[libc-commits] [libc] [libc][math][c23] Add tanpif16 function (PR #115183)

via libc-commits libc-commits at lists.llvm.org
Wed Nov 6 09:14:05 PST 2024


https://github.com/wldfngrs created https://github.com/llvm/llvm-project/pull/115183

- Implementation of `tan` for 16-bit floating point inputs scaled by pi. i.e,. `tanpif16()`
- Implementation of Tanpi in MPFRWrapper for MPFR versions < 4.2
- Exhaustive tests for `tanpif16()`

>From 2a64451d6c82c9804a364df18c52562eda16753d Mon Sep 17 00:00:00 2001
From: wldfngrs <wldfngrs at gmail.com>
Date: Wed, 6 Nov 2024 00:02:46 +0100
Subject: [PATCH 1/4] add tanpif16 function

---
 libc/config/linux/x86_64/entrypoints.txt   |   1 +
 libc/newhdrgen/yaml/math.yaml              |   7 ++
 libc/src/math/CMakeLists.txt               |   1 +
 libc/src/math/cospif16.h                   |   2 +-
 libc/src/math/generic/CMakeLists.txt       |  20 ++++
 libc/src/math/generic/cospif16.cpp         |   2 +-
 libc/src/math/generic/tanpif16.cpp         | 112 +++++++++++++++++++++
 libc/src/math/tanpif16.h                   |  21 ++++
 libc/test/src/math/CMakeLists.txt          |  11 ++
 libc/test/src/math/smoke/CMakeLists.txt    |  11 ++
 libc/test/src/math/smoke/tanpif16_test.cpp |  33 ++++++
 libc/test/src/math/tanpif16_test.cpp       |  41 ++++++++
 libc/utils/MPFRWrapper/MPFRUtils.cpp       |  24 +++++
 libc/utils/MPFRWrapper/MPFRUtils.h         |   1 +
 14 files changed, 285 insertions(+), 2 deletions(-)
 create mode 100644 libc/src/math/generic/tanpif16.cpp
 create mode 100644 libc/src/math/tanpif16.h
 create mode 100644 libc/test/src/math/smoke/tanpif16_test.cpp
 create mode 100644 libc/test/src/math/tanpif16_test.cpp

diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index a2fb97d04584d5..1b850a6df60841 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -687,6 +687,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.sinpif16
     libc.src.math.sqrtf16
     libc.src.math.tanhf16
+    libc.src.math.tanpif16
     libc.src.math.totalorderf16
     libc.src.math.totalordermagf16
     libc.src.math.truncf16
diff --git a/libc/newhdrgen/yaml/math.yaml b/libc/newhdrgen/yaml/math.yaml
index 3cc4b599c777bf..07a0b80d6e4ccc 100644
--- a/libc/newhdrgen/yaml/math.yaml
+++ b/libc/newhdrgen/yaml/math.yaml
@@ -2410,6 +2410,13 @@ functions:
     arguments:
       - type: _Float16
     guard: LIBC_TYPES_HAS_FLOAT16
+  - name: tanpif16
+    standards:
+      - stdc
+    return_type: _Float16
+    arguments:
+      - type: _Float16
+    guard: LIBC_TYPES_HAS_FLOAT16
   - name: totalorder
     standards:
       - stdc
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 80c1867d2116f6..9f376193e0e740 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -502,6 +502,7 @@ add_math_entrypoint_object(tanf)
 add_math_entrypoint_object(tanh)
 add_math_entrypoint_object(tanhf)
 add_math_entrypoint_object(tanhf16)
+add_math_entrypoint_object(tanpif16)
 
 add_math_entrypoint_object(tgamma)
 add_math_entrypoint_object(tgammaf)
diff --git a/libc/src/math/cospif16.h b/libc/src/math/cospif16.h
index ef9625dfed45f6..122b548dfb0983 100644
--- a/libc/src/math/cospif16.h
+++ b/libc/src/math/cospif16.h
@@ -18,4 +18,4 @@ float16 cospif16(float16 x);
 
 } // namespace LIBC_NAMESPACE_DECL
 
-#endif // LLVM_LIBC_SRC_MATH_SINPIF16_H
+#endif // LLVM_LIBC_SRC_MATH_COSPIF16_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index ca27759d3212f2..ceb8f0df00129c 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -620,6 +620,26 @@ add_entrypoint_object(
     -O3
 )
 
+add_entrypoint_object(
+  tanpif16
+  SRCS
+    tanpif16.cpp
+  HDRS
+    ../tanpif16.h
+  DEPENDS
+    .sincosf16_utils
+    libc.hdr.errno_macros
+    libc.hdr.fenv_macros
+    libc.src.__support.FPUtil.cast
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.except_value_utils
+    libc.src.__support.FPUtil.multiply_add
+    libc.src.__support.macros.optimization
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   fabs
   SRCS
diff --git a/libc/src/math/generic/cospif16.cpp b/libc/src/math/generic/cospif16.cpp
index dd8c7ab6afa3d6..384b39ff8e2c44 100644
--- a/libc/src/math/generic/cospif16.cpp
+++ b/libc/src/math/generic/cospif16.cpp
@@ -37,7 +37,7 @@ LLVM_LIBC_FUNCTION(float16, cospif16, (float16 x)) {
   //   k = round(x * 32)
   //   y = x * 32 - k
   //
-  // Once k and y are computed, we then deduce the answer by the sine of sum
+  // Once k and y are computed, we then deduce the answer by the cosine of sum
   // formula:
   //   cos(x * pi) = cos((k + y) * pi/32)
   //               = cos(k * pi/32) * cos(y * pi/32) +
diff --git a/libc/src/math/generic/tanpif16.cpp b/libc/src/math/generic/tanpif16.cpp
new file mode 100644
index 00000000000000..f4fe265f6f7620
--- /dev/null
+++ b/libc/src/math/generic/tanpif16.cpp
@@ -0,0 +1,112 @@
+//===-- Half-precision tanpif 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/tanpif16.h"
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
+#include "sincosf16_utils.h"
+#include "src/__support/FPUtil/except_value_utils.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/macros/optimization.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+constexpr size_t N_EXCEPTS = 21;
+
+constexpr fputil::ExceptValues<float16, N_EXCEPTS> TANF16_EXCEPTS{{
+  // (input, RZ output, RU offset, RD offset, RN offset)
+  {0x07f2, 0x0e3d, 1, 0, 0},
+  {0x086a, 0x0eee, 1, 0, 1},
+  {0x08db, 0x0fa0, 1, 0, 0},
+  {0x094c, 0x1029, 1, 0, 0},
+  {0x0b10, 0x118c, 1, 0, 0},
+  {0x1ce0, 0x23a8, 1, 0, 1},
+  {0x1235, 0x18e0, 1, 0, 0},
+  {0x2579, 0x2c4e, 1, 0, 0},
+  {0x28b2, 0x2f68, 1, 0, 1},
+  {0x2a43, 0x30f4, 1, 0, 1},
+  {0x31b7, 0x3907, 1, 0, 0},
+  {0x329d, 0x3a12, 1, 0, 1},
+  {0x34f1, 0x3dd7, 1, 0, 0},
+  {0x3658, 0x41ee, 1, 0, 0},
+  {0x38d4, 0xc1ee, 0, 1, 0},
+  {0x3d96, 0x41ee, 1, 0, 0},
+  {0x3e6a, 0xc1ee, 0, 1, 0},
+  {0x40cb, 0x41ee, 1, 0, 0},
+  {0x4135, 0xc1ee, 0, 1, 0},
+  {0x42cb, 0x41ee, 1, 0, 0},
+  {0x4335, 0xc1ee, 0, 1, 0},
+}};
+
+LLVM_LIBC_FUNCTION(float16, tanpif16, (float16 x)) {
+  using FPBits = typename fputil::FPBits<float16>;
+  FPBits xbits(x);
+
+  uint16_t x_u = xbits.uintval(); 
+  bool x_sign = x_u >> 15;
+  uint16_t x_abs = x_u & 0x7fff;
+
+  if (LIBC_UNLIKELY(x_abs == 0U)) return x;
+  
+  // Handle exceptional values 
+  if (LIBC_UNLIKELY(x_abs <= 0x4335)) {
+    if (auto r = TANF16_EXCEPTS.lookup_odd(x_abs, x_sign);
+	LIBC_UNLIKELY(r.has_value()))
+      return r.value(); 
+  }
+  
+  // 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 (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();
+  }
+  // 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 tthe formula:
+  // tan(x) = sin(x) / cos(x)
+  //        = (sin_y * cos_k + cos_y * sin_k) / (cos_y * cos_k - sin_y * sin_k) 
+  float xf = x;
+  float sin_k, cos_k, sin_y, cosm1_y;
+  sincospif16_eval(xf, sin_k, cos_k, sin_y, cosm1_y);
+
+  if (LIBC_UNLIKELY(sin_y == 0 && cos_k == 0)) {
+    fputil::set_errno_if_required(EDOM);
+    fputil::raise_except_if_required(FE_DIVBYZERO);
+
+    int16_t x_mp5_u = static_cast<int16_t>(x - 0.5);
+    return ((x_mp5_u & 0x1) ? -1 : 1) * FPBits::inf().get_val();
+ }
+  
+  using fputil::multiply_add;
+  return fputil::cast<float16>(
+      multiply_add(sin_y, cos_k, multiply_add(cosm1_y, sin_k, sin_k)) /
+      multiply_add(sin_y, -sin_k, multiply_add(cosm1_y, cos_k, cos_k)));
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/tanpif16.h b/libc/src/math/tanpif16.h
new file mode 100644
index 00000000000000..c07a955564de37
--- /dev/null
+++ b/libc/src/math/tanpif16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for tanpif16 ----------------------*- 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_TANPIF16_H
+#define LLVM_LIBC_SRC_MATH_TANPIF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+float16 tanpif16(float16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_TANPIF16_H
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index b46ef4028915ba..ebe98d346b8320 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -168,6 +168,17 @@ add_fp_unittest(
     libc.src.__support.FPUtil.fp_bits
 )
 
+add_fp_unittest(
+  tanpif16_test
+  NEED_MPFR
+  SUITE
+    libc-math-unittests
+  SRCS
+    tanpif16_test.cpp
+  DEPENDS
+    libc.src.math.tanpif16
+)
+
 add_fp_unittest(
   fabs_test
   NEED_MPFR
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 269e92c5900628..8c75d1577081d0 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -99,6 +99,17 @@ add_fp_unittest(
     libc.src.__support.FPUtil.fp_bits
 )
 
+add_fp_unittest(
+  tanpif16_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    tanpif16_test.cpp
+  DEPENDS
+    libc.src.errno.errno
+    libc.src.math.tanpif16
+)
+
 add_fp_unittest(
   fabs_test
   SUITE
diff --git a/libc/test/src/math/smoke/tanpif16_test.cpp b/libc/test/src/math/smoke/tanpif16_test.cpp
new file mode 100644
index 00000000000000..a378cfb0a62e1f
--- /dev/null
+++ b/libc/test/src/math/smoke/tanpif16_test.cpp
@@ -0,0 +1,33 @@
+//===-- Unittests for tanpif16 --------------------------------------------===//
+//
+// 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/tanpif16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcTanpif16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+TEST_F(LlvmLibcTanpif16Test, SpecialNumbers) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::tanpif16(aNaN));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(zero, LIBC_NAMESPACE::tanpif16(zero));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::tanpif16(neg_zero));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::tanpif16(inf));
+  EXPECT_MATH_ERRNO(EDOM);
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::tanpif16(neg_inf));
+  EXPECT_MATH_ERRNO(EDOM);
+}
diff --git a/libc/test/src/math/tanpif16_test.cpp b/libc/test/src/math/tanpif16_test.cpp
new file mode 100644
index 00000000000000..6360c93bb0935d
--- /dev/null
+++ b/libc/test/src/math/tanpif16_test.cpp
@@ -0,0 +1,41 @@
+//===-- Exhaustive test for cospif16 --------------------------------------===//
+//
+// 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/tanpif16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcTanpif16Test = 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(LlvmLibcTanpif16Test, PositiveRange) {
+  for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+    float16 x = FPBits(v).get_val();
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Tanpi, x,
+                                   LIBC_NAMESPACE::tanpif16(x), 0.5);
+  }
+}
+
+
+TEST_F(LlvmLibcTanpif16Test, NegativeRange) {
+  for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) {
+    float16 x = FPBits(v).get_val();
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Tanpi, x,
+		                   LIBC_NAMESPACE::tanpif16(x), 0.5);
+  }
+}
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
index 5afc3d007d4d7a..1eb4c9ebc3ea8c 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -560,6 +560,28 @@ class MPFRNumber {
     return result;
   }
 
+  MPFRNumber tanpi() const {
+    MPFRNumber result(*this);
+
+#if MPFR_VERSION_MAJOR > 4 ||                                                  \
+    (MPFR_VERSION_MAJOR == 4 && MPFR_VERSION_MINOR >= 2)
+
+    mpfr_tanpi(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_pi(0.0, 1280);
+    mpfr_const_pi(value_pi.value, MPFR_RNDN);
+    mpfr_mul(value_pi.value, value_pi.value, value, MPFR_RNDN);
+    mpfr_tan(result.value, value_pi.value, mpfr_rounding);
+    return result;
+#endif
+  }
+  
   MPFRNumber trunc() const {
     MPFRNumber result(*this);
     mpfr_trunc(result.value, value);
@@ -798,6 +820,8 @@ unary_operation(Operation op, InputType input, unsigned int precision,
     return mpfrInput.tan();
   case Operation::Tanh:
     return mpfrInput.tanh();
+  case Operation::Tanpi:
+    return mpfrInput.tanpi();
   case Operation::Trunc:
     return mpfrInput.trunc();
   default:
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.h b/libc/utils/MPFRWrapper/MPFRUtils.h
index 9fc12a6adefb56..c7a57819f68b79 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.h
+++ b/libc/utils/MPFRWrapper/MPFRUtils.h
@@ -60,6 +60,7 @@ enum class Operation : int {
   Sqrt,
   Tan,
   Tanh,
+  Tanpi,
   Trunc,
   EndUnaryOperationsSingleOutput,
 

>From 0a27bd5c9eb64600d6111bf87ce19aea40ac2bbb Mon Sep 17 00:00:00 2001
From: wldfngrs <wldfngrs at gmail.com>
Date: Wed, 6 Nov 2024 00:04:45 +0100
Subject: [PATCH 2/4] mend

---
 libc/src/math/generic/tanpif16.cpp   | 59 ++++++++++++----------------
 libc/test/src/math/tanpif16_test.cpp |  3 +-
 libc/utils/MPFRWrapper/MPFRUtils.cpp |  2 +-
 3 files changed, 27 insertions(+), 37 deletions(-)

diff --git a/libc/src/math/generic/tanpif16.cpp b/libc/src/math/generic/tanpif16.cpp
index f4fe265f6f7620..450022f5992343 100644
--- a/libc/src/math/generic/tanpif16.cpp
+++ b/libc/src/math/generic/tanpif16.cpp
@@ -10,10 +10,10 @@
 #include "hdr/errno_macros.h"
 #include "hdr/fenv_macros.h"
 #include "sincosf16_utils.h"
-#include "src/__support/FPUtil/except_value_utils.h"
 #include "src/__support/FPUtil/FEnvImpl.h"
 #include "src/__support/FPUtil/FPBits.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/macros/optimization.h"
 
@@ -22,54 +22,45 @@ namespace LIBC_NAMESPACE_DECL {
 constexpr size_t N_EXCEPTS = 21;
 
 constexpr fputil::ExceptValues<float16, N_EXCEPTS> TANF16_EXCEPTS{{
-  // (input, RZ output, RU offset, RD offset, RN offset)
-  {0x07f2, 0x0e3d, 1, 0, 0},
-  {0x086a, 0x0eee, 1, 0, 1},
-  {0x08db, 0x0fa0, 1, 0, 0},
-  {0x094c, 0x1029, 1, 0, 0},
-  {0x0b10, 0x118c, 1, 0, 0},
-  {0x1ce0, 0x23a8, 1, 0, 1},
-  {0x1235, 0x18e0, 1, 0, 0},
-  {0x2579, 0x2c4e, 1, 0, 0},
-  {0x28b2, 0x2f68, 1, 0, 1},
-  {0x2a43, 0x30f4, 1, 0, 1},
-  {0x31b7, 0x3907, 1, 0, 0},
-  {0x329d, 0x3a12, 1, 0, 1},
-  {0x34f1, 0x3dd7, 1, 0, 0},
-  {0x3658, 0x41ee, 1, 0, 0},
-  {0x38d4, 0xc1ee, 0, 1, 0},
-  {0x3d96, 0x41ee, 1, 0, 0},
-  {0x3e6a, 0xc1ee, 0, 1, 0},
-  {0x40cb, 0x41ee, 1, 0, 0},
-  {0x4135, 0xc1ee, 0, 1, 0},
-  {0x42cb, 0x41ee, 1, 0, 0},
-  {0x4335, 0xc1ee, 0, 1, 0},
+    // (input, RZ output, RU offset, RD offset, RN offset)
+    {0x07f2, 0x0e3d, 1, 0, 0}, {0x086a, 0x0eee, 1, 0, 1},
+    {0x08db, 0x0fa0, 1, 0, 0}, {0x094c, 0x1029, 1, 0, 0},
+    {0x0b10, 0x118c, 1, 0, 0}, {0x1ce0, 0x23a8, 1, 0, 1},
+    {0x1235, 0x18e0, 1, 0, 0}, {0x2579, 0x2c4e, 1, 0, 0},
+    {0x28b2, 0x2f68, 1, 0, 1}, {0x2a43, 0x30f4, 1, 0, 1},
+    {0x31b7, 0x3907, 1, 0, 0}, {0x329d, 0x3a12, 1, 0, 1},
+    {0x34f1, 0x3dd7, 1, 0, 0}, {0x3658, 0x41ee, 1, 0, 0},
+    {0x38d4, 0xc1ee, 0, 1, 0}, {0x3d96, 0x41ee, 1, 0, 0},
+    {0x3e6a, 0xc1ee, 0, 1, 0}, {0x40cb, 0x41ee, 1, 0, 0},
+    {0x4135, 0xc1ee, 0, 1, 0}, {0x42cb, 0x41ee, 1, 0, 0},
+    {0x4335, 0xc1ee, 0, 1, 0},
 }};
 
 LLVM_LIBC_FUNCTION(float16, tanpif16, (float16 x)) {
   using FPBits = typename fputil::FPBits<float16>;
   FPBits xbits(x);
 
-  uint16_t x_u = xbits.uintval(); 
+  uint16_t x_u = xbits.uintval();
   bool x_sign = x_u >> 15;
   uint16_t x_abs = x_u & 0x7fff;
 
-  if (LIBC_UNLIKELY(x_abs == 0U)) return x;
-  
-  // Handle exceptional values 
+  if (LIBC_UNLIKELY(x_abs == 0U))
+    return x;
+
+  // Handle exceptional values
   if (LIBC_UNLIKELY(x_abs <= 0x4335)) {
     if (auto r = TANF16_EXCEPTS.lookup_odd(x_abs, x_sign);
-	LIBC_UNLIKELY(r.has_value()))
-      return r.value(); 
+        LIBC_UNLIKELY(r.has_value()))
+      return r.value();
   }
-  
+
   // 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 (x_abs == 0x7c00) {
         fputil::set_errno_if_required(EDOM);
-	fputil::raise_except_if_required(FE_INVALID);
+        fputil::raise_except_if_required(FE_INVALID);
       }
 
       return x + FPBits::quiet_nan().get_val();
@@ -90,7 +81,7 @@ LLVM_LIBC_FUNCTION(float16, tanpif16, (float16 x)) {
   //
   // Once k and y are computed, we then deduce the answer by tthe formula:
   // tan(x) = sin(x) / cos(x)
-  //        = (sin_y * cos_k + cos_y * sin_k) / (cos_y * cos_k - sin_y * sin_k) 
+  //        = (sin_y * cos_k + cos_y * sin_k) / (cos_y * cos_k - sin_y * sin_k)
   float xf = x;
   float sin_k, cos_k, sin_y, cosm1_y;
   sincospif16_eval(xf, sin_k, cos_k, sin_y, cosm1_y);
@@ -101,8 +92,8 @@ LLVM_LIBC_FUNCTION(float16, tanpif16, (float16 x)) {
 
     int16_t x_mp5_u = static_cast<int16_t>(x - 0.5);
     return ((x_mp5_u & 0x1) ? -1 : 1) * FPBits::inf().get_val();
- }
-  
+  }
+
   using fputil::multiply_add;
   return fputil::cast<float16>(
       multiply_add(sin_y, cos_k, multiply_add(cosm1_y, sin_k, sin_k)) /
diff --git a/libc/test/src/math/tanpif16_test.cpp b/libc/test/src/math/tanpif16_test.cpp
index 6360c93bb0935d..629ba963135c06 100644
--- a/libc/test/src/math/tanpif16_test.cpp
+++ b/libc/test/src/math/tanpif16_test.cpp
@@ -31,11 +31,10 @@ TEST_F(LlvmLibcTanpif16Test, PositiveRange) {
   }
 }
 
-
 TEST_F(LlvmLibcTanpif16Test, NegativeRange) {
   for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) {
     float16 x = FPBits(v).get_val();
     EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Tanpi, x,
-		                   LIBC_NAMESPACE::tanpif16(x), 0.5);
+                                   LIBC_NAMESPACE::tanpif16(x), 0.5);
   }
 }
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
index 1eb4c9ebc3ea8c..eadc82502c5261 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -581,7 +581,7 @@ class MPFRNumber {
     return result;
 #endif
   }
-  
+
   MPFRNumber trunc() const {
     MPFRNumber result(*this);
     mpfr_trunc(result.value, value);

>From 4edcddd60e03069ddfd8db3efff5db74e0ac937c Mon Sep 17 00:00:00 2001
From: wldfngrs <wldfngrs at gmail.com>
Date: Wed, 6 Nov 2024 18:07:17 +0100
Subject: [PATCH 3/4] Add implementation of tanpi for MPFR < 4.2

---
 libc/test/src/math/tanpif16_test.cpp |  4 +++-
 libc/utils/MPFRWrapper/MPFRUtils.cpp | 28 ++++++++++++++++++++++++++--
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/libc/test/src/math/tanpif16_test.cpp b/libc/test/src/math/tanpif16_test.cpp
index 629ba963135c06..67834dac0f569e 100644
--- a/libc/test/src/math/tanpif16_test.cpp
+++ b/libc/test/src/math/tanpif16_test.cpp
@@ -23,6 +23,7 @@ static constexpr uint16_t POS_STOP = 0x7c00U;
 static constexpr uint16_t NEG_START = 0x8000U;
 static constexpr uint16_t NEG_STOP = 0xfc00U;
 
+
 TEST_F(LlvmLibcTanpif16Test, PositiveRange) {
   for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
     float16 x = FPBits(v).get_val();
@@ -36,5 +37,6 @@ TEST_F(LlvmLibcTanpif16Test, NegativeRange) {
     float16 x = FPBits(v).get_val();
     EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Tanpi, x,
                                    LIBC_NAMESPACE::tanpif16(x), 0.5);
-  }
+ }
 }
+
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
index eadc82502c5261..ebe362c7466d24 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -569,8 +569,32 @@ class MPFRNumber {
     mpfr_tanpi(result.value, value, mpfr_rounding);
     return result;
 #else
-    if (mpfr_integer_p(value)) {
-      mpfr_set_si(result.value, 0, mpfr_rounding);
+    MPFRNumber value_ret_exact(*this);
+    mpfr_fmod_ui(value_ret_exact.value, value, 1, mpfr_rounding);
+    mpfr_mul_si(value_ret_exact.value, value_ret_exact.value, 4, MPFR_RNDN);
+
+    if (mpfr_integer_p(value_ret_exact.value)) {
+      int mod = mpfr_get_si(value_ret_exact.value, MPFR_RNDN);
+      mod = (mod < 0 ? -1*mod : mod);
+
+      switch(mod) {
+        case 0:
+	  mpfr_set_si(result.value, 0, mpfr_rounding);
+	  break;
+	case 1:
+	  mpfr_set_si(result.value, (mpfr_signbit(value) ? -1 : 1), mpfr_rounding);
+	  break;
+	case 2: {
+	  auto d = mpfr_get_si(value, MPFR_RNDZ);
+	  d += mpfr_sgn(value) > 0 ? 0 : 1; 
+	  mpfr_set_inf(result.value, (d & 1) ? -1 : 1);
+	  break;
+	}
+	case 3:
+	  mpfr_set_si(result.value, (mpfr_signbit(value) ? 1 : -1), mpfr_rounding);
+	  break;
+      }
+
       return result;
     }
 

>From d89dbaf5c10b99a86b4820fd1fbdcbdffc5137ca Mon Sep 17 00:00:00 2001
From: wldfngrs <wldfngrs at gmail.com>
Date: Wed, 6 Nov 2024 18:08:17 +0100
Subject: [PATCH 4/4] mend

---
 libc/test/src/math/tanpif16_test.cpp |  4 +--
 libc/utils/MPFRWrapper/MPFRUtils.cpp | 38 +++++++++++++++-------------
 2 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/libc/test/src/math/tanpif16_test.cpp b/libc/test/src/math/tanpif16_test.cpp
index 67834dac0f569e..629ba963135c06 100644
--- a/libc/test/src/math/tanpif16_test.cpp
+++ b/libc/test/src/math/tanpif16_test.cpp
@@ -23,7 +23,6 @@ static constexpr uint16_t POS_STOP = 0x7c00U;
 static constexpr uint16_t NEG_START = 0x8000U;
 static constexpr uint16_t NEG_STOP = 0xfc00U;
 
-
 TEST_F(LlvmLibcTanpif16Test, PositiveRange) {
   for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
     float16 x = FPBits(v).get_val();
@@ -37,6 +36,5 @@ TEST_F(LlvmLibcTanpif16Test, NegativeRange) {
     float16 x = FPBits(v).get_val();
     EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Tanpi, x,
                                    LIBC_NAMESPACE::tanpif16(x), 0.5);
- }
+  }
 }
-
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
index ebe362c7466d24..00ac8a8ba271ac 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -575,24 +575,26 @@ class MPFRNumber {
 
     if (mpfr_integer_p(value_ret_exact.value)) {
       int mod = mpfr_get_si(value_ret_exact.value, MPFR_RNDN);
-      mod = (mod < 0 ? -1*mod : mod);
-
-      switch(mod) {
-        case 0:
-	  mpfr_set_si(result.value, 0, mpfr_rounding);
-	  break;
-	case 1:
-	  mpfr_set_si(result.value, (mpfr_signbit(value) ? -1 : 1), mpfr_rounding);
-	  break;
-	case 2: {
-	  auto d = mpfr_get_si(value, MPFR_RNDZ);
-	  d += mpfr_sgn(value) > 0 ? 0 : 1; 
-	  mpfr_set_inf(result.value, (d & 1) ? -1 : 1);
-	  break;
-	}
-	case 3:
-	  mpfr_set_si(result.value, (mpfr_signbit(value) ? 1 : -1), mpfr_rounding);
-	  break;
+      mod = (mod < 0 ? -1 * mod : mod);
+
+      switch (mod) {
+      case 0:
+        mpfr_set_si(result.value, 0, mpfr_rounding);
+        break;
+      case 1:
+        mpfr_set_si(result.value, (mpfr_signbit(value) ? -1 : 1),
+                    mpfr_rounding);
+        break;
+      case 2: {
+        auto d = mpfr_get_si(value, MPFR_RNDZ);
+        d += mpfr_sgn(value) > 0 ? 0 : 1;
+        mpfr_set_inf(result.value, (d & 1) ? -1 : 1);
+        break;
+      }
+      case 3:
+        mpfr_set_si(result.value, (mpfr_signbit(value) ? 1 : -1),
+                    mpfr_rounding);
+        break;
       }
 
       return result;



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