Retro68/gcc/libcilkrts/include/cilk/reducer_opmul.h
2014-09-21 19:33:12 +02:00

443 lines
16 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/* reducer_opmul.h -*- C++ -*-
*
* @copyright
* Copyright (C) 2012-2013, 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_opmul.h
*
* @brief Defines classes for doing parallel multiplication reductions.
*
* @ingroup ReducersMul
*
* @see ReducersMul
*/
#ifndef REDUCER_OPMUL_H_INCLUDED
#define REDUCER_OPMUL_H_INCLUDED
#include <cilk/reducer.h>
/** @defgroup ReducersMul Multiplication Reducers
*
* Multiplication reducers allow the computation of the product 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 redopmul_usage Usage Example
*
* cilk::reducer< cilk::op_mul<double> > r;
* cilk_for (int i = 0; i != N; ++i) {
* *r *= a[i];
* }
* double product;
* r.move_out(product);
*
* @section redopmul_monoid The Monoid
*
* @subsection redopmul_monoid_values Value Set
*
* The value set of a multiplication reducer is the set of values of `Type`,
* which is expected to be a builtin numeric type (or something like it, such
* as `std::complex`).
*
* @subsection redopmul_monoid_operator Operator
*
* The operator of a multiplication reducer is the multiplication operation,
* defined by the “`*`” binary operator on `Type`.
*
* @subsection redopmul_monoid_identity Identity
*
* The identity value of the reducer is the numeric value “`1`”. This is
* expected to be the value of the expression `Type(1)`.
*
* @section redopmul_operations Operations
*
* @subsection redopmul_constructors Constructors
*
* reducer() // identity
* reducer(const Type& value)
* reducer(move_in(Type& variable))
*
* @subsection redopmul_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 redopmul_initial Initial Values
*
* If a multiplication 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 redopmul_types.
*
* @subsection redopmul_view_ops View Operations
*
* *r *= a
* *r = *r * a
* *r = *r * a1 * a2 … * an
*
* @section redopmul_floating_point Issues with Floating-Point Types
*
* Because of overflow and underflow issues, floating-point multiplication is
* not really associative. For example, `(1e200 * 1e-200) * 1e-200 == 1e-200`,
* but `1e200 * (1e-200 * 1e-200 == 0.
*
* In many cases, this wont matter, but computations which have been
* carefully ordered to control overflow and underflow may not deal well with
* being reassociated. In general, you should be sure to understand the
* floating-point behavior of your program before doing any transformation
* that will reassociate its computations.
*
* @section redopmul_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(1)` must be a valid expression which yields the
* identity value (the value of `Type` whose numeric value is `1`).
*
* @section redopmul_in_c Multiplication Reducers in C
*
* The @ref CILK_C_REDUCER_OPMUL and @ref CILK_C_REDUCER_OPMUL_TYPE macros can
* be used to do multiplication reductions in C. For example:
*
* CILK_C_REDUCER_OPMUL(r, double, 1);
* 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 product of the elements of a is %f\n", REDUCER_VIEW(r));
*
* See @ref reducers_c_predefined.
*/
#ifdef __cplusplus
namespace cilk {
/** The multiplication reducer view class.
*
* This is the view class for reducers created with
* `cilk::reducer< cilk::op_mul<Type> >`. It holds the accumulator variable
* for the reduction, and allows only multiplication operations to be
* performed on it.
*
* @note The reducer “dereference” operation (`reducer::operator *()`)
* yields a reference to the view. Thus, for example, the view classs
* `*=` operation would be used in an expression like `*r *= a`, where
* `r` is an op_mul 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 ReducersMul
* @see op_mul
*
* @ingroup ReducersMul
*/
template <typename Type>
class op_mul_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_mul_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_mul_view are
* ones which generate an rhs_proxy — that is, expressions of the form
* `op_mul_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_mul_view
*/
class rhs_proxy {
friend class op_mul_view;
const op_mul_view* m_view;
Type m_value;
// Constructor is invoked only from op_mul_view::operator*().
//
rhs_proxy(const op_mul_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:
/** Multiply by an additional rhs value. If `v` is an op_mul_view and
* `a1` is a value, then the expression `v * a1` invokes the views
* `operator*()` to create an rhs_proxy for `(v, a1)`; then
* `v * a1 * a2` invokes the rhs_proxys `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(1)`, which is expected to be the identity
* value for multiplication on `Type`.
*/
op_mul_view() : base(Type(1)) {}
/** Construct with a specified initial value.
*/
explicit op_mul_view(const Type& v) : base(v) {}
/** Reduction operation.
*
* This function is invoked by the @ref op_mul monoid to combine the views
* of two strands when the right strand merges with the left one. It
* multiplies the value contained in the left-strand view by 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_mul monoid to implement the monoid
* reduce operation.
*/
void reduce(op_mul_view* right) { this->m_value *= right->m_value; }
/** @name Accumulator variable updates.
*
* These functions support the various syntaxes for multiplying the
* accumulator variable contained in the view by some value.
*/
//@{
/** Multiply the accumulator variable by @a x.
*/
op_mul_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_mul_view& operator=(const rhs_proxy& rhs) {
__CILKRTS_ASSERT(this == rhs.m_view);
this->m_value *= rhs.m_value;
return *this;
}
//@}
};
/** Monoid class for multiplication reductions. Instantiate the cilk::reducer
* template class with an op_mul monoid to create a multiplication reducer
* class. For example, to compute the product of a set of `double` values:
*
* cilk::reducer< cilk::op_mul<double> > r;
*
* @see ReducersMul
* @see op_mul_view
*
* @ingroup ReducersMul
*/
template <typename Type>
struct op_mul : public monoid_with_view< op_mul_view<Type> > {};
} // namespace cilk
#endif // __cplusplus
/** @ingroup ReducersAdd
*/
//@{
/** @name C language reducer macros
*
* These macros are used to declare and work with numeric op_mul reducers in
* C code.
*
* @see @ref page_reducers_in_c
*/
//@{
__CILKRTS_BEGIN_EXTERN_C
/** Opmul reducer type name.
*
* This macro expands into the identifier which is the name of the op_mul
* 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 ReducersMul
*/
#define CILK_C_REDUCER_OPMUL_TYPE(tn) \
__CILKRTS_MKIDENT(cilk_c_reducer_opmul_,tn)
/** Declare an op_mul reducer object.
*
* This macro expands into a declaration of an op_mul reducer object for a
* specified numeric type. For example:
*
* CILK_C_REDUCER_OPMUL(my_reducer, double, 1.0);
*
* @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 ReducersMul
*/
#define CILK_C_REDUCER_OPMUL(obj,tn,v) \
CILK_C_REDUCER_OPMUL_TYPE(tn) obj = \
CILK_C_INIT_REDUCER(_Typeof(obj.value), \
__CILKRTS_MKIDENT(cilk_c_reducer_opmul_reduce_,tn), \
__CILKRTS_MKIDENT(cilk_c_reducer_opmul_identity_,tn), \
__cilkrts_hyperobject_noop_destroy, v)
/// @cond internal
/** Declare the op_mul reducer functions for a numeric type.
*
* This macro expands into external function declarations for functions which
* implement the reducer functionality for the op_mul 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_OPMUL_DECLARATION(t,tn) \
typedef CILK_C_DECLARE_REDUCER(t) CILK_C_REDUCER_OPMUL_TYPE(tn); \
__CILKRTS_DECLARE_REDUCER_REDUCE(cilk_c_reducer_opmul,tn,l,r); \
__CILKRTS_DECLARE_REDUCER_IDENTITY(cilk_c_reducer_opmul,tn);
/** Define the op_mul reducer functions for a numeric type.
*
* This macro expands into function definitions for functions which implement
* the reducer functionality for the op_mul 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_OPMUL_DEFINITION(t,tn) \
typedef CILK_C_DECLARE_REDUCER(t) CILK_C_REDUCER_OPMUL_TYPE(tn); \
__CILKRTS_DECLARE_REDUCER_REDUCE(cilk_c_reducer_opmul,tn,l,r) \
{ *(t*)l *= *(t*)r; } \
__CILKRTS_DECLARE_REDUCER_IDENTITY(cilk_c_reducer_opmul,tn) \
{ *(t*)v = 1; }
//@{
/** @def CILK_C_REDUCER_OPMUL_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_OPMUL_INSTANCE(t,tn) \
CILK_C_REDUCER_OPMUL_DEFINITION(t,tn)
#else
# define CILK_C_REDUCER_OPMUL_INSTANCE(t,tn) \
CILK_C_REDUCER_OPMUL_DECLARATION(t,tn)
#endif
//@}
/* Declare or define an instance of the reducer type and its functions for each
* numeric type.
*/
CILK_C_REDUCER_OPMUL_INSTANCE(char, char)
CILK_C_REDUCER_OPMUL_INSTANCE(unsigned char, uchar)
CILK_C_REDUCER_OPMUL_INSTANCE(signed char, schar)
CILK_C_REDUCER_OPMUL_INSTANCE(wchar_t, wchar_t)
CILK_C_REDUCER_OPMUL_INSTANCE(short, short)
CILK_C_REDUCER_OPMUL_INSTANCE(unsigned short, ushort)
CILK_C_REDUCER_OPMUL_INSTANCE(int, int)
CILK_C_REDUCER_OPMUL_INSTANCE(unsigned int, uint)
CILK_C_REDUCER_OPMUL_INSTANCE(unsigned int, unsigned) /* alternate name */
CILK_C_REDUCER_OPMUL_INSTANCE(long, long)
CILK_C_REDUCER_OPMUL_INSTANCE(unsigned long, ulong)
CILK_C_REDUCER_OPMUL_INSTANCE(long long, longlong)
CILK_C_REDUCER_OPMUL_INSTANCE(unsigned long long, ulonglong)
CILK_C_REDUCER_OPMUL_INSTANCE(float, float)
CILK_C_REDUCER_OPMUL_INSTANCE(double, double)
CILK_C_REDUCER_OPMUL_INSTANCE(long double, longdouble)
//@endcond
__CILKRTS_END_EXTERN_C
//@}
//@}
#endif /* REDUCER_OPMUL_H_INCLUDED */