Implement P0035R4 -- Add C++17 aligned allocation functions

Summary:
This patch implements the library side of P0035R4. The implementation is thanks to @rsmith.

In addition to the C++17 implementation, the library implementation can be explicitly turned on using `-faligned-allocation` in all dialects.


Reviewers: mclow.lists, rsmith

Subscribers: rsmith, cfe-commits

Differential Revision: https://reviews.llvm.org/D25591

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@284206 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/language.support/support.dynamic/new_faligned_allocation.sh.cpp

@@ -0,0 +1,77 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// test libc++'s implementation of align_val_t, and the relevent new/delete
+// overloads in all dialects when -faligned-allocation is present.
+
+// REQUIRES: -faligned-allocation
+
+// RUN: %build -faligned-allocation
+// RUN: %run
+
+#include <new>
+#include <typeinfo>
+#include <string>
+#include <cassert>
+
+#include "test_macros.h"
+
+int main() {
+  {
+    static_assert(std::is_enum<std::align_val_t>::value, "");
+    typedef std::underlying_type<std::align_val_t>::type UT;
+    static_assert((std::is_same<UT, std::size_t>::value), "");
+  }
+  {
+    static_assert((!std::is_constructible<std::align_val_t, std::size_t>::value), "");
+#if TEST_STD_VER >= 11
+    static_assert(!std::is_constructible<std::size_t, std::align_val_t>::value, "");
+#else
+    static_assert((std::is_constructible<std::size_t, std::align_val_t>::value), "");
+#endif
+  }
+  {
+    std::align_val_t a = std::align_val_t(0);
+    std::align_val_t b = std::align_val_t(32);
+    assert(a != b);
+    assert(a == std::align_val_t(0));
+    assert(b == std::align_val_t(32));
+  }
+  {
+    void *ptr = ::operator new(1, std::align_val_t(128));
+    assert(ptr);
+    assert(reinterpret_cast<std::uintptr_t>(ptr) % 128 == 0);
+    ::operator delete(ptr, std::align_val_t(128));
+  }
+  {
+    void *ptr = ::operator new(1, std::align_val_t(128), std::nothrow);
+    assert(ptr);
+    assert(reinterpret_cast<std::uintptr_t>(ptr) % 128 == 0);
+    ::operator delete(ptr, std::align_val_t(128), std::nothrow);
+  }
+  {
+    void *ptr = ::operator new[](1, std::align_val_t(128));
+    assert(ptr);
+    assert(reinterpret_cast<std::uintptr_t>(ptr) % 128 == 0);
+    ::operator delete[](ptr, std::align_val_t(128));
+  }
+  {
+    void *ptr = ::operator new[](1, std::align_val_t(128), std::nothrow);
+    assert(ptr);
+    assert(reinterpret_cast<std::uintptr_t>(ptr) % 128 == 0);
+    ::operator delete[](ptr, std::align_val_t(128), std::nothrow);
+  }
+#ifndef TEST_HAS_NO_RTTI
+  {
+    // Check that libc++ doesn't define align_val_t in a versioning namespace.
+    // And that it mangles the same in C++03 through C++17
+    assert(typeid(std::align_val_t).name() == std::string("St11align_val_t"));
+  }
+#endif
+}