[libcxx-commits] [libcxx] [libcxx] Configuration option to lower deque block size (PR #198348)

[Nikolas Klauser via libcxx-commits]

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@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <deque>
+
+// Test that std::__deque_block_size has default sizes when _LIBCPP_ABI_USE_SMALL_DEQUE_BLOCK_SIZE is not defined.
+
+#include <deque>
+#include <cstddef>
+
+template <std::size_t Size>
+struct TypeOfSize {
+  char data[Size];
+};
+
+static_assert(_LIBCPP_ABI_USE_SMALL_DEQUE_BLOCK_SIZE == 0, "");
+
+static_assert(std::__deque_block_size<char, std::ptrdiff_t>::value == 4096, "");
+static_assert(std::__deque_block_size<int, std::ptrdiff_t>::value == 1024, "");
+static_assert(std::__deque_block_size<double, std::ptrdiff_t>::value == 512, "");
+
+static_assert(std::__deque_block_size<TypeOfSize<255>, std::ptrdiff_t>::value == 16, "");
+static_assert(std::__deque_block_size<TypeOfSize<256>, std::ptrdiff_t>::value == 16, "");
+static_assert(std::__deque_block_size<TypeOfSize<512>, std::ptrdiff_t>::value == 16, "");
+
+int main(int, char**) { return 0; }
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philnik777 wrote:

```suggestion
```

https://github.com/llvm/llvm-project/pull/198348