[libcxx-commits] [libcxx] [libc++] Add assumption for align of begin and end pointers of vector. (PR #108961)

[Louis Dionne via libcxx-commits]

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@@ -1027,6 +1027,10 @@ private:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(vector&, false_type) _NOEXCEPT {}
+
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer __add_alignment_assumption(pointer __p) const _NOEXCEPT {
+    return static_cast<pointer>(__builtin_assume_aligned(__p, alignof(decltype(*__p))));
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ldionne wrote:

We should have plenty of `constexpr` tests with iterators in `libcxx/test/std/containers/sequences/vector/iterators.pass.cpp`. Are you able to reduce the issue you were seeing a bit so we can confirm whether there is coverage for this in the test suite?

https://github.com/llvm/llvm-project/pull/108961