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// Copyright 2009-2021 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include "parallel_for.h"
namespace embree
{
template<typename Index, typename Value, typename Func, typename Reduction>
__forceinline Value sequential_reduce( const Index first, const Index last, const Value& identity, const Func& func, const Reduction& reduction )
{
return func(range<Index>(first,last));
}
template<typename Index, typename Value, typename Func, typename Reduction>
__forceinline Value sequential_reduce( const Index first, const Index last, const Index minStepSize, const Value& identity, const Func& func, const Reduction& reduction )
{
return func(range<Index>(first,last));
}
template<typename Index, typename Value, typename Func, typename Reduction>
__noinline Value parallel_reduce_internal( Index taskCount, const Index first, const Index last, const Index minStepSize, const Value& identity, const Func& func, const Reduction& reduction )
{
const Index maxTasks = 512;
const Index threadCount = (Index) TaskScheduler::threadCount();
taskCount = min(taskCount,threadCount,maxTasks);
/* parallel invocation of all tasks */
dynamic_large_stack_array(Value,values,taskCount,8192); // consumes at most 8192 bytes on the stack
parallel_for(taskCount, [&](const Index taskIndex) {
const Index k0 = first+(taskIndex+0)*(last-first)/taskCount;
const Index k1 = first+(taskIndex+1)*(last-first)/taskCount;
values[taskIndex] = func(range<Index>(k0,k1));
});
/* perform reduction over all tasks */
Value v = identity;
for (Index i=0; i<taskCount; i++) v = reduction(v,values[i]);
return v;
}
template<typename Index, typename Value, typename Func, typename Reduction>
__forceinline Value parallel_reduce( const Index first, const Index last, const Index minStepSize, const Value& identity, const Func& func, const Reduction& reduction )
{
#if defined(TASKING_INTERNAL) && !defined(TASKING_TBB)
/* fast path for small number of iterations */
Index taskCount = (last-first+minStepSize-1)/minStepSize;
if (likely(taskCount == 1)) {
return func(range<Index>(first,last));
}
return parallel_reduce_internal(taskCount,first,last,minStepSize,identity,func,reduction);
#elif defined(TASKING_TBB)
#if TBB_INTERFACE_VERSION >= 12002
tbb::task_group_context context;
const Value v = tbb::parallel_reduce(tbb::blocked_range<Index>(first,last,minStepSize),identity,
[&](const tbb::blocked_range<Index>& r, const Value& start) { return reduction(start,func(range<Index>(r.begin(),r.end()))); },
reduction,context);
if (context.is_group_execution_cancelled())
throw std::runtime_error("task cancelled");
return v;
#else
const Value v = tbb::parallel_reduce(tbb::blocked_range<Index>(first,last,minStepSize),identity,
[&](const tbb::blocked_range<Index>& r, const Value& start) { return reduction(start,func(range<Index>(r.begin(),r.end()))); },
reduction);
if (tbb::task::self().is_cancelled())
throw std::runtime_error("task cancelled");
return v;
#endif
#else // TASKING_PPL
struct AlignedValue
{
char storage[__alignof(Value)+sizeof(Value)];
static uintptr_t alignUp(uintptr_t p, size_t a) { return p + (~(p - 1) % a); };
Value* getValuePtr() { return reinterpret_cast<Value*>(alignUp(uintptr_t(storage), __alignof(Value))); }
const Value* getValuePtr() const { return reinterpret_cast<Value*>(alignUp(uintptr_t(storage), __alignof(Value))); }
AlignedValue(const Value& v) { new(getValuePtr()) Value(v); }
AlignedValue(const AlignedValue& v) { new(getValuePtr()) Value(*v.getValuePtr()); }
AlignedValue(const AlignedValue&& v) { new(getValuePtr()) Value(*v.getValuePtr()); };
AlignedValue& operator = (const AlignedValue& v) { *getValuePtr() = *v.getValuePtr(); return *this; };
AlignedValue& operator = (const AlignedValue&& v) { *getValuePtr() = *v.getValuePtr(); return *this; };
operator Value() const { return *getValuePtr(); }
};
struct Iterator_Index
{
Index v;
typedef std::forward_iterator_tag iterator_category;
typedef AlignedValue value_type;
typedef Index difference_type;
typedef Index distance_type;
typedef AlignedValue* pointer;
typedef AlignedValue& reference;
__forceinline Iterator_Index() {}
__forceinline Iterator_Index(Index v) : v(v) {}
__forceinline bool operator== (Iterator_Index other) { return v == other.v; }
__forceinline bool operator!= (Iterator_Index other) { return v != other.v; }
__forceinline Iterator_Index operator++() { return Iterator_Index(++v); }
__forceinline Iterator_Index operator++(int) { return Iterator_Index(v++); }
};
auto range_reduction = [&](Iterator_Index begin, Iterator_Index end, const AlignedValue& start) {
assert(begin.v < end.v);
return reduction(start, func(range<Index>(begin.v, end.v)));
};
const Value v = concurrency::parallel_reduce(Iterator_Index(first), Iterator_Index(last), AlignedValue(identity), range_reduction, reduction);
return v;
#endif
}
template<typename Index, typename Value, typename Func, typename Reduction>
__forceinline Value parallel_reduce( const Index first, const Index last, const Index minStepSize, const Index parallel_threshold, const Value& identity, const Func& func, const Reduction& reduction )
{
if (likely(last-first < parallel_threshold)) {
return func(range<Index>(first,last));
} else {
return parallel_reduce(first,last,minStepSize,identity,func,reduction);
}
}
template<typename Index, typename Value, typename Func, typename Reduction>
__forceinline Value parallel_reduce( const range<Index> range, const Index minStepSize, const Index parallel_threshold, const Value& identity, const Func& func, const Reduction& reduction )
{
return parallel_reduce(range.begin(),range.end(),minStepSize,parallel_threshold,identity,func,reduction);
}
template<typename Index, typename Value, typename Func, typename Reduction>
__forceinline Value parallel_reduce( const Index first, const Index last, const Value& identity, const Func& func, const Reduction& reduction )
{
auto funcr = [&] ( const range<Index> r ) {
Value v = identity;
for (Index i=r.begin(); i<r.end(); i++)
v = reduction(v,func(i));
return v;
};
return parallel_reduce(first,last,Index(1),identity,funcr,reduction);
}
template<typename Index, typename Value, typename Func, typename Reduction>
__forceinline Value parallel_reduce( const range<Index> range, const Value& identity, const Func& func, const Reduction& reduction )
{
return parallel_reduce(range.begin(),range.end(),Index(1),identity,func,reduction);
}
}
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