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/***************************************************************************************************
* Copyright (c) 2017-2018, NVIDIA CORPORATION. All rights reserved.
*
* 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 the NVIDIA CORPORATION nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific prior written
* permission.
*
* 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 NVIDIA CORPORATION 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 TOR (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
\brief Implements the epilogue phase of the GEMM kernel that efficiently updates global memory
with
the computed matrix product.
*/
#pragma once
#include <cutlass/convert.h>
#include <cutlass/coord.h>
#include <cutlass/fragment.h>
namespace cutlass {
namespace gemm {
////////////////////////////////////////////////////////////////////////////////////////////////////
template <typename T>
CUTLASS_DEVICE bool is_zero(T x) {
return x == T(0);
}
#if !defined(__CUDACC_RTC__) || defined(CUTLASS_NVRTC_HAS_FP16)
CUTLASS_DEVICE bool is_zero(half x) { return reinterpret_cast<int16_t&>(x) == int16_t(0); }
#endif
////////////////////////////////////////////////////////////////////////////////////////////////////
template <typename GemmEpilogueTraits_>
struct GemmEpilogue {
/// The traits class.
typedef GemmEpilogueTraits_ Traits;
/// The params.
typedef typename Traits::Params Params;
/// The shared storage.
typedef typename Traits::SharedStorage SharedStorage;
/// The output tile.
typedef typename Traits::OutputTile OutputTile;
/// The number of iterations.
typedef typename Traits::Iterations Iterations;
/// The accumulators.
typedef typename Traits::Accumulators Accumulators;
/// The scalar.
typedef typename Traits::Scalar Scalar;
/// The functor in charge of the math.
typedef typename Traits::Functor Functor;
/// We do not support 3D or 4D shapes.
static_assert(Iterations::kD == 1 && Iterations::kC == 1, "Unsupported 3D/4D shapes");
/// The iterator for C in global memory.
typedef typename Traits::GlobalLoadIteratorC GlobalLoadIteratorC;
/// The transformer for C.
typedef typename Traits::GlobalTransformerC GlobalTransformerC;
/// The transformer for D.
typedef typename Traits::GlobalTransformerD GlobalTransformerD;
/// The iterator for D in global memory.
typedef typename Traits::GlobalStoreIteratorD GlobalStoreIteratorD;
/// The iterator to store D in shared memory.
typedef typename Traits::SharedStoreIteratorD SharedStoreIteratorD;
/// The shared store transformer for D.
typedef typename Traits::SharedStoreTransformerD SharedStoreTransformerD;
/// The iterator to load D in shared memory.
typedef typename Traits::SharedLoadIteratorD SharedLoadIteratorD;
/// The shared load transformer for D.
typedef Copy<typename SharedLoadIteratorD::Fragment> SharedLoadTransformerD;
/// The index.
typedef typename Traits::Index Index;
/// The scalar for C.
typedef typename GlobalLoadIteratorC::Scalar ScalarC;
/// The scalar for D.
typedef typename GlobalStoreIteratorD::Scalar ScalarD;
/// Ctor.
CUTLASS_DEVICE GemmEpilogue(Params const& params_,
SharedStorage& shared_storage_,
Index m_,
Index n_)
: params(params_), shared_storage(shared_storage_), m(m_), n(n_) {}
/// Execute the epilogue.
CUTLASS_DEVICE void epilogue(Coord<3> const& block, Accumulators& accumulators) {
if (is_zero(params.functor.beta)) {
epilogue_with_or_without_beta<true>(block, accumulators);
} else {
epilogue_with_or_without_beta<false>(block, accumulators);
}
}
template <bool kBetaIsZero_>
CUTLASS_DEVICE void epilogue_with_or_without_beta(Coord<3> const& block,
Accumulators& accumulators) {
// The problem size.
Coord<3> const bounds = cutlass::make_Coord(0, n, m);
// The functor.
Functor functor(params.functor);
// The C fragment.
typename GlobalLoadIteratorC::Fragment fragment_c;
// The transformed C fragment.
typename GlobalTransformerC::OutputFragment transformed_c;
CUTLASS_PRAGMA_UNROLL
for (int h = 0; h < Iterations::kH; ++h) {
// Compute pointer and predicate offsets for C and D global iterators.
int const pointer_offset =
((params.iterator_d.inc_h * (GlobalStoreIteratorD::Iterations::kH - 1) +
params.iterator_d.inc_advance) *
Iterations::kW +
params.stride_h) *
h;
int const predicate_offset =
((params.iterator_d.predicate_inc_h * (GlobalStoreIteratorD::Iterations::kH - 1) +
params.iterator_d.predicate_inc_advance) *
Iterations::kW +
Traits::Delta::kH) *
h;
// The iterator to load the elements of the C matrix.
GlobalLoadIteratorC global_load_iterator(
params.iterator_c, bounds, block, pointer_offset, predicate_offset);
// The transformer for C.
GlobalTransformerC transformer_c;
// The transformer for D.
GlobalTransformerD transformer_d;
// The iterator to store into the D matrix.
GlobalStoreIteratorD global_store_iterator(
params.iterator_d, bounds, block, pointer_offset, predicate_offset);
// The transformer to transform before storing to shared memory.
SharedStoreTransformerD shared_store_transformer;
typename SharedStoreTransformerD::OutputFragment shared_store_transformed_d;
// The iterator to store to shared memory.
SharedStoreIteratorD shared_store_iterator(params.shared_store_iterator_d,
shared_storage.shared_stream.store);
// The iterator to load from shared memory. TODO: Use a stream.
SharedLoadIteratorD shared_load_iterator(params.shared_load_iterator_d,
shared_storage.shared_stream.load);
CUTLASS_PRAGMA_UNROLL
for (int w = 0; w < Iterations::kW; ++w) {
// Load the C matrix into fragment.
if (!kBetaIsZero_) {
iterator_load(global_load_iterator, fragment_c);
}
// Make sure we can write to shared memory.
shared_load_fence();
// Copy the accumulators to shared memory.
int const offset = (h * Iterations::kW + w) * SharedStoreIteratorD::Fragment::kElements;
shared_store_transformer.transform(accumulators, offset, shared_store_transformed_d);
shared_iterator_store(shared_store_iterator, shared_store_transformed_d);
// Make sure the data is in shared memory.
shared_store_fence();
// Copy the accumulators back to registers from shared memory.
typename SharedLoadIteratorD::Fragment fetched_d;
shared_iterator_load(shared_load_iterator, fetched_d);
// Do the math.
typename GlobalTransformerD::InputFragment fragment_d;
if (kBetaIsZero_) {
functor.evaluate(fetched_d, fragment_d);
} else {
// Transform C fragment.
transformer_c.transform(fragment_c, transformed_c);
// Do the math.
functor.evaluate(fetched_d, transformed_c, fragment_d);
}
// Transform D fragment.
typename GlobalTransformerD::OutputFragment transformed_d;
transformer_d.transform(fragment_d, transformed_d);
// Copy the results to global memory.
iterator_store(global_store_iterator, transformed_d);
}
}
}
/// The memory fence for shared loads.
CUTLASS_DEVICE void shared_load_fence() { __syncthreads(); }
/// The memory fence for shared stores.
CUTLASS_DEVICE void shared_store_fence() { __syncthreads(); }
/// The params.
Params const& params;
/// The shared storage.
SharedStorage& shared_storage;
/// The dimensions of the GEMM.
Index m, n;
};
////////////////////////////////////////////////////////////////////////////////////////////////////
} // namespace gemm
} // namespace cutlass
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