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// Copyright Verizon Media. 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 <cmath>
#include <cfenv>
#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, 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);
std::feclearexcept(FE_ALL_EXCEPT);
EXPECT_TRUE(std::fetestexcept(FE_INVALID) == 0);
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;
EXPECT_TRUE(std::fetestexcept(FE_INVALID) == 0);
// float->double conversion of signaling NaN:
double d_snan = b_snan;
EXPECT_TRUE(std::fetestexcept(FE_INVALID) != 0);
std::feclearexcept(FE_ALL_EXCEPT);
EXPECT_TRUE(std::fetestexcept(FE_INVALID) == 0);
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);
// none of the BF16 operations should trigger FPE:
EXPECT_TRUE(std::fetestexcept(FE_INVALID) == 0);
}
GTEST_MAIN_RUN_ALL_TESTS()
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