Files
composable_kernel/include/ck/utility/random_gen.hpp
Rostyslav Geyyer 14bbc545ea Fix UB caused by reinterpret_cast (#2849)
* Use bit_cast instead of reinterpret_cast to avoid UB

* Apply same fix in ck_tile
2025-09-18 07:12:37 -07:00

62 lines
2.1 KiB
C++

// SPDX-License-Identifier: MIT
// Copyright (c) 2018-2025, Advanced Micro Devices, Inc. All rights reserved.
#pragma once
#include <ck/utility/ignore.hpp>
#include <ck/utility/type.hpp>
#include "ck/ck.hpp"
#ifdef CK_CODE_GEN_RTC
using uint8_t = unsigned char;
using uint16_t = unsigned short;
using uint32_t = unsigned int;
#endif
namespace ck {
// Pseudo random number generator
// version for fp32
template <typename T, uint32_t seed_t, ck::enable_if_t<std::is_same<float, T>{}, bool> = false>
__host__ __device__ uint32_t prand_generator(index_t id, T val, uint32_t seed = seed_t)
{
uint32_t x = bit_cast<uint32_t>(val);
uint32_t drop_bits = uint32_t(x) & 0xFFFFu;
drop_bits ^= x >> 16;
drop_bits = ((drop_bits & 31) << 11) | (drop_bits >> 5);
drop_bits *= 0x7000149;
// NOTE: If id is in 64 bit, we are only using lower 32 bit.
// So, it can have an effect of using same id for multiple elements when the id is very
// large!
uint32_t rng = (drop_bits ^ 0x13371337 ^ (id * 229791) ^ seed);
return rng;
}
// version for fp16
template <typename T, uint32_t seed_t, ck::enable_if_t<std::is_same<_Float16, T>{}, bool> = false>
__host__ __device__ uint32_t prand_generator(index_t id, T val, uint32_t seed = seed_t)
{
uint16_t x = bit_cast<uint16_t>(val);
uint32_t drop_bits = uint32_t(x) & 0xFFFFu;
drop_bits = ((drop_bits & 31) << 11) | (drop_bits >> 5);
drop_bits *= 0x7000149;
// NOTE: If id is in 64 bit, we are only using lower 32 bit.
// So, it can have an effect of using same id for multiple elements when the id is very
// large!
uint32_t rng = (drop_bits ^ 0x13371337 ^ (id * 229791) ^ seed);
return rng;
}
// return 0 if data is not fp16 or fp32
template <typename T,
uint32_t seed_t,
ck::enable_if_t<!(std::is_same<float, T>{} || std::is_same<_Float16, T>{}), bool> = false>
__host__ __device__ uint32_t prand_generator(int id, T val, uint32_t seed = seed_t)
{
ck::ignore = id;
ck::ignore = val;
ck::ignore = seed;
return 0;
}
} // namespace ck