From 324894cc3d64f724fb1e060ffc49df9b6bc6a17d Mon Sep 17 00:00:00 2001
From: Martin Kronbichler <martin.kronbichler@uni-a.de>
Date: Mon, 12 Sep 2022 09:06:14 +0200
Subject: [PATCH] Provide inlined fast code path for Vector::reinit(Vector&)

---
 include/deal.II/lac/vector.h           | 17 +++++++++++++++++
 include/deal.II/lac/vector.templates.h | 12 ------------
 source/lac/vector.cc                   |  3 ---
 source/lac/vector.inst.in              |  3 ---
 4 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/include/deal.II/lac/vector.h b/include/deal.II/lac/vector.h
index 2e43459f2a..c049ce3898 100644
--- a/include/deal.II/lac/vector.h
+++ b/include/deal.II/lac/vector.h
@@ -1354,6 +1354,23 @@ Vector<Number>::update_ghost_values() const
 
 
 
+template <typename Number>
+template <typename Number2>
+inline void
+Vector<Number>::reinit(const Vector<Number2> &v,
+                       const bool             omit_zeroing_entries)
+{
+  // go to actual reinit functions in case we need to change something with
+  // the vector, else there is nothing to be done
+  if (!omit_zeroing_entries || size() != v.size())
+    {
+      do_reinit(v.size(), omit_zeroing_entries, false);
+      thread_loop_partitioner = v.thread_loop_partitioner;
+    }
+}
+
+
+
 // Moved from vector.templates.h as an inline function by Luca Heltai
 // on 2009/04/12 to prevent strange compiling errors, after making
 // swap virtual.
diff --git a/include/deal.II/lac/vector.templates.h b/include/deal.II/lac/vector.templates.h
index 98b24bd7d0..850603b317 100644
--- a/include/deal.II/lac/vector.templates.h
+++ b/include/deal.II/lac/vector.templates.h
@@ -242,18 +242,6 @@ Vector<Number>::grow_or_shrink(const size_type n)
 
 
 
-template <typename Number>
-template <typename Number2>
-void
-Vector<Number>::reinit(const Vector<Number2> &v,
-                       const bool             omit_zeroing_entries)
-{
-  do_reinit(v.size(), omit_zeroing_entries, false);
-  thread_loop_partitioner = v.thread_loop_partitioner;
-}
-
-
-
 template <typename Number>
 bool
 Vector<Number>::all_zero() const
diff --git a/source/lac/vector.cc b/source/lac/vector.cc
index 09eb1facd9..fe893dcba4 100644
--- a/source/lac/vector.cc
+++ b/source/lac/vector.cc
@@ -33,9 +33,6 @@ Vector<double>::operator=<int>(const dealii::Vector<int> &);
 template bool
 Vector<int>::operator==<int>(dealii::Vector<int> const &) const;
 
-template void
-Vector<int>::reinit<double>(const Vector<double> &, const bool);
-
 // instantiate for long double manually because we use it in a few places:
 template class Vector<long double>;
 template long double
diff --git a/source/lac/vector.inst.in b/source/lac/vector.inst.in
index 173d5f5ade..23e5b47fac 100644
--- a/source/lac/vector.inst.in
+++ b/source/lac/vector.inst.in
@@ -24,18 +24,15 @@ for (S1, S2 : REAL_SCALARS)
   {
     template bool Vector<S1>::operator==<S2>(const Vector<S2> &) const;
     template S1 Vector<S1>::operator*<S2>(const Vector<S2> &) const;
-    template void Vector<S1>::reinit<S2>(const Vector<S2> &, const bool);
   }
 
 for (S1, S2 : COMPLEX_SCALARS)
   {
     template bool Vector<S1>::operator==<S2>(const Vector<S2> &) const;
     template S1 Vector<S1>::operator*<S2>(const Vector<S2> &) const;
-    template void Vector<S1>::reinit<S2>(const Vector<S2> &, const bool);
   }
 
 for (S1 : COMPLEX_SCALARS; S2 : REAL_SCALARS)
   {
     template Vector<S1> &Vector<S1>::operator=<S2>(const Vector<S2> &);
-    template void Vector<S1>::reinit<S2>(const Vector<S2> &, const bool);
   }
-- 
2.39.5