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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include <vespa/vespalib/util/bfloat16.h>
#include <vespa/vespalib/objects/nbostream.h>
#include <vespa/vespalib/gtest/gtest.h>
#include <stdio.h>
#include <cmath>
#include <cstring>
#include <vector>
using namespace vespalib;
using Limits = std::numeric_limits<BFloat16>;
static std::vector<float> simple_values = {
0.0, 1.0, -1.0, -0.0, 1.75, 0x1.02p20, -0x1.02p-20, 0x3.0p-100, 0x7.0p100
};
TEST(BFloat16Test, normal_usage) {
EXPECT_EQ(sizeof(float), 4);
EXPECT_EQ(sizeof(BFloat16), 2);
BFloat16 answer = 42;
double fortytwo = answer;
EXPECT_EQ(fortytwo, 42);
std::vector<BFloat16> vec;
for (float value : simple_values) {
BFloat16 b = value;
float recover = b;
EXPECT_EQ(value, recover);
}
BFloat16 b1 = 0x101;
EXPECT_EQ(float(b1), 0x100);
BFloat16 b2 = 0x111;
EXPECT_EQ(float(b2), 0x110);
}
TEST(BFloat16Test, has_range_of_int_8) {
for (int i = -128; i < 128; ++i) {
int8_t byte = i;
float flt = byte;
EXPECT_EQ(byte, i);
EXPECT_EQ(flt, i);
BFloat16 value = flt;
float recover = value;
EXPECT_EQ(recover, flt);
}
}
TEST(BFloat16Test, with_nbostream) {
nbostream buf;
for (BFloat16 value : simple_values) {
buf << value;
}
for (float value : simple_values) {
BFloat16 stored;
buf >> stored;
EXPECT_EQ(float(stored), value);
}
}
TEST(BFloat16Test, constants_check) {
EXPECT_EQ(0x1.0p-7, (1.0/128.0));
float n_min = Limits::min();
float d_min = Limits::denorm_min();
float eps = Limits::epsilon();
float big = Limits::max();
float low = Limits::lowest();
EXPECT_EQ(n_min, 0x1.0p-126);
EXPECT_EQ(d_min, 0x1.0p-133);
EXPECT_EQ(eps, 0x1.0p-7);
EXPECT_EQ(big, 0x1.FEp127);
EXPECT_EQ(low, -big);
EXPECT_EQ(n_min, std::numeric_limits<float>::min());
EXPECT_EQ(d_min, n_min / 128.0);
EXPECT_GT(eps, std::numeric_limits<float>::epsilon());
BFloat16 try_epsilon = 1.0f + eps;
EXPECT_GT(try_epsilon.to_float(), 1.0f);
BFloat16 try_half_epsilon = 1.0f + (0.5f * eps);
EXPECT_EQ(try_half_epsilon.to_float(), 1.0f);
EXPECT_LT(big, std::numeric_limits<float>::max());
EXPECT_GT(low, std::numeric_limits<float>::lowest());
printf("bfloat16 epsilon: %.10g (float has %.20g)\n", eps, std::numeric_limits<float>::epsilon());
printf("bfloat16 norm_min: %.20g (float has %.20g)\n", n_min, std::numeric_limits<float>::min());
printf("bfloat16 denorm_min: %.20g (float has %.20g)\n", d_min, std::numeric_limits<float>::denorm_min());
printf("bfloat16 max: %.20g (float has %.20g)\n", big, std::numeric_limits<float>::max());
printf("bfloat16 lowest: %.20g (float has %.20g)\n", low, std::numeric_limits<float>::lowest());
}
TEST(BFloat16Test, traits_check) {
EXPECT_TRUE(std::is_trivially_constructible<BFloat16>::value);
EXPECT_TRUE(std::is_trivially_move_constructible<BFloat16>::value);
EXPECT_TRUE(std::is_trivially_default_constructible<BFloat16>::value);
EXPECT_TRUE((std::is_trivially_assignable<BFloat16,BFloat16>::value));
EXPECT_TRUE(std::is_trivially_move_assignable<BFloat16>::value);
EXPECT_TRUE(std::is_trivially_copy_assignable<BFloat16>::value);
EXPECT_TRUE(std::is_trivially_copyable<BFloat16>::value);
EXPECT_TRUE(std::is_trivially_destructible<BFloat16>::value);
EXPECT_TRUE(std::is_trivial<BFloat16>::value);
EXPECT_TRUE(std::is_swappable<BFloat16>::value);
EXPECT_TRUE(std::has_unique_object_representations<BFloat16>::value);
}
static std::string hexdump(const void *p, size_t sz) {
char tmpbuf[10];
if (sz == 2) {
uint16_t bits;
memcpy(&bits, p, sz);
snprintf(tmpbuf, 10, "%04x", bits);
} else if (sz == 4) {
uint32_t bits;
memcpy(&bits, p, sz);
snprintf(tmpbuf, 10, "%08x", bits);
} else {
abort();
}
return tmpbuf;
}
#define HEX_DUMP(arg) hexdump(&arg, sizeof(arg)).c_str()
TEST(BFloat16Test, check_special_values) {
// we should not need to support HW without normal float support:
EXPECT_TRUE(std::numeric_limits<float>::has_quiet_NaN);
EXPECT_TRUE(std::numeric_limits<float>::has_signaling_NaN);
EXPECT_TRUE(std::numeric_limits<BFloat16>::has_quiet_NaN);
EXPECT_TRUE(std::numeric_limits<BFloat16>::has_signaling_NaN);
float f_inf = std::numeric_limits<float>::infinity();
float f_neg = -f_inf;
float f_qnan = std::numeric_limits<float>::quiet_NaN();
float f_snan = std::numeric_limits<float>::signaling_NaN();
BFloat16 b_inf = std::numeric_limits<BFloat16>::infinity();
BFloat16 b_qnan = std::numeric_limits<BFloat16>::quiet_NaN();
BFloat16 b_snan = std::numeric_limits<BFloat16>::signaling_NaN();
BFloat16 b_from_f_inf = f_inf;
BFloat16 b_from_f_neg = f_neg;
BFloat16 b_from_f_qnan = f_qnan;
BFloat16 b_from_f_snan = f_snan;
EXPECT_EQ(memcmp(&b_inf, &b_from_f_inf, sizeof(BFloat16)), 0);
EXPECT_EQ(memcmp(&b_qnan, &b_from_f_qnan, sizeof(BFloat16)), 0);
EXPECT_EQ(memcmp(&b_snan, &b_from_f_snan, sizeof(BFloat16)), 0);
printf("+inf float is '%s' / bf16 is '%s'\n", HEX_DUMP(f_inf), HEX_DUMP(b_from_f_inf));
printf("-inf float is '%s' / bf16 is '%s'\n", HEX_DUMP(f_neg), HEX_DUMP(b_from_f_neg));
printf("qNaN float is '%s' / bf16 is '%s'\n", HEX_DUMP(f_qnan), HEX_DUMP(b_from_f_qnan));
printf("sNan float is '%s' / bf16 is '%s'\n", HEX_DUMP(f_snan), HEX_DUMP(b_from_f_snan));
double d_inf = b_inf;
double d_neg = b_from_f_neg;
double d_qnan = b_qnan;
double d_snan = b_snan;
EXPECT_EQ(d_inf, std::numeric_limits<double>::infinity());
EXPECT_EQ(d_neg, -std::numeric_limits<double>::infinity());
EXPECT_TRUE(std::isnan(d_qnan));
EXPECT_TRUE(std::isnan(d_snan));
float f_from_b_inf = b_inf;
float f_from_b_neg = b_from_f_neg;
float f_from_b_qnan = b_qnan;
float f_from_b_snan = b_snan;
EXPECT_EQ(memcmp(&f_inf, &f_from_b_inf, sizeof(float)), 0);
EXPECT_EQ(memcmp(&f_neg, &f_from_b_neg, sizeof(float)), 0);
EXPECT_EQ(memcmp(&f_qnan, &f_from_b_qnan, sizeof(float)), 0);
EXPECT_EQ(memcmp(&f_snan, &f_from_b_snan, sizeof(float)), 0);
}
#include <onnxruntime/core/framework/endian.h>
// extract from onnx-internal header file:
namespace onnxruntime {
//BFloat16
struct BFloat16 {
uint16_t val{0};
explicit BFloat16() = default;
explicit BFloat16(uint16_t v) : val(v) {}
explicit BFloat16(float v) {
if (endian::native == endian::little) {
std::memcpy(&val, reinterpret_cast<char*>(&v) + sizeof(uint16_t), sizeof(uint16_t));
} else {
std::memcpy(&val, &v, sizeof(uint16_t));
}
}
float ToFloat() const {
float result;
char* const first = reinterpret_cast<char*>(&result);
char* const second = first + sizeof(uint16_t);
if (endian::native == endian::little) {
std::memset(first, 0, sizeof(uint16_t));
std::memcpy(second, &val, sizeof(uint16_t));
} else {
std::memcpy(first, &val, sizeof(uint16_t));
std::memset(second, 0, sizeof(uint16_t));
}
return result;
}
};
} // namespace onnxruntime
TEST(OnnxBFloat16Test, has_same_encoding) {
EXPECT_EQ(sizeof(vespalib::BFloat16), sizeof(onnxruntime::BFloat16));
EXPECT_EQ(sizeof(vespalib::BFloat16), sizeof(uint16_t));
EXPECT_EQ(sizeof(onnxruntime::BFloat16), sizeof(uint16_t));
vespalib::BFloat16 our_value;
uint32_t ok_count = 0;
uint32_t nan_count = 0;
for (uint32_t i = 0; i < (1u << 16u); ++i) {
uint16_t bits = i;
our_value.assign_bits(bits);
onnxruntime::BFloat16 their_value(bits);
if (our_value.get_bits() != bits) {
printf("bad bits %04x -> %04x (vespalib)\n", bits, our_value.get_bits());
printf("onnx converts -> %04x\n", their_value.val);
EXPECT_EQ(our_value.get_bits(), their_value.val);
continue;
}
EXPECT_EQ(their_value.val, bits);
EXPECT_EQ(memcmp(&our_value, &their_value, sizeof(our_value)), 0);
if (their_value.val != bits) {
printf("bad bits %04x -> %04x (onnx)\n", bits, their_value.val);
continue;
}
EXPECT_EQ(our_value.get_bits(), their_value.val);
if (our_value.get_bits() != their_value.val) {
printf("vespalib bits %04x != %04x onnx bits\n", our_value.get_bits(), their_value.val);
printf("corresponds to floats %g and %g\n", our_value.to_float(), their_value.ToFloat());
continue;
}
float our_float = our_value.to_float();
float their_float = their_value.ToFloat();
EXPECT_EQ(std::isnan(our_float), std::isnan(their_float));
if (std::isnan(our_float) && std::isnan(their_float)) {
++nan_count;
continue;
}
if (our_float != their_float) {
printf("bits %04x as float differs: vespalib %g != %g onnx\n", bits, our_value.to_float(), their_value.ToFloat());
} else {
++ok_count;
}
EXPECT_EQ(our_float, their_float);
vespalib::BFloat16 our_back(our_float);
onnxruntime::BFloat16 their_back(their_float);
EXPECT_EQ(our_back.get_bits(), their_back.val);
}
printf("normal floats behave equally OK in both vespalib and onnx: %d (0x%04x)\n", ok_count, ok_count);
printf("floats that are NaN in both vespalib and onnx: %d (0x%04x)\n", nan_count, nan_count);
printf("total count (OK + NaN): %d (0x%04x)\n", ok_count + nan_count, ok_count + nan_count);
}
GTEST_MAIN_RUN_ALL_TESTS()
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