Retro68/gcc/libcilkrts/include/cilk/reducer_opand.h
2017-10-07 02:16:47 +02:00

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22 KiB
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/* reducer_opand.h -*- C++ -*-
*
* Copyright (C) 2009-2016, Intel Corporation
* All rights reserved.
*
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* modification, are permitted provided that the following conditions
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*
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* PLEASE NOTE: This file is a downstream copy of a file mainitained in
* a repository at cilkplus.org. Changes made to this file that are not
* submitted through the contribution process detailed at
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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 "Intel(R) Cilk(TM) Plus 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 bitwise AND operator is 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) {}
/** Reduces the views of two strands.
*
* 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.
*/
///@{
/** Performs AND between the accumulator variable and @a x.
*/
op_and_view& operator&=(const Type& x) { this->m_value &= x; return *this; }
/** Creates an object representing `*this & x`.
*
* @see rhs_proxy
*/
rhs_proxy operator&(const Type& x) const { return rhs_proxy(this, x); }
/** Assigns 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 Intel Cilk Plus library 1.0
* behavior). If `true`, reducers instantiated on this monoid
* will be cache-aligned for binary compatibility with
* reducers in Intel Cilk Plus 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 Intel Cilk Plus 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
/** Declares `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)
/** Declares 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
/** Declares 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);
/** Defines 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 Declares or defines 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
///@}
/* Declares or defines 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 */