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Edit File: reducer_opand.h
/* reducer_opand.h -*- C++ -*- * * @copyright * Copyright (C) 2009-2013, Intel Corporation * All rights reserved. * * @copyright * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * Neither the name of Intel Corporation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * @copyright * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /** @file reducer_opand.h * * @brief Defines classes for doing parallel bitwise and reductions. * * @ingroup ReducersAnd * * @see ReducersAnd */ #ifndef REDUCER_OPAND_H_INCLUDED #define REDUCER_OPAND_H_INCLUDED #include <cilk/reducer.h> /** @defgroup ReducersAnd Bitwise And Reducers * * Bitwise and reducers allow the computation of the bitwise and of a set of * values in parallel. * * @ingroup Reducers * * You should be familiar with @ref pagereducers "Cilk reducers", described in * file `reducers.md`, and particularly with @ref reducers_using, before trying * to use the information in this file. * * @section redopand_usage Usage Example * * cilk::reducer< cilk::op_and<unsigned> > r; * cilk_for (int i = 0; i != N; ++i) { * *r &= a[i]; * } * unsigned result; * r.move_out(result); * * @section redopand_monoid The Monoid * * @subsection redopand_monoid_values Value Set * * The value set of a bitwise and reducer is the set of values of `Type`, * which is expected to be a builtin integer type which has a representation * as a sequence of bits (or something like it, such as `bool` or * `std::bitset`). * * @subsection redopand_monoid_operator Operator * * The operator of a bitwise and reducer is the bitwise and operator, defined * by the “`&`” binary operator on `Type`. * * @subsection redopand_monoid_identity Identity * * The identity value of the reducer is the value whose representation * contains all 1-bits. This is expected to be the value of the expression * `~Type()` (i.e., the bitwise negation operator applied to the default value * of the value type). * * @section redopand_operations Operations * * @subsection redopand_constructors Constructors * * reducer() // identity * reducer(const Type& value) * reducer(move_in(Type& variable)) * * @subsection redopand_get_set Set and Get * * r.set_value(const Type& value) * const Type& = r.get_value() const * r.move_in(Type& variable) * r.move_out(Type& variable) * * @subsection redopand_initial Initial Values * * If a bitwise and reducer is constructed without an explicit initial value, * then its initial value will be its identity value, as long as `Type` * satisfies the requirements of @ref redopand_types. * * @subsection redopand_view_ops View Operations * * *r &= a * *r = *r & a * *r = *r & a1 & a2 … & an * * @section redopand_types Type and Operator Requirements * * `Type` must be `Copy Constructible`, `Default Constructible`, and * `Assignable`. * * The operator “`&=`” must be defined on `Type`, with `x &= a` having the * same meaning as `x = x & a`. * * The expression `~ Type()` must be a valid expression which yields the * identity value (the value of `Type` whose representation consists of all * 1-bits). * * @section redopand_in_c Bitwise And Reducers in C * * The @ref CILK_C_REDUCER_OPAND and @ref CILK_C_REDUCER_OPAND_TYPE macros can * be used to do bitwise and reductions in C. For example: * * CILK_C_REDUCER_OPAND(r, uint, ~0); * CILK_C_REGISTER_REDUCER(r); * cilk_for(int i = 0; i != n; ++i) { * REDUCER_VIEW(r) &= a[i]; * } * CILK_C_UNREGISTER_REDUCER(r); * printf("The bitwise AND of the elements of a is %x\n", REDUCER_VIEW(r)); * * See @ref reducers_c_predefined. */ #ifdef __cplusplus namespace cilk { /** The bitwise and reducer view class. * * This is the view class for reducers created with * `cilk::reducer< cilk::op_and<Type> >`. It holds the accumulator variable * for the reduction, and allows only `and` operations to be performed on it. * * @note The reducer “dereference” operation (`reducer::operator *()`) * yields a reference to the view. Thus, for example, the view class’s * `&=` operation would be used in an expression like `*r &= a`, where * `r` is an opmod reducer variable. * * @tparam Type The type of the contained accumulator variable. This will * be the value type of a monoid_with_view that is * instantiated with this view. * * @see ReducersAnd * @see op_and * * @ingroup ReducersAnd */ template <typename Type> class op_and_view : public scalar_view<Type> { typedef scalar_view<Type> base; public: /** Class to represent the right-hand side of `*reducer = *reducer & value`. * * The only assignment operator for the op_and_view class takes an * rhs_proxy as its operand. This results in the syntactic restriction * that the only expressions that can be assigned to an op_and_view are * ones which generate an rhs_proxy — that is, expressions of the form * `op_and_view & value ... & value`. * * @warning * The lhs and rhs views in such an assignment must be the same; * otherwise, the behavior will be undefined. (I.e., `v1 = v1 & x` is * legal; `v1 = v2 & x` is illegal.) This condition will be checked with * a runtime assertion when compiled in debug mode. * * @see op_and_view */ class rhs_proxy { private: friend class op_and_view; const op_and_view* m_view; Type m_value; // Constructor is invoked only from op_and_view::operator&(). // rhs_proxy(const op_and_view* view, const Type& value) : m_view(view), m_value(value) {} rhs_proxy& operator=(const rhs_proxy&); // Disable assignment operator rhs_proxy(); // Disable default constructor public: /** Bitwise and with an additional rhs value. If `v` is an op_and_view * and `a1` is a value, then the expression `v & a1` invokes the * view’s `operator&()` to create an rhs_proxy for `(v, a1)`; then * `v & a1 & a2` invokes the rhs_proxy’s `operator&()` to create a new * rhs_proxy for `(v, a1&a2)`. This allows the right-hand side of an * assignment to be not just `view & value`, but * `view & value & value ... & value`. The effect is that * * v = v & a1 & a2 ... & an; * * is evaluated as * * v = v & (a1 & a2 ... & an); */ rhs_proxy& operator&(const Type& x) { m_value &= x; return *this; } }; /** Default/identity constructor. This constructor initializes the * contained value to `~ Type()`. */ op_and_view() : base(~Type()) {} /** Construct with a specified initial value. */ explicit op_and_view(const Type& v) : base(v) {} /** Reduction operation. * * This function is invoked by the @ref op_and monoid to combine the views * of two strands when the right strand merges with the left one. It * “ands” the value contained in the left-strand view with the value * contained in the right-strand view, and leaves the value in the * right-strand view undefined. * * @param right A pointer to the right-strand view. (`this` points to * the left-strand view.) * * @note Used only by the @ref op_and monoid to implement the monoid * reduce operation. */ void reduce(op_and_view* right) { this->m_value &= right->m_value; } /** @name Accumulator variable updates. * * These functions support the various syntaxes for “anding” the * accumulator variable contained in the view with some value. */ //@{ /** And the accumulator variable with @a x. */ op_and_view& operator&=(const Type& x) { this->m_value &= x; return *this; } /** Create an object representing `*this & x`. * * @see rhs_proxy */ rhs_proxy operator&(const Type& x) const { return rhs_proxy(this, x); } /** Assign the result of a `view & value` expression to the view. Note that * this is the only assignment operator for this class. * * @see rhs_proxy */ op_and_view& operator=(const rhs_proxy& rhs) { __CILKRTS_ASSERT(this == rhs.m_view); this->m_value &= rhs.m_value; return *this; } //@} }; /** Monoid class for bitwise and reductions. Instantiate the cilk::reducer * template class with an op_and monoid to create a bitwise and reducer * class. For example, to compute the bitwise and of a set of `unsigned long` * values: * * cilk::reducer< cilk::op_and<unsigned long> > r; * * @tparam Type The reducer value type. * @tparam Align If `false` (the default), reducers instantiated on this * monoid will be naturally aligned (the Cilk library 1.0 * behavior). If `true`, reducers instantiated on this monoid * will be cache-aligned for binary compatibility with * reducers in Cilk library version 0.9. * * @see ReducersAnd * @see op_and_view * * @ingroup ReducersAnd */ template <typename Type, bool Align = false> struct op_and : public monoid_with_view<op_and_view<Type>, Align> {}; /** Deprecated bitwise and reducer class. * * reducer_opand is the same as @ref reducer<@ref op_and>, except that * reducer_opand is a proxy for the contained view, so that accumulator * variable update operations can be applied directly to the reducer. For * example, a value is anded with a `reducer<%op_and>` with `*r &= a`, but a * value can be anded with a `%reducer_opand` with `r &= a`. * * @deprecated Users are strongly encouraged to use `reducer<monoid>` * reducers rather than the old wrappers like reducer_opand. * The `reducer<monoid>` reducers show the reducer/monoid/view * architecture more clearly, are more consistent in their * implementation, and present a simpler model for new * user-implemented reducers. * * @note Implicit conversions are provided between `%reducer_opand` * and `reducer<%op_and>`. This allows incremental code * conversion: old code that used `%reducer_opand` can pass a * `%reducer_opand` to a converted function that now expects a * pointer or reference to a `reducer<%op_and>`, and vice * versa. * * @tparam Type The value type of the reducer. * * @see op_and * @see reducer * @see ReducersAnd * * @ingroup ReducersAnd */ template <typename Type> class reducer_opand : public reducer< op_and<Type, true> > { typedef reducer< op_and<Type, true> > base; using base::view; public: /// The view type for the reducer. typedef typename base::view_type view_type; /// The view’s rhs proxy type. typedef typename view_type::rhs_proxy rhs_proxy; /// The view type for the reducer. typedef view_type View; /// The monoid type for the reducer. typedef typename base::monoid_type Monoid; /** @name Constructors */ //@{ /** Default constructor. * * Constructs the wrapper with the default initial value of `Type()` * (not the identity value). */ reducer_opand() : base(Type()) {} /** Value constructor. * * Constructs the wrapper with a specified initial value. */ explicit reducer_opand(const Type& initial_value) : base(initial_value) {} //@} /** @name Forwarded functions * @details Functions that update the contained accumulator variable are * simply forwarded to the contained @ref op_and_view. */ //@{ /// @copydoc op_and_view::operator&=(const Type&) reducer_opand& operator&=(const Type& x) { view() &= x; return *this; } // The legacy definition of reducer_opand::operator&() has different // behavior and a different return type than this definition. The legacy // version is defined as a member function, so this new version is defined // as a free function to give it a different signature, so that they won’t // end up sharing a single object file entry. /// @copydoc op_and_view::operator&(const Type&) const friend rhs_proxy operator&(const reducer_opand& r, const Type& x) { return r.view() & x; } /// @copydoc op_and_view::operator=(const rhs_proxy&) reducer_opand& operator=(const rhs_proxy& temp) { view() = temp; return *this; } //@} /** @name Dereference * @details Dereferencing a wrapper is a no-op. It simply returns the * wrapper. Combined with the rule that the wrapper forwards view * operations to its contained view, this means that view operations can * be written the same way on reducers and wrappers, which is convenient * for incrementally converting old code using wrappers to use reducers * instead. That is: * * reducer< op_and<int> > r; * *r &= a; // *r returns the view * // operator &= is a view member function * * reducer_opand<int> w; * *w &= a; // *w returns the wrapper * // operator &= is a wrapper member function that * // calls the corresponding view function */ //@{ reducer_opand& operator*() { return *this; } reducer_opand const& operator*() const { return *this; } reducer_opand* operator->() { return this; } reducer_opand const* operator->() const { return this; } //@} /** @name Upcast * @details In Cilk library 0.9, reducers were always cache-aligned. In * library 1.0, reducer cache alignment is optional. By default, reducers * are unaligned (i.e., just naturally aligned), but legacy wrappers * inherit from cache-aligned reducers for binary compatibility. * * This means that a wrapper will automatically be upcast to its aligned * reducer base class. The following conversion operators provide * pseudo-upcasts to the corresponding unaligned reducer class. */ //@{ operator reducer< op_and<Type, false> >& () { return *reinterpret_cast< reducer< op_and<Type, false> >* >(this); } operator const reducer< op_and<Type, false> >& () const { return *reinterpret_cast< const reducer< op_and<Type, false> >* >(this); } //@} }; /// @cond internal /** Metafunction specialization for reducer conversion. * * This specialization of the @ref legacy_reducer_downcast template class * defined in reducer.h causes the `reducer< op_and<Type> >` class to have an * `operator reducer_opand<Type>& ()` conversion operator that statically * downcasts the `reducer<op_and>` to the corresponding `reducer_opand` type. * (The reverse conversion, from `reducer_opand` to `reducer<op_and>`, is just * an upcast, which is provided for free by the language.) * * @ingroup ReducersAnd */ template <typename Type, bool Align> struct legacy_reducer_downcast<reducer<op_and<Type, Align> > > { typedef reducer_opand<Type> type; }; /// @endcond } // namespace cilk #endif // __cplusplus /** @ingroup ReducersAdd */ //@{ /** @name C language reducer macros * * These macros are used to declare and work with op_and reducers in C code. * * @see @ref page_reducers_in_c */ //@{ __CILKRTS_BEGIN_EXTERN_C /** Opand reducer type name. * * This macro expands into the identifier which is the name of the op_and * reducer type for a specified numeric type. * * @param tn The @ref reducers_c_type_names "numeric type name" specifying * the type of the reducer. * * @see @ref reducers_c_predefined * @see ReducersAnd */ #define CILK_C_REDUCER_OPAND_TYPE(tn) \ __CILKRTS_MKIDENT(cilk_c_reducer_opand_,tn) /** Declare an op_and reducer object. * * This macro expands into a declaration of an op_and reducer object for a * specified numeric type. For example: * * CILK_C_REDUCER_OPAND(my_reducer, ulong, ~0UL); * * @param obj The variable name to be used for the declared reducer object. * @param tn The @ref reducers_c_type_names "numeric type name" specifying * the type of the reducer. * @param v The initial value for the reducer. (A value which can be * assigned to the numeric type represented by @a tn.) * * @see @ref reducers_c_predefined * @see ReducersAnd */ #define CILK_C_REDUCER_OPAND(obj,tn,v) \ CILK_C_REDUCER_OPAND_TYPE(tn) obj = \ CILK_C_INIT_REDUCER(_Typeof(obj.value), \ __CILKRTS_MKIDENT(cilk_c_reducer_opand_reduce_,tn), \ __CILKRTS_MKIDENT(cilk_c_reducer_opand_identity_,tn), \ __cilkrts_hyperobject_noop_destroy, v) /// @cond internal /** Declare the op_and reducer functions for a numeric type. * * This macro expands into external function declarations for functions which * implement the reducer functionality for the op_and reducer type for a * specified numeric type. * * @param t The value type of the reducer. * @param tn The value “type name” identifier, used to construct the reducer * type name, function names, etc. */ #define CILK_C_REDUCER_OPAND_DECLARATION(t,tn) \ typedef CILK_C_DECLARE_REDUCER(t) CILK_C_REDUCER_OPAND_TYPE(tn); \ __CILKRTS_DECLARE_REDUCER_REDUCE(cilk_c_reducer_opand,tn,l,r); \ __CILKRTS_DECLARE_REDUCER_IDENTITY(cilk_c_reducer_opand,tn); /** Define the op_and reducer functions for a numeric type. * * This macro expands into function definitions for functions which implement * the reducer functionality for the op_and reducer type for a specified * numeric type. * * @param t The value type of the reducer. * @param tn The value “type name” identifier, used to construct the reducer * type name, function names, etc. */ #define CILK_C_REDUCER_OPAND_DEFINITION(t,tn) \ typedef CILK_C_DECLARE_REDUCER(t) CILK_C_REDUCER_OPAND_TYPE(tn); \ __CILKRTS_DECLARE_REDUCER_REDUCE(cilk_c_reducer_opand,tn,l,r) \ { *(t*)l &= *(t*)r; } \ __CILKRTS_DECLARE_REDUCER_IDENTITY(cilk_c_reducer_opand,tn) \ { *(t*)v = ~((t)0); } //@{ /** @def CILK_C_REDUCER_OPAND_INSTANCE * @brief Declare or define implementation functions for a reducer type. * * In the runtime source file c_reducers.c, the macro `CILK_C_DEFINE_REDUCERS` * will be defined, and this macro will generate reducer implementation * functions. Everywhere else, `CILK_C_DEFINE_REDUCERS` will be undefined, and * this macro will expand into external declarations for the functions. */ #ifdef CILK_C_DEFINE_REDUCERS # define CILK_C_REDUCER_OPAND_INSTANCE(t,tn) \ CILK_C_REDUCER_OPAND_DEFINITION(t,tn) #else # define CILK_C_REDUCER_OPAND_INSTANCE(t,tn) \ CILK_C_REDUCER_OPAND_DECLARATION(t,tn) #endif //@} /* Declare or define an instance of the reducer type and its functions for * each numeric type. */ CILK_C_REDUCER_OPAND_INSTANCE(char, char) CILK_C_REDUCER_OPAND_INSTANCE(unsigned char, uchar) CILK_C_REDUCER_OPAND_INSTANCE(signed char, schar) CILK_C_REDUCER_OPAND_INSTANCE(wchar_t, wchar_t) CILK_C_REDUCER_OPAND_INSTANCE(short, short) CILK_C_REDUCER_OPAND_INSTANCE(unsigned short, ushort) CILK_C_REDUCER_OPAND_INSTANCE(int, int) CILK_C_REDUCER_OPAND_INSTANCE(unsigned int, uint) CILK_C_REDUCER_OPAND_INSTANCE(unsigned int, unsigned) /* alternate name */ CILK_C_REDUCER_OPAND_INSTANCE(long, long) CILK_C_REDUCER_OPAND_INSTANCE(unsigned long, ulong) CILK_C_REDUCER_OPAND_INSTANCE(long long, longlong) CILK_C_REDUCER_OPAND_INSTANCE(unsigned long long, ulonglong) //@endcond __CILKRTS_END_EXTERN_C //@} //@} #endif /* REDUCER_OPAND_H_INCLUDED */