Solve a big issue with data alignment and dynamic allocation:

* add a WithAlignedOperatorNew class with overloaded operator new
* make Matrix (and Quaternion, Transform, Hyperplane, etc.) use it
  if needed such that "*(new Vector4) = xpr" does not failed anymore.
* Please: make sure your classes having fixed size Eigen's vector
  or matrice attributes inherit WithAlignedOperatorNew
* add a ei_new_allocator STL memory allocator to use with STL containers.
  This allocator really calls operator new on your types (unlike GCC's
  new_allocator). Example:
  std::vector<Vector4f> data(10);
  will segfault if the vectorization is enabled, instead use:
  std::vector<Vector4f,ei_new_allocator<Vector4f> > data(10);
NOTE: you only have to worry if you deal with fixed-size matrix types
with "sizeof(matrix_type)%16==0"...

test/dynalloc.cpp

@@ -0,0 +1,138 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra. Eigen itself is part of the KDE project.
+//
+// Copyright (C) 2008 Gael Guennebaud <g.gael@free.fr>
+//
+// Eigen is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 3 of the License, or (at your option) any later version.
+//
+// Alternatively, you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of
+// the License, or (at your option) any later version.
+//
+// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License or the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License and a copy of the GNU General Public License along with
+// Eigen. If not, see <http://www.gnu.org/licenses/>.
+
+#include "main.h"
+
+#include <ext/malloc_allocator.h>
+
+// test compilation with both a struct and a class...
+struct MyStruct : WithAlignedOperatorNew
+{
+  char dummychar;
+  Vector4f avec;
+};
+
+class MyClassA : public WithAlignedOperatorNew
+{
+  public:
+    char dummychar;
+    Vector4f avec;
+};
+
+// ..as well as with some other base classes
+
+class MyBaseClass
+{
+  public:
+    char dummychar;
+    float afloat;
+};
+
+class MyClassB : public WithAlignedOperatorNew, public MyBaseClass
+{
+  public:
+    char dummychar;
+    Vector4f avec;
+};
+
+class MyClassC : public MyBaseClass, public WithAlignedOperatorNew
+{
+  public:
+    char dummychar;
+    Vector4f avec;
+};
+
+template<typename T> void check_dynaligned()
+{
+  T* obj = new T;
+  VERIFY(size_t(obj)%16==0);
+  delete obj;
+}
+
+void test_dynalloc()
+{
+
+#ifdef EIGEN_VECTORIZE
+  for (int i=0; i<g_repeat*100; ++i)
+  {
+    CALL_SUBTEST( check_dynaligned<Vector4f>() );
+    CALL_SUBTEST( check_dynaligned<Vector2d>() );
+    CALL_SUBTEST( check_dynaligned<Matrix4f>() );
+    CALL_SUBTEST( check_dynaligned<Vector4d>() );
+    CALL_SUBTEST( check_dynaligned<Vector4i>() );
+  }
+  
+  // check static allocation, who knows ?
+  {
+    MyStruct foo0;  VERIFY(size_t(foo0.avec.data())%16==0);
+    MyClassA fooA;  VERIFY(size_t(fooA.avec.data())%16==0);
+    MyClassB fooB;  VERIFY(size_t(fooB.avec.data())%16==0);
+    MyClassC fooC;  VERIFY(size_t(fooC.avec.data())%16==0);
+  }
+
+  // dynamic allocation, single object
+  for (int i=0; i<g_repeat*100; ++i)
+  {
+    MyStruct *foo0 = new MyStruct();  VERIFY(size_t(foo0->avec.data())%16==0);
+    MyClassA *fooA = new MyClassA();  VERIFY(size_t(fooA->avec.data())%16==0);
+    MyClassB *fooB = new MyClassB();  VERIFY(size_t(fooB->avec.data())%16==0);
+    MyClassC *fooC = new MyClassC();  VERIFY(size_t(fooC->avec.data())%16==0);
+    delete foo0;
+    delete fooA;
+    delete fooB;
+    delete fooC;
+  }
+
+  // dynamic allocation, array
+  const int N = 10;
+  for (int i=0; i<g_repeat*100; ++i)
+  {
+    MyStruct *foo0 = new MyStruct[N];  VERIFY(size_t(foo0->avec.data())%16==0);
+    MyClassA *fooA = new MyClassA[N];  VERIFY(size_t(fooA->avec.data())%16==0);
+    MyClassB *fooB = new MyClassB[N];  VERIFY(size_t(fooB->avec.data())%16==0);
+    MyClassC *fooC = new MyClassC[N];  VERIFY(size_t(fooC->avec.data())%16==0);
+    delete[] foo0;
+    delete[] fooA;
+    delete[] fooB;
+    delete[] fooC;
+  }
+
+  // std::vector
+  for (int i=0; i<g_repeat*100; ++i)
+  {
+    std::vector<Vector4f, ei_new_allocator<Vector4f> > vecs(N);
+    for (int j=0; j<N; ++j)
+    {
+      VERIFY(size_t(vecs[j].data())%16==0);
+    }
+    std::vector<MyStruct,ei_new_allocator<MyStruct> > foos(N);
+    for (int j=0; j<N; ++j)
+    {
+      VERIFY(size_t(foos[j].avec.data())%16==0);
+    }
+  }
+  
+#endif // EIGEN_VECTORIZE
+
+}