _IndexSigned = std::make_signed_t<_Index>;
 
-        _IndexSigned idx1_from = __rng1_from;
-        _IndexSigned idx1_to = __rng1_to;
-        assert(idx1_from <= idx1_to);
+    _IndexSigned idx1_from = __rng1_from;
+    _IndexSigned idx1_to = __rng1_to;
+    assert(idx1_from <= idx1_to);
 
-        _IndexSigned idx2_from = __index_sum - (__rng1_to - 1);
-        _IndexSigned idx2_to = __index_sum - __rng1_from + 1;
-        assert(idx2_from <= idx2_to);
+    _IndexSigned idx2_from = __index_sum - (__rng1_to - 1);
+    _IndexSigned idx2_to = __index_sum - __rng1_from + 1;
+    assert(idx2_from <= idx2_to);
 
-        const _IndexSigned idx2_from_diff =
-            idx2_from < (_IndexSigned)__rng2_from ? (_IndexSigned)__rng2_from - idx2_from : 0;
-        const _IndexSigned idx2_to_diff = idx2_to > (_IndexSigned)__rng2_to ? idx2_to - (_IndexSigned)__rng2_to : 0;
+    const _IndexSigned idx2_from_diff =
+        idx2_from < (_IndexSigned)__rng2_from ? (_IndexSigned)__rng2_from - idx2_from : 0;
+    const _IndexSigned idx2_to_diff = idx2_to > (_IndexSigned)__rng2_to ? idx2_to - (_IndexSigned)__rng2_to : 0;
 
-        idx1_to -= idx2_from_diff;
-        idx1_from += idx2_to_diff;
+    idx1_to -= idx2_from_diff;
+    idx1_from += idx2_to_diff;
 
-        idx2_from = __index_sum - (idx1_to - 1);
-        idx2_to = __index_sum - idx1_from + 1;
+    idx2_from = __index_sum - (idx1_to - 1);
+    idx2_to = __index_sum - idx1_from + 1;
 
-        assert(idx1_from <= idx1_to);
-        assert(__rng1_from <= idx1_from && idx1_to <= __rng1_to);
+    assert(idx1_from <= idx1_to);
+    assert(__rng1_from <= idx1_from && idx1_to <= __rng1_to);
 
-        assert(idx2_from <= idx2_to);
-        assert(__rng2_from <= idx2_from && idx2_to <= __rng2_to);
+    assert(idx2_from <= idx2_to);
+    assert(__rng2_from <= idx2_from && idx2_to <= __rng2_to);
 
-        ////////////////////////////////////////////////////////////////////////////////////
-        // Run search of split point on diagonal
+    ////////////////////////////////////////////////////////////////////////////////////
+    // Run search of split point on diagonal
 
-        using __it_t = oneapi::dpl::counting_iterator<_Index>;
+    using __it_t = oneapi::dpl::counting_iterator<_Index>;
 
-        __it_t __diag_it_begin(idx1_from);
-        __it_t __diag_it_end(idx1_to);
+    __it_t __diag_it_begin(idx1_from);
+    __it_t __diag_it_end(idx1_to);
 
-        constexpr int kValue = 1;
-        const __it_t __res =
-            std::lower_bound(__diag_it_begin, __diag_it_end, kValue, [&](_Index __idx, const auto& __value) {
-                const auto __rng1_idx = __idx;
-                const auto __rng2_idx = __index_sum - __idx;
+    constexpr int kValue = 1;
+    const __it_t __res =
+        std::lower_bound(__diag_it_begin, __diag_it_end, kValue, [&](_Index __idx, const auto& __value) {
+            const auto __rng1_idx = __idx;
+            const auto __rng2_idx = __index_sum - __idx;
 
-                assert(__rng1_from <= __rng1_idx && __rng1_idx < __rng1_to);
-                assert(__rng2_from <= __rng2_idx && __rng2_idx < __rng2_to);
-                assert(__rng1_idx + __rng2_idx == __index_sum);
+            assert(__rng1_from <= __rng1_idx && __rng1_idx < __rng1_to);
+            assert(__rng2_from <= __rng2_idx && __rng2_idx < __rng2_to);
+            assert(__rng1_idx + __rng2_idx == __index_sum);
 
-                const auto __zero_or_one = __comp(__rng2[__rng2_idx], __rng1[__rng1_idx]);
-                return __zero_or_one < kValue;
-            });
+            const auto __zero_or_one = __comp(__rng2[__rng2_idx], __rng1[__rng1_idx]);
+            return __zero_or_one < kValue;
+        });
 
-        const _split_point_t<_Index> __result{ *__res, __index_sum - *__res + 1 };
-        assert(__result.first + __result.second == __i_elem);
+    const _split_point_t<_Index> __result{ *__res, __index_sum - *__res + 1 };
+    assert(__result.first + __result.second == __i_elem);
 
-        assert(__rng1_from <= __result.first && __result.first <= __rng1_to);
-        assert(__rng2_from <= __result.second && __result.second <= __rng2_to);
+    assert(__rng1_from <= __result.first && __result.first <= __rng1_to);
+    assert(__rng2_from <= __result.second && __result.second <= __rng2_to);
 
-        return __result;
-    }
-    else
-    {
-        assert(__rng1_from == 0);
-        assert(__rng2_from == 0);
-        return { __rng1_from, __rng2_from };
-    }
+    return __result;
 }
 
 // Do serial merge of the data from rng1 (starting from start1) and rng2 (starting from start2) and writing