57b08b0944
to reflect the new license. These used slightly different spellings that defeated my regular expressions. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351648
81 lines
1.9 KiB
C++
81 lines
1.9 KiB
C++
//===------------------------- dynamic_cast_stress.cpp --------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++98, c++03
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#include <cassert>
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#include <tuple>
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#include "support/timer.hpp"
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template <std::size_t Indx, std::size_t Depth>
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struct C
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: public virtual C<Indx, Depth-1>,
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public virtual C<Indx+1, Depth-1>
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{
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virtual ~C() {}
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};
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template <std::size_t Indx>
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struct C<Indx, 0>
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{
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virtual ~C() {}
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};
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template <std::size_t Indx, std::size_t Depth>
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struct B
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: public virtual C<Indx, Depth-1>,
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public virtual C<Indx+1, Depth-1>
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{
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};
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template <class Indx, std::size_t Depth>
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struct makeB;
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template <std::size_t ...Indx, std::size_t Depth>
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struct makeB<std::__tuple_indices<Indx...>, Depth>
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: public B<Indx, Depth>...
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{
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};
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template <std::size_t Width, std::size_t Depth>
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struct A
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: public makeB<typename std::__make_tuple_indices<Width>::type, Depth>
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{
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};
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void test()
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{
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const std::size_t Width = 10;
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const std::size_t Depth = 5;
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A<Width, Depth> a;
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typedef B<Width/2, Depth> Destination;
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// typedef A<Width, Depth> Destination;
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Destination *b = nullptr;
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{
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timer t;
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b = dynamic_cast<Destination*>((C<Width/2, 0>*)&a);
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}
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assert(b != 0);
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}
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int main()
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{
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test();
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}
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/*
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Timing results I'm seeing (median of 3 microseconds):
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libc++abi gcc's dynamic_cast
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B<Width/2, Depth> -O3 48.334 93.190 libc++abi 93% faster
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B<Width/2, Depth> -Os 58.535 94.103 libc++abi 61% faster
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A<Width, Depth> -O3 11.515 33.134 libc++abi 188% faster
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A<Width, Depth> -Os 12.631 31.553 libc++abi 150% faster
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*/
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