[libc-commits] [libc] [libc] Add sinpif16 function (PR #110994)
via libc-commits
libc-commits at lists.llvm.org
Thu Oct 3 06:47:27 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: wldfngrs (wldfngrs)
<details>
<summary>Changes</summary>
Half-precision floating point (16-bit) implementation of the trigonometric function Sin for inputs scaled by pi
---
Full diff: https://github.com/llvm/llvm-project/pull/110994.diff
12 Files Affected:
- (modified) libc/config/linux/aarch64/entrypoints.txt (+1)
- (modified) libc/config/linux/arm/entrypoints.txt (+1)
- (modified) libc/config/linux/riscv/entrypoints.txt (+1)
- (modified) libc/config/linux/x86_64/entrypoints.txt (+1)
- (modified) libc/config/windows/entrypoints.txt (+2-1)
- (modified) libc/newhdrgen/yaml/math.yaml (+6)
- (modified) libc/src/math/CMakeLists.txt (+1)
- (modified) libc/src/math/generic/CMakeLists.txt (+16)
- (added) libc/src/math/generic/sinpif16.cpp (+173)
- (added) libc/src/math/sinpif16.h (+22)
- (modified) libc/test/src/math/smoke/CMakeLists.txt (+13)
- (added) libc/test/src/math/smoke/sinpif16_test.cpp (+44)
``````````diff
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 283c7bd77b4e8e..85ae7be80b4616 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -570,6 +570,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.sinf
libc.src.math.sinhf
libc.src.math.sinpif
+ libc.src.math.sinpif16
libc.src.math.sqrt
libc.src.math.sqrtf
libc.src.math.sqrtl
diff --git a/libc/config/linux/arm/entrypoints.txt b/libc/config/linux/arm/entrypoints.txt
index 1be9a872dd2f7f..dbd21f6b5d4388 100644
--- a/libc/config/linux/arm/entrypoints.txt
+++ b/libc/config/linux/arm/entrypoints.txt
@@ -390,6 +390,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.sincosf
libc.src.math.sinf
libc.src.math.sinhf
+ libc.src.math.sinpif16
libc.src.math.sqrt
libc.src.math.sqrtf
libc.src.math.sqrtl
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 8312b2c453f231..8b71f44cf93549 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -573,6 +573,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.sinf
libc.src.math.sinhf
libc.src.math.sinpif
+ libc.src.math.sinpif16
libc.src.math.sqrt
libc.src.math.sqrtf
libc.src.math.sqrtl
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 806ccbcdf820a0..b7d0406fe6f007 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -573,6 +573,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.sinf
libc.src.math.sinhf
libc.src.math.sinpif
+ libc.src.math.sinpif16
libc.src.math.sqrt
libc.src.math.sqrtf
libc.src.math.sqrtl
diff --git a/libc/config/windows/entrypoints.txt b/libc/config/windows/entrypoints.txt
index 8f0b50bcc83ea2..5b0d84669e9244 100644
--- a/libc/config/windows/entrypoints.txt
+++ b/libc/config/windows/entrypoints.txt
@@ -275,7 +275,8 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.sincosf
libc.src.math.sincosf
libc.src.math.sinf
- libc.src.math.sinhf
+ libc.src.math.sinhfi
+ libc.src.math.sinpif16
libc.src.math.sqrt
libc.src.math.sqrtf
libc.src.math.sqrtl
diff --git a/libc/newhdrgen/yaml/math.yaml b/libc/newhdrgen/yaml/math.yaml
index 04b6a073deace0..fb79f15a314604 100644
--- a/libc/newhdrgen/yaml/math.yaml
+++ b/libc/newhdrgen/yaml/math.yaml
@@ -2290,6 +2290,12 @@ functions:
return_type: float
arguments:
- type: float
+ - name: sinpif16
+ standards:
+ - stdc
+ return_type: _Float16
+ arguments:
+ - type: _Float16
- name: sqrt
standards:
- stdc
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 97e2d0d64a147b..ad3f916130e86d 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -474,6 +474,7 @@ 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 93e632c38af238..a87f041b558440 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -528,6 +528,22 @@ add_entrypoint_object(
-O3
)
+add_entrypoint_object(
+ sinpif16
+ SRCS
+ sinpif16.cpp
+ HDRS
+ ../sinpif16.h
+ DEPENDS
+ libc.src.__support.macros.properties.types
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.FPUtil.multiply_add
+ libc.src.__support.common
+ libc.src.__support.macros.config
+ 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..b878e09d542007
--- /dev/null
+++ b/libc/src/math/generic/sinpif16.cpp
@@ -0,0 +1,173 @@
+//===-- 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/multiply_add.h"
+#include "src/__support/FPUtil/nearest_integer.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+// TODO: Should probably create a new file; sincospif16_utils.h
+// To store the following helper functions and constants.
+// I'd defer to @lntue for suggestions regarding that
+
+// HELPER_START
+namespace LIBC_NAMESPACE_DECL {
+
+constexpr float PI_OVER_32 = 0x1.921fb6p-4f;
+
+// In Sollya generate 10 coeffecients for a degree-9 chebyshev polynomial
+// approximating the sine function in [-pi / 32, pi / 32] with the following
+// commands:
+// > prec=24;
+// > TL = chebyshevform(sin(x), 9, [-pi / 32, pi / 32]);
+// > TL[0];
+const float SIN_COEFF[10] = {
+ 0x1.d333p-26, 0x1.000048p0, -0x1.a5d2p-14, -0x1.628588p-3, 0x1.c1eep-5,
+ 0x1.4455p1, -0x1.317a8p3, -0x1.6bb9p8, 0x1.00ef8p9, 0x1.0edcp14
+};
+// In Sollya generate 10 coefficients for a degree-9 chebyshev polynomial
+// approximating the sine function in [-pi/32, pi/32] with the following
+// commands:
+// > prec = 24;
+// > TL = chebyshevform(cos(x), 9, [-pi / 32, pi / 32]);
+// > TL[0];
+const float COS_COEFF[10] = {
+ 0x1.000006p0, 0x1.e1eap-15, -0x1.0071p-1, -0x1.3b56p-4, 0x1.f3dfp-2,
+ 0x1.ccbap4, -0x1.3034p6, -0x1.f817p11, 0x1.fc59p11, 0x1.7079p17
+};
+// Lookup table for sin(k * pi / 32) with k = 0, ..., 63.
+// Table is generated with Sollya as follows:
+// > display = hexadecimmal;
+// > prec = 24;
+// > for k from 0 to 63 do {sin(k * pi/32);};
+
+const float SIN_K_PI_OVER_32[64] = {
+ 0, 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,
+ 0, -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
+};
+
+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);
+}
+// HELPER_END
+
+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.
+
+ if (LIBC_UNLIKELY(x_abs == 0U)) {
+ // For signed zeros
+ return x;
+ }
+
+ // Numbers greater or equal to 2^10 are integers 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);
+ }
+
+ // If value is NaN
+ return x + FPBits::quiet_nan().get_val();
+ }
+ return FPBits::zero(xbits.sign()).get_val();
+ }
+
+ float f32 = static_cast<float>(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];
+
+ float cos_y, sin_y;
+ if (y == 0) {
+ cos_y = 1;
+ sin_y = 0;
+ } else {
+ cos_y = fputil::polyeval(y * PI_OVER_32,
+ COS_COEFF[0], COS_COEFF[1],
+ COS_COEFF[2], COS_COEFF[3],
+ COS_COEFF[4], COS_COEFF[5],
+ COS_COEFF[6], COS_COEFF[7],
+ COS_COEFF[8], COS_COEFF[9]);
+ sin_y = fputil::polyeval(y * PI_OVER_32,
+ SIN_COEFF[0], SIN_COEFF[1],
+ SIN_COEFF[2], SIN_COEFF[3],
+ SIN_COEFF[4], SIN_COEFF[5],
+ SIN_COEFF[6], SIN_COEFF[7],
+ SIN_COEFF[8], SIN_COEFF[9]);
+ }
+
+ return static_cast<float16>(fputil::multiply_add(
+ sin_k, cos_y, fputil::multiply_add(sin_y, cos_k, 0.0f)));
+}
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/sinpif16.h b/libc/src/math/sinpif16.h
new file mode 100644
index 00000000000000..f7c653383ba5ef
--- /dev/null
+++ b/libc/src/math/sinpif16.h
@@ -0,0 +1,22 @@
+//===-- 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 "include/llvm-libc-macros/float16-macros.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/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index a70b65f23f4b71..a72ad128e21d1d 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -51,6 +51,19 @@ 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.math.sinpif16
+ libc.src.errno.errno
+ libc.src.__support.CPP.array
+ libc.src.__support.FPUtil.fp_bits
+)
+
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..bf55a4854bfb3a
--- /dev/null
+++ b/libc/test/src/math/smoke/sinpif16_test.cpp
@@ -0,0 +1,44 @@
+//===-- 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 <stdint.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(0.0f, LIBC_NAMESPACE::sinpif16(0.0f));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(-0.0f, LIBC_NAMESPACE::sinpif16(-0.0f));
+ 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(-0.0, LIBC_NAMESPACE::sinpif16(-0x420));
+ EXPECT_FP_EQ(-0.0, LIBC_NAMESPACE::sinpif16(-0x1p+10));
+ EXPECT_FP_EQ(-0.0, LIBC_NAMESPACE::sinpif16(-0x1.4p+14));
+ EXPECT_FP_EQ(0.0, LIBC_NAMESPACE::sinpif16(0x420));
+ EXPECT_FP_EQ(0.0, LIBC_NAMESPACE::sinpif16(0x1.cp+15));
+ EXPECT_FP_EQ(0.0, LIBC_NAMESPACE::sinpif16(0x1.cp+7));
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/110994
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