From: Peter Munch <peterrmuench@gmail.com>
Date: Sun, 11 Dec 2022 16:04:53 +0000 (+0100)
Subject: Add helper function to indicate power of two
X-Git-Tag: v9.5.0-rc1~735^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9896d06bc99125ab1789ec4126bc23565b1d5792;p=dealii.git

Add helper function to indicate power of two
---

diff --git a/include/deal.II/matrix_free/util.h b/include/deal.II/matrix_free/util.h
index 922e7a1cf2..0c6b27baca 100644
--- a/include/deal.II/matrix_free/util.h
+++ b/include/deal.II/matrix_free/util.h
@@ -161,6 +161,17 @@ namespace internal
 
       return {Quadrature<dim - 1>(), Quadrature<dim - 1>()};
     }
+
+    inline DEAL_II_ALWAYS_INLINE unsigned int
+    indicate_power_of_two(const unsigned int vectorization_length)
+    {
+      unsigned int vectorization_length_bits = 0;
+      unsigned int my_length                 = vectorization_length;
+      while (my_length >>= 1)
+        ++vectorization_length_bits;
+      return 1 << vectorization_length_bits;
+    }
+
   } // end of namespace MatrixFreeFunctions
 } // end of namespace internal
 
diff --git a/source/matrix_free/task_info.cc b/source/matrix_free/task_info.cc
index 04b46ea1fc..d50e46ff85 100644
--- a/source/matrix_free/task_info.cc
+++ b/source/matrix_free/task_info.cc
@@ -24,6 +24,7 @@
 #include <deal.II/lac/dynamic_sparsity_pattern.h>
 
 #include <deal.II/matrix_free/task_info.h>
+#include <deal.II/matrix_free/util.h>
 
 
 #ifdef DEAL_II_WITH_TBB
@@ -825,11 +826,7 @@ namespace internal
 
       // Give the compiler a chance to detect that vectorization_length is a
       // power of two, which allows it to replace integer divisions by shifts
-      unsigned int vectorization_length_bits = 0;
-      unsigned int my_length                 = vectorization_length;
-      while ((my_length >>= 1) != 0u)
-        ++vectorization_length_bits;
-      const unsigned int n_lanes = 1 << vectorization_length_bits;
+      const unsigned int n_lanes = indicate_power_of_two(vectorization_length);
 
       // Step 1: find tight map of categories for not taking exceeding amounts
       // of memory below. Sort the new categories by the numbers in the