[libc-commits] [libc] ddc3f2d - [libc] Add sinpif16 function (#110994)
via libc-commits
libc-commits at lists.llvm.org
Tue Oct 15 15:40:12 PDT 2024
Author: wldfngrs
Date: 2024-10-15T18:40:08-04:00
New Revision: ddc3f2dd26c10b830d7137fc5f89049feec29033
URL: https://github.com/llvm/llvm-project/commit/ddc3f2dd26c10b830d7137fc5f89049feec29033
DIFF: https://github.com/llvm/llvm-project/commit/ddc3f2dd26c10b830d7137fc5f89049feec29033.diff
LOG: [libc] Add sinpif16 function (#110994)
Half-precision floating point (16-bit) implementation of the
trigonometric function Sin for inputs scaled by pi
Added:
libc/src/math/generic/sinpif16.cpp
libc/src/math/sinpif16.h
libc/test/src/math/sinpif16_test.cpp
libc/test/src/math/smoke/sinpif16_test.cpp
Modified:
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/x86_64/entrypoints.txt
libc/docs/math/index.rst
libc/newhdrgen/yaml/math.yaml
libc/src/math/CMakeLists.txt
libc/src/math/generic/CMakeLists.txt
libc/test/src/math/CMakeLists.txt
libc/test/src/math/smoke/CMakeLists.txt
libc/utils/MPFRWrapper/MPFRUtils.cpp
Removed:
################################################################################
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 32c0d199489317..885827d304efe3 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -679,6 +679,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
libc.src.math.scalbnf16
libc.src.math.setpayloadf16
libc.src.math.setpayloadsigf16
+ libc.src.math.sinpif16
libc.src.math.totalorderf16
libc.src.math.totalordermagf16
libc.src.math.truncf16
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 1cd817171de4be..2589da3756e155 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -677,6 +677,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
libc.src.math.scalbnf16
libc.src.math.setpayloadf16
libc.src.math.setpayloadsigf16
+ libc.src.math.sinpif16
libc.src.math.totalorderf16
libc.src.math.totalordermagf16
libc.src.math.truncf16
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
index 806dcc64bb9396..72e8f6689a3623 100644
--- a/libc/docs/math/index.rst
+++ b/libc/docs/math/index.rst
@@ -342,7 +342,7 @@ Higher Math Functions
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| sinh | |check| | | | | | 7.12.5.5 | F.10.2.5 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| sinpi | |check| | | | | | 7.12.4.13 | F.10.1.13 |
+| sinpi | |check| | | | |check| | | 7.12.4.13 | F.10.1.13 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| sqrt | |check| | |check| | |check| | | |check| | 7.12.7.10 | F.10.4.10 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/newhdrgen/yaml/math.yaml b/libc/newhdrgen/yaml/math.yaml
index d8b810b542cb9f..98ea1a0d25fbb7 100644
--- a/libc/newhdrgen/yaml/math.yaml
+++ b/libc/newhdrgen/yaml/math.yaml
@@ -2297,6 +2297,13 @@ functions:
return_type: float
arguments:
- type: float
+ - name: sinpif16
+ standards:
+ - stdc
+ return_type: _Float16
+ arguments:
+ - type: _Float16
+ guard: LIBC_TYPES_HAS_FLOAT16
- name: sqrt
standards:
- stdc
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 53907e47323e9e..7803369583de47 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -475,6 +475,7 @@ add_math_entrypoint_object(sincosf)
add_math_entrypoint_object(sin)
add_math_entrypoint_object(sinf)
add_math_entrypoint_object(sinpif)
+add_math_entrypoint_object(sinpif16)
add_math_entrypoint_object(sinh)
add_math_entrypoint_object(sinhf)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index b58935abdf056d..1ad611fa168cc0 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -528,6 +528,25 @@ add_entrypoint_object(
-O3
)
+add_entrypoint_object(
+ sinpif16
+ SRCS
+ sinpif16.cpp
+ HDRS
+ ../sinpif16.h
+ DEPENDS
+ libc.src.__support.common
+ libc.src.__support.FPUtil.cast
+ libc.src.__support.FPUtil.fenv_impl
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.FPUtil.multiply_add
+ libc.src.__support.FPUtil.nearest_integer
+ libc.src.__support.FPUtil.polyeval
+ libc.src.__support.macros.properties.types
+ COMPILE_OPTIONS
+ -O3
+)
+
add_entrypoint_object(
tan
SRCS
diff --git a/libc/src/math/generic/sinpif16.cpp b/libc/src/math/generic/sinpif16.cpp
new file mode 100644
index 00000000000000..17cca583e0c0ec
--- /dev/null
+++ b/libc/src/math/generic/sinpif16.cpp
@@ -0,0 +1,136 @@
+//===-- Half-precision sinpif 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/sinpif16.h"
+#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/multiply_add.h"
+#include "src/__support/FPUtil/nearest_integer.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+// Lookup table for sin(k * pi / 32) with k = 0, ..., 63.
+// Table is generated with Sollya as follows:
+// > display = hexadecimmal;
+// > for k from 0 to 63 do { round(sin(k * pi/32), SG, RN); };
+static constexpr float SIN_K_PI_OVER_32[64] = {
+ 0x0.0p0, 0x1.917a6cp-4, 0x1.8f8b84p-3, 0x1.294062p-2,
+ 0x1.87de2ap-2, 0x1.e2b5d4p-2, 0x1.1c73b4p-1, 0x1.44cf32p-1,
+ 0x1.6a09e6p-1, 0x1.8bc806p-1, 0x1.a9b662p-1, 0x1.c38b3p-1,
+ 0x1.d906bcp-1, 0x1.e9f416p-1, 0x1.f6297cp-1, 0x1.fd88dap-1,
+ 0x1p0, 0x1.fd88dap-1, 0x1.f6297cp-1, 0x1.e9f416p-1,
+ 0x1.d906bcp-1, 0x1.c38b3p-1, 0x1.a9b662p-1, 0x1.8bc806p-1,
+ 0x1.6a09e6p-1, 0x1.44cf32p-1, 0x1.1c73b4p-1, 0x1.e2b5d4p-2,
+ 0x1.87de2ap-2, 0x1.294062p-2, 0x1.8f8b84p-3, 0x1.917a6cp-4,
+ 0x0.0p0, -0x1.917a6cp-4, -0x1.8f8b84p-3, -0x1.294062p-2,
+ -0x1.87de2ap-2, -0x1.e2b5d4p-2, -0x1.1c73b4p-1, -0x1.44cf32p-1,
+ -0x1.6a09e6p-1, -0x1.8bc806p-1, -0x1.a9b662p-1, -0x1.c38b3p-1,
+ -0x1.d906bcp-1, -0x1.e9f416p-1, -0x1.f6297ep-1, -0x1.fd88dap-1,
+ -0x1p0, -0x1.fd88dap-1, -0x1.f6297cp-1, -0x1.e9f416p-1,
+ -0x1.d906bcp-1, -0x1.c38b3p-1, -0x1.a9b662p-1, -0x1.8bc806p-1,
+ -0x1.6a09e6p-1, -0x1.44cf32p-1, -0x1.1c73b4p-1, -0x1.e2b5d4p-2,
+ -0x1.87de2ap-2, -0x1.294062p-2, -0x1.8f8b84p-3, -0x1.917a6cp-4};
+
+static LIBC_INLINE int32_t range_reduction(float x, float &y) {
+ float kf = fputil::nearest_integer(x * 32);
+ y = fputil::multiply_add<float>(x, 32.0, -kf);
+
+ return static_cast<int32_t>(kf);
+}
+
+LLVM_LIBC_FUNCTION(float16, sinpif16, (float16 x)) {
+ using FPBits = typename fputil::FPBits<float16>;
+ FPBits xbits(x);
+
+ uint16_t x_u = xbits.uintval();
+ uint16_t x_abs = x_u & 0x7fff;
+
+ // Range reduction:
+ // For |x| > 1/32, we perform range reduction as follows:
+ // Find k and y such that:
+ // x = (k + y) * 1/32
+ // k is an integer
+ // |y| < 0.5
+ //
+ // This is done by performing:
+ // k = round(x * 32)
+ // y = x * 32 - k
+ //
+ // Once k and y are computed, we then deduce the answer by the sine of sum
+ // formula:
+ // sin(x * pi) = sin((k + y) * pi/32)
+ // = sin(k * pi/32) * cos(y * pi/32) + sin (y * pi/32) * cos (k *
+ // pi/32)
+ // The values of sin(k * pi/32) and cos (k * pi/32) for k = 0...63 are
+ // precomputed and stored using a vector of 64 single precision floats. sin(y
+ // * pi/32) and cos(y * pi/32) are computed using degree-9 chebyshev
+ // polynomials generated by Sollya.
+
+ // For signed zeros
+ if (LIBC_UNLIKELY(x_abs == 0U))
+ return x;
+
+ // Numbers greater or equal to 2^10 are integers, or infinity, or NaN
+ if (LIBC_UNLIKELY(x_abs >= 0x6400)) {
+ // Check for NaN or infinity values
+ if (LIBC_UNLIKELY(x_abs >= 0x7c00)) {
+ // If value is equal to infinity
+ if (x_abs == 0x7c00) {
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ }
+
+ return x + FPBits::quiet_nan().get_val();
+ }
+ return FPBits::zero(xbits.sign()).get_val();
+ }
+
+ float f32 = x;
+ float y;
+ int32_t k = range_reduction(f32, y);
+
+ float sin_k = SIN_K_PI_OVER_32[k & 63];
+ float cos_k = SIN_K_PI_OVER_32[(k + 16) & 63];
+
+ // Recall;
+ // sin(x * pi/32) = sin((k + y) * pi/32)
+ // = sin(y * pi/32) * cos(k * pi/32) + cos(y * pi/32) * sin(k *
+ // pi/32) Recall, after range reduction, -0.5 <= y <= 0.5. For very small
+ // values of y, calculating sin(y * p/32) can be inaccurate. Generating a
+ // polynomial for sin(y * p/32)/y instead significantly reduces the relative
+ // errors.
+ float ysq = y * y;
+
+ // Degree-6 minimax even polynomial for sin(y*pi/32)/y generated by Sollya
+ // with: > Q = fpminimax(sin(y*pi/32)/y, [|0, 2, 4, 6|], [|SG...|], [0, 0.5]);
+ float sin_y = y * fputil::polyeval(ysq, 0x1.921fb6p-4f, -0x1.4aeabcp-13f,
+ 0x1.a03354p-21f, -0x1.ad02d2p-20f);
+
+ // Note that cosm1_y = cos(y*pi/32) - 1 = cos_y - 1
+ // Derivation:
+ // sin(x * pi) = sin((k + y) * pi/32)
+ // = sin_y * cos_k + cos_y * sin_k
+ // = cos_k * sin_y + sin_k * (1 + cos_y - 1)
+ // Degree-6 minimax even polynomial for cos(y*pi/32) generated by Sollya with:
+ // > P = fpminimax(cos(y*pi/32), [|0, 2, 4, 6|],[|1, SG...|], [0, 0.5]);
+ float cosm1_y = ysq * fputil::polyeval(ysq, -0x1.3bd3ccp-8f, 0x1.03a61ap-18f,
+ 0x1.a6f7a2p-29f);
+
+ if (LIBC_UNLIKELY(sin_y == 0 && sin_k == 0))
+ return FPBits::zero(xbits.sign()).get_val();
+
+ // Since, cosm1_y = cos_y - 1, therefore:
+ // sin(x * pi) = cos_k * sin_y + sin_k + (cosm1_y * sin_k)
+ return fputil::cast<float16>(fputil::multiply_add(
+ sin_y, cos_k, fputil::multiply_add(cosm1_y, sin_k, sin_k)));
+}
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/sinpif16.h b/libc/src/math/sinpif16.h
new file mode 100644
index 00000000000000..33a0ae26584012
--- /dev/null
+++ b/libc/src/math/sinpif16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for sinpif16 ---------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache Licese 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_SINPIF16_H
+#define LLVM_LIBC_SRC_MATH_SINPIF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+float16 sinpif16(float16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_SINPIF16_H
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 07a9405081f97d..12e1d078b29b32 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -90,6 +90,17 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ sinpif16_test
+ NEED_MPFR
+ SUITE
+ libc-math-unittests
+ SRCS
+ sinpif16_test.cpp
+ DEPENDS
+ libc.src.math.sinpif16
+)
+
add_fp_unittest(
sin_test
NEED_MPFR
diff --git a/libc/test/src/math/sinpif16_test.cpp b/libc/test/src/math/sinpif16_test.cpp
new file mode 100644
index 00000000000000..8477124b2e6e37
--- /dev/null
+++ b/libc/test/src/math/sinpif16_test.cpp
@@ -0,0 +1,40 @@
+//===-- Exhaustive test for sinpif16 --------------------------------------===//
+//
+// 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/sinpif16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcSinpif16Test = 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(LlvmLibcSinpif16Test, PositiveRange) {
+ for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+ float16 x = FPBits(v).get_val();
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Sinpi, x,
+ LIBC_NAMESPACE::sinpif16(x), 0.5);
+ }
+}
+
+TEST_F(LlvmLibcSinpif16Test, NegativeRange) {
+ for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) {
+ float16 x = FPBits(v).get_val();
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Sinpi, x,
+ LIBC_NAMESPACE::sinpif16(x), 0.5);
+ }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index c4787229c3ec15..447ea695271397 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -51,6 +51,17 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ sinpif16_test
+ SUITE
+ libc-math-smoke-tests
+ SRCS
+ sinpif16_test.cpp
+ DEPENDS
+ libc.src.errno.errno
+ libc.src.math.sinpif16
+)
+
add_fp_unittest(
sincosf_test
SUITE
diff --git a/libc/test/src/math/smoke/sinpif16_test.cpp b/libc/test/src/math/smoke/sinpif16_test.cpp
new file mode 100644
index 00000000000000..0bcd38a60d8499
--- /dev/null
+++ b/libc/test/src/math/smoke/sinpif16_test.cpp
@@ -0,0 +1,42 @@
+//===-- Unittests for sinpif16 --------------------------------------------===//
+//
+// 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/errno/libc_errno.h"
+#include "src/math/sinpif16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcSinpif16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+TEST_F(LlvmLibcSinpif16Test, SpecialNumbers) {
+ LIBC_NAMESPACE::libc_errno = 0;
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::sinpif16(aNaN));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(zero, LIBC_NAMESPACE::sinpif16(zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::sinpif16(neg_zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::sinpif16(inf));
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::sinpif16(neg_inf));
+ EXPECT_MATH_ERRNO(EDOM);
+}
+
+TEST_F(LlvmLibcSinpif16Test, Integers) {
+ EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::sinpif16(-0x420));
+ EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::sinpif16(-0x1p+10));
+ EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::sinpif16(-0x1.4p+14));
+ EXPECT_FP_EQ(zero, LIBC_NAMESPACE::sinpif16(0x420));
+ EXPECT_FP_EQ(zero, LIBC_NAMESPACE::sinpif16(0x1.cp+15));
+ EXPECT_FP_EQ(zero, LIBC_NAMESPACE::sinpif16(0x1.cp+7));
+}
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
index 27ff1f7190ef95..eecffc782c1a74 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -488,14 +488,28 @@ class MPFRNumber {
(MPFR_VERSION_MAJOR == 4 && MPFR_VERSION_MINOR >= 2)
mpfr_sinpi(result.value, value, mpfr_rounding);
+ return result;
#else
+ if (mpfr_integer_p(value)) {
+ mpfr_set_si(result.value, 0, mpfr_rounding);
+ return result;
+ }
+
+ MPFRNumber value_mul_two(*this);
+ mpfr_mul_si(value_mul_two.value, value, 2, MPFR_RNDN);
+
+ if (mpfr_integer_p(value_mul_two.value)) {
+ auto d = mpfr_get_si(value, MPFR_RNDD);
+ mpfr_set_si(result.value, (d & 1) ? -1 : 1, mpfr_rounding);
+ return result;
+ }
+
MPFRNumber value_pi(0.0, 1280);
mpfr_const_pi(value_pi.value, MPFR_RNDN);
mpfr_mul(value_pi.value, value_pi.value, value, MPFR_RNDN);
mpfr_sin(result.value, value_pi.value, mpfr_rounding);
-#endif
-
return result;
+#endif
}
MPFRNumber sinh() const {
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