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8187443: Forest Consolidation: Move files to unified layout
Reviewed-by: darcy, ihse
This commit is contained in:
Erik Joelsson
parent
270fe13182
commit
3789983e89
56923 changed files with 3 additions and 15727 deletions
170
src/hotspot/share/metaprogramming/primitiveConversions.hpp
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src/hotspot/share/metaprogramming/primitiveConversions.hpp
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/*
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* Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_VM_METAPROGRAMMING_PRIMITIVECONVERSIONS_HPP
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#define SHARE_VM_METAPROGRAMMING_PRIMITIVECONVERSIONS_HPP
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#include "memory/allocation.hpp"
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#include "metaprogramming/enableIf.hpp"
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#include "metaprogramming/integralConstant.hpp"
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#include "metaprogramming/isFloatingPoint.hpp"
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#include "metaprogramming/isIntegral.hpp"
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#include "metaprogramming/isRegisteredEnum.hpp"
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#include "utilities/debug.hpp"
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class PrimitiveConversions : public AllStatic {
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public:
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// Return a value of type T with the same representation as x.
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//
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// T and U must be of the same size.
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//
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// At least one of T or U must be an integral type. The other must
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// be an integral, floating point, or pointer type.
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template<typename T, typename U> static T cast(U x);
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// Support thin wrappers over primitive types.
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// If derived from TrueType, provides representational conversion
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// from T to some other type. When true, must provide
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// - Value: typedef for T.
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// - Decayed: typedef for decayed type.
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// - static Decayed decay(T x): return value of type Decayed with
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// the same representation as x.
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// - static T recover(Decayed x): return a value of type T with the
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// same representation as x.
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template<typename T> struct Translate : public FalseType {};
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private:
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template<typename T,
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typename U,
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bool same_size = sizeof(T) == sizeof(U),
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typename Enable = void>
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struct Cast;
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template<typename T, typename U> static T cast_using_union(U x);
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};
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// Return an object of type T with the same value representation as x.
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//
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// T and U must be of the same size. It is expected that one of T and
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// U is an integral type, and the other is an integral type, a
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// (registered) enum type, or a floating point type
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//
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// This implementation uses the "union trick", which seems to be the
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// best of a bad set of options. Though technically undefined
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// behavior, it is widely and well supported, producing good code. In
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// some cases, such as gcc, that support is explicitly documented.
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//
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// Using memcpy is the correct method, but some compilers produce
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// wretched code for that method, even at maximal optimization levels.
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//
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// Using static_cast is only possible for integral and enum types, not
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// for floating point types. And for integral and enum conversions,
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// static_cast has unspecified or implementation-defined behavior for
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// some cases. C++11 <type_traits> can be used to avoid most or all
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// of those unspecified or implementation-defined issues, though that
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// may require multi-step conversions.
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//
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// Using reinterpret_cast of references has undefined behavior for
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// many cases, and there is much less empirical basis for its use, as
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// compared to the union trick.
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template<typename T, typename U>
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inline T PrimitiveConversions::cast_using_union(U x) {
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STATIC_ASSERT(sizeof(T) == sizeof(U));
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union { T t; U u; };
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u = x;
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return t;
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}
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//////////////////////////////////////////////////////////////////////////////
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// cast<T>(x)
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//
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// Cast<T, U, same_size, Enable>
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// Give an informative error if the sizes differ.
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template<typename T, typename U>
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struct PrimitiveConversions::Cast<T, U, false> VALUE_OBJ_CLASS_SPEC {
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STATIC_ASSERT(sizeof(T) == sizeof(U));
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};
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// Conversion between integral types.
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template<typename T, typename U>
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struct PrimitiveConversions::Cast<
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T, U, true,
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typename EnableIf<IsIntegral<T>::value && IsIntegral<U>::value>::type>
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VALUE_OBJ_CLASS_SPEC
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{
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T operator()(U x) const { return cast_using_union<T>(x); }
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};
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// Convert an enum or floating point value to an integer value.
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template<typename T, typename U>
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struct PrimitiveConversions::Cast<
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T, U, true,
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typename EnableIf<IsIntegral<T>::value &&
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(IsRegisteredEnum<U>::value ||
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IsFloatingPoint<U>::value)>::type>
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VALUE_OBJ_CLASS_SPEC
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{
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T operator()(U x) const { return cast_using_union<T>(x); }
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};
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// Convert an integer to an enum or floating point value.
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template<typename T, typename U>
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struct PrimitiveConversions::Cast<
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T, U, true,
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typename EnableIf<IsIntegral<U>::value &&
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(IsRegisteredEnum<T>::value ||
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IsFloatingPoint<T>::value)>::type>
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VALUE_OBJ_CLASS_SPEC
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{
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T operator()(U x) const { return cast_using_union<T>(x); }
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};
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// Convert a pointer to an integral value.
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template<typename T, typename U>
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struct PrimitiveConversions::Cast<
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T, U*, true,
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typename EnableIf<IsIntegral<T>::value>::type>
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VALUE_OBJ_CLASS_SPEC
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{
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T operator()(U* x) const { return reinterpret_cast<T>(x); }
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};
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// Convert an integral value to a pointer.
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template<typename T, typename U>
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struct PrimitiveConversions::Cast<
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T*, U, true,
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typename EnableIf<IsIntegral<U>::value>::type>
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VALUE_OBJ_CLASS_SPEC
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{
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T* operator()(U x) const { return reinterpret_cast<T*>(x); }
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};
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template<typename T, typename U>
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inline T PrimitiveConversions::cast(U x) {
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return Cast<T, U>()(x);
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}
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#endif // SHARE_VM_METAPROGRAMMING_PRIMITIVECONVERSIONS_HPP
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