From dc682df55cc51b03dadff5d9df89c2ef007d4e17 Mon Sep 17 00:00:00 2001
From: Paul Toffoloni <paultoffoloni@gmail.com>
Date: Mon, 19 May 2025 11:27:29 +0200
Subject: [PATCH 1/3] Unroll loop on sum if possible

---
 Sources/AccelerateLinux/VectorOps/vDSP.swift | 45 +++++++++++++++++---
 1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/Sources/AccelerateLinux/VectorOps/vDSP.swift b/Sources/AccelerateLinux/VectorOps/vDSP.swift
index 0151f5a..916f0e1 100644
--- a/Sources/AccelerateLinux/VectorOps/vDSP.swift
+++ b/Sources/AccelerateLinux/VectorOps/vDSP.swift
@@ -57,15 +57,48 @@ public enum vDSP {
     @inlinable
     @inline(__always)
     public static func sum<U>(_ vector: U) -> Double where U: AccelerateBuffer, U.Element == Double {
-        vector.withUnsafeBufferPointer { ptr in
-            var sum: Double = 0
-            var i = ptr.startIndex
-            while i < ptr.endIndex {
-                sum += ptr[i]
-                i += 1
+        if vector.count == 0 { return 0.0 }
+        if vector.count <= 8 {
+            var sum: Double = 0.0
+            vector.withUnsafeBufferPointer { buffer in
+                for i in buffer.indices {
+                    sum += buffer[i]
+                }
             }
             return sum
         }
+        vector.withUnsafeBufferPointer { buffer in
+            guard let baseAddress = buffer.baseAddress else { return 0.0 }
+
+            let count = buffer.count
+            var sum1: Double = 0.0
+            var sum2: Double = 0.0
+            var sum3: Double = 0.0
+            var sum4: Double = 0.0
+            var sum5: Double = 0.0
+            var sum6: Double = 0.0
+            var sum7: Double = 0.0
+            var sum8: Double = 0.0
+
+            let vectorCount = count - (count % 8)
+            for i in stride(from: 0, to: vectorCount, by: 8) {
+                sum1 += baseAddress[i]
+                sum2 += baseAddress[i + 1]
+                sum3 += baseAddress[i + 2]
+                sum4 += baseAddress[i + 3]
+                sum5 += baseAddress[i + 4]
+                sum6 += baseAddress[i + 5]
+                sum7 += baseAddress[i + 6]
+                sum8 += baseAddress[i + 7]
+            }
+
+            var remainingSum: Double = 0.0
+            for i in vectorCount..<count {
+                remainingSum += baseAddress[i]
+            }
+
+            return sum1 + sum2 + sum3 + sum4 + sum5 + sum6 + sum7 + sum8 + remainingSum
+        }
     }
 
     /// Returns the double-precision element-wise subtraction of two vectors.

From aa1cb63a957102c52d0921ac1abb764deafd76ea Mon Sep 17 00:00:00 2001
From: Paul Toffoloni <paultoffoloni@gmail.com>
Date: Mon, 19 May 2025 11:28:31 +0200
Subject: [PATCH 2/3] Clean up

---
 Sources/AccelerateLinux/VectorOps/vDSP.swift | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Sources/AccelerateLinux/VectorOps/vDSP.swift b/Sources/AccelerateLinux/VectorOps/vDSP.swift
index 916f0e1..0e77041 100644
--- a/Sources/AccelerateLinux/VectorOps/vDSP.swift
+++ b/Sources/AccelerateLinux/VectorOps/vDSP.swift
@@ -58,15 +58,19 @@ public enum vDSP {
     @inline(__always)
     public static func sum<U>(_ vector: U) -> Double where U: AccelerateBuffer, U.Element == Double {
         if vector.count == 0 { return 0.0 }
+
         if vector.count <= 8 {
             var sum: Double = 0.0
             vector.withUnsafeBufferPointer { buffer in
-                for i in buffer.indices {
+                var i = 0
+                while i < vector.count {
                     sum += buffer[i]
+                    i += 1
                 }
             }
             return sum
         }
+
         vector.withUnsafeBufferPointer { buffer in
             guard let baseAddress = buffer.baseAddress else { return 0.0 }
 

From 8e623306e8270976bb510c79561a8af4aa1abd17 Mon Sep 17 00:00:00 2001
From: Paul Toffoloni <paultoffoloni@gmail.com>
Date: Mon, 19 May 2025 09:31:17 +0000
Subject: [PATCH 3/3] Fix error

---
 Sources/AccelerateLinux/VectorOps/vDSP.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Sources/AccelerateLinux/VectorOps/vDSP.swift b/Sources/AccelerateLinux/VectorOps/vDSP.swift
index 0e77041..1157a45 100644
--- a/Sources/AccelerateLinux/VectorOps/vDSP.swift
+++ b/Sources/AccelerateLinux/VectorOps/vDSP.swift
@@ -71,7 +71,7 @@ public enum vDSP {
             return sum
         }
 
-        vector.withUnsafeBufferPointer { buffer in
+        return vector.withUnsafeBufferPointer { buffer in
             guard let baseAddress = buffer.baseAddress else { return 0.0 }
 
             let count = buffer.count