[llvm-branch-commits] [libc] [libc][math][c23] Add log10f16 C23 math function (PR #106091)
via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Thu Oct 17 11:53:37 PDT 2024
https://github.com/overmighty updated https://github.com/llvm/llvm-project/pull/106091
>From d4ff8e37305f98ebb140bfd5d6968c73dc10a1c4 Mon Sep 17 00:00:00 2001
From: OverMighty <its.overmighty at gmail.com>
Date: Mon, 26 Aug 2024 17:23:01 +0200
Subject: [PATCH 1/2] [libc][math][c23] Add log10f16 C23 math function
Part of #95250.
---
libc/config/gpu/entrypoints.txt | 1 +
libc/config/linux/x86_64/entrypoints.txt | 1 +
libc/docs/math/index.rst | 2 +-
libc/spec/stdc.td | 1 +
libc/src/math/CMakeLists.txt | 1 +
libc/src/math/generic/CMakeLists.txt | 21 +++
libc/src/math/generic/expxf16.h | 14 ++
libc/src/math/generic/log10f16.cpp | 163 +++++++++++++++++++++
libc/src/math/log10f16.h | 21 +++
libc/test/src/math/CMakeLists.txt | 11 ++
libc/test/src/math/log10f16_test.cpp | 40 +++++
libc/test/src/math/smoke/CMakeLists.txt | 12 ++
libc/test/src/math/smoke/log10f16_test.cpp | 47 ++++++
13 files changed, 334 insertions(+), 1 deletion(-)
create mode 100644 libc/src/math/generic/log10f16.cpp
create mode 100644 libc/src/math/log10f16.h
create mode 100644 libc/test/src/math/log10f16_test.cpp
create mode 100644 libc/test/src/math/smoke/log10f16_test.cpp
diff --git a/libc/config/gpu/entrypoints.txt b/libc/config/gpu/entrypoints.txt
index 2cc54e8a4b970c..13bb88894297ca 100644
--- a/libc/config/gpu/entrypoints.txt
+++ b/libc/config/gpu/entrypoints.txt
@@ -567,6 +567,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
libc.src.math.llogbf16
libc.src.math.llrintf16
libc.src.math.llroundf16
+ libc.src.math.log10f16
libc.src.math.log2f16
libc.src.math.logbf16
libc.src.math.logf16
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 06ea7bba81f345..6ed6ad8c2400f3 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -660,6 +660,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
libc.src.math.llogbf16
libc.src.math.llrintf16
libc.src.math.llroundf16
+ libc.src.math.log10f16
libc.src.math.log2f16
libc.src.math.logbf16
libc.src.math.logf16
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
index 6591cbbdc15584..88751e2453f2c8 100644
--- a/libc/docs/math/index.rst
+++ b/libc/docs/math/index.rst
@@ -312,7 +312,7 @@ Higher Math Functions
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| log | |check| | |check| | | |check| | | 7.12.6.11 | F.10.3.11 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| log10 | |check| | |check| | | | | 7.12.6.12 | F.10.3.12 |
+| log10 | |check| | |check| | | |check| | | 7.12.6.12 | F.10.3.12 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| log10p1 | | | | | | 7.12.6.13 | F.10.3.13 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index d2a073847503ef..33bec2f71627e5 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -642,6 +642,7 @@ def StdC : StandardSpec<"stdc"> {
FunctionSpec<"log10", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
FunctionSpec<"log10f", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
+ GuardedFunctionSpec<"log10f16", RetValSpec<Float16Type>, [ArgSpec<Float16Type>], "LIBC_TYPES_HAS_FLOAT16">,
FunctionSpec<"log1p", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
FunctionSpec<"log1pf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 516bed499b1941..9239f029abf87a 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -334,6 +334,7 @@ add_math_entrypoint_object(ldexpf128)
add_math_entrypoint_object(log10)
add_math_entrypoint_object(log10f)
+add_math_entrypoint_object(log10f16)
add_math_entrypoint_object(log1p)
add_math_entrypoint_object(log1pf)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index d7c7a3431d3d95..eb7e83611fcd2e 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -2173,6 +2173,27 @@ add_entrypoint_object(
-O3
)
+add_entrypoint_object(
+ log10f16
+ SRCS
+ log10f16.cpp
+ HDRS
+ ../log10f16.h
+ DEPENDS
+ .expxf16
+ libc.hdr.errno_macros
+ libc.hdr.fenv_macros
+ libc.src.__support.FPUtil.except_value_utils
+ libc.src.__support.FPUtil.fenv_impl
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.FPUtil.multiply_add
+ libc.src.__support.FPUtil.polyeval
+ libc.src.__support.macros.optimization
+ libc.src.__support.macros.properties.cpu_features
+ COMPILE_OPTIONS
+ -O3
+)
+
add_entrypoint_object(
log1p
SRCS
diff --git a/libc/src/math/generic/expxf16.h b/libc/src/math/generic/expxf16.h
index 87fe68a143a86a..5549dfe14bfb81 100644
--- a/libc/src/math/generic/expxf16.h
+++ b/libc/src/math/generic/expxf16.h
@@ -316,6 +316,20 @@ constexpr cpp::array<float, 32> LOG2F_F = {
0x1.d053f6p-1f, 0x1.dc899ap-1f, 0x1.e88c6cp-1f, 0x1.f45e08p-1f,
};
+// Generated by Sollya with the following commands:
+// > display = hexadecimal;
+// > for i from 0 to 31 do print(round(log10(1 + i * 2^-5), SG, RN));
+constexpr cpp::array<float, 32> LOG10F_F = {
+ 0x0p+0f, 0x1.b5e908p-7f, 0x1.af5f92p-6f, 0x1.3ed11ap-5f,
+ 0x1.a30a9ep-5f, 0x1.02428cp-4f, 0x1.31b306p-4f, 0x1.5fe804p-4f,
+ 0x1.8cf184p-4f, 0x1.b8de4ep-4f, 0x1.e3bc1ap-4f, 0x1.06cbd6p-3f,
+ 0x1.1b3e72p-3f, 0x1.2f3b6ap-3f, 0x1.42c7e8p-3f, 0x1.55e8c6p-3f,
+ 0x1.68a288p-3f, 0x1.7af974p-3f, 0x1.8cf184p-3f, 0x1.9e8e7cp-3f,
+ 0x1.afd3e4p-3f, 0x1.c0c514p-3f, 0x1.d1653p-3f, 0x1.e1b734p-3f,
+ 0x1.f1bdeep-3f, 0x1.00be06p-2f, 0x1.087a08p-2f, 0x1.101432p-2f,
+ 0x1.178da6p-2f, 0x1.1ee778p-2f, 0x1.2622bp-2f, 0x1.2d404cp-2f,
+};
+
// Generated by Sollya with the following commands:
// > display = hexadecimal;
// > for i from 0 to 31 do print(round(1 / (1 + i * 2^-5), SG, RN));
diff --git a/libc/src/math/generic/log10f16.cpp b/libc/src/math/generic/log10f16.cpp
new file mode 100644
index 00000000000000..7de54e75af4507
--- /dev/null
+++ b/libc/src/math/generic/log10f16.cpp
@@ -0,0 +1,163 @@
+//===-- Half-precision log10(x) function ----------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/math/log10f16.h"
+#include "expxf16.h"
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/PolyEval.h"
+#include "src/__support/FPUtil/except_value_utils.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h"
+#include "src/__support/macros/properties/cpu_features.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+#ifdef LIBC_TARGET_CPU_HAS_FMA
+static constexpr size_t N_LOG10F16_EXCEPTS = 11;
+#else
+static constexpr size_t N_LOG10F16_EXCEPTS = 17;
+#endif
+
+static constexpr fputil::ExceptValues<float16, N_LOG10F16_EXCEPTS>
+ LOG10F16_EXCEPTS = {{
+ // (input, RZ output, RU offset, RD offset, RN offset)
+ // x = 0x1.e3cp-3, log10f16(x) = -0x1.40cp-1 (RZ)
+ {0x338fU, 0xb903U, 0U, 1U, 0U},
+ // x = 0x1.fep-3, log10f16(x) = -0x1.35p-1 (RZ)
+ {0x33f8U, 0xb8d4U, 0U, 1U, 1U},
+#ifndef LIBC_TARGET_CPU_HAS_FMA
+ // x = 0x1.394p-1, log10f16(x) = -0x1.b4cp-3 (RZ)
+ {0x38e5U, 0xb2d3U, 0U, 1U, 1U},
+#endif
+ // x = 0x1.ea8p-1, log10f16(x) = -0x1.31p-6 (RZ)
+ {0x3baaU, 0xa4c4U, 0U, 1U, 1U},
+ // x = 0x1.ebp-1, log10f16(x) = -0x1.29cp-6 (RZ)
+ {0x3bacU, 0xa4a7U, 0U, 1U, 1U},
+ // x = 0x1.f3p-1, log10f16(x) = -0x1.6dcp-7 (RZ)
+ {0x3bccU, 0xa1b7U, 0U, 1U, 1U},
+// x = 0x1.f38p-1, log10f16(x) = -0x1.5f8p-7 (RZ)
+#ifndef LIBC_TARGET_CPU_HAS_FMA
+ {0x3bceU, 0xa17eU, 0U, 1U, 1U},
+ // x = 0x1.fd8p-1, log10f16(x) = -0x1.168p-9 (RZ)
+ {0x3bf6U, 0x985aU, 0U, 1U, 1U},
+ // x = 0x1.ff8p-1, log10f16(x) = -0x1.bccp-12 (RZ)
+ {0x3bfeU, 0x8ef3U, 0U, 1U, 1U},
+ // x = 0x1.374p+0, log10f16(x) = 0x1.5b8p-4 (RZ)
+ {0x3cddU, 0x2d6eU, 1U, 0U, 1U},
+ // x = 0x1.3ecp+1, log10f16(x) = 0x1.958p-2 (RZ)
+ {0x40fbU, 0x3656U, 1U, 0U, 1U},
+#endif
+ // x = 0x1.4p+3, log10f16(x) = 0x1p+0 (RZ)
+ {0x4900U, 0x3c00U, 0U, 0U, 0U},
+ // x = 0x1.9p+6, log10f16(x) = 0x1p+1 (RZ)
+ {0x5640U, 0x4000U, 0U, 0U, 0U},
+ // x = 0x1.f84p+6, log10f16(x) = 0x1.0ccp+1 (RZ)
+ {0x57e1U, 0x4033U, 1U, 0U, 0U},
+ // x = 0x1.f4p+9, log10f16(x) = 0x1.8p+1 (RZ)
+ {0x63d0U, 0x4200U, 0U, 0U, 0U},
+ // x = 0x1.388p+13, log10f16(x) = 0x1p+2 (RZ)
+ {0x70e2U, 0x4400U, 0U, 0U, 0U},
+ // x = 0x1.674p+13, log10f16(x) = 0x1.03cp+2 (RZ)
+ {0x719dU, 0x440fU, 1U, 0U, 0U},
+ }};
+
+LLVM_LIBC_FUNCTION(float16, log10f16, (float16 x)) {
+ using FPBits = fputil::FPBits<float16>;
+ FPBits x_bits(x);
+
+ uint16_t x_u = x_bits.uintval();
+
+ // If x <= 0, or x is 1, or x is +inf, or x is NaN.
+ if (LIBC_UNLIKELY(x_u == 0U || x_u == 0x3c00U || x_u >= 0x7c00U)) {
+ // log10(NaN) = NaN
+ if (x_bits.is_nan()) {
+ if (x_bits.is_signaling_nan()) {
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+
+ return x;
+ }
+
+ // log10(+/-0) = −inf
+ if ((x_u & 0x7fffU) == 0U) {
+ fputil::raise_except_if_required(FE_DIVBYZERO);
+ return FPBits::inf(Sign::NEG).get_val();
+ }
+
+ if (x_u == 0x3c00U)
+ return FPBits::zero().get_val();
+
+ // When x < 0.
+ if (x_u > 0x8000U) {
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+
+ // log10(+inf) = +inf
+ return FPBits::inf().get_val();
+ }
+
+ if (auto r = LOG10F16_EXCEPTS.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
+ return r.value();
+
+ // To compute log10(x), we perform the following range reduction:
+ // x = 2^m * 1.mant,
+ // log10(x) = m * log10(2) + log10(1.mant).
+ // To compute log10(1.mant), let f be the highest 6 bits including the hidden
+ // bit, and d be the difference (1.mant - f), i.e., the remaining 5 bits of
+ // the mantissa, then:
+ // log10(1.mant) = log10(f) + log10(1.mant / f)
+ // = log10(f) + log10(1 + d/f)
+ // since d/f is sufficiently small.
+ // We store log10(f) and 1/f in the lookup tables LOG10F_F and ONE_OVER_F
+ // respectively.
+
+ int m = -FPBits::EXP_BIAS;
+
+ // When x is subnormal.
+ if ((x_u & FPBits::EXP_MASK) == 0U) {
+ // Normalize x.
+ x_bits = FPBits(x_bits.get_val() *
+ static_cast<float16>((1U << FPBits::FRACTION_LEN)));
+ x_u = x_bits.uintval();
+ m -= FPBits::FRACTION_LEN;
+ }
+
+ uint16_t mant = x_bits.get_mantissa();
+ // Leading 10 - 5 = 5 bits of the mantissa.
+ int f = mant >> 5;
+ // Unbiased exponent.
+ m += x_u >> FPBits::FRACTION_LEN;
+
+ // Set bits to 1.mant instead of 2^m * 1.mant.
+ x_bits.set_biased_exponent(FPBits::EXP_BIAS);
+ float mant_f = x_bits.get_val();
+ // v = 1.mant * 1/f - 1 = d/f
+ float v = fputil::multiply_add(mant_f, ONE_OVER_F[f], -1.0f);
+
+ // Degree-3 minimax polynomial generated by Sollya with the following
+ // commands:
+ // > display = hexadecimal;
+ // > P = fpminimax(log10(1 + x)/x, 2, [|SG...|], [-2^-5, 2^-5]);
+ // > x * P;
+ float log10p1_d_over_f =
+ v * fputil::polyeval(v, 0x1.bcb7bp-2f, -0x1.bce168p-3f, 0x1.28acb8p-3f);
+ // log10(1.mant) = log10(f) + log10(1 + d/f)
+ float log10_1_mant = LOG10F_F[f] + log10p1_d_over_f;
+ return static_cast<float16>(
+ fputil::multiply_add(static_cast<float>(m), LOG10F_2, log10_1_mant));
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/log10f16.h b/libc/src/math/log10f16.h
new file mode 100644
index 00000000000000..298deb370e0b0f
--- /dev/null
+++ b/libc/src/math/log10f16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for log10f16 ----------------------*- 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_MATH_LOG10F16_H
+#define LLVM_LIBC_SRC_MATH_LOG10F16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+float16 log10f16(float16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_LOG10F16_H
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 24a5abec898a89..befa8cff0720cf 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -1846,6 +1846,17 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ log10f16_test
+ NEED_MPFR
+ SUITE
+ libc-math-unittests
+ SRCS
+ log10f16_test.cpp
+ DEPENDS
+ libc.src.math.log10f16
+)
+
add_fp_unittest(
log1p_test
NEED_MPFR
diff --git a/libc/test/src/math/log10f16_test.cpp b/libc/test/src/math/log10f16_test.cpp
new file mode 100644
index 00000000000000..a71e3309ac5f08
--- /dev/null
+++ b/libc/test/src/math/log10f16_test.cpp
@@ -0,0 +1,40 @@
+//===-- Exhaustive test for log10f16 --------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/math/log10f16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcLog10f16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+// Range: [0, Inf];
+static constexpr uint16_t POS_START = 0x0000U;
+static constexpr uint16_t POS_STOP = 0x7c00U;
+
+// Range: [-Inf, 0];
+static constexpr uint16_t NEG_START = 0x8000U;
+static constexpr uint16_t NEG_STOP = 0xfc00U;
+
+TEST_F(LlvmLibcLog10f16Test, PositiveRange) {
+ for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+ float16 x = FPBits(v).get_val();
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Log10, x,
+ LIBC_NAMESPACE::log10f16(x), 0.5);
+ }
+}
+
+TEST_F(LlvmLibcLog10f16Test, NegativeRange) {
+ for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) {
+ float16 x = FPBits(v).get_val();
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Log10, x,
+ LIBC_NAMESPACE::log10f16(x), 0.5);
+ }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 3c077240356bd3..14e55ce10cb2bf 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3632,6 +3632,18 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ log10f16_test
+ SUITE
+ libc-math-smoke-tests
+ SRCS
+ log10f16_test.cpp
+ DEPENDS
+ libc.hdr.fenv_macros
+ libc.src.errno.errno
+ libc.src.math.log10f16
+)
+
add_fp_unittest(
log1p_test
SUITE
diff --git a/libc/test/src/math/smoke/log10f16_test.cpp b/libc/test/src/math/smoke/log10f16_test.cpp
new file mode 100644
index 00000000000000..1c434fc18a4be5
--- /dev/null
+++ b/libc/test/src/math/smoke/log10f16_test.cpp
@@ -0,0 +1,47 @@
+//===-- Unittests for log10f16 --------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "hdr/fenv_macros.h"
+#include "src/errno/libc_errno.h"
+#include "src/math/log10f16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcLog10f16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+TEST_F(LlvmLibcLog10f16Test, SpecialNumbers) {
+ LIBC_NAMESPACE::libc_errno = 0;
+
+ EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::log10f16(aNaN));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(aNaN, LIBC_NAMESPACE::log10f16(sNaN), FE_INVALID);
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(inf, LIBC_NAMESPACE::log10f16(inf));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::log10f16(neg_inf));
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING(
+ neg_inf, LIBC_NAMESPACE::log10f16(zero), FE_DIVBYZERO);
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING(
+ neg_inf, LIBC_NAMESPACE::log10f16(neg_zero), FE_DIVBYZERO);
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(
+ zero, LIBC_NAMESPACE::log10f16(static_cast<float16>(1.0)));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(
+ aNaN, LIBC_NAMESPACE::log10f16(static_cast<float16>(-1.0)));
+ EXPECT_MATH_ERRNO(EDOM);
+}
>From 67699bf4c7578bda03dd481621bc68d947581d2f Mon Sep 17 00:00:00 2001
From: OverMighty <its.overmighty at gmail.com>
Date: Tue, 15 Oct 2024 17:04:56 +0200
Subject: [PATCH 2/2] Migrate to fputil::cast
---
libc/src/math/generic/CMakeLists.txt | 1 +
libc/src/math/generic/log10f16.cpp | 11 ++++++-----
libc/test/src/math/smoke/CMakeLists.txt | 1 +
libc/test/src/math/smoke/log10f16_test.cpp | 7 +++++--
4 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index eb7e83611fcd2e..00cad6f85b4b98 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -2183,6 +2183,7 @@ add_entrypoint_object(
.expxf16
libc.hdr.errno_macros
libc.hdr.fenv_macros
+ libc.src.__support.FPUtil.cast
libc.src.__support.FPUtil.except_value_utils
libc.src.__support.FPUtil.fenv_impl
libc.src.__support.FPUtil.fp_bits
diff --git a/libc/src/math/generic/log10f16.cpp b/libc/src/math/generic/log10f16.cpp
index 7de54e75af4507..65e91f05c3d819 100644
--- a/libc/src/math/generic/log10f16.cpp
+++ b/libc/src/math/generic/log10f16.cpp
@@ -13,6 +13,7 @@
#include "src/__support/FPUtil/FEnvImpl.h"
#include "src/__support/FPUtil/FPBits.h"
#include "src/__support/FPUtil/PolyEval.h"
+#include "src/__support/FPUtil/cast.h"
#include "src/__support/FPUtil/except_value_utils.h"
#include "src/__support/FPUtil/multiply_add.h"
#include "src/__support/common.h"
@@ -126,11 +127,11 @@ LLVM_LIBC_FUNCTION(float16, log10f16, (float16 x)) {
int m = -FPBits::EXP_BIAS;
- // When x is subnormal.
+ // When x is subnormal, normalize it.
if ((x_u & FPBits::EXP_MASK) == 0U) {
- // Normalize x.
- x_bits = FPBits(x_bits.get_val() *
- static_cast<float16>((1U << FPBits::FRACTION_LEN)));
+ // Can't pass an integer to fputil::cast directly.
+ constexpr float NORMALIZE_EXP = 1U << FPBits::FRACTION_LEN;
+ x_bits = FPBits(x_bits.get_val() * fputil::cast<float16>(NORMALIZE_EXP));
x_u = x_bits.uintval();
m -= FPBits::FRACTION_LEN;
}
@@ -156,7 +157,7 @@ LLVM_LIBC_FUNCTION(float16, log10f16, (float16 x)) {
v * fputil::polyeval(v, 0x1.bcb7bp-2f, -0x1.bce168p-3f, 0x1.28acb8p-3f);
// log10(1.mant) = log10(f) + log10(1 + d/f)
float log10_1_mant = LOG10F_F[f] + log10p1_d_over_f;
- return static_cast<float16>(
+ return fputil::cast<float16>(
fputil::multiply_add(static_cast<float>(m), LOG10F_2, log10_1_mant));
}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 14e55ce10cb2bf..d41041c9bb0a4a 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3642,6 +3642,7 @@ add_fp_unittest(
libc.hdr.fenv_macros
libc.src.errno.errno
libc.src.math.log10f16
+ libc.src.__support.FPUtil.cast
)
add_fp_unittest(
diff --git a/libc/test/src/math/smoke/log10f16_test.cpp b/libc/test/src/math/smoke/log10f16_test.cpp
index 1c434fc18a4be5..471e1989333268 100644
--- a/libc/test/src/math/smoke/log10f16_test.cpp
+++ b/libc/test/src/math/smoke/log10f16_test.cpp
@@ -7,6 +7,7 @@
//===----------------------------------------------------------------------===//
#include "hdr/fenv_macros.h"
+#include "src/__support/FPUtil/cast.h"
#include "src/errno/libc_errno.h"
#include "src/math/log10f16.h"
#include "test/UnitTest/FPMatcher.h"
@@ -38,10 +39,12 @@ TEST_F(LlvmLibcLog10f16Test, SpecialNumbers) {
EXPECT_MATH_ERRNO(0);
EXPECT_FP_EQ_ALL_ROUNDING(
- zero, LIBC_NAMESPACE::log10f16(static_cast<float16>(1.0)));
+ zero,
+ LIBC_NAMESPACE::log10f16(LIBC_NAMESPACE::fputil::cast<float16>(1.0)));
EXPECT_MATH_ERRNO(0);
EXPECT_FP_EQ_ALL_ROUNDING(
- aNaN, LIBC_NAMESPACE::log10f16(static_cast<float16>(-1.0)));
+ aNaN,
+ LIBC_NAMESPACE::log10f16(LIBC_NAMESPACE::fputil::cast<float16>(-1.0)));
EXPECT_MATH_ERRNO(EDOM);
}
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