[PATCH] D48342: [libcxx] Optimize vectors construction of trivial types from an iterator range with const-ness mismatch.

[Volodymyr Sapsai via Phabricator via cfe-commits]

vsapsai updated this revision to Diff 154327.
vsapsai added a comment.

- Clean up tests according to review. We don't need a new test for custom allocators, parent patch covers that.


https://reviews.llvm.org/D48342

Files:
  libcxx/include/memory
  libcxx/test/std/containers/sequences/vector/vector.cons/construct_iter_iter.pass.cpp


Index: libcxx/test/std/containers/sequences/vector/vector.cons/construct_iter_iter.pass.cpp
===================================================================
--- libcxx/test/std/containers/sequences/vector/vector.cons/construct_iter_iter.pass.cpp
+++ libcxx/test/std/containers/sequences/vector/vector.cons/construct_iter_iter.pass.cpp
@@ -13,6 +13,8 @@
 
 #include <vector>
 #include <cassert>
+#include <cfloat>
+#include <cmath>
 #include <cstddef>
 
 #include "test_macros.h"
@@ -176,9 +178,20 @@
 #endif
 }
 
+// Initialize a vector with a different value type. Make sure initialization
+// is performed with each element value, not with a memory blob.
+void test_ctor_with_different_value_type() {
+  int array[3] = {0, 1, 2};
+  std::vector<float> v(array, array + 3);
+  assert(std::fabs(v[0] - 0.0f) < FLT_EPSILON);
+  assert(std::fabs(v[1] - 1.0f) < FLT_EPSILON);
+  assert(std::fabs(v[2] - 2.0f) < FLT_EPSILON);
+}
+
 
 int main() {
   basic_test_cases();
   emplaceable_concept_tests(); // See PR34898
   test_ctor_under_alloc();
+  test_ctor_with_different_value_type();
 }
Index: libcxx/include/memory
===================================================================
--- libcxx/include/memory
+++ libcxx/include/memory
@@ -1642,23 +1642,29 @@
                 construct(__a, _VSTD::__to_raw_pointer(__begin2), *__begin1);
         }
 
-    template <class _Tp>
+    template <class _SourceTp, class _DestTp>
         _LIBCPP_INLINE_VISIBILITY
         static
         typename enable_if
         <
-            (is_same<allocator_type, allocator<_Tp> >::value
-                || !__has_construct<allocator_type, _Tp*, _Tp>::value) &&
-             is_trivially_move_constructible<_Tp>::value,
+            is_same
+            <
+                typename _VSTD::remove_const<_SourceTp>::type,
+                typename _VSTD::remove_const<_DestTp>::type
+            >::value &&
+            (is_same<allocator_type, allocator<typename _VSTD::remove_const<_SourceTp>::type> >::value
+                || is_same<allocator_type, allocator<const _SourceTp> >::value
+                || !__has_construct<allocator_type, _DestTp*, const _SourceTp&>::value) &&
+             is_trivially_move_constructible<_DestTp>::value,
             void
         >::type
-        __construct_range_forward(allocator_type&, _Tp* __begin1, _Tp* __end1, _Tp*& __begin2)
+        __construct_range_forward(allocator_type&, _SourceTp* __begin1, _SourceTp* __end1, _DestTp*& __begin2)
         {
-            typedef typename remove_const<_Tp>::type _Vp;
+            typedef typename remove_const<_DestTp>::type _Vp;
             ptrdiff_t _Np = __end1 - __begin1;
             if (_Np > 0)
             {
-                _VSTD::memcpy(const_cast<_Vp*>(__begin2), __begin1, _Np * sizeof(_Tp));
+                _VSTD::memcpy(const_cast<_Vp*>(__begin2), __begin1, _Np * sizeof(_DestTp));
                 __begin2 += _Np;
             }
         }


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