flash-attention/hopper/static_switch.h

159 lines
10 KiB
C++

// Inspired by
// https://github.com/NVIDIA/DALI/blob/main/include/dali/core/static_switch.h
// and https://github.com/pytorch/pytorch/blob/master/aten/src/ATen/Dispatch.h
#pragma once
/// @param COND - a boolean expression to switch by
/// @param CONST_NAME - a name given for the constexpr bool variable.
/// @param ... - code to execute for true and false
///
/// Usage:
/// ```
/// BOOL_SWITCH(flag, BoolConst, [&] {
/// some_function<BoolConst>(...);
/// });
/// ```
//
#define BOOL_SWITCH(COND, CONST_NAME, ...) \
[&] { \
if (COND) { \
constexpr static bool CONST_NAME = true; \
return __VA_ARGS__(); \
} else { \
constexpr static bool CONST_NAME = false; \
return __VA_ARGS__(); \
} \
}()
#define PREC_SWITCH(PRECTYPE, NAME, ...) \
[&] { \
if (PRECTYPE == 3) { \
using NAME = cutlass::float_e4m3_t; \
return __VA_ARGS__(); \
} else if (PRECTYPE == 2) { \
using NAME = cutlass::bfloat16_t; \
return __VA_ARGS__(); \
} else { \
using NAME = cutlass::half_t; \
return __VA_ARGS__(); \
} \
}()
#define HEADDIM_SWITCH(HEADDIM, CONST_NAME, ...) \
[&] { \
if (HEADDIM == 64) { \
constexpr static int CONST_NAME = 64; \
return __VA_ARGS__(); \
} else if (HEADDIM == 128) { \
constexpr static int CONST_NAME = 128; \
return __VA_ARGS__(); \
} else { \
constexpr static int CONST_NAME = 256; \
return __VA_ARGS__(); \
} \
}()
#define SEQLEN_SWITCH(USE_VAR_SEQ_LEN, NAME, ...) \
[&] { \
bool useSeqLen = USE_VAR_SEQ_LEN; \
if (useSeqLen) { \
using NAME = flash::VarSeqLenTraits; \
return __VA_ARGS__(); \
} else { \
using NAME = flash::FixedSeqLenTraits; \
return __VA_ARGS__(); \
} \
}()
#define SEQLEN_SWITCH_FWD(VAR_SEQ_LEN_Q, SEQ_USED_K, NAME_Q, NAME_K, ...) \
[&] { \
bool useVarSeqLenQ = VAR_SEQ_LEN_Q; \
bool useSeqUsedK = SEQ_USED_K; \
if (useVarSeqLenQ) { \
using NAME_Q = flash::VarSeqLenTraits; \
using NAME_K = flash::VarSeqLenTraits; \
return __VA_ARGS__(); \
} else if (useSeqUsedK) { \
using NAME_Q = flash::FixedSeqLenTraits; \
using NAME_K = flash::FixedSeqLenTraitsDynamic; \
return __VA_ARGS__(); \
} else { \
using NAME_Q = flash::FixedSeqLenTraits; \
using NAME_K = flash::FixedSeqLenTraits; \
return __VA_ARGS__(); \
} \
}()
#define QUERYHEAD_SWITCH(QUERYHEADS, CONST_NAME, ...) \
[&] { \
if (QUERYHEADS <= 2) { \
constexpr static int CONST_NAME = 2; \
return __VA_ARGS__(); \
} else if (QUERYHEADS <= 4) { \
constexpr static int CONST_NAME = 4; \
return __VA_ARGS__(); \
} else if (QUERYHEADS <= 8) { \
constexpr static int CONST_NAME = 8; \
return __VA_ARGS__(); \
} else if (QUERYHEADS <= 16) { \
constexpr static int CONST_NAME = 16; \
return __VA_ARGS__(); \
} else { \
constexpr static int CONST_NAME = 32; \
return __VA_ARGS__(); \
} \
}()
#define MMA_3WG_SWITCH(QLEN, CONST_NAME, ...) \
[&] { \
if (QLEN <= 64) { \
constexpr static int CONST_NAME = 1; \
return __VA_ARGS__(); \
} else if (QLEN <= 128) { \
constexpr static int CONST_NAME = 2; \
return __VA_ARGS__(); \
} else { \
constexpr static int CONST_NAME = 3; \
return __VA_ARGS__(); \
} \
}()
#define MMA_2WG_SWITCH(QLEN, CONST_NAME, ...) \
[&] { \
if (QLEN <= 64) { \
constexpr static int CONST_NAME = 1; \
return __VA_ARGS__(); \
} else { \
constexpr static int CONST_NAME = 2; \
return __VA_ARGS__(); \
} \
}()
#define NUM_SPLITS_SWITCH(NUM_SPLITS, LOG_MAX_SPLITS, ...) \
[&] { \
if (NUM_SPLITS <= 2) { \
constexpr static int LOG_MAX_SPLITS = 1; \
return __VA_ARGS__(); \
} else if (NUM_SPLITS <= 4) { \
constexpr static int LOG_MAX_SPLITS = 2; \
return __VA_ARGS__(); \
} else if (NUM_SPLITS <= 8) { \
constexpr static int LOG_MAX_SPLITS = 3; \
return __VA_ARGS__(); \
} else if (NUM_SPLITS <= 16) { \
constexpr static int LOG_MAX_SPLITS = 4; \
return __VA_ARGS__(); \
} else if (NUM_SPLITS <= 32) { \
constexpr static int LOG_MAX_SPLITS = 5; \
return __VA_ARGS__(); \
} else if (NUM_SPLITS <= 64) { \
constexpr static int LOG_MAX_SPLITS = 6; \
return __VA_ARGS__(); \
} else { \
constexpr static int LOG_MAX_SPLITS = 7; \
return __VA_ARGS__(); \
} \
}()