From bb13d5d917d8b4fadec24ab0f3465bbad0e6635f Mon Sep 17 00:00:00 2001
From: Eugene Zhulenev <ezhulenev@google.com>
Date: Fri, 28 Sep 2018 14:34:42 -0700
Subject: Fix bug in copy optimization in Tensor slicing.

---
 .../Eigen/CXX11/src/Tensor/TensorMorphing.h        | 53 ++++++++++++----------
 1 file changed, 30 insertions(+), 23 deletions(-)

(limited to 'unsupported/Eigen/CXX11/src/Tensor/TensorMorphing.h')

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorMorphing.h b/unsupported/Eigen/CXX11/src/Tensor/TensorMorphing.h
index d19aba3b3..213379dbd 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorMorphing.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorMorphing.h
@@ -979,44 +979,51 @@ struct TensorEvaluator<const TensorStridingSlicingOp<StartIndices, StopIndices,
   };
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorEvaluator(const XprType& op, const Device& device)
-      : m_impl(op.expression(), device), m_device(device), m_strides(op.strides()), m_exprStartIndices(op.startIndices()), m_exprStopIndices(op.stopIndices())
+      : m_impl(op.expression(), device),
+        m_device(device),
+        m_strides(op.strides()), m_exprStartIndices(op.startIndices()),
+        m_exprStopIndices(op.stopIndices())
   {
     // Handle degenerate intervals by gracefully clamping and allowing m_dimensions to be zero
-    DSizes<Index,NumDims> startIndicesClamped, stopIndicesClamped;
-    m_is_identity = true;
-    for (Index i = 0; i < internal::array_size<Dimensions>::value; ++i) {
-      if (m_strides[i] != 1 || op.startIndices()[i] != 0 ||
-          op.stopIndices()[i] != (m_impl.dimensions()[i] - 1)) {
-        m_is_identity = false;
-      }
-
+    DSizes<Index, NumDims> startIndicesClamped, stopIndicesClamped;
+    for (ptrdiff_t i = 0; i < internal::array_size<Dimensions>::value; ++i) {
       eigen_assert(m_strides[i] != 0 && "0 stride is invalid");
-      if(m_strides[i]>0){
-        startIndicesClamped[i] = clamp(op.startIndices()[i], 0, m_impl.dimensions()[i]);
-        stopIndicesClamped[i] = clamp(op.stopIndices()[i], 0, m_impl.dimensions()[i]);
-      }else{
-      /* implies m_strides[i]<0 by assert */
-        startIndicesClamped[i] = clamp(op.startIndices()[i], -1, m_impl.dimensions()[i] - 1);
-        stopIndicesClamped[i] = clamp(op.stopIndices()[i], -1, m_impl.dimensions()[i] - 1);
+      if (m_strides[i] > 0) {
+        startIndicesClamped[i] =
+            clamp(op.startIndices()[i], 0, m_impl.dimensions()[i]);
+        stopIndicesClamped[i] =
+            clamp(op.stopIndices()[i], 0, m_impl.dimensions()[i]);
+      } else {
+        /* implies m_strides[i] < 0 by assert */
+        startIndicesClamped[i] =
+            clamp(op.startIndices()[i], -1, m_impl.dimensions()[i] - 1);
+        stopIndicesClamped[i] =
+            clamp(op.stopIndices()[i], -1, m_impl.dimensions()[i] - 1);
       }
       m_startIndices[i] = startIndicesClamped[i];
     }
 
-    const typename TensorEvaluator<ArgType, Device>::Dimensions& input_dims = m_impl.dimensions();
+    typedef typename TensorEvaluator<ArgType, Device>::Dimensions InputDimensions;
+    const InputDimensions& input_dims = m_impl.dimensions();
 
     // check for degenerate intervals and compute output tensor shape
-    bool degenerate = false;;
-    for(int i = 0; i < NumDims; i++){
+    bool degenerate = false;
+    m_is_identity = true;
+    for (int i = 0; i < NumDims; i++) {
       Index interval = stopIndicesClamped[i] - startIndicesClamped[i];
-      if(interval == 0 || ((interval<0) != (m_strides[i]<0))){
+      if (interval == 0 || ((interval < 0) != (m_strides[i] < 0))) {
         m_dimensions[i] = 0;
         degenerate = true;
-      }else{
-        m_dimensions[i] = interval / m_strides[i]
-                          + (interval % m_strides[i] != 0 ? 1 : 0);
+      } else {
+        m_dimensions[i] =
+            (interval / m_strides[i]) + (interval % m_strides[i] != 0 ? 1 : 0);
         eigen_assert(m_dimensions[i] >= 0);
       }
+      if (m_strides[i] != 1 || interval != m_impl.dimensions()[i]) {
+        m_is_identity = false;
+      }
     }
+
     Strides output_dims = m_dimensions;
 
     if (static_cast<int>(Layout) == static_cast<int>(ColMajor)) {
-- 
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