| /* reducer_opand.h -*- C++ -*- |
| * |
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| * Copyright (C) 2009-2013, Intel Corporation |
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| |
| /** @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 */ |
