From 9c9e90f6db7e93617cdfd617083013ca5b176adb Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Thu, 14 Dec 2017 14:24:33 +0100
Subject: [PATCH] Fix packet and alignment propagation logic of Block<Xpr>
 expressions. In particular, (A+B).col(j) lost vectorisation. (grafted from
 9c3aed9d48d7dbc0f88d2fb92ca232dcbf0d402e )

---
 Eigen/src/Core/CoreEvaluators.h | 6 ++++--
 test/vectorization_logic.cpp    | 6 ++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/Eigen/src/Core/CoreEvaluators.h b/Eigen/src/Core/CoreEvaluators.h
index f7c1effca..90e70fb4f 100644
--- a/Eigen/src/Core/CoreEvaluators.h
+++ b/Eigen/src/Core/CoreEvaluators.h
@@ -977,7 +977,7 @@ struct evaluator<Block<ArgType, BlockRows, BlockCols, InnerPanel> >
     OuterStrideAtCompileTime = HasSameStorageOrderAsArgType
                              ? int(outer_stride_at_compile_time<ArgType>::ret)
                              : int(inner_stride_at_compile_time<ArgType>::ret),
-    MaskPacketAccessBit = (InnerStrideAtCompileTime == 1) ? PacketAccessBit : 0,
+    MaskPacketAccessBit = (InnerStrideAtCompileTime == 1 || HasSameStorageOrderAsArgType) ? PacketAccessBit : 0,
     
     FlagsLinearAccessBit = (RowsAtCompileTime == 1 || ColsAtCompileTime == 1 || (InnerPanel && (evaluator<ArgType>::Flags&LinearAccessBit))) ? LinearAccessBit : 0,    
     FlagsRowMajorBit = XprType::Flags&RowMajorBit,
@@ -987,7 +987,9 @@ struct evaluator<Block<ArgType, BlockRows, BlockCols, InnerPanel> >
     Flags = Flags0 | FlagsLinearAccessBit | FlagsRowMajorBit,
     
     PacketAlignment = unpacket_traits<PacketScalar>::alignment,
-    Alignment0 = (InnerPanel && (OuterStrideAtCompileTime!=Dynamic) && (((OuterStrideAtCompileTime * int(sizeof(Scalar))) % int(PacketAlignment)) == 0)) ? int(PacketAlignment) : 0,
+    Alignment0 = (InnerPanel && (OuterStrideAtCompileTime!=Dynamic)
+                             && (OuterStrideAtCompileTime!=0)
+                             && (((OuterStrideAtCompileTime * int(sizeof(Scalar))) % int(PacketAlignment)) == 0)) ? int(PacketAlignment) : 0,
     Alignment = EIGEN_PLAIN_ENUM_MIN(evaluator<ArgType>::Alignment, Alignment0)
   };
   typedef block_evaluator<ArgType, BlockRows, BlockCols, InnerPanel> block_evaluator_type;
diff --git a/test/vectorization_logic.cpp b/test/vectorization_logic.cpp
index 83c1439ad..37e7495f5 100644
--- a/test/vectorization_logic.cpp
+++ b/test/vectorization_logic.cpp
@@ -207,6 +207,12 @@ struct vectorization_logic
     VERIFY(test_redux(Vector1(),
       LinearVectorizedTraversal,CompleteUnrolling));
 
+    VERIFY(test_redux(Vector1().array()*Vector1().array(),
+      LinearVectorizedTraversal,CompleteUnrolling));
+
+    VERIFY(test_redux((Vector1().array()*Vector1().array()).col(0),
+      LinearVectorizedTraversal,CompleteUnrolling));
+
     VERIFY(test_redux(Matrix<Scalar,PacketSize,3>(),
       LinearVectorizedTraversal,CompleteUnrolling));