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[libc][math] Refactor hypotf16 to Header Only (#180511).

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closes #175337
part of #175336
This commit is contained in:
Zorojuro 2026-02-14 11:51:34 +05:30 committed by GitHub
parent 20605617ac
commit 8ccc40ee0e
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GPG Key ID: B5690EEEBB952194
9 changed files with 169 additions and 84 deletions
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1
libc/shared/math.h
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@ -76,6 +76,7 @@
#include "math/fsqrtf128.h"
#include "math/fsqrtl.h"
#include "math/hypotf.h"
#include "math/hypotf16.h"
#include "math/ilogb.h"
#include "math/ilogbf.h"
#include "math/ilogbf128.h"

31
libc/shared/math/hypotf16.h Normal file
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@ -0,0 +1,31 @@
//===-- Shared hypotf16 function --------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_SHARED_MATH_HYPOTF16_H
#define LLVM_LIBC_SHARED_MATH_HYPOTF16_H
#include "include/llvm-libc-macros/float16-macros.h"
#include "shared/libc_common.h"
#ifdef LIBC_TYPES_HAS_FLOAT16
#include "src/__support/math/hypotf16.h"
namespace LIBC_NAMESPACE_DECL {
namespace shared {
using math::hypotf16;
} // namespace shared
} // namespace LIBC_NAMESPACE_DECL
#endif // LIBC_TYPES_HAS_FLOAT16
#endif // LLVM_LIBC_SHARED_MATH_HYPOTF16_H

15
libc/src/__support/math/CMakeLists.txt
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@ -1164,6 +1164,21 @@ add_header_library(
libc.src.__support.macros.optimization
)
add_header_library(
hypotf16
HDRS
hypotf16.h
DEPENDS
libc.src.__support.FPUtil.fenv_impl
libc.src.__support.FPUtil.fp_bits
libc.src.__support.FPUtil.cast
libc.src.__support.FPUtil.multiply_add
libc.src.__support.FPUtil.sqrt
libc.src.__support.macros.optimization
libc.src.__support.macros.properties.types
libc.include.llvm-libc-macros.float16_macros
)
add_header_library(
ilogbl
HDRS

99
libc/src/__support/math/hypotf16.h Normal file
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@ -0,0 +1,99 @@
//===-- Implementation header for hypotf16 ----------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_SRC___SUPPORT_MATH_HYPOTF16_H
#define LLVM_LIBC_SRC___SUPPORT_MATH_HYPOTF16_H
#include "src/__support/FPUtil/FEnvImpl.h"
#include "src/__support/FPUtil/FPBits.h"
#include "src/__support/FPUtil/cast.h"
#include "src/__support/FPUtil/multiply_add.h"
#include "src/__support/FPUtil/sqrt.h"
#include "src/__support/common.h"
#include "src/__support/macros/optimization.h"
#include "src/__support/macros/properties/types.h"
namespace LIBC_NAMESPACE_DECL {
namespace math {
// For targets where conversion from float to float16 has to be
// emulated, fputil::hypot<float16> is faster
LIBC_INLINE float16 hypotf16(float16 x, float16 y) {
using FloatBits = fputil::FPBits<float>;
using FPBits = fputil::FPBits<float16>;
FPBits x_abs = FPBits(x).abs();
FPBits y_abs = FPBits(y).abs();
bool x_abs_larger = x_abs.uintval() >= y_abs.uintval();
FPBits a_bits = x_abs_larger ? x_abs : y_abs;
FPBits b_bits = x_abs_larger ? y_abs : x_abs;
uint16_t a_u = a_bits.uintval();
uint16_t b_u = b_bits.uintval();
// Note: replacing `a_u >= FPBits::EXP_MASK` with `a_bits.is_inf_or_nan()`
// generates extra exponent bit masking instructions on x86-64.
if (LIBC_UNLIKELY(a_u >= FPBits::EXP_MASK)) {
// x or y is inf or nan
if (a_bits.is_signaling_nan() || b_bits.is_signaling_nan()) {
fputil::raise_except_if_required(FE_INVALID);
return FPBits::quiet_nan().get_val();
}
if (a_bits.is_inf() || b_bits.is_inf())
return FPBits::inf().get_val();
return a_bits.get_val();
}
float af = fputil::cast<float>(a_bits.get_val());
float bf = fputil::cast<float>(b_bits.get_val());
// Compiler runtime basic operations for float16 might not be correctly
// rounded for all rounding modes.
if (LIBC_UNLIKELY(a_u - b_u >=
static_cast<uint16_t>((FPBits::FRACTION_LEN + 2)
<< FPBits::FRACTION_LEN)))
return fputil::cast<float16>(af + bf);
// These squares are exact.
float a_sq = af * af;
float sum_sq = fputil::multiply_add(bf, bf, a_sq);
FloatBits result(fputil::sqrt<float>(sum_sq));
uint32_t r_u = result.uintval();
// If any of the sticky bits of the result are non-zero, except the LSB, then
// the rounded result is correct.
if (LIBC_UNLIKELY(((r_u + 1) & 0x0000'0FFE) == 0)) {
float r_d = result.get_val();
// Perform rounding correction.
float sum_sq_lo = fputil::multiply_add(bf, bf, a_sq - sum_sq);
float err = sum_sq_lo - fputil::multiply_add(r_d, r_d, -sum_sq);
if (err > 0) {
r_u |= 1;
} else if ((err < 0) && (r_u & 1) == 0) {
r_u -= 1;
} else if ((r_u & 0x0000'1FFF) == 0) {
// The rounded result is exact.
fputil::clear_except_if_required(FE_INEXACT);
}
return fputil::cast<float16>(FloatBits(r_u).get_val());
}
return fputil::cast<float16>(result.get_val());
}
} // namespace math
} // namespace LIBC_NAMESPACE_DECL
#endif // LLVM_LIBC_SRC___SUPPORT_MATH_HYPOTF16_H

8
libc/src/math/generic/CMakeLists.txt
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@ -3125,13 +3125,7 @@ add_entrypoint_object(
HDRS
../hypotf16.h
DEPENDS
libc.src.__support.FPUtil.fenv_impl
libc.src.__support.FPUtil.fp_bits
libc.src.__support.FPUtil.cast
libc.src.__support.FPUtil.multiply_add
libc.src.__support.FPUtil.sqrt
libc.src.__support.macros.optimization
libc.src.__support.macros.properties.types
libc.src.__support.math.hypotf16
)
add_entrypoint_object(

77
libc/src/math/generic/hypotf16.cpp
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@ -7,85 +7,12 @@
//===----------------------------------------------------------------------===//
#include "src/math/hypotf16.h"
#include "src/__support/FPUtil/FEnvImpl.h"
#include "src/__support/FPUtil/FPBits.h"
#include "src/__support/FPUtil/cast.h"
#include "src/__support/FPUtil/multiply_add.h"
#include "src/__support/FPUtil/sqrt.h"
#include "src/__support/common.h"
#include "src/__support/macros/optimization.h"
#include "src/__support/macros/properties/types.h"
#include "src/__support/math/hypotf16.h"
namespace LIBC_NAMESPACE_DECL {
// For targets where conversion from float to float16 has to be
// emulated, fputil::hypot<float16> is faster
LLVM_LIBC_FUNCTION(float16, hypotf16, (float16 x, float16 y)) {
using FloatBits = fputil::FPBits<float>;
using FPBits = fputil::FPBits<float16>;
FPBits x_abs = FPBits(x).abs();
FPBits y_abs = FPBits(y).abs();
bool x_abs_larger = x_abs.uintval() >= y_abs.uintval();
FPBits a_bits = x_abs_larger ? x_abs : y_abs;
FPBits b_bits = x_abs_larger ? y_abs : x_abs;
uint16_t a_u = a_bits.uintval();
uint16_t b_u = b_bits.uintval();
// Note: replacing `a_u >= FPBits::EXP_MASK` with `a_bits.is_inf_or_nan()`
// generates extra exponent bit masking instructions on x86-64.
if (LIBC_UNLIKELY(a_u >= FPBits::EXP_MASK)) {
// x or y is inf or nan
if (a_bits.is_signaling_nan() || b_bits.is_signaling_nan()) {
fputil::raise_except_if_required(FE_INVALID);
return FPBits::quiet_nan().get_val();
}
if (a_bits.is_inf() || b_bits.is_inf())
return FPBits::inf().get_val();
return a_bits.get_val();
}
float af = fputil::cast<float>(a_bits.get_val());
float bf = fputil::cast<float>(b_bits.get_val());
// Compiler runtime basic operations for float16 might not be correctly
// rounded for all rounding modes.
if (LIBC_UNLIKELY(a_u - b_u >=
static_cast<uint16_t>((FPBits::FRACTION_LEN + 2)
<< FPBits::FRACTION_LEN)))
return fputil::cast<float16>(af + bf);
// These squares are exact.
float a_sq = af * af;
float sum_sq = fputil::multiply_add(bf, bf, a_sq);
FloatBits result(fputil::sqrt<float>(sum_sq));
uint32_t r_u = result.uintval();
// If any of the sticky bits of the result are non-zero, except the LSB, then
// the rounded result is correct.
if (LIBC_UNLIKELY(((r_u + 1) & 0x0000'0FFE) == 0)) {
float r_d = result.get_val();
// Perform rounding correction.
float sum_sq_lo = fputil::multiply_add(bf, bf, a_sq - sum_sq);
float err = sum_sq_lo - fputil::multiply_add(r_d, r_d, -sum_sq);
if (err > 0) {
r_u |= 1;
} else if ((err < 0) && (r_u & 1) == 0) {
r_u -= 1;
} else if ((r_u & 0x0000'1FFF) == 0) {
// The rounded result is exact.
fputil::clear_except_if_required(FE_INEXACT);
}
return fputil::cast<float16>(FloatBits(r_u).get_val());
}
return fputil::cast<float16>(result.get_val());
return math::hypotf16(x, y);
}
} // namespace LIBC_NAMESPACE_DECL

1
libc/test/shared/CMakeLists.txt
View File

@ -72,6 +72,7 @@ add_fp_unittest(
libc.src.__support.math.fsqrtf128
libc.src.__support.math.fsqrtl
libc.src.__support.math.hypotf
libc.src.__support.math.hypotf16
libc.src.__support.math.ilogb
libc.src.__support.math.ilogbf
libc.src.__support.math.ilogbf16

1
libc/test/shared/shared_math_test.cpp
View File

@ -33,6 +33,7 @@ TEST(LlvmLibcSharedMathTest, AllFloat16) {
EXPECT_FP_EQ(0x0p+0f16, LIBC_NAMESPACE::shared::exp2m1f16(0.0f16));
EXPECT_FP_EQ(0x1p+0f16, LIBC_NAMESPACE::shared::expf16(0.0f16));
EXPECT_FP_EQ(0x0p+0f16, LIBC_NAMESPACE::shared::expm1f16(0.0f16));
EXPECT_FP_EQ(0x0p+0f16, LIBC_NAMESPACE::shared::hypotf16(0.0f16, 0.0f16));
EXPECT_FP_EQ(0x0p+0f16, LIBC_NAMESPACE::shared::logf16(1.0f16));
EXPECT_FP_EQ(0x0p+0f16, LIBC_NAMESPACE::shared::sinhf16(0.0f16));

20
utils/bazel/llvm-project-overlay/libc/BUILD.bazel
View File

@ -3867,6 +3867,23 @@ libc_support_library(
],
)
libc_support_library(
name = "__support_math_hypotf16",
hdrs = ["src/__support/math/hypotf16.h"],
deps = [
":__support_common",
":__support_fputil_cast",
":__support_fputil_fenv_impl",
":__support_fputil_fp_bits",
":__support_fputil_multiply_add",
":__support_fputil_sqrt",
":__support_macros_config",
":__support_macros_optimization",
":__support_macros_properties_types",
":llvm_libc_macros_float16_macros",
],
)
libc_support_library(
name = "__support_math_sinhf",
hdrs = ["src/__support/math/sinhf.h"],
@ -4906,8 +4923,7 @@ libc_math_function(
libc_math_function(
name = "hypotf16",
additional_deps = [
":__support_fputil_multiply_add",
":__support_fputil_sqrt",
":__support_math_hypotf16",
],
)