[GitHub] [arrow-rs] tustvold commented on a diff in pull request #2658: Change max/min string macro to generic helper function min_max_helper

[GitBox <gi...@apache.org>]

tustvold commented on code in PR #2658:
URL: https://github.com/apache/arrow-rs/pull/2658#discussion_r963523215


##########
arrow/src/compute/kernels/aggregate.rs:
##########
@@ -142,46 +105,48 @@ pub fn max_boolean(array: &BooleanArray) -> Option<bool> {
         .or(Some(false))
 }
 
-/// Helper to compute min/max of [`GenericStringArray`] and [`GenericBinaryArray`]
-macro_rules! min_max_binary_string {
-    ($array: expr, $cmp: expr) => {{
-        let null_count = $array.null_count();
-        if null_count == $array.len() {
-            None
-        } else if null_count == 0 {
-            // JUSTIFICATION
-            //  Benefit:  ~8% speedup
-            //  Soundness: `i` is always within the array bounds
-            (0..$array.len())
-                .map(|i| unsafe { $array.value_unchecked(i) })
-                .reduce(|acc, item| if $cmp(acc, item) { item } else { acc })
-        } else {
-            $array
-                .iter()
-                .flatten()
-                .reduce(|acc, item| if $cmp(acc, item) { item } else { acc })
-        }
-    }};
+/// Helper to compute min/max of [`ArrayAccessor`].
+#[multiversion]
+#[clone(target = "x86_64+avx")]
+fn min_max_helper<T, A: ArrayAccessor<Item = T>, F>(array: A, cmp: F) -> Option<T>
+where
+    F: Fn(&T, &T) -> bool,
+{
+    let null_count = array.null_count();
+    if null_count == array.len() {
+        None
+    } else if null_count == 0 {
+        // JUSTIFICATION
+        //  Benefit:  ~8% speedup
+        //  Soundness: `i` is always within the array bounds
+        (0..array.len())
+            .map(|i| unsafe { array.value_unchecked(i) })
+            .reduce(|acc, item| if cmp(&acc, &item) { item } else { acc })
+    } else {
+        let iter = ArrayIter::new(array);

Review Comment:
   It might be faster to use `BitIndexIterator` here, something potentially for a future PR



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