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7eafdcd454
If `fast_is<T>` was not available but `static_cast<T>` was, we would call into `is<T>` causing a `dynamic_cast` there, throwing away the result and return a `static_cast`ed pointer. We can encourage better codegen by checking for the presence of `fast_is<T>` ourselves. This does not change anything for when `fast_is<T>` is present, but if it's unavailable we now reduce `as_if<T>` to a simple tailcall of `dynamic_cast<T>`. Old: ``` stp x20, x19, [sp, #-32]! stp x29, x30, [sp, #16] add x29, sp, #16 mov x19, x0 adrp x1, typeinfo for Base@PAGE add x1, x1, typeinfo for Base@PAGEOFF adrp x2, typeinfo for WithoutFastIs@PAGE add x2, x2, typeinfo for WithoutFastIs@PAGEOFF mov x3, #0 bl ___dynamic_cast cmp x0, #0 csel x0, xzr, x19, eq ldp x29, x30, [sp, #16] ldp x20, x19, [sp], #32 ret ``` New: ``` adrp x1, typeinfo for Base@PAGE add x1, x1, typeinfo for Base@PAGEOFF adrp x2, typeinfo for WithoutFastIs@PAGE add x2, x2, typeinfo for WithoutFastIs@PAGEOFF mov x3, #0 b ___dynamic_cast ```
93 lines
2.4 KiB
C++
93 lines
2.4 KiB
C++
/*
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* Copyright (c) 2020-2021, Andreas Kling <andreas@ladybird.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Assertions.h>
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#include <AK/Concepts.h>
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#include <AK/Forward.h>
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#include <AK/Platform.h>
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namespace AK {
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE bool is(InputType& input)
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{
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static_assert(!SameAs<RemoveCVReference<OutputType>, RemoveCVReference<InputType>>);
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if constexpr (requires { input.template fast_is<RemoveCVReference<OutputType>>(); }) {
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return input.template fast_is<RemoveCVReference<OutputType>>();
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}
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return dynamic_cast<CopyConst<InputType, OutputType>*>(&input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE bool is(InputType* input)
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{
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return input && is<OutputType>(*input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE bool is(NonnullRefPtr<InputType> const& input)
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{
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return is<OutputType>(*input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE CopyConst<InputType, OutputType>* as_if(InputType& input)
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{
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if constexpr (requires { input.template fast_is<RemoveCVReference<OutputType>>(); static_cast<CopyConst<InputType, OutputType>*>(&input); }) {
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if (!is<OutputType>(input))
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return nullptr;
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return static_cast<CopyConst<InputType, OutputType>*>(&input);
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}
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return dynamic_cast<CopyConst<InputType, OutputType>*>(&input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE CopyConst<InputType, OutputType>* as_if(InputType* input)
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{
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if (!input)
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return nullptr;
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return as_if<OutputType>(*input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE CopyConst<InputType, OutputType>& as(InputType& input)
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{
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auto* result = as_if<OutputType>(input);
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VERIFY(result);
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return *result;
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE CopyConst<InputType, OutputType>* as(InputType* input)
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{
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if (!input)
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return nullptr;
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auto* result = as_if<OutputType>(input);
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VERIFY(result);
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return result;
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE CopyConst<InputType, OutputType>* bridge_cast(InputType input)
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{
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#ifdef AK_HAS_OBJC_ARC
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return (__bridge CopyConst<InputType, OutputType>*)(input);
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#else
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return static_cast<CopyConst<InputType, OutputType>*>(input);
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#endif
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}
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}
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#if USING_AK_GLOBALLY
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using AK::as;
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using AK::as_if;
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using AK::bridge_cast;
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using AK::is;
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#endif
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