cutlass/include/cutlass/cutlass.h

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/*! \file
    \brief Basic include for CUTLASS.
*/

/*
  Note:  CUTLASS 3x increases the host compiler requirements to C++17. However, certain
         existing integrations of CUTLASS require C++11 host compilers.

         Until this requirement can be lifted, certain headers with this annotation are required
         to be remain consistent with C++11 syntax.

         C++11 compatibility is enforced by `cutlass_test_unit_core_cpp11`.
*/

#pragma once

#include "cutlass/detail/helper_macros.hpp"

////////////////////////////////////////////////////////////////////////////////////////////////////

namespace cutlass {

/// Status code returned by CUTLASS operations
enum class Status {
  kSuccess,                    ///< Operation was successful.
  kErrorMisalignedOperand,     ///< operands fail alignment requirements.
  kErrorInvalidDataType,       ///< DataType fails requirement.
  kErrorInvalidLayout,         ///< Layout fails alignment requirement.
  kErrorInvalidProblem,        ///< Specified problem size is not supported by operator.
  kErrorNotSupported,          ///< Operation is not supported on current device.
  kErrorWorkspaceNull,         ///< The given workspace is null when it is required to be non-null.
  kErrorInternal,              ///< An error within CUTLASS occurred.
  kErrorArchMismatch,          ///< CUTLASS runs on a device that it was not compiled for.
  kErrorInsufficientDriver,    ///< CUTLASS runs with a driver that is too old.
  kErrorMemoryAllocation,      ///< Kernel launch failed due to insufficient device memory.
  kInvalid                     ///< Status is unspecified.
};

/// Convert cutlass status to status strings
CUTLASS_HOST_DEVICE
static char const* cutlassGetStatusString(cutlass::Status status) {
  switch (status) {
    case cutlass::Status::kSuccess:
      return "Success";
    case cutlass::Status::kErrorMisalignedOperand:
      return "Error Misaligned Operand";
    case cutlass::Status::kErrorInvalidDataType:
      return "Error Invalid Data Type";
    case cutlass::Status::kErrorInvalidLayout:
      return "Error Invalid Layout";
    case cutlass::Status::kErrorInvalidProblem:
      return "Error Invalid Problem";
    case cutlass::Status::kErrorNotSupported:
      return "Error Not Supported";
    case cutlass::Status::kErrorWorkspaceNull:
      return "Error Workspace Null";
    case cutlass::Status::kErrorInternal:
      return "Error Internal";
    case cutlass::Status::kErrorInsufficientDriver:
      return "Error Insufficient Driver";
    case cutlass::Status::kErrorArchMismatch:
      return "Error Architecture Mismatch";
    case cutlass::Status::kErrorMemoryAllocation:
      return "Error Memory Allocation failed";
    case cutlass::Status::kInvalid: break;
  }

  return "Invalid status";
}

////////////////////////////////////////////////////////////////////////////////////////////////////

static const int NumThreadsPerWarp = 32;
static const int NumThreadsPerWarpGroup = 128;
static const int NumWarpsPerWarpGroup = NumThreadsPerWarpGroup / NumThreadsPerWarp;
static const int NumThreadsPerHalfWarp = NumThreadsPerWarp / 2;
static const int NumThreadsPerQuad = 4;
static const int NumThreadsPerQuadPair = NumThreadsPerQuad * 2;

////////////////////////////////////////////////////////////////////////////////////////////////////

/// Helper function to return true when called by thread 0 of threadblock 0.
CUTLASS_HOST_DEVICE bool thread0() {
  #if defined(__CUDA_ARCH__)
    return (!threadIdx.x && !threadIdx.y && !threadIdx.z) && (!blockIdx.x && !blockIdx.y && !blockIdx.z);
  #else
    return false;
  #endif
}

/// Returns a lane index in the warp. The threads in warp may not be convergent
CUTLASS_DEVICE
int canonical_lane_idx() { 
  #if defined(__CUDA_ARCH__)
    return threadIdx.x % NumThreadsPerWarp;
  #else
    return 0;
  #endif
}

/// Returns a warp-uniform value indicating the canonical warp index of the calling threads.
/// Threads within the warp must be converged.
CUTLASS_DEVICE
int canonical_warp_idx_sync() { 
  #if defined(__CUDA_ARCH__)
    return __shfl_sync(0xffffffff, threadIdx.x / NumThreadsPerWarp, 0);
  #else
    return 0;
  #endif
}

/// Returns a warp index in the CTA. The threads in warp may not be convergent
/// As it doesn't sync the warp, it faster and allows forward progress
CUTLASS_DEVICE
int canonical_warp_idx() { 
  #if defined(__CUDA_ARCH__)
    return threadIdx.x / NumThreadsPerWarp;
  #else
    return 0;
  #endif
}

/// Returns a warp-uniform value indicating the canonical warp group index of the calling threads.
/// Threads within the warp must be converged.
CUTLASS_DEVICE
int canonical_warp_group_idx() {
  #if defined(__CUDA_ARCH__)
    return __shfl_sync(0xffffffff, threadIdx.x / NumThreadsPerWarpGroup, 0);
  #else
    return 0;
  #endif
}

////////////////////////////////////////////////////////////////////////////////////////////////////

}  // namespace cutlass

////////////////////////////////////////////////////////////////////////////////////////////////////