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paddlepaddle--paddle/paddle/phi/common/float8_e4m3fn.h
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2026-07-13 12:40:42 +08:00

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// Copyright (c) 2024 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#pragma once
#include <stdint.h>
#include <cmath>
#include <cstring>
#include <iostream>
#include <limits>
#include "paddle/common/hostdevice.h"
#ifdef PADDLE_WITH_CUDA
#include <cuda.h>
#endif
#if defined(__CUDACC__) && CUDA_VERSION >= 11080
#define PADDLE_CUDA_FP8
#include <cuda_fp8.h>
#endif
#ifndef PADDLE_WITH_HIP
#if !defined(_WIN32)
#define PADDLE_ALIGN(x) __attribute__((aligned(x)))
#else
#define PADDLE_ALIGN(x) __declspec(align(x))
#endif
#else
#define PADDLE_ALIGN(x)
#endif
namespace phi {
namespace dtype {
struct PADDLE_ALIGN(1) float8_e4m3fn {
public:
uint8_t x;
// Constructors
float8_e4m3fn() = default;
float8_e4m3fn(const float8_e4m3fn& o) = default;
float8_e4m3fn& operator=(const float8_e4m3fn& o) = default;
float8_e4m3fn(float8_e4m3fn&& o) = default;
float8_e4m3fn& operator=(float8_e4m3fn&& o) = default;
~float8_e4m3fn() = default;
HOSTDEVICE inline float8_e4m3fn(float val) {
#if defined(PADDLE_CUDA_FP8)
__nv_fp8_e4m3 tmp = __nv_fp8_e4m3(val);
x = *reinterpret_cast<uint8_t*>(&tmp);
#else
// CPU implementation.
Bits fb, denorm_mask;
fb.f = val;
constexpr uint32_t fp8_max = UINT32_C(1087) << 20;
denorm_mask.ui = UINT32_C(141) << 23;
uint8_t result = 0u;
const uint32_t sign = fb.ui & UINT32_C(0x80000000);
fb.ui ^= sign;
if (fb.ui >= fp8_max) {
result = 0x7e;
} else {
if (fb.ui < (UINT32_C(121) << 23)) {
fb.f = fb.f + denorm_mask.f;
fb.ui = fb.ui - denorm_mask.ui;
result = static_cast<uint8_t>(fb.ui);
} else {
uint8_t mant_odd = (fb.ui >> 20) & 1;
fb.ui += ((uint32_t)(7 - 127) << 23) + 0x7FFFF;
fb.ui += mant_odd;
result = static_cast<uint8_t>(fb.ui >> 20);
}
}
result |= static_cast<uint8_t>(sign >> 24);
x = result;
#endif
}
#if defined(PADDLE_CUDA_FP8)
HOSTDEVICE inline explicit float8_e4m3fn(const __nv_fp8_e4m3& val) {
x = *reinterpret_cast<const uint8_t*>(&val); // NOLINT
}
#endif
template <class T>
HOSTDEVICE inline explicit float8_e4m3fn(const T& val)
: x(float8_e4m3fn(static_cast<float>(val)).x) {}
// Assignment operators
#if defined(PADDLE_CUDA_FP8)
HOSTDEVICE inline float8_e4m3fn& operator=(const __nv_fp8_e4m3& val) {
x = *reinterpret_cast<const uint8_t*>(&val); // NOLINT
return *this;
}
#endif
HOSTDEVICE inline float8_e4m3fn& operator=(int8_t val) {
x = float8_e4m3fn(val).x;
return *this;
}
HOSTDEVICE inline float8_e4m3fn& operator=(uint8_t val) {
x = float8_e4m3fn(val).x;
return *this;
}
HOSTDEVICE inline float8_e4m3fn& operator=(int16_t val) {
x = float8_e4m3fn(val).x;
return *this;
}
HOSTDEVICE inline float8_e4m3fn& operator=(uint16_t val) {
x = float8_e4m3fn(val).x;
return *this;
}
HOSTDEVICE inline float8_e4m3fn& operator=(int32_t val) {
x = float8_e4m3fn(val).x;
return *this;
}
HOSTDEVICE inline float8_e4m3fn& operator=(uint32_t val) {
x = float8_e4m3fn(val).x;
return *this;
}
HOSTDEVICE inline float8_e4m3fn& operator=(int64_t val) {
x = float8_e4m3fn(val).x;
return *this;
}
HOSTDEVICE inline float8_e4m3fn& operator=(uint64_t val) {
x = float8_e4m3fn(val).x;
return *this;
}
HOSTDEVICE inline float8_e4m3fn& operator=(float val) {
x = float8_e4m3fn(val).x;
return *this;
}
HOSTDEVICE inline float8_e4m3fn& operator=(double val) {
x = float8_e4m3fn(val).x;
return *this;
}
// Conversion operators
HOSTDEVICE inline operator float() const {
#ifdef PADDLE_CUDA_FP8
return static_cast<float>(
*reinterpret_cast<const __nv_fp8_e4m3*>(&x)); // NOLINT
#else
// CPU implementation.
const uint32_t w = (uint32_t)x << 24;
const uint32_t sign = w & UINT32_C(0x80000000);
const uint32_t nonsign = w & UINT32_C(0x7FFFFFFF);
// get the leading 0-bits in nonsin.
uint32_t nonsign_tmp = nonsign;
uint32_t renorm_shift = 0;
if (nonsign_tmp == 0) {
renorm_shift = sizeof(uint32_t) * 8;
} else {
if ((nonsign_tmp & 0xFFFF0000) == 0) {
renorm_shift += 16;
nonsign_tmp <<= 16;
}
if ((nonsign_tmp & 0xFF000000) == 0) {
renorm_shift += 8;
nonsign_tmp <<= 8;
}
if ((nonsign_tmp & 0xF0000000) == 0) {
renorm_shift += 4;
nonsign_tmp <<= 4;
}
if ((nonsign_tmp & 0xC0000000) == 0) {
renorm_shift += 2;
nonsign_tmp <<= 2;
}
if ((nonsign_tmp & 0x80000000) == 0) {
renorm_shift += 1;
}
}
renorm_shift = renorm_shift > 4 ? renorm_shift - 4 : 0;
const int32_t inf_nan_mask =
((int32_t)(nonsign + 0x01000000) >> 8) & INT32_C(0x7F800000);
const int32_t zero_mask = (int32_t)(nonsign - 1) >> 31;
Bits result;
result.ui =
sign |
((((nonsign << renorm_shift >> 4) + ((0x78 - renorm_shift) << 23)) |
inf_nan_mask) &
~zero_mask);
return result.f;
#endif
}
#ifdef PADDLE_CUDA_FP8
HOSTDEVICE inline __nv_fp8_e4m3 to_nv_fp8_e4m3() const {
return *reinterpret_cast<const __nv_fp8_e4m3*>(&x);
}
#endif
HOSTDEVICE inline explicit operator int8_t() const {
return static_cast<int8_t>(static_cast<float>(*this));
}
HOSTDEVICE inline explicit operator uint8_t() const {
return static_cast<uint8_t>(static_cast<float>(*this));
}
HOSTDEVICE inline explicit operator int16_t() const {
return static_cast<int16_t>(static_cast<float>(*this));
}
HOSTDEVICE inline explicit operator uint16_t() const {
return static_cast<uint16_t>(static_cast<float>(*this));
}
HOSTDEVICE inline explicit operator int32_t() const {
return static_cast<int32_t>(static_cast<float>(*this));
}
HOSTDEVICE inline explicit operator uint32_t() const {
return static_cast<uint32_t>(static_cast<float>(*this));
}
HOSTDEVICE inline explicit operator int64_t() const {
return static_cast<int64_t>(static_cast<float>(*this));
}
HOSTDEVICE inline explicit operator uint64_t() const {
return static_cast<uint64_t>(static_cast<float>(*this));
}
private:
union Bits {
float f;
uint32_t ui;
};
};
HOSTDEVICE inline float8_e4m3fn operator+(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return float8_e4m3fn(static_cast<float>(a) + static_cast<float>(b));
}
HOSTDEVICE inline float8_e4m3fn operator-(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return float8_e4m3fn(static_cast<float>(a) - static_cast<float>(b));
}
HOSTDEVICE inline float8_e4m3fn operator*(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return float8_e4m3fn(static_cast<float>(a) * static_cast<float>(b));
}
HOSTDEVICE inline float8_e4m3fn operator/(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return float8_e4m3fn(static_cast<float>(a) / static_cast<float>(b));
}
HOSTDEVICE inline float8_e4m3fn operator-(const float8_e4m3fn& a) {
return float8_e4m3fn(-static_cast<float>(a));
}
HOSTDEVICE inline float8_e4m3fn& operator+=(float8_e4m3fn& a, // NOLINT
const float8_e4m3fn& b) {
a = float8_e4m3fn(static_cast<float>(a) + static_cast<float>(b));
return a;
}
HOSTDEVICE inline float8_e4m3fn& operator-=(float8_e4m3fn& a, // NOLINT
const float8_e4m3fn& b) {
a = float8_e4m3fn(static_cast<float>(a) - static_cast<float>(b));
return a;
}
HOSTDEVICE inline float8_e4m3fn& operator*=(float8_e4m3fn& a, // NOLINT
const float8_e4m3fn& b) {
a = float8_e4m3fn(static_cast<float>(a) * static_cast<float>(b));
return a;
}
HOSTDEVICE inline float8_e4m3fn& operator/=(float8_e4m3fn& a, // NOLINT
const float8_e4m3fn& b) {
a = float8_e4m3fn(static_cast<float>(a) / static_cast<float>(b));
return a;
}
HOSTDEVICE inline float8_e4m3fn raw_uint8_to_float8_e4m3fn(uint8_t a) {
float8_e4m3fn res;
res.x = a;
return res;
}
// Comparison operators
HOSTDEVICE inline bool operator==(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return static_cast<float>(a) == static_cast<float>(b);
}
HOSTDEVICE inline bool operator!=(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return static_cast<float>(a) != static_cast<float>(b);
}
HOSTDEVICE inline bool operator<(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return static_cast<float>(a) < static_cast<float>(b);
}
HOSTDEVICE inline bool operator<=(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return static_cast<float>(a) <= static_cast<float>(b);
}
HOSTDEVICE inline bool operator>(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return static_cast<float>(a) > static_cast<float>(b);
}
HOSTDEVICE inline bool operator>=(const float8_e4m3fn& a,
const float8_e4m3fn& b) {
return static_cast<float>(a) >= static_cast<float>(b);
}
HOSTDEVICE inline bool(isnan)(const float8_e4m3fn& a) {
return (a.x & 0b01111111) == 0b01111111;
}
// TODO(Wanglongzhi2001): According to https://arxiv.org/pdf/2209.05433.pdf,
// inf in float8_e4m3fn is undefined, to avoid compilation errors,
// we use 0b01111000 to represent inf for now!
HOSTDEVICE inline bool(isinf)(const float8_e4m3fn& a) {
return (a.x & 0b01111111) == 0b01111000;
}
HOSTDEVICE inline bool(isfinite)(const float8_e4m3fn& a) {
return !((isnan)(a)) && !((isinf)(a));
}
HOSTDEVICE inline float8_e4m3fn(abs)(const float8_e4m3fn& a) {
return float8_e4m3fn(std::abs(static_cast<float>(a)));
}
inline std::ostream& operator<<(std::ostream& os, const float8_e4m3fn& a) {
os << static_cast<float>(a);
return os;
}
} // namespace dtype
} // namespace phi
namespace std {
template <>
struct is_pod<phi::dtype::float8_e4m3fn> {
static const bool value =
is_trivial<phi::dtype::float8_e4m3fn>::value &&
is_standard_layout<phi::dtype::float8_e4m3fn>::value;
};
template <>
struct is_floating_point<phi::dtype::float8_e4m3fn>
: std::integral_constant<
bool,
std::is_same<phi::dtype::float8_e4m3fn,
typename std::remove_cv<
phi::dtype::float8_e4m3fn>::type>::value> {};
template <>
struct is_signed<phi::dtype::float8_e4m3fn> {
static const bool value = true;
};
template <>
struct is_unsigned<phi::dtype::float8_e4m3fn> {
static const bool value = false;
};
inline bool isnan(const phi::dtype::float8_e4m3fn& a) {
return phi::dtype::isnan(a);
}
inline bool isinf(const phi::dtype::float8_e4m3fn& a) {
return phi::dtype::isinf(a);
}
template <>
struct numeric_limits<phi::dtype::float8_e4m3fn> {
static constexpr bool is_specialized = true;
static constexpr bool is_signed = true;
static constexpr bool is_integer = false;
static constexpr bool is_exact = false;
static constexpr bool has_infinity = false;
static constexpr bool has_quiet_NaN = true;
static constexpr bool has_signaling_NaN = false;
static constexpr auto has_denorm = true;
static constexpr auto has_denorm_loss = true;
static constexpr auto round_style = numeric_limits<float>::round_style;
static constexpr bool is_iec559 = false;
static constexpr bool is_bounded = true;
static constexpr bool is_modulo = false;
static constexpr int digits = 4;
static constexpr int digits10 = 0;
static constexpr int max_digits10 = 3;
static constexpr int radix = 2;
static constexpr int min_exponent = -5;
static constexpr int min_exponent10 = -1;
static constexpr int max_exponent = 8;
static constexpr int max_exponent10 = 2;
static constexpr auto traps = numeric_limits<float>::traps;
static constexpr auto tinyness_before = false;
HOSTDEVICE static phi::dtype::float8_e4m3fn(min)() {
return phi::dtype::raw_uint8_to_float8_e4m3fn(0x08);
}
HOSTDEVICE static phi::dtype::float8_e4m3fn lowest() {
return phi::dtype::raw_uint8_to_float8_e4m3fn(0xFE);
}
HOSTDEVICE static phi::dtype::float8_e4m3fn(max)() {
return phi::dtype::raw_uint8_to_float8_e4m3fn(0x7E);
}
HOSTDEVICE static phi::dtype::float8_e4m3fn epsilon() {
return phi::dtype::raw_uint8_to_float8_e4m3fn(0x20);
}
HOSTDEVICE static phi::dtype::float8_e4m3fn round_error() {
return phi::dtype::raw_uint8_to_float8_e4m3fn(0x30);
}
HOSTDEVICE static phi::dtype::float8_e4m3fn infinity() {
return phi::dtype::raw_uint8_to_float8_e4m3fn(0x7F);
}
HOSTDEVICE static phi::dtype::float8_e4m3fn quiet_NaN() {
return phi::dtype::raw_uint8_to_float8_e4m3fn(0x7F);
}
HOSTDEVICE static phi::dtype::float8_e4m3fn denorm_min() {
return phi::dtype::raw_uint8_to_float8_e4m3fn(0x01);
}
};
// 新增特化:定义 float 和 float8_e4m3fn 的公共类型为 float
template <>
struct common_type<float, phi::dtype::float8_e4m3fn> {
using type = float;
};
} // namespace std