From e3a521be6beeb0db55861a42bb4483a41e553a62 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Sat, 21 May 2011 22:19:12 +0200
Subject: [PATCH] backport 7209d6a12610d4682c65a99f12b0d0278fbbe81d  (fix
 gemv_static_vector_if on architectures that cannot aligned on the stack
 (e.g., ARM NEON))

---
 Eigen/src/Core/Product.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Eigen/src/Core/Product.h b/Eigen/src/Core/Product.h
index bde25375d..b45946044 100644
--- a/Eigen/src/Core/Product.h
+++ b/Eigen/src/Core/Product.h
@@ -375,8 +375,23 @@ struct gemv_static_vector_if<Scalar,Size,Dynamic,true>
 template<typename Scalar,int Size,int MaxSize>
 struct gemv_static_vector_if<Scalar,Size,MaxSize,true>
 {
+  #if EIGEN_ALIGN_STATICALLY
   internal::plain_array<Scalar,EIGEN_SIZE_MIN_PREFER_FIXED(Size,MaxSize),0> m_data;
   EIGEN_STRONG_INLINE Scalar* data() { return m_data.array; }
+  #else
+  // Some architectures cannot align on the stack,
+  // => let's manually enforce alignment by allocating more data and return the address of the first aligned element.
+  enum {
+    ForceAlignment  = internal::packet_traits<Scalar>::Vectorizable,
+    PacketSize      = internal::packet_traits<Scalar>::size
+  };
+  internal::plain_array<Scalar,EIGEN_SIZE_MIN_PREFER_FIXED(Size,MaxSize)+(ForceAlignment?PacketSize:0),0> m_data;
+  EIGEN_STRONG_INLINE Scalar* data() {
+    return ForceAlignment
+            ? reinterpret_cast<Scalar*>((reinterpret_cast<size_t>(m_data.array) & ~(size_t(15))) + 16)
+            : m_data.array;
+  }
+  #endif
 };
 
 template<> struct gemv_selector<OnTheRight,ColMajor,true>