From 23886fd7db3aca144dbe513f7d5dc257b05fd50f Mon Sep 17 00:00:00 2001
From: Charles Schlosser <cs.schlosser@gmail.com>
Date: Mon, 20 Nov 2023 17:26:39 +0000
Subject: [PATCH] Gemv microoptimization

(cherry picked from commit d1b03fb5c91dcf0e48555bba8387201a0b1425d9)
---
 Eigen/src/Core/products/GeneralMatrixVector.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Eigen/src/Core/products/GeneralMatrixVector.h b/Eigen/src/Core/products/GeneralMatrixVector.h
index b6579cc99..0b622c8da 100644
--- a/Eigen/src/Core/products/GeneralMatrixVector.h
+++ b/Eigen/src/Core/products/GeneralMatrixVector.h
@@ -359,9 +359,9 @@ EIGEN_DEVICE_FUNC EIGEN_DONT_INLINE void general_matrix_vector_product<Index,Lhs
          HasQuarter = (int)ResPacketSizeQuarter < (int)ResPacketSizeHalf
   };
 
-  const Index fullColBlockEnd = LhsPacketSize * (cols / LhsPacketSize);
-  const Index halfColBlockEnd = LhsPacketSizeHalf * (cols / LhsPacketSizeHalf);
-  const Index quarterColBlockEnd = LhsPacketSizeQuarter * (cols / LhsPacketSizeQuarter);
+  const Index fullColBlockEnd = cols & (-LhsPacketSize);
+  const Index halfColBlockEnd = cols & (-LhsPacketSizeHalf);
+  const Index quarterColBlockEnd = cols & (-LhsPacketSizeQuarter);
 
   Index i=0;
   for(; i<n8; i+=8)