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/*************************************************************************
* Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
*
* See LICENSE.txt for license information
************************************************************************/
#ifndef PRIMITIVES_H_
#define PRIMITIVES_H_
#include <type_traits>
#include "copy_kernel.h" // for FuncPassA
#include "reduce_kernel.h" // for reduction funcs
/* Defines primitive operations: Copy, Reduce, DoubleCopy, and ReduceCopy.
*
* In order to reduce the reptetion of template arguments, the operations
* are bundled as static methods of the Primitives class.
*
* Each primitive operation copies/reduces a contiguous buffer and syncs
* an optional set of flags against a sub-step counter. The sync value is
* based on the step parameter. Sync flags must be of type WaitFlag or
* PostFlag. The primitive routines wait for all WaitFlag args to attain
* at least a value of SUBSTEPS*(step-1)+substep+1 (i.e. completion of
* corresponding substep by previous step) before executing the transfer.
* After each substep is transfered, all PostFlag arguments get updated to
* the value SUBSTEPS*step+substep+1.
*/
class WaitFlag {
volatile int * const flag;
const int shift;
public:
__device__ __forceinline__
WaitFlag(volatile int * const flag, const int shift) : flag(flag), shift(shift) { }
__device__ __forceinline__
void wait(int val) { while (*flag < (val + shift)) /*SPIN*/; }
};
class PostFlag {
volatile int * const flag;
const int shift;
public:
__device__ __forceinline__
PostFlag(volatile int* const flag, const int shift) : flag(flag), shift(shift) { }
__device__ __forceinline__
void post(int val) { *flag = (val + shift); }
};
// Helper to check if any argument is of type T.
// e.g. AnyAre<WaitFlag>(Flag1, Flag2, ...)
template<typename T> __device__ __forceinline__
bool AnyAre() { return false; }
template<typename T, typename FIRST_T, typename... TAIL_Ts>
__device__ __forceinline__
bool AnyAre(FIRST_T first, TAIL_Ts... tail) {
return std::is_same<T, FIRST_T>::value || AnyAre<T>(tail...);
}
// Wait on all WaitFlags, ignore PostFlags
__device__ __forceinline__
void WaitOnFlags(int val) { }
template <typename... TAIL_Ts> __device__ __forceinline__
void WaitOnFlags(int val, WaitFlag flag, TAIL_Ts... tail) {
flag.wait(val);
WaitOnFlags(val, tail...);
}
template <typename... TAIL_Ts> __device__ __forceinline__
void WaitOnFlags(int val, PostFlag, TAIL_Ts... tail) {
WaitOnFlags(val, tail...);
}
// Post all PostFlags, ingnore WaitFlags
__device__ __forceinline__
void PostToFlags(int val) { }
template <typename... TAIL_Ts> __device__ __forceinline__
void PostToFlags(int val, WaitFlag flag, TAIL_Ts... tail) {
PostToFlags(val, tail...);
}
template <typename... TAIL_Ts> __device__ __forceinline__
void PostToFlags(int val, PostFlag flag, TAIL_Ts... tail) {
flag.post(val);
PostToFlags(val, tail...);
}
// Create pointer arithmetic syntax that doesn't break for nullptr_t
template <typename Tptr> __device__ __forceinline__
Tptr ptradd(Tptr ptr, int i) {
return ptr + i;
}
__device__ __forceinline__
std::nullptr_t ptradd(std::nullptr_t ptr, int i) {
return nullptr;
}
// Implementation of primitive types
template <int THREADS, int UNROLL, int SUBSTEPS, typename T, typename REDOP=FuncSum<T> >
class Primitives {
private:
template <typename SRC2_T, // either T* or nullptr_t
typename DST2_T, // either T* or nullptr_t
typename... SYNC_Ts> // either WaitFunc or PostFunc
static __device__ __forceinline__ void
GenericOp(const T* src1,
const SRC2_T src2,
T* dst1,
DST2_T dst2,
int len, int maxoffset, int step, SYNC_Ts... flags) {
enum { noSrc2 = std::is_same<SRC2_T, std::nullptr_t>::value };
enum { noDst2 = std::is_same<DST2_T, std::nullptr_t>::value };
static_assert(noSrc2 || std::is_same<SRC2_T, const T*>::value,
"src2 must be of type T* or nullptr_t");
static_assert(noDst2 || std::is_same<DST2_T, T*>::value,
"dst2 must be of type T* or nullptr_t");
using OpType = typename std::conditional<noSrc2, FuncPassA<T>, REDOP>::type;
if (threadIdx.x < THREADS) {
int sliceSize = len / SUBSTEPS;
int sliceOffset = 0;
#pragma unroll 1
for (int sub=0; sub<SUBSTEPS; ++sub) {
if (AnyAre<WaitFlag>(flags...)) {
if (threadIdx.x == 0) {
WaitOnFlags(SUBSTEPS*step + sub + 1, flags...);
}
asm volatile ("bar.sync 1, %0;" :: "r"(THREADS));
}
ReduceOrCopy
<
UNROLL,
THREADS,
OpType,
T,
!std::is_same<DST2_T, std::nullptr_t>::value, // HAS_DEST1
!std::is_same<SRC2_T, std::nullptr_t>::value // HAS_SRC1
>
(
threadIdx.x,
ptradd(dst1, sliceOffset),
ptradd(dst2, sliceOffset),
ptradd(src1, sliceOffset),
ptradd(src2, sliceOffset),
min(sliceSize, maxoffset-sliceOffset)
);
if (AnyAre<PostFlag>(flags...)) {
__syncthreads();
}
sliceOffset += sliceSize;
}
} else {
for(int sub=0; sub<SUBSTEPS; ++sub) {
if (AnyAre<PostFlag>(flags...)) {
__syncthreads();
__threadfence_system();
PostToFlags(SUBSTEPS*step + sub + 1, flags...);
}
}
}
}
public:
template <typename... SYNC_Ts>
static __device__ __forceinline__ void
Copy(const T* src, T* dst,
int len, int maxOffset, int step, SYNC_Ts... flags) {
GenericOp(src, nullptr, dst, nullptr, len, maxOffset, step, flags...);
}
template <typename... SYNC_Ts>
static __device__ __forceinline__ void
DoubleCopy(const T* src, T* dst1, T* dst2,
int len, int maxOffset, int step, SYNC_Ts... flags) {
GenericOp(src, nullptr, dst1, dst2, len, maxOffset, step, flags...);
}
template <typename... SYNC_Ts>
static __device__ __forceinline__ void
Reduce(const T* src1, const T* src2, T* dst,
int len, int maxOffset, int step, SYNC_Ts... flags) {
GenericOp(src1, src2, dst, nullptr, len, maxOffset, step, flags...);
}
template <typename... SYNC_Ts>
static __device__ __forceinline__ void
ReduceCopy(const T* src1, const T* src2, T* dst1, T* dst2,
int len, int maxOffset, int step, SYNC_Ts... flags) {
GenericOp(src1, src2, dst1, dst2, len, maxOffset, step, flags...);
}
};
#endif // end include guard
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