From ca60c5b76bbb3e675fb21fd1a1f9aa47cccee394 Mon Sep 17 00:00:00 2001
From: Denis Bakhvalov <denis.bakhvalov@intel.com>
Date: Tue, 7 Sep 2021 22:22:04 -0700
Subject: [PATCH 1/5] [ESIMD] Allow constructing simd_view from simd

The patch allows the following code to work:
```
  simd<int, 16> s = 0;
  simd_view v = s;
```

I added default template parameter for simd_view_impl class
and put it as a last template argument.
---
 .../esimd/detail/simd_view_impl.hpp           |  5 +++-
 .../intel/experimental/esimd/simd_view.hpp    | 26 ++++++++++++-------
 sycl/test/esimd/simd_view.cpp                 |  6 +++++
 3 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/sycl/include/sycl/ext/intel/experimental/esimd/detail/simd_view_impl.hpp b/sycl/include/sycl/ext/intel/experimental/esimd/detail/simd_view_impl.hpp
index 56c4e626118b8..ec9bddacc6c6d 100644
--- a/sycl/include/sycl/ext/intel/experimental/esimd/detail/simd_view_impl.hpp
+++ b/sycl/include/sycl/ext/intel/experimental/esimd/detail/simd_view_impl.hpp
@@ -25,7 +25,9 @@ namespace detail {
 /// It is an internal class implementing basic functionality of simd_view.
 ///
 /// \ingroup sycl_esimd
-template <typename BaseTy, typename RegionTy, typename Derived>
+template <typename BaseTy, typename Derived,
+          typename RegionTy =
+              region1d_t<typename BaseTy::element_type, BaseTy::length, 1>>
 class simd_view_impl {
   template <typename, int> friend class simd;
   template <typename, typename, typename> friend class simd_view_impl;
@@ -61,6 +63,7 @@ class simd_view_impl {
       : M_base(Base), M_region(Region) {}
   simd_view_impl(BaseTy &&Base, RegionTy Region)
       : M_base(Base), M_region(Region) {}
+  simd_view_impl(BaseTy &Base) : M_base(Base), M_region(RegionTy(0)) {}
 
 public:
   // Default copy and move constructors.
diff --git a/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp b/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
index 93772330450ca..0ab2ded19e2a2 100644
--- a/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
+++ b/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
@@ -24,15 +24,18 @@ namespace esimd {
 /// via an instance of this class.
 ///
 /// \ingroup sycl_esimd
-template <typename BaseTy, typename RegionTy>
-class simd_view : public detail::simd_view_impl<BaseTy, RegionTy,
-                                                simd_view<BaseTy, RegionTy>> {
+template <typename BaseTy,
+          typename RegionTy =
+              region1d_t<typename BaseTy::element_type, BaseTy::length, 1>>
+class simd_view
+    : public detail::simd_view_impl<BaseTy, simd_view<BaseTy, RegionTy>,
+                                    RegionTy> {
   template <typename, int> friend class simd;
   template <typename, typename, typename> friend class detail::simd_view_impl;
 
 public:
   using BaseClass =
-      detail::simd_view_impl<BaseTy, RegionTy, simd_view<BaseTy, RegionTy>>;
+      detail::simd_view_impl<BaseTy, simd_view<BaseTy, RegionTy>, RegionTy>;
   using ShapeTy = typename shape_type<RegionTy>::type;
   static constexpr int length = ShapeTy::Size_x * ShapeTy::Size_y;
 
@@ -41,6 +44,9 @@ class simd_view : public detail::simd_view_impl<BaseTy, RegionTy,
   /// The simd type if reading this simd_view object.
   using value_type = simd<element_type, length>;
 
+  // Construct a complete view of a vector
+  simd_view(BaseTy &Base) : BaseClass(Base) {}
+
 private:
   simd_view(BaseTy &Base, RegionTy Region) : BaseClass(Base, Region) {}
   simd_view(BaseTy &&Base, RegionTy Region) : BaseClass(Base, Region) {}
@@ -173,15 +179,15 @@ class simd_view : public detail::simd_view_impl<BaseTy, RegionTy,
 template <typename BaseTy, typename T, int StrideY, int StrideX>
 class simd_view<BaseTy, region1d_scalar_t<T, StrideY, StrideX>>
     : public detail::simd_view_impl<
-          BaseTy, region1d_scalar_t<T, StrideY, StrideX>,
-          simd_view<BaseTy, region1d_scalar_t<T, StrideY, StrideX>>> {
+          BaseTy, simd_view<BaseTy, region1d_scalar_t<T, StrideY, StrideX>>,
+          region1d_scalar_t<T, StrideY, StrideX>> {
   template <typename, int> friend class simd;
   template <typename, typename, typename> friend class detail::simd_view_impl;
 
 public:
   using RegionTy = region1d_scalar_t<T, StrideY, StrideX>;
   using BaseClass =
-      detail::simd_view_impl<BaseTy, RegionTy, simd_view<BaseTy, RegionTy>>;
+      detail::simd_view_impl<BaseTy, simd_view<BaseTy, RegionTy>, RegionTy>;
   using ShapeTy = typename shape_type<RegionTy>::type;
   static constexpr int length = ShapeTy::Size_x * ShapeTy::Size_y;
   static_assert(1 == length, "length of this view is not equal to 1");
@@ -237,9 +243,9 @@ class simd_view<BaseTy,
                 std::pair<region1d_scalar_t<T, StrideY, StrideX>, NestedRegion>>
     : public detail::simd_view_impl<
           BaseTy,
-          std::pair<region1d_scalar_t<T, StrideY, StrideX>, NestedRegion>,
           simd_view<BaseTy, std::pair<region1d_scalar_t<T, StrideY, StrideX>,
-                                      NestedRegion>>> {
+                                      NestedRegion>>,
+          std::pair<region1d_scalar_t<T, StrideY, StrideX>, NestedRegion>> {
   template <typename, int> friend class simd;
   template <typename, typename, typename> friend class detail::simd_view_impl;
 
@@ -247,7 +253,7 @@ class simd_view<BaseTy,
   using RegionTy =
       std::pair<region1d_scalar_t<T, StrideY, StrideX>, NestedRegion>;
   using BaseClass =
-      detail::simd_view_impl<BaseTy, RegionTy, simd_view<BaseTy, RegionTy>>;
+      detail::simd_view_impl<BaseTy, simd_view<BaseTy, RegionTy>, RegionTy>;
   using ShapeTy = typename shape_type<RegionTy>::type;
   static constexpr int length = ShapeTy::Size_x * ShapeTy::Size_y;
   static_assert(1 == length, "length of this view is not equal to 1");
diff --git a/sycl/test/esimd/simd_view.cpp b/sycl/test/esimd/simd_view.cpp
index d90eb600b27a0..79cad8756bb0f 100644
--- a/sycl/test/esimd/simd_view.cpp
+++ b/sycl/test/esimd/simd_view.cpp
@@ -69,6 +69,12 @@ SYCL_ESIMD_FUNCTION void test_simd_view_copy_ctor() {
   auto v0_view_copy(v0_view);
 }
 
+// test construction from vector.
+SYCL_ESIMD_FUNCTION void test_simd_view_from_vector() {
+  simd<int, 16> s = 0;
+  simd_view v = s;
+}
+
 // move constructor transfers the same view of the underlying data.
 SYCL_ESIMD_FUNCTION void test_simd_view_move_ctor() {
   simd<int, 16> v0 = 1;

From d58dbd2cc3fa887e973a62647b99137a894093a3 Mon Sep 17 00:00:00 2001
From: Denis Bakhvalov <denis.bakhvalov@intel.com>
Date: Wed, 15 Sep 2021 21:49:39 -0700
Subject: [PATCH 2/5] fixed code review comments

---
 sycl/test/esimd/simd_view.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/sycl/test/esimd/simd_view.cpp b/sycl/test/esimd/simd_view.cpp
index 79cad8756bb0f..bc97506583be0 100644
--- a/sycl/test/esimd/simd_view.cpp
+++ b/sycl/test/esimd/simd_view.cpp
@@ -72,7 +72,14 @@ SYCL_ESIMD_FUNCTION void test_simd_view_copy_ctor() {
 // test construction from vector.
 SYCL_ESIMD_FUNCTION void test_simd_view_from_vector() {
   simd<int, 16> s = 0;
-  simd_view v = s;
+  simd_view v1 = s;
+  simd_view v2(s);
+  // expected-error@+4 {{no matching constructor for initialization of 'simd_view}}
+  // expected-note@sycl/ext/intel/experimental/esimd/simd_view.hpp:* {{candidate constructor not viable: expects an lvalue for 1st argument}}
+  // expected-note@sycl/ext/intel/experimental/esimd/simd_view.hpp:* 4+ {{candidate constructor not viable:}}
+  // expected-note@sycl/ext/intel/experimental/esimd/simd.hpp:* {{candidate template ignored:}}
+  simd_view<simd<int, 16>, region_base<false, int, 1, 0, 16, 1>> v3(
+      (simd<int, 16>()));
 }
 
 // move constructor transfers the same view of the underlying data.

From 7a99aa036d4d6b06e34e4e2cd393b7de9d8cc5a8 Mon Sep 17 00:00:00 2001
From: Vyacheslav N Klochkov <vyacheslav.n.klochkov@intel.com>
Date: Mon, 1 Nov 2021 15:10:47 -0700
Subject: [PATCH 3/5] Fix the LIT test; fix clang-format

Signed-off-by: Vyacheslav N Klochkov <vyacheslav.n.klochkov@intel.com>
---
 .../experimental/esimd/detail/simd_view_impl.hpp      |  3 ++-
 .../sycl/ext/intel/experimental/esimd/simd_view.hpp   |  3 ++-
 sycl/test/esimd/simd_view.cpp                         | 11 ++++++-----
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/sycl/include/sycl/ext/intel/experimental/esimd/detail/simd_view_impl.hpp b/sycl/include/sycl/ext/intel/experimental/esimd/detail/simd_view_impl.hpp
index 491225e4d9b03..d87f64e464909 100644
--- a/sycl/include/sycl/ext/intel/experimental/esimd/detail/simd_view_impl.hpp
+++ b/sycl/include/sycl/ext/intel/experimental/esimd/detail/simd_view_impl.hpp
@@ -25,7 +25,8 @@ namespace detail {
 /// It is an internal class implementing basic functionality of simd_view.
 ///
 /// \ingroup sycl_esimd
-template <typename BaseTy, typename RegionTy =
+template <typename BaseTy,
+          typename RegionTy =
               region1d_t<typename BaseTy::element_type, BaseTy::length, 1>>
 class simd_view_impl {
   using Derived = simd_view<BaseTy, RegionTy>;
diff --git a/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp b/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
index 42aadebb6ee4b..c88ee4907d1b6 100644
--- a/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
+++ b/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
@@ -25,7 +25,8 @@ namespace esimd {
 /// via an instance of this class.
 ///
 /// \ingroup sycl_esimd
-template <typename BaseTy, typename RegionTy =
+template <typename BaseTy,
+          typename RegionTy =
               region1d_t<typename BaseTy::element_type, BaseTy::length, 1>>
 class simd_view : public detail::simd_view_impl<BaseTy, RegionTy> {
   template <typename, int, class, class> friend class detail::simd_obj_impl;
diff --git a/sycl/test/esimd/simd_view.cpp b/sycl/test/esimd/simd_view.cpp
index 05c4c0aa1f55c..710f7bf2cb24f 100644
--- a/sycl/test/esimd/simd_view.cpp
+++ b/sycl/test/esimd/simd_view.cpp
@@ -111,11 +111,12 @@ SYCL_ESIMD_FUNCTION void test_simd_view_from_vector() {
   simd<int, 16> s = 0;
   simd_view v1 = s;
   simd_view v2(s);
-  // expected-error@+4 {{no matching constructor for initialization of 'simd_view}}
-  // expected-note@sycl/ext/intel/experimental/esimd/simd_view.hpp:* {{candidate constructor not viable: expects an lvalue for 1st argument}}
-  // expected-note@sycl/ext/intel/experimental/esimd/simd_view.hpp:* 4+ {{candidate constructor not viable:}}
-  // expected-note@sycl/ext/intel/experimental/esimd/simd.hpp:* {{candidate template ignored:}}
-  simd_view<simd<int, 16>, region_base<false, int, 1, 0, 16, 1>> v3(
+  // expected-error@+5 {{no matching constructor for initialization of 'simd_view}}
+  // expected-note@sycl/ext/intel/experimental/esimd/simd_view.hpp:* 3 {{candidate }}
+  // expected-note@sycl/ext/intel/experimental/esimd/simd.hpp:* {{candidate }}
+  // expected-note@sycl/ext/intel/experimental/esimd/detail/simd_obj_impl.hpp:* {{candidate }}
+  // expected-note@sycl/ext/intel/experimental/esimd/simd_view.hpp:* 2 {{candidate }}
+  simd_view<simd<int, 16>, region_base<false, int, 1, 1, 16, 1>> v3(
       (simd<int, 16>()));
 }
 

From 33eede79f2ca2d92d21dca4b85ca2227bebeb47d Mon Sep 17 00:00:00 2001
From: Vyacheslav N Klochkov <vyacheslav.n.klochkov@intel.com>
Date: Tue, 2 Nov 2021 12:11:04 -0700
Subject: [PATCH 4/5] Also support simd_view constructor from 1 element simd

Signed-off-by: Vyacheslav N Klochkov <vyacheslav.n.klochkov@intel.com>
---
 .../sycl/ext/intel/experimental/esimd/simd_view.hpp  |  3 +++
 sycl/test/esimd/simd_view.cpp                        | 12 ++++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp b/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
index c88ee4907d1b6..774d6c1e2715c 100644
--- a/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
+++ b/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
@@ -142,6 +142,9 @@ class simd_view<BaseTy, region1d_scalar_t<T>>
   simd_view(BaseTy &&Base, RegionTy Region) : BaseClass(Base, Region) {}
 
 public:
+  // Construct a complete view of a vector
+  simd_view(BaseTy &Base) : BaseClass(Base) {}
+
   operator element_type() const {
     const auto v = BaseClass::read();
     return v[0];
diff --git a/sycl/test/esimd/simd_view.cpp b/sycl/test/esimd/simd_view.cpp
index 710f7bf2cb24f..602dd8fa48c20 100644
--- a/sycl/test/esimd/simd_view.cpp
+++ b/sycl/test/esimd/simd_view.cpp
@@ -108,16 +108,20 @@ SYCL_ESIMD_FUNCTION void test_simd_view_copy_ctor() {
 
 // test construction from vector.
 SYCL_ESIMD_FUNCTION void test_simd_view_from_vector() {
-  simd<int, 16> s = 0;
-  simd_view v1 = s;
-  simd_view v2(s);
+  simd<int, 16> v16 = 0;
+  simd_view sv16a = v16;
+  simd_view sv16b(v16);
   // expected-error@+5 {{no matching constructor for initialization of 'simd_view}}
   // expected-note@sycl/ext/intel/experimental/esimd/simd_view.hpp:* 3 {{candidate }}
   // expected-note@sycl/ext/intel/experimental/esimd/simd.hpp:* {{candidate }}
   // expected-note@sycl/ext/intel/experimental/esimd/detail/simd_obj_impl.hpp:* {{candidate }}
   // expected-note@sycl/ext/intel/experimental/esimd/simd_view.hpp:* 2 {{candidate }}
-  simd_view<simd<int, 16>, region_base<false, int, 1, 1, 16, 1>> v3(
+  simd_view<simd<int, 16>, region_base<false, int, 1, 1, 16, 1>> sv16c(
       (simd<int, 16>()));
+
+  simd<int, 1> v1 = 0;
+  simd_view sv1a = v1;
+  simd_view sv1b(v1);
 }
 
 // move constructor transfers the same view of the underlying data.

From b4d1d4e8954af7ce1a557facc8b1556e9d751ced Mon Sep 17 00:00:00 2001
From: Vyacheslav N Klochkov <vyacheslav.n.klochkov@intel.com>
Date: Tue, 2 Nov 2021 12:17:14 -0700
Subject: [PATCH 5/5] Address reviewer's comment - convert a comment to doxygen
 style

Signed-off-by: Vyacheslav N Klochkov <vyacheslav.n.klochkov@intel.com>
---
 .../include/sycl/ext/intel/experimental/esimd/simd_view.hpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp b/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
index 774d6c1e2715c..9000f8fee80f7 100644
--- a/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
+++ b/sycl/include/sycl/ext/intel/experimental/esimd/simd_view.hpp
@@ -68,11 +68,11 @@ class simd_view : public detail::simd_view_impl<BaseTy, RegionTy> {
   /// @}
 
 public:
-  // Default copy and move constructors for simd_view.
+  /// Default copy and move constructors for simd_view.
   simd_view(const simd_view &Other) = default;
   simd_view(simd_view &&Other) = default;
 
-  // Construct a complete view of a vector
+  /// Construct a complete view of a vector
   simd_view(BaseTy &Base) : BaseClass(Base) {}
 
   simd_view &operator=(const simd_view &Other) {
@@ -142,7 +142,7 @@ class simd_view<BaseTy, region1d_scalar_t<T>>
   simd_view(BaseTy &&Base, RegionTy Region) : BaseClass(Base, Region) {}
 
 public:
-  // Construct a complete view of a vector
+  /// Construct a complete view of a vector
   simd_view(BaseTy &Base) : BaseClass(Base) {}
 
   operator element_type() const {