[libc-commits] [libc] [libc][math][C23] implementation of cospi (PR #131018)
via libc-commits
libc-commits at lists.llvm.org
Wed Mar 12 12:56:59 PDT 2025
https://github.com/lara254 created https://github.com/llvm/llvm-project/pull/131018
initial draft of the implementation of cospi
>From a56711de0eac448eb488500e3cc519629b139504 Mon Sep 17 00:00:00 2001
From: Job Hernandez <lara2993 at proton.me>
Date: Wed, 12 Mar 2025 12:54:02 -0700
Subject: [PATCH] add initial draft
---
libc/config/darwin/arm/entrypoints.txt | 1 +
libc/config/linux/aarch64/entrypoints.txt | 1 +
libc/include/math.yaml | 6 ++
libc/src/math/CMakeLists.txt | 1 +
libc/src/math/cospi.h | 20 +++++
libc/src/math/generic/CMakeLists.txt | 19 ++++-
libc/src/math/generic/cospi.cpp | 91 +++++++++++++++++++++++
libc/test/src/math/CMakeLists.txt | 16 ++++
libc/test/src/math/cospi_test.cpp | 30 ++++++++
libc/test/src/math/smoke/CMakeLists.txt | 12 +++
libc/test/src/math/smoke/cospi_test.cpp | 48 ++++++++++++
11 files changed, 243 insertions(+), 2 deletions(-)
create mode 100644 libc/src/math/cospi.h
create mode 100644 libc/src/math/generic/cospi.cpp
create mode 100644 libc/test/src/math/cospi_test.cpp
create mode 100644 libc/test/src/math/smoke/cospi_test.cpp
diff --git a/libc/config/darwin/arm/entrypoints.txt b/libc/config/darwin/arm/entrypoints.txt
index 7972d285f963a..f02aab5b65e31 100644
--- a/libc/config/darwin/arm/entrypoints.txt
+++ b/libc/config/darwin/arm/entrypoints.txt
@@ -139,6 +139,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.coshf
libc.src.math.cos
libc.src.math.cosf
+ libc.src.math.cospi
libc.src.math.cospif
libc.src.math.dfmal
libc.src.math.dsqrtl
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 6c2be4d3b0b99..ff9f65f05774f 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -424,6 +424,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.cos
libc.src.math.cosf
libc.src.math.coshf
+ libc.src.math.cospi
libc.src.math.cospif
libc.src.math.daddl
libc.src.math.ddivl
diff --git a/libc/include/math.yaml b/libc/include/math.yaml
index a66f981030864..4c6744ca18633 100644
--- a/libc/include/math.yaml
+++ b/libc/include/math.yaml
@@ -249,6 +249,12 @@ functions:
arguments:
- type: long double
- type: long double
+ - name: cospi
+ standards:
+ - stdc
+ return_type: double
+ arguments:
+ - type: double
- name: dmulf128
standards:
- llvm_libc_ext
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index f18a73d46f9aa..3623bb637d691 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -99,6 +99,7 @@ add_math_entrypoint_object(cosh)
add_math_entrypoint_object(coshf)
add_math_entrypoint_object(coshf16)
+add_math_entrypoint_object(cospi)
add_math_entrypoint_object(cospif)
add_math_entrypoint_object(cospif16)
diff --git a/libc/src/math/cospi.h b/libc/src/math/cospi.h
new file mode 100644
index 0000000000000..fc68b8d046267
--- /dev/null
+++ b/libc/src/math/cospi.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for cospi -------------------------*- 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_COSPI_H
+#define LLVM_LIBC_SRC_MATH_COSPI_H
+
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+double cospi(double x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_SINPIF_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 3114289bad486..38981bfd0eae7 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -1,5 +1,3 @@
-
-
add_entrypoint_object(
canonicalize
SRCS
@@ -381,6 +379,23 @@ add_entrypoint_object(
libc.src.__support.macros.optimization
libc.src.__support.macros.properties.types
)
+add_entrypoint_object(
+ cospi
+ SRCS
+ cospi.cpp
+ HDRS
+ ../cospi.h
+ DEPENDS
+ .sincosf_utils
+ libc.src.__support.FPUtil.fenv_impl
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.FPUtil.fma
+ libc.src.__support.FPUtil.multiply_add
+ libc.src.__support.macros.optimization
+ libc.src.__support.FPUtil.polyeval
+ libc.src.math.pow
+ libc.src.__support.FPUtil.basic_operations
+)
add_entrypoint_object(
cospif
diff --git a/libc/src/math/generic/cospi.cpp b/libc/src/math/generic/cospi.cpp
new file mode 100644
index 0000000000000..8c743b85a756a
--- /dev/null
+++ b/libc/src/math/generic/cospi.cpp
@@ -0,0 +1,91 @@
+//===-- double-precision cospi 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/cospi.h"
+#include "sincos_eval.h"
+#include "src/__support/FPUtil/BasicOperations.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/PolyEval.h"
+#include "src/__support/FPUtil/double_double.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" // LIBC_UNLIKELY
+#include "src/math/fmul.h"
+#include "src/math/generic/sincosf_utils.h"
+#include "src/math/pow.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static LIBC_INLINE void sincospi_poly_eval(double k, double y, double &sin_k,
+ double &cos_k, double &sin_y,
+
+ double &cosm1_y) {
+
+ // Q3 = fpminimax(sin(x*pi), 7, [|64...|], [-0.0078125, 0.0078125]);
+ sin_k =
+ k * fputil::polyeval(k, 0x1.59b6a771a45cbab8p-94, 0x1.921fb54442d1846ap1,
+ -0x1.8633470ba8bd806cp-76, -0x1.4abbce625be56346p2,
+ 0x1.d3e01dfd72e97a92p-61, 0x1.466bc67713dbbfp1,
+ -0x1.14c2648595e2ad4p-47, -0x1.32d1cc20b89301fcp-1);
+
+ sin_y =
+ y * fputil::polyeval(k, 0x1.59b6a771a45cbab8p-94, 0x1.921fb54442d1846ap1,
+ -0x1.8633470ba8bd806cp-76, -0x1.4abbce625be56346p2,
+ 0x1.d3e01dfd72e97a92p-61, 0x1.466bc67713dbbfp1,
+ -0x1.14c2648595e2ad4p-47, -0x1.32d1cc20b89301fcp-1);
+
+ // Q1 = fpminimax(cos(x * pi), 7, [|64...|], [-0.0078125, 0.0078125]);
+ cos_k =
+ k * fputil::polyeval(k, 0x1p0, 0x1.a5b22c564ee1d862p-84,
+ -0x1.3bd3cc9be45d30e6p2, -0x1.5c2328fefbe60d3ep-66,
+ 0x1.03c1f080a6907a6p2, 0x1.569a4d5c5018eecap-51,
+ -0x1.55d1f72455a9848ap0, -0x1.6b18e5f7fc6c39a6p-38);
+
+ cosm1_y =
+ y * fputil::polyeval(y, 0x1p0, 0x1.a5b22c564ee1d862p-84,
+ -0x1.3bd3cc9be45d30e6p2, -0x1.5c2328fefbe60d3ep-66,
+ 0x1.03c1f080a6907a6p2, 0x1.569a4d5c5018eecap-51,
+ -0x1.55d1f72455a9848ap0, -0x1.6b18e5f7fc6c39a6p-38);
+}
+
+LLVM_LIBC_FUNCTION(double, cospi, (double x)) {
+ using FPBits = typename fputil::FPBits<double>;
+ FPBits xbits(x);
+
+ double x_abs = fputil::abs(x);
+ double p = 0x1p52; // 2^p where p is the precision
+
+ if (LIBC_UNLIKELY(x_abs == 0U))
+ return x;
+
+ if (x_abs >= p) {
+ if (xbits.is_nan())
+ return x;
+ if (xbits.is_inf()) {
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+ return FPBits::zero(xbits.sign()).get_val();
+ }
+ double n = pow(2, -52);
+ double k = fputil::nearest_integer(x * n);
+ double y = x - k;
+ double sin_k, cos_k, sin_y, cosm1_y;
+
+ sincospi_poly_eval(k, y, sin_k, cos_k, sin_y, cosm1_y);
+
+ if (LIBC_UNLIKELY(sin_y == 0 && cos_k == 0))
+ return FPBits::zero(xbits.sign()).get_val();
+
+ return fputil::cast<double>(fputil::multiply_add(
+ cos_k, cosm1_y, fputil::multiply_add(-sin_k, sin_y, cos_k)));
+}
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 53ddd301900c0..155178a0eb50f 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -39,6 +39,22 @@ add_fp_unittest(
libc.src.math.cosf16
)
+add_fp_unittest(
+ cospi_test
+ NEED_MPFR
+ SUITE
+ libc-math-unittests
+ SRCS
+ cospi_test.cpp
+ HDRS
+ sdcomp26094.h
+ DEPENDS
+ libc.src.errno.errno
+ libc.src.math.cospi
+ libc.src.__support.CPP.array
+ libc.src.__support.FPUtil.fp_bits
+)
+
add_fp_unittest(
cospif_test
NEED_MPFR
diff --git a/libc/test/src/math/cospi_test.cpp b/libc/test/src/math/cospi_test.cpp
new file mode 100644
index 0000000000000..ff31bea42c742
--- /dev/null
+++ b/libc/test/src/math/cospi_test.cpp
@@ -0,0 +1,30 @@
+//===-- Exhaustive test for cospi -----------------------------------------===//
+//
+// 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/cospi.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+#include <iostream>
+
+using LlvmLibcCospiTest = LIBC_NAMESPACE::testing::FPTest<double>;
+using namespace std;
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+static constexpr double POS_START = 0;
+static constexpr double POS_STOP = 200;
+
+TEST_F(LlvmLibcCospiTest, PositiveRange) {
+ for (double v = POS_START; v <= POS_STOP; ++v) {
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cospi, v,
+ LIBC_NAMESPACE::cospi(v), 0.5);
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cospi, -v,
+ LIBC_NAMESPACE::cospi(-v), 0.5);
+ }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 6f94440d826d9..5fc99cb45f9a1 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -23,6 +23,18 @@ add_fp_unittest(
libc.src.math.cosf16
)
+add_fp_unittest(
+ cospi_test
+ SUITE
+ libc-math-smoke-tests
+ SRCS
+ cospi_test.cpp
+ DEPENDS
+ libc.src.errno.errno
+ libc.src.math.cospi
+ libc.src.__support.CPP.array
+ libc.src.__support.FPUtil.fp_bits
+)
add_fp_unittest(
cospif_test
SUITE
diff --git a/libc/test/src/math/smoke/cospi_test.cpp b/libc/test/src/math/smoke/cospi_test.cpp
new file mode 100644
index 0000000000000..9c1feff995a26
--- /dev/null
+++ b/libc/test/src/math/smoke/cospi_test.cpp
@@ -0,0 +1,48 @@
+//===-- Unittests for cospi -----------------------------------------------===//
+//
+// 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/__support/FPUtil/cast.h"
+#include "src/errno/libc_errno.h"
+#include "src/math/cospi.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcCospiTest = LIBC_NAMESPACE::testing::FPTest<double>;
+
+TEST_F(LlvmLibcCospiTest, SpecialNumbers) {
+ LIBC_NAMESPACE::libc_errno = 0;
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cospi(aNaN));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(zero, LIBC_NAMESPACE::cospi(zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::cospi(neg_zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cospi(inf));
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cospi(neg_inf));
+ EXPECT_MATH_ERRNO(EDOM);
+}
+
+TEST_F(LlvmLibcCospiTest, Integers) {
+ EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::cospi(-0x1.0000000000003p52));
+
+ EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::cospi(-0x1.0000000000005p52));
+
+ EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::cospi(-0x1.0000000000006p52));
+
+ EXPECT_FP_EQ(zero, LIBC_NAMESPACE::cospi(0x1.0000000000003p52));
+
+ EXPECT_FP_EQ(zero, LIBC_NAMESPACE::cospi(0x1.0000000000005p52));
+
+ EXPECT_FP_EQ(zero, LIBC_NAMESPACE::cospi(0x1.0000000000006p52));
+}
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