Allow iterators to be decremented past begin and incremented past end

Author: AlexeySachkov

sycl/include/sycl/detail/accessor_iterator.hpp

@@ -60,8 +60,7 @@ template <typename _DataT, int _Dimensions> class __accessor_iterator {
   }
 
   __accessor_iterator &operator++() {
-    if (_MLinearId < _MEnd)
-      ++_MLinearId;
+    ++_MLinearId;
     return *this;
   }
 
@@ -72,8 +71,7 @@ template <typename _DataT, int _Dimensions> class __accessor_iterator {
   }
 
   __accessor_iterator &operator--() {
-    if (_MLinearId > _MBegin)
-      --_MLinearId;
+    --_MLinearId;
     return *this;
   }
 
@@ -84,15 +82,7 @@ template <typename _DataT, int _Dimensions> class __accessor_iterator {
   }
 
   __accessor_iterator &operator+=(difference_type _N) {
-    if (_N < 0) {
-      *this -= -_N;
-      return *this;
-    }
-
-    if (static_cast<size_t>(_N) > _MEnd || _MEnd - _N < _MLinearId)
-      _MLinearId = _MEnd;
-    else
-      _MLinearId += _N;
+    _MLinearId += _N;
 
     return *this;
   }
@@ -112,15 +102,7 @@ template <typename _DataT, int _Dimensions> class __accessor_iterator {
   }
 
   __accessor_iterator &operator-=(difference_type _N) {
-    if (_N < 0) {
-      *this += -_N;
-      return *this;
-    }
-
-    if (_MBegin + _N > _MLinearId)
-      _MLinearId = _MBegin;
-    else
-      _MLinearId -= _N;
+    _MLinearId -= _N;
 
     return *this;
   }

sycl/unittests/accessor/AccessorIterator.cpp

@@ -116,31 +116,6 @@ class AccessorIteratorTest : public ::testing::Test {
   }
 };
 
-TEST_F(AccessorIteratorTest, ImplementationDetails) {
-  std::vector<int> reference(5);
-  std::iota(reference.begin(), reference.end(), 0);
-  sycl::buffer<int> buffer(reference.data(), sycl::range<1>{reference.size()});
-  auto accessor = buffer.template get_access<sycl::access_mode::read_write>();
-  {
-    auto It = accessor.begin();
-    // Check that It can't be decremented past begin
-    ASSERT_EQ(--It, accessor.begin());
-    ASSERT_EQ(It - 1, accessor.begin());
-    ASSERT_EQ(It -= 1, accessor.begin());
-    ASSERT_EQ(It - 10, accessor.begin());
-    ASSERT_EQ(It -= 10, accessor.begin());
-  }
-  {
-    auto It = accessor.end();
-    // Check that It can't be incremented past end
-    ASSERT_EQ(++It, accessor.end());
-    ASSERT_EQ(It + 1, accessor.end());
-    ASSERT_EQ(It += 1, accessor.end());
-    ASSERT_EQ(It + 10, accessor.end());
-    ASSERT_EQ(It += 10, accessor.end());
-  }
-}
-
 // FIXME: consider turning this into parameterized test to check various
 // accessor types
 TEST_F(AccessorIteratorTest, IteratorTraits) {