mirror of
https://github.com/zebrajr/pytorch.git
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f231be25c6
This PR adds unused parameter name comments in C++ declarations to improve code readability. Pull Request resolved: https://github.com/pytorch/pytorch/pull/164912 Approved by: https://github.com/Skylion007
445 lines
14 KiB
C++
445 lines
14 KiB
C++
#pragma once
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/// Defines the Float8_e4m3fnuz type (8-bit floating-point) including
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/// conversions to standard C types and basic arithmetic operations. Note that
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/// arithmetic operations are implemented by converting to floating point and
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/// performing the operation in float32.
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/// Binary configuration remains the same as Float8_e4m3fn:
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/// s eeee mmm
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/// 1 sign bit
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/// 4 exponent bits
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/// 3 mantissa bits
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/// The key differences versus Float8_e4m3fn are:
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/// bias = 8
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/// no infinities or negative zero
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/// NaN only when sign bit is 1, rest all 0s
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///
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/// Implementation based on the paper https://arxiv.org/pdf/2206.02915.pdf and
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/// the existing Float8_e4m3fn implementation.
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#include <torch/headeronly/macros/Macros.h>
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#include <torch/headeronly/util/Float8_fnuz_cvt.h>
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#include <torch/headeronly/util/floating_point_utils.h>
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#include <limits>
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#if defined(__cplusplus)
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#include <cstdint>
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#elif !defined(__OPENCL_VERSION__)
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#include <math.h>
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#include <stdint.h>
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#endif
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#include <iosfwd>
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#include <ostream>
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namespace c10 {
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struct alignas(1) Float8_e4m3fnuz {
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uint8_t x;
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struct from_bits_t {};
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C10_HOST_DEVICE static constexpr from_bits_t from_bits() {
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return from_bits_t();
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}
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Float8_e4m3fnuz() = default;
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constexpr C10_HOST_DEVICE Float8_e4m3fnuz(
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uint8_t bits,
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from_bits_t /*unused*/)
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: x(bits) {}
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inline C10_HOST_DEVICE Float8_e4m3fnuz(float value);
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inline C10_HOST_DEVICE operator float() const;
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inline C10_HOST_DEVICE bool isnan() const;
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};
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inline std::ostream& operator<<(
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std::ostream& out,
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const Float8_e4m3fnuz& value) {
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out << (float)value;
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return out;
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}
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namespace detail {
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/*
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* Convert a 32-bit floating-point number in IEEE single-precision format to a
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* 8-bit floating-point number in fp8 E4M3FNUZ format, in bit representation.
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*/
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inline C10_HOST_DEVICE uint8_t fp8e4m3fnuz_from_fp32_value(float f) {
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/*
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* Binary representation of 256.0f, which is the first value not representable
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* (i.e. the first value which would overflow in to the sign bit, resulting in
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* a NaN) in fp8e4m3fnuz range:
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* 1 0000 000 - fp8e4m3fnuz
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* 0 10000111 00000000000000000000000 - fp32
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*/
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constexpr uint32_t fnuz_max = UINT32_C(0x87) << 23;
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/*
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* A mask for converting fp32 numbers lower than fp8e4m3fnuz normal range
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* into denorm representation
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* magic number: ((127 - 8) + (23 - 3) + 1)
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*/
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constexpr uint32_t denorm_mask = UINT32_C(0x8C) << 23;
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uint32_t f_bits = fp32_to_bits(f);
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uint32_t result = 0u;
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/*
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* Extract the sign of the input number into the high bit of the 32-bit word:
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*
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* +---+----------------------------------+
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* | S |0000000 00000000 00000000 00000000|
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* +---+----------------------------------+
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* Bits 31 0-31
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*/
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const uint32_t sign = f_bits & UINT32_C(0x80000000);
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/*
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* Set sign bit to 0
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*/
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f_bits ^= sign;
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if (f_bits >= fnuz_max) {
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// NaN -- sign bit set to 1, rest 0s.
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return 0x80;
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}
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if (f_bits < (UINT32_C(0x78) << 23) /* 2^-7 in float32 */) {
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// Input exponent is less than -7, the smallest e4m3fnuz exponent, so the
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// number will become subnormal.
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f_bits = fp32_to_bits(fp32_from_bits(f_bits) + fp32_from_bits(denorm_mask));
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result = static_cast<uint8_t>(f_bits - denorm_mask);
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if (result == 0) {
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// fnuz types don't have negative zero.
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return 0;
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}
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} else {
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// resulting mantissa is odd
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uint8_t mant_odd = (f_bits >> 20) & 1;
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// update exponent, rounding bias part 1
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f_bits += ((uint32_t)(8 - 127) << 23) + 0x7FFFF;
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// rounding bias part 2
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f_bits += mant_odd;
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// take the bits!
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result = static_cast<uint8_t>(f_bits >> 20);
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}
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result |= sign >> 24;
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return result;
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}
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} // namespace detail
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//------ below is copied from c10/util/Float8_e4m3fnuz-inl.h ------//
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C10_CLANG_DIAGNOSTIC_PUSH()
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#if C10_CLANG_HAS_WARNING("-Wimplicit-int-float-conversion")
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C10_CLANG_DIAGNOSTIC_IGNORE("-Wimplicit-int-float-conversion")
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#endif
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/// Constructors
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inline C10_HOST_DEVICE Float8_e4m3fnuz::Float8_e4m3fnuz(float value)
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: x(detail::fp8e4m3fnuz_from_fp32_value(value)) {}
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/// Implicit conversions
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inline C10_HOST_DEVICE Float8_e4m3fnuz::operator float() const {
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return torch::headeronly::detail::fp8_fnuz_to_fp32_value<4, 3>(x);
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}
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/// Special values helper
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inline C10_HOST_DEVICE bool Float8_e4m3fnuz::isnan() const {
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return x == 0b10000000;
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}
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/// Arithmetic
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inline C10_HOST_DEVICE Float8_e4m3fnuz
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operator+(const Float8_e4m3fnuz& a, const Float8_e4m3fnuz& b) {
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return static_cast<float>(a) + static_cast<float>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz
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operator-(const Float8_e4m3fnuz& a, const Float8_e4m3fnuz& b) {
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return static_cast<float>(a) - static_cast<float>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz
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operator*(const Float8_e4m3fnuz& a, const Float8_e4m3fnuz& b) {
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return static_cast<float>(a) * static_cast<float>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator/(
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const Float8_e4m3fnuz& a,
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const Float8_e4m3fnuz& b) __ubsan_ignore_float_divide_by_zero__ {
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return static_cast<float>(a) / static_cast<float>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator-(const Float8_e4m3fnuz& a) {
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return -static_cast<float>(a);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz& operator+=(
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Float8_e4m3fnuz& a,
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const Float8_e4m3fnuz& b) {
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a = a + b;
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return a;
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz& operator-=(
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Float8_e4m3fnuz& a,
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const Float8_e4m3fnuz& b) {
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a = a - b;
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return a;
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz& operator*=(
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Float8_e4m3fnuz& a,
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const Float8_e4m3fnuz& b) {
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a = a * b;
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return a;
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz& operator/=(
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Float8_e4m3fnuz& a,
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const Float8_e4m3fnuz& b) {
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a = a / b;
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return a;
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}
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/// Arithmetic with floats
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inline C10_HOST_DEVICE float operator+(Float8_e4m3fnuz a, float b) {
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return static_cast<float>(a) + b;
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}
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inline C10_HOST_DEVICE float operator-(Float8_e4m3fnuz a, float b) {
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return static_cast<float>(a) - b;
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}
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inline C10_HOST_DEVICE float operator*(Float8_e4m3fnuz a, float b) {
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return static_cast<float>(a) * b;
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}
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inline C10_HOST_DEVICE float operator/(Float8_e4m3fnuz a, float b)
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__ubsan_ignore_float_divide_by_zero__ {
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return static_cast<float>(a) / b;
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}
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inline C10_HOST_DEVICE float operator+(float a, Float8_e4m3fnuz b) {
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return a + static_cast<float>(b);
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}
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inline C10_HOST_DEVICE float operator-(float a, Float8_e4m3fnuz b) {
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return a - static_cast<float>(b);
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}
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inline C10_HOST_DEVICE float operator*(float a, Float8_e4m3fnuz b) {
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return a * static_cast<float>(b);
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}
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inline C10_HOST_DEVICE float operator/(float a, Float8_e4m3fnuz b)
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__ubsan_ignore_float_divide_by_zero__ {
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return a / static_cast<float>(b);
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}
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inline C10_HOST_DEVICE float& operator+=(float& a, const Float8_e4m3fnuz& b) {
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return a += static_cast<float>(b);
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}
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inline C10_HOST_DEVICE float& operator-=(float& a, const Float8_e4m3fnuz& b) {
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return a -= static_cast<float>(b);
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}
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inline C10_HOST_DEVICE float& operator*=(float& a, const Float8_e4m3fnuz& b) {
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return a *= static_cast<float>(b);
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}
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inline C10_HOST_DEVICE float& operator/=(float& a, const Float8_e4m3fnuz& b) {
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return a /= static_cast<float>(b);
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}
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/// Arithmetic with doubles
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inline C10_HOST_DEVICE double operator+(Float8_e4m3fnuz a, double b) {
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return static_cast<double>(a) + b;
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}
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inline C10_HOST_DEVICE double operator-(Float8_e4m3fnuz a, double b) {
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return static_cast<double>(a) - b;
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}
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inline C10_HOST_DEVICE double operator*(Float8_e4m3fnuz a, double b) {
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return static_cast<double>(a) * b;
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}
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inline C10_HOST_DEVICE double operator/(Float8_e4m3fnuz a, double b)
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__ubsan_ignore_float_divide_by_zero__ {
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return static_cast<double>(a) / b;
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}
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inline C10_HOST_DEVICE double operator+(double a, Float8_e4m3fnuz b) {
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return a + static_cast<double>(b);
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}
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inline C10_HOST_DEVICE double operator-(double a, Float8_e4m3fnuz b) {
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return a - static_cast<double>(b);
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}
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inline C10_HOST_DEVICE double operator*(double a, Float8_e4m3fnuz b) {
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return a * static_cast<double>(b);
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}
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inline C10_HOST_DEVICE double operator/(double a, Float8_e4m3fnuz b)
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__ubsan_ignore_float_divide_by_zero__ {
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return a / static_cast<double>(b);
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}
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/// Arithmetic with ints
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator+(Float8_e4m3fnuz a, int b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return a + static_cast<Float8_e4m3fnuz>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator-(Float8_e4m3fnuz a, int b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return a - static_cast<Float8_e4m3fnuz>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator*(Float8_e4m3fnuz a, int b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return a * static_cast<Float8_e4m3fnuz>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator/(Float8_e4m3fnuz a, int b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return a / static_cast<Float8_e4m3fnuz>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator+(int a, Float8_e4m3fnuz b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return static_cast<Float8_e4m3fnuz>(a) + b;
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator-(int a, Float8_e4m3fnuz b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return static_cast<Float8_e4m3fnuz>(a) - b;
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator*(int a, Float8_e4m3fnuz b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return static_cast<Float8_e4m3fnuz>(a) * b;
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator/(int a, Float8_e4m3fnuz b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return static_cast<Float8_e4m3fnuz>(a) / b;
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}
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//// Arithmetic with int64_t
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator+(Float8_e4m3fnuz a, int64_t b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return a + static_cast<Float8_e4m3fnuz>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator-(Float8_e4m3fnuz a, int64_t b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return a - static_cast<Float8_e4m3fnuz>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator*(Float8_e4m3fnuz a, int64_t b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return a * static_cast<Float8_e4m3fnuz>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator/(Float8_e4m3fnuz a, int64_t b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return a / static_cast<Float8_e4m3fnuz>(b);
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator+(int64_t a, Float8_e4m3fnuz b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return static_cast<Float8_e4m3fnuz>(a) + b;
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator-(int64_t a, Float8_e4m3fnuz b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return static_cast<Float8_e4m3fnuz>(a) - b;
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator*(int64_t a, Float8_e4m3fnuz b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return static_cast<Float8_e4m3fnuz>(a) * b;
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}
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inline C10_HOST_DEVICE Float8_e4m3fnuz operator/(int64_t a, Float8_e4m3fnuz b) {
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// NOLINTNEXTLINE(bugprone-narrowing-conversions,cppcoreguidelines-narrowing-conversions)
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return static_cast<Float8_e4m3fnuz>(a) / b;
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}
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/// NOTE: we do not define comparisons directly and instead rely on the implicit
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/// conversion from c10::Float8_e4m3fnuz to float.
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C10_CLANG_DIAGNOSTIC_POP()
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} // namespace c10
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namespace torch::headeronly {
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using c10::Float8_e4m3fnuz;
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using c10::operator+;
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using c10::operator-;
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using c10::operator*;
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using c10::operator/;
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using c10::operator+=;
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using c10::operator-=;
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using c10::operator*=;
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using c10::operator/=;
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using c10::operator<<;
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namespace detail {
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using c10::detail::fp8e4m3fnuz_from_fp32_value;
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} // namespace detail
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} // namespace torch::headeronly
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namespace std {
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template <>
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class numeric_limits<c10::Float8_e4m3fnuz> {
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public:
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static constexpr bool is_specialized = true;
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static constexpr bool is_signed = true;
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static constexpr bool is_integer = false;
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static constexpr bool is_exact = false;
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static constexpr bool has_infinity = false;
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static constexpr bool has_quiet_NaN = true;
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static constexpr bool has_signaling_NaN = false;
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static constexpr auto has_denorm = true;
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static constexpr auto has_denorm_loss = true;
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static constexpr auto round_style = numeric_limits<float>::round_style;
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static constexpr bool is_iec559 = false;
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static constexpr bool is_bounded = true;
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static constexpr bool is_modulo = false;
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static constexpr int digits = 4;
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static constexpr int digits10 = 0;
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static constexpr int max_digits10 = 3;
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static constexpr int radix = 2;
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static constexpr int min_exponent = -6;
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static constexpr int min_exponent10 = -1;
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static constexpr int max_exponent = 8;
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static constexpr int max_exponent10 = 2;
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static constexpr auto traps = numeric_limits<float>::traps;
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static constexpr auto tinyness_before = false;
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static constexpr c10::Float8_e4m3fnuz min() {
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return c10::Float8_e4m3fnuz(0x08, c10::Float8_e4m3fnuz::from_bits());
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}
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static constexpr c10::Float8_e4m3fnuz lowest() {
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return c10::Float8_e4m3fnuz(0xFF, c10::Float8_e4m3fnuz::from_bits());
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}
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static constexpr c10::Float8_e4m3fnuz max() {
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return c10::Float8_e4m3fnuz(0x7F, c10::Float8_e4m3fnuz::from_bits());
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}
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static constexpr c10::Float8_e4m3fnuz epsilon() {
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return c10::Float8_e4m3fnuz(0x28, c10::Float8_e4m3fnuz::from_bits());
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}
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static constexpr c10::Float8_e4m3fnuz round_error() {
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return c10::Float8_e4m3fnuz(0x38, c10::Float8_e4m3fnuz::from_bits());
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}
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static constexpr c10::Float8_e4m3fnuz infinity() {
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// NaN (no infinities)
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return c10::Float8_e4m3fnuz(0x80, c10::Float8_e4m3fnuz::from_bits());
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}
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static constexpr c10::Float8_e4m3fnuz quiet_NaN() {
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return c10::Float8_e4m3fnuz(0x80, c10::Float8_e4m3fnuz::from_bits());
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}
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static constexpr c10::Float8_e4m3fnuz denorm_min() {
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return c10::Float8_e4m3fnuz(0x01, c10::Float8_e4m3fnuz::from_bits());
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}
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};
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} // namespace std
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