[libc-commits] [libc] [libc][math] Implement double precision sincos correctly rounded to all rounding modes. (PR #96719)

via libc-commits libc-commits at lists.llvm.org
Tue Jun 25 18:16:43 PDT 2024


https://github.com/lntue created https://github.com/llvm/llvm-project/pull/96719

Sharing the same algorithm as double precision sin: https://github.com/llvm/llvm-project/pull/95736 and cos: https://github.com/llvm/llvm-project/pull/96591

>From 4b120d38c4793c1a1c6c22166e222df7b49a2316 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Wed, 26 Jun 2024 01:12:32 +0000
Subject: [PATCH] [libc][math] Implement double precision sincos correctly
 rounded to all rounding modes.

---
 libc/config/darwin/arm/entrypoints.txt    |   1 +
 libc/config/linux/aarch64/entrypoints.txt |   1 +
 libc/config/linux/arm/entrypoints.txt     |   1 +
 libc/config/linux/riscv/entrypoints.txt   |   1 +
 libc/config/linux/x86_64/entrypoints.txt  |   1 +
 libc/config/windows/entrypoints.txt       |   1 +
 libc/docs/math/index.rst                  |   2 +-
 libc/src/math/generic/CMakeLists.txt      |  22 ++
 libc/src/math/generic/sincos.cpp          | 247 ++++++++++++++++++++++
 libc/test/src/math/CMakeLists.txt         |  12 ++
 libc/test/src/math/sincos_test.cpp        | 120 +++++++++++
 libc/test/src/math/smoke/CMakeLists.txt   |  10 +
 libc/test/src/math/smoke/sincos_test.cpp  |  41 ++++
 13 files changed, 459 insertions(+), 1 deletion(-)
 create mode 100644 libc/src/math/generic/sincos.cpp
 create mode 100644 libc/test/src/math/sincos_test.cpp
 create mode 100644 libc/test/src/math/smoke/sincos_test.cpp

diff --git a/libc/config/darwin/arm/entrypoints.txt b/libc/config/darwin/arm/entrypoints.txt
index 2843c469559ba..4d5536318724d 100644
--- a/libc/config/darwin/arm/entrypoints.txt
+++ b/libc/config/darwin/arm/entrypoints.txt
@@ -225,6 +225,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.scalbn
     libc.src.math.scalbnf
     libc.src.math.scalbnl
+    libc.src.math.sincos
     libc.src.math.sincosf
     libc.src.math.sinhf
     libc.src.math.sin
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 746cc675e8fcd..f23b3da06308c 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -480,6 +480,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.scalbn
     libc.src.math.scalbnf
     libc.src.math.scalbnl
+    libc.src.math.sincos
     libc.src.math.sincosf
     libc.src.math.sinhf
     libc.src.math.sin
diff --git a/libc/config/linux/arm/entrypoints.txt b/libc/config/linux/arm/entrypoints.txt
index 01f2cc83700c8..a9d0a12598889 100644
--- a/libc/config/linux/arm/entrypoints.txt
+++ b/libc/config/linux/arm/entrypoints.txt
@@ -358,6 +358,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.scalbn
     libc.src.math.scalbnf
     libc.src.math.scalbnl
+    libc.src.math.sincos
     libc.src.math.sincosf
     libc.src.math.sin
     libc.src.math.sinf
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 70102a08f1255..7ef5ed899e83f 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -488,6 +488,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.scalbn
     libc.src.math.scalbnf
     libc.src.math.scalbnl
+    libc.src.math.sincos
     libc.src.math.sincosf
     libc.src.math.sinhf
     libc.src.math.sin
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 34748ff5950ad..bea2eb32eccd9 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -510,6 +510,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.scalbnf
     libc.src.math.scalbnl
     libc.src.math.sin
+    libc.src.math.sincos
     libc.src.math.sincosf
     libc.src.math.sinhf
     libc.src.math.sinf
diff --git a/libc/config/windows/entrypoints.txt b/libc/config/windows/entrypoints.txt
index a4898724daf86..b33d572cf999a 100644
--- a/libc/config/windows/entrypoints.txt
+++ b/libc/config/windows/entrypoints.txt
@@ -251,6 +251,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.scalbnl
     libc.src.math.sin
     libc.src.math.sincosf
+    libc.src.math.sincosf
     libc.src.math.sinf
     libc.src.math.sinhf
     libc.src.math.sqrt
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
index e05149d8e1dc9..6b06f1515143d 100644
--- a/libc/docs/math/index.rst
+++ b/libc/docs/math/index.rst
@@ -326,7 +326,7 @@ Higher Math Functions
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | sin       | |check|          | |check|         |                        |                      |                        | 7.12.4.6               | F.10.1.6                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| sincos    | |check|          | large           |                        |                      |                        |                        |                            |
+| sincos    | |check|          | |check|         |                        |                      |                        |                        |                            |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | sinh      | |check|          |                 |                        |                      |                        | 7.12.5.5               | F.10.2.5                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 41a77c8710f6b..5fe3b8f7b4ad3 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -261,6 +261,28 @@ add_entrypoint_object(
     -O3
 )
 
+add_entrypoint_object(
+  sincos
+  SRCS
+    sincos.cpp
+  HDRS
+    ../sincos.h
+  DEPENDS
+    .range_reduction_double
+    .sincos_eval
+    libc.hdr.errno_macros
+    libc.src.errno.errno
+    libc.src.__support.FPUtil.double_double
+    libc.src.__support.FPUtil.dyadic_float
+    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.macros.optimization
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   sincosf
   SRCS
diff --git a/libc/src/math/generic/sincos.cpp b/libc/src/math/generic/sincos.cpp
new file mode 100644
index 0000000000000..a0dd3a018af59
--- /dev/null
+++ b/libc/src/math/generic/sincos.cpp
@@ -0,0 +1,247 @@
+//===-- Double-precision sincos 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/sincos.h"
+#include "hdr/errno_macros.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/double_double.h"
+#include "src/__support/FPUtil/dyadic_float.h"
+#include "src/__support/FPUtil/except_value_utils.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/FPUtil/rounding_mode.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/optimization.h"            // LIBC_UNLIKELY
+#include "src/__support/macros/properties/cpu_features.h" // LIBC_TARGET_CPU_HAS_FMA
+#include "src/math/generic/sincos_eval.h"
+
+#ifdef LIBC_TARGET_CPU_HAS_FMA
+#include "range_reduction_double_fma.h"
+
+using LIBC_NAMESPACE::fma::FAST_PASS_EXPONENT;
+using LIBC_NAMESPACE::fma::ONE_TWENTY_EIGHT_OVER_PI;
+using LIBC_NAMESPACE::fma::range_reduction_small;
+using LIBC_NAMESPACE::fma::SIN_K_PI_OVER_128;
+
+LIBC_INLINE constexpr bool NO_FMA = false;
+#else
+#include "range_reduction_double_nofma.h"
+
+using LIBC_NAMESPACE::nofma::FAST_PASS_EXPONENT;
+using LIBC_NAMESPACE::nofma::ONE_TWENTY_EIGHT_OVER_PI;
+using LIBC_NAMESPACE::nofma::range_reduction_small;
+using LIBC_NAMESPACE::nofma::SIN_K_PI_OVER_128;
+
+LIBC_INLINE constexpr bool NO_FMA = true;
+#endif // LIBC_TARGET_CPU_HAS_FMA
+
+// TODO: We might be able to improve the performance of large range reduction of
+// non-FMA targets further by operating directly on 25-bit chunks of 128/pi and
+// pre-split SIN_K_PI_OVER_128, but that might double the memory footprint of
+// those lookup table.
+#include "range_reduction_double_common.h"
+
+#if ((LIBC_MATH & LIBC_MATH_SKIP_ACCURATE_PASS) != 0)
+#define LIBC_MATH_SINCOS_SKIP_ACCURATE_PASS
+#endif
+
+namespace LIBC_NAMESPACE {
+
+using DoubleDouble = fputil::DoubleDouble;
+using Float128 = typename fputil::DyadicFloat<128>;
+
+LLVM_LIBC_FUNCTION(void, sincos, (double x, double *sin_x, double *cos_x)) {
+  using FPBits = typename fputil::FPBits<double>;
+  FPBits xbits(x);
+
+  uint16_t x_e = xbits.get_biased_exponent();
+
+  DoubleDouble y;
+  unsigned k;
+  generic::LargeRangeReduction<NO_FMA> range_reduction_large;
+
+  // |x| < 2^32 (with FMA) or |x| < 2^23 (w/o FMA)
+  if (LIBC_LIKELY(x_e < FPBits::EXP_BIAS + FAST_PASS_EXPONENT)) {
+    // |x| < 2^-27
+    if (LIBC_UNLIKELY(x_e < FPBits::EXP_BIAS - 27)) {
+      // Signed zeros.
+      if (LIBC_UNLIKELY(x == 0.0)) {
+        *sin_x = x;
+        *cos_x = 1.0;
+        return;
+      }
+
+      // For |x| < 2^-27, max(|sin(x) - x|, |cos(x) - 1|) < ulp(x)/2.
+#ifdef LIBC_TARGET_CPU_HAS_FMA
+      *sin_x = fputil::multiply_add(x, -0x1.0p-54, x);
+      *cos_x = fputil::multiply_add(x, -x, 1.0);
+#else
+      *cos_x = fputil::round_result_slightly_down(1.0);
+
+      if (LIBC_UNLIKELY(x_e < 4)) {
+        int rounding_mode = fputil::quick_get_round();
+        if (rounding_mode == FE_TOWARDZERO ||
+            (xbits.sign() == Sign::POS && rounding_mode == FE_DOWNWARD) ||
+            (xbits.sign() == Sign::NEG && rounding_mode == FE_UPWARD))
+          *sin_x = FPBits(xbits.uintval() - 1).get_val();
+      }
+      *sin_x = fputil::multiply_add(x, -0x1.0p-54, x);
+#endif // LIBC_TARGET_CPU_HAS_FMA
+      return;
+    }
+
+    // // Small range reduction.
+    k = range_reduction_small(x, y);
+  } else {
+    // Inf or NaN
+    if (LIBC_UNLIKELY(x_e > 2 * FPBits::EXP_BIAS)) {
+      // sin(+-Inf) = NaN
+      if (xbits.get_mantissa() == 0) {
+        fputil::set_errno_if_required(EDOM);
+        fputil::raise_except_if_required(FE_INVALID);
+      }
+      *sin_x = *cos_x = x + FPBits::quiet_nan().get_val();
+      return;
+    }
+
+    // Large range reduction.
+    k = range_reduction_large.compute_high_part(x);
+    y = range_reduction_large.fast();
+  }
+
+  DoubleDouble sin_y, cos_y;
+
+  generic::sincos_eval(y, sin_y, cos_y);
+
+  // Look up sin(k * pi/128) and cos(k * pi/128)
+  // Memory saving versions:
+
+  // Use 128-entry table instead:
+  // DoubleDouble sin_k = SIN_K_PI_OVER_128[k & 127];
+  // uint64_t sin_s = static_cast<uint64_t>(k & 128) << (63 - 7);
+  // sin_k.hi = FPBits(FPBits(sin_k.hi).uintval() ^ sin_s).get_val();
+  // sin_k.lo = FPBits(FPBits(sin_k.hi).uintval() ^ sin_s).get_val();
+  // DoubleDouble cos_k = SIN_K_PI_OVER_128[(k + 64) & 127];
+  // uint64_t cos_s = static_cast<uint64_t>((k + 64) & 128) << (63 - 7);
+  // cos_k.hi = FPBits(FPBits(cos_k.hi).uintval() ^ cos_s).get_val();
+  // cos_k.lo = FPBits(FPBits(cos_k.hi).uintval() ^ cos_s).get_val();
+
+  // Use 64-entry table instead:
+  // auto get_idx_dd = [](unsigned kk) -> DoubleDouble {
+  //   unsigned idx = (kk & 64) ? 64 - (kk & 63) : (kk & 63);
+  //   DoubleDouble ans = SIN_K_PI_OVER_128[idx];
+  //   if (kk & 128) {
+  //     ans.hi = -ans.hi;
+  //     ans.lo = -ans.lo;
+  //   }
+  //   return ans;
+  // };
+  // DoubleDouble sin_k = get_idx_dd(k);
+  // DoubleDouble cos_k = get_idx_dd(k + 64);
+
+  // Fast look up version, but needs 256-entry table.
+  // cos(k * pi/128) = sin(k * pi/128 + pi/2) = sin((k + 64) * pi/128).
+  DoubleDouble sin_k = SIN_K_PI_OVER_128[k & 255];
+  DoubleDouble cos_k = SIN_K_PI_OVER_128[(k + 64) & 255];
+  DoubleDouble msin_k{-sin_k.lo, -sin_k.hi};
+
+  // After range reduction, k = round(x * 128 / pi) and y = x - k * (pi / 128).
+  // So k is an integer and -pi / 256 <= y <= pi / 256.
+  // Then sin(x) = sin((k * pi/128 + y)
+  //             = sin(y) * cos(k*pi/128) + cos(y) * sin(k*pi/128)
+  DoubleDouble sin_k_cos_y = fputil::quick_mult<NO_FMA>(cos_y, sin_k);
+  DoubleDouble cos_k_sin_y = fputil::quick_mult<NO_FMA>(sin_y, cos_k);
+  //      cos(x) = cos((k * pi/128 + y)
+  //             = cos(y) * cos(k*pi/128) - sin(y) * sin(k*pi/128)
+  DoubleDouble cos_k_cos_y = fputil::quick_mult<NO_FMA>(cos_y, cos_k);
+  DoubleDouble msin_k_sin_y = fputil::quick_mult<NO_FMA>(sin_y, msin_k);
+
+  DoubleDouble sin_dd =
+      fputil::exact_add<false>(sin_k_cos_y.hi, cos_k_sin_y.hi);
+  DoubleDouble cos_dd =
+      fputil::exact_add<false>(cos_k_cos_y.hi, msin_k_sin_y.hi);
+  sin_dd.lo += sin_k_cos_y.lo + cos_k_sin_y.lo;
+  cos_dd.lo += msin_k_sin_y.lo + cos_k_cos_y.lo;
+
+#ifdef LIBC_MATH_SINCOS_SKIP_ACCURATE_PASS
+  *sin_x = sin_dd.hi + sin_dd.lo;
+  *cos_x = cos_dd.hi + cos_dd.lo;
+  return;
+#else
+  // Accurate test and pass for correctly rounded implementation.
+
+#ifdef LIBC_TARGET_CPU_HAS_FMA
+  constexpr double ERR = 0x1.0p-70;
+#else
+  // TODO: Improve non-FMA fast pass accuracy.
+  constexpr double ERR = 0x1.0p-66;
+#endif // LIBC_TARGET_CPU_HAS_FMA
+
+  double sin_lp = sin_dd.lo + ERR;
+  double sin_lm = sin_dd.lo - ERR;
+  double cos_lp = cos_dd.lo + ERR;
+  double cos_lm = cos_dd.lo - ERR;
+
+  double sin_upper = sin_dd.hi + sin_lp;
+  double sin_lower = sin_dd.hi + sin_lm;
+  double cos_upper = cos_dd.hi + cos_lp;
+  double cos_lower = cos_dd.hi + cos_lm;
+
+  // Ziv's rounding test.
+  if (LIBC_LIKELY(sin_upper == sin_lower && cos_upper == cos_lower)) {
+    *sin_x = sin_upper;
+    *cos_x = cos_upper;
+    return;
+  }
+
+  Float128 u_f128, sin_u, cos_u;
+  if (LIBC_LIKELY(x_e < FPBits::EXP_BIAS + FAST_PASS_EXPONENT))
+    u_f128 = generic::range_reduction_small_f128(x);
+  else
+    u_f128 = range_reduction_large.accurate();
+
+  generic::sincos_eval(u_f128, sin_u, cos_u);
+
+  auto get_sin_k = [](unsigned kk) -> Float128 {
+    unsigned idx = (kk & 64) ? 64 - (kk & 63) : (kk & 63);
+    Float128 ans = generic::SIN_K_PI_OVER_128_F128[idx];
+    if (kk & 128)
+      ans.sign = Sign::NEG;
+    return ans;
+  };
+
+  // cos(k * pi/128) = sin(k * pi/128 + pi/2) = sin((k + 64) * pi/128).
+  Float128 sin_k_f128 = get_sin_k(k);
+  Float128 cos_k_f128 = get_sin_k(k + 64);
+  Float128 msin_k_f128 = get_sin_k(k + 128);
+
+  // TODO: Add assertion if Ziv's accuracy tests fail in debug mode.
+  // https://github.com/llvm/llvm-project/issues/96452.
+
+  if (sin_upper == sin_lower)
+    *sin_x = sin_upper;
+  else
+    // sin(x) = sin((k * pi/128 + u)
+    //        = sin(u) * cos(k*pi/128) + cos(u) * sin(k*pi/128)
+    *sin_x = static_cast<double>(
+        fputil::quick_add(fputil::quick_mul(sin_k_f128, cos_u),
+                          fputil::quick_mul(cos_k_f128, sin_u)));
+
+  if (cos_upper == cos_lower)
+    *cos_x = cos_upper;
+  else
+    // cos(x) = cos((k * pi/128 + u)
+    //        = cos(u) * cos(k*pi/128) - sin(u) * sin(k*pi/128)
+    *cos_x = static_cast<double>(
+        fputil::quick_add(fputil::quick_mul(cos_k_f128, cos_u),
+                          fputil::quick_mul(msin_k_f128, sin_u)));
+
+#endif // !LIBC_MATH_SINCOS_SKIP_ACCURATE_PASS
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index ba588662f469e..1ddb5c7c33664 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -72,6 +72,18 @@ add_fp_unittest(
     libc.src.__support.FPUtil.fp_bits
 )
 
+add_fp_unittest(
+  sincos_test
+  NEED_MPFR
+  SUITE
+    libc-math-unittests
+  SRCS
+    sincos_test.cpp
+  DEPENDS
+    libc.src.math.sincos
+    libc.src.__support.FPUtil.fp_bits
+)
+
 add_fp_unittest(
   tanf_test
   NEED_MPFR
diff --git a/libc/test/src/math/sincos_test.cpp b/libc/test/src/math/sincos_test.cpp
new file mode 100644
index 0000000000000..c0cbff7084d19
--- /dev/null
+++ b/libc/test/src/math/sincos_test.cpp
@@ -0,0 +1,120 @@
+//===-- Unittests for sincos ----------------------------------------------===//
+//
+// 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/FPBits.h"
+#include "src/math/sincos.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcSincosTest = LIBC_NAMESPACE::testing::FPTest<double>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+using LIBC_NAMESPACE::testing::tlog;
+
+#define ASSERT_SINCOS_MATCH_ALL_ROUNDING(input)                                \
+  do {                                                                         \
+    double sin_x, cos_x;                                                       \
+    namespace mpfr = LIBC_NAMESPACE::testing::mpfr;                            \
+                                                                               \
+    mpfr::ForceRoundingMode __r1(mpfr::RoundingMode::Nearest);                 \
+    if (__r1.success) {                                                        \
+      LIBC_NAMESPACE::sincos(input, &sin_x, &cos_x);                           \
+      ASSERT_MPFR_MATCH(mpfr::Operation::Sin, input, sin_x, 0.5,               \
+                        mpfr::RoundingMode::Nearest);                          \
+      ASSERT_MPFR_MATCH(mpfr::Operation::Cos, input, cos_x, 0.5,               \
+                        mpfr::RoundingMode::Nearest);                          \
+    }                                                                          \
+                                                                               \
+    mpfr::ForceRoundingMode __r2(mpfr::RoundingMode::Upward);                  \
+    if (__r2.success) {                                                        \
+      LIBC_NAMESPACE::sincos(input, &sin_x, &cos_x);                           \
+      ASSERT_MPFR_MATCH(mpfr::Operation::Sin, input, sin_x, 0.5,               \
+                        mpfr::RoundingMode::Upward);                           \
+      ASSERT_MPFR_MATCH(mpfr::Operation::Cos, input, cos_x, 0.5,               \
+                        mpfr::RoundingMode::Upward);                           \
+    }                                                                          \
+                                                                               \
+    mpfr::ForceRoundingMode __r3(mpfr::RoundingMode::Downward);                \
+    if (__r3.success) {                                                        \
+      LIBC_NAMESPACE::sincos(input, &sin_x, &cos_x);                           \
+      ASSERT_MPFR_MATCH(mpfr::Operation::Sin, input, sin_x, 0.5,               \
+                        mpfr::RoundingMode::Downward);                         \
+      ASSERT_MPFR_MATCH(mpfr::Operation::Cos, input, cos_x, 0.5,               \
+                        mpfr::RoundingMode::Downward);                         \
+    }                                                                          \
+                                                                               \
+    mpfr::ForceRoundingMode __r4(mpfr::RoundingMode::TowardZero);              \
+    if (__r4.success) {                                                        \
+      LIBC_NAMESPACE::sincos(input, &sin_x, &cos_x);                           \
+      ASSERT_MPFR_MATCH(mpfr::Operation::Sin, input, sin_x, 0.5,               \
+                        mpfr::RoundingMode::TowardZero);                       \
+      ASSERT_MPFR_MATCH(mpfr::Operation::Cos, input, cos_x, 0.5,               \
+                        mpfr::RoundingMode::TowardZero);                       \
+    }                                                                          \
+  } while (0)
+
+TEST_F(LlvmLibcSincosTest, TrickyInputs) {
+  constexpr double INPUTS[] = {
+      0x1.8000000000009p-23,    0x1.8000000000024p-22,
+      0x1.800000000009p-21,     0x1.20000000000f3p-20,
+      0x1.800000000024p-20,     0x1.e0000000001c2p-20,
+      0x1.940c877fb7dacp-7,     -0x1.f42fb19b5b9b2p-6,
+      -0x1.0285070f9f1bcp-5,    0x1.23f40dccdef72p+0,
+      0x1.43cf16358c9d7p+0,     0x1.addf3b9722265p+0,
+      0x1.ae78d360afa15p+0,     0x1.e31b55306f22cp+2,
+      0x1.e639103a05997p+2,     -0x1.f7898d5a756ddp+2,
+      0x1.1685973506319p+3,     0x1.5f09cad750ab1p+3,
+      -0x1.aaf85537ea4c7p+3,    0x1.4f2b874135d27p+4,
+      0x1.13114266f9764p+4,     0x1.a211877de55dbp+4,
+      -0x1.a5eece87e8606p+4,    0x1.a65d441ea6dcep+4,
+      0x1.1ffb509f3db15p+5,     0x1.2345d1e090529p+5,
+      0x1.c96e28eb679f8p+5,     0x1.be886d9c2324dp+6,
+      -0x1.ab514bfc61c76p+7,    -0x1.14823229799c2p+7,
+      0x1.48ff1782ca91dp+8,     0x1.dcbfda0c7559ep+8,
+      0x1.dcbfda0c7559ep+8,     0x1.2e566149bf5fdp+9,
+      0x1.cb996c60f437ep+9,     0x1.ae945054939c2p+10,
+      -0x1.119471e9216cdp+10,   0x1.ae945054939c2p+10,
+      0x1.fffffffffdb6p+24,     0x1.fd4da4ef37075p+29,
+      0x1.55202aefde314p+31,    0x1.b951f1572eba5p+31,
+      0x1.7776c2343ba4ep+101,   0x1.85fc0f04c0128p+101,
+      0x1.678309fa50d58p+110,   0x1.fffffffffef4ep+199,
+      0x1.3eec5912ea7cdp+331,   -0x1.3eec5912ea7cdp+331,
+      -0x1.6deb37da81129p+205,  0x1.08087e9aad90bp+887,
+      -0x1.08087e9aad90bp+887,  -0x1.8bb5847d49973p+845,
+      0x1.6ac5b262ca1ffp+849,   0x1.f08b14e1c4d0fp+890,
+      0x1.2b5fe88a9d8d5p+903,   0x1.f6d7518808571p+1023,
+      -0x1.a880417b7b119p+1023, 0x1.00a33764a0a83p-7,
+      0x1.fe81868fc47fep+1,     0x1.0da8cc189b47dp-10,
+      0x1.da1838053b866p+5,
+
+  };
+  constexpr int N = sizeof(INPUTS) / sizeof(INPUTS[0]);
+
+  for (int i = 0; i < N; ++i) {
+    ASSERT_SINCOS_MATCH_ALL_ROUNDING(INPUTS[i]);
+  }
+}
+
+TEST_F(LlvmLibcSincosTest, InDoubleRange) {
+  constexpr uint64_t COUNT = 123'451;
+  uint64_t START = LIBC_NAMESPACE::fputil::FPBits<double>(0x1.0p-50).uintval();
+  uint64_t STOP = LIBC_NAMESPACE::fputil::FPBits<double>(0x1.0p200).uintval();
+  uint64_t STEP = (STOP - START) / COUNT;
+
+  auto test = [&](mpfr::RoundingMode rounding_mode) {
+    for (uint64_t i = 0, v = START; i <= COUNT; ++i, v += STEP) {
+      double x = FPBits(v).get_val();
+      if (isnan(x) || isinf(x))
+        continue;
+
+      ASSERT_SINCOS_MATCH_ALL_ROUNDING(x);
+    }
+  };
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index d79e296913e32..1ec585337e25c 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3687,3 +3687,13 @@ add_fp_unittest(
   DEPENDS
     libc.src.math.cos
 )
+
+add_fp_unittest(
+  sincos_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    sincos_test.cpp
+  DEPENDS
+    libc.src.math.sincos
+)
diff --git a/libc/test/src/math/smoke/sincos_test.cpp b/libc/test/src/math/smoke/sincos_test.cpp
new file mode 100644
index 0000000000000..371c0ad63cbf5
--- /dev/null
+++ b/libc/test/src/math/smoke/sincos_test.cpp
@@ -0,0 +1,41 @@
+//===-- Unittests for sincos ----------------------------------------------===//
+//
+// 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/sincos.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcSincosTest = LIBC_NAMESPACE::testing::FPTest<double>;
+
+TEST_F(LlvmLibcSincosTest, SpecialNumbers) {
+  double sin_x, cos_x;
+
+  LIBC_NAMESPACE::sincos(aNaN, &sin_x, &cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(aNaN, cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(aNaN, sin_x);
+
+  LIBC_NAMESPACE::sincos(zero, &sin_x, &cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(1.0, cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(0.0, sin_x);
+
+  LIBC_NAMESPACE::sincos(neg_zero, &sin_x, &cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(1.0, cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(neg_zero, sin_x);
+
+  LIBC_NAMESPACE::sincos(inf, &sin_x, &cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(aNaN, cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(aNaN, sin_x);
+
+  LIBC_NAMESPACE::sincos(neg_inf, &sin_x, &cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(aNaN, cos_x);
+  EXPECT_FP_EQ_ALL_ROUNDING(aNaN, sin_x);
+
+  LIBC_NAMESPACE::sincos(0x1.0p-28, &sin_x, &cos_x);
+  EXPECT_FP_EQ(1.0, cos_x);
+  EXPECT_FP_EQ(0x1.0p-28, sin_x);
+}



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