[libc][math] Added coshf function.

Kirill Okhotnikov · Kirill Okhotnikov · commit fcb9d7e2cf17 · 2022-07-29T16:57:28.000+02:00
Differential Revision: https://reviews.llvm.org/D129275
diff --git a/libc/config/darwin/arm/entrypoints.txt b/libc/config/darwin/arm/entrypoints.txt
@@ -111,6 +111,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.ceil
     libc.src.math.ceilf
     libc.src.math.ceill
+    libc.src.math.coshf
     libc.src.math.cosf
     libc.src.math.expf
     libc.src.math.exp2f
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
@@ -130,6 +130,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.ceil
     libc.src.math.ceilf
     libc.src.math.ceill
+    libc.src.math.coshf
     libc.src.math.cosf
     libc.src.math.expf
     libc.src.math.exp2f
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
@@ -136,6 +136,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.ceilf
     libc.src.math.ceill
     libc.src.math.cos
+    libc.src.math.coshf
     libc.src.math.cosf
     libc.src.math.expf
     libc.src.math.exp2f
diff --git a/libc/config/windows/entrypoints.txt b/libc/config/windows/entrypoints.txt
@@ -114,6 +114,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.ceill
     libc.src.math.cos
     libc.src.math.cosf
+    libc.src.math.coshf
     libc.src.math.expf
     libc.src.math.exp2f
     libc.src.math.expm1f
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
@@ -470,6 +470,8 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"nextafterf", RetValSpec<FloatType>, [ArgSpec<FloatType>, ArgSpec<FloatType>]>,
           FunctionSpec<"nextafter", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,
           FunctionSpec<"nextafterl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>]>,
+
+          FunctionSpec<"coshf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
       ]
   >;
 
diff --git a/libc/src/__support/FPUtil/FPBits.h b/libc/src/__support/FPUtil/FPBits.h
@@ -153,8 +153,8 @@ template <typename T> struct FPBits {
 
   static constexpr FPBits<T> neg_zero() { return zero(true); }
 
-  static constexpr FPBits<T> inf() {
-    FPBits<T> bits;
+  static constexpr FPBits<T> inf(bool sign = false) {
+    FPBits<T> bits(sign ? FloatProp::SIGN_MASK : UIntType(0));
     bits.set_unbiased_exponent(MAX_EXPONENT);
     return bits;
   }
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
@@ -76,6 +76,7 @@ add_math_entrypoint_object(copysignl)
 
 add_math_entrypoint_object(cos)
 add_math_entrypoint_object(cosf)
+add_math_entrypoint_object(coshf)
 
 add_math_entrypoint_object(expf)
 
diff --git a/libc/src/math/coshf.h b/libc/src/math/coshf.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for coshf -------------------------*- 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_COSHF_H
+#define LLVM_LIBC_SRC_MATH_COSHF_H
+
+namespace __llvm_libc {
+
+float coshf(float x);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_MATH_COSHF_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
@@ -1128,3 +1128,22 @@ add_entrypoint_object(
   COMPILE_OPTIONS
     -O3
 )
+
+add_entrypoint_object(
+  coshf
+  SRCS
+    coshf.cpp
+  HDRS
+    ../coshf.h
+    expxf.h
+  DEPENDS
+    .common_constants
+    libc.src.__support.FPUtil.fputil
+    libc.src.__support.FPUtil.multiply_add
+    libc.src.__support.FPUtil.nearest_integer
+    libc.src.__support.FPUtil.polyeval
+    libc.include.math
+  COMPILE_OPTIONS
+    -O3
+)
+
diff --git a/libc/src/math/generic/coshf.cpp b/libc/src/math/generic/coshf.cpp
@@ -0,0 +1,54 @@
+//===-- Single-precision cosh 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/coshf.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/math/generic/expxf.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(float, coshf, (float x)) {
+  using FPBits = typename fputil::FPBits<float>;
+  FPBits xbits(x);
+  xbits.set_sign(false);
+  x = xbits.get_val();
+
+  uint32_t x_u = xbits.uintval();
+
+  // |x| <= 2^-26
+  if (unlikely(x_u <= 0x3280'0000U)) {
+    return 1.0f + x;
+  }
+
+  // When |x| >= 90, or x is inf or nan
+  if (unlikely(x_u >= 0x42b4'0000U)) {
+    if (xbits.is_inf_or_nan())
+      return x + FPBits::inf().get_val();
+
+    int rounding = fputil::get_round();
+    if (unlikely(rounding == FE_DOWNWARD || rounding == FE_TOWARDZERO))
+      return FPBits(FPBits::MAX_NORMAL).get_val();
+
+    errno = ERANGE;
+
+    return x + FPBits::inf().get_val();
+  }
+  auto ep_p = exp_eval<-1>(x);
+  auto ep_m = exp_eval<-1>(-x);
+  // 0.5 * exp(x)  = ep_p.mult_exp * (ep_p.r + 1)
+  //               = ep_p.mult_exp * ep_p.r + ep_p.mult_exp
+  // 0.5 * exp(-x) = ep_m.mult_exp * (ep_m.r + 1)
+  //               = ep_m.mult_exp * ep_m.r + ep_m.mult_exp
+  // cos(x) = 0.5 * exp(x) + 0.5 * expm1(-x)
+  double ep = fputil::multiply_add(ep_p.mult_exp, ep_p.r, ep_p.mult_exp) +
+              fputil::multiply_add(ep_m.mult_exp, ep_m.r, ep_m.mult_exp);
+  return ep;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
@@ -1314,6 +1314,22 @@ add_fp_unittest(
     libc.src.__support.FPUtil.fputil
 )
 
+add_fp_unittest(
+  coshf_test
+  NEED_MPFR
+  SUITE
+    libc_math_unittests
+  SRCS
+    coshf_test.cpp
+  HDRS
+    sdcomp26094.h
+  DEPENDS
+    libc.include.errno
+    libc.src.math.coshf
+    libc.src.__support.CPP.array
+    libc.src.__support.FPUtil.fputil
+)
+
 add_subdirectory(generic)
 add_subdirectory(exhaustive)
 add_subdirectory(differential_testing)
diff --git a/libc/test/src/math/coshf_test.cpp b/libc/test/src/math/coshf_test.cpp
@@ -0,0 +1,78 @@
+//===-- Unittests for coshf -----------------------------------------------===//
+//
+// 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/CPP/Array.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/math/coshf.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+#include "utils/UnitTest/FPMatcher.h"
+#include "utils/UnitTest/Test.h"
+#include <math.h>
+
+#include <errno.h>
+#include <stdint.h>
+
+using FPBits = __llvm_libc::fputil::FPBits<float>;
+
+namespace mpfr = __llvm_libc::testing::mpfr;
+
+DECLARE_SPECIAL_CONSTANTS(float)
+
+TEST(LlvmLibcCoshfTest, SpecialNumbers) {
+  errno = 0;
+
+  EXPECT_FP_EQ(aNaN, __llvm_libc::coshf(aNaN));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(inf, __llvm_libc::coshf(inf));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(inf, __llvm_libc::coshf(neg_inf));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(1.0f, __llvm_libc::coshf(0.0f));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(1.0f, __llvm_libc::coshf(-0.0f));
+  EXPECT_MATH_ERRNO(0);
+}
+
+TEST(LlvmLibcCoshfTest, Overflow) {
+  errno = 0;
+  EXPECT_FP_EQ(inf, __llvm_libc::coshf(float(FPBits(0x7f7fffffU))));
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ(inf, __llvm_libc::coshf(float(FPBits(0x42cffff8U))));
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ(inf, __llvm_libc::coshf(float(FPBits(0x42d00008U))));
+  EXPECT_MATH_ERRNO(ERANGE);
+}
+
+TEST(LlvmLibcCoshfTest, InFloatRange) {
+  constexpr uint32_t COUNT = 1000000;
+  constexpr uint32_t STEP = UINT32_MAX / COUNT;
+  for (uint32_t i = 0, v = 0; i <= COUNT; ++i, v += STEP) {
+    float x = float(FPBits(v));
+    if (isnan(x) || isinf(x))
+      continue;
+    ASSERT_MPFR_MATCH(mpfr::Operation::Cosh, x, __llvm_libc::coshf(x), 0.5);
+  }
+}
+
+TEST(LlvmLibcCoshfTest, SmallValues) {
+  float x = float(FPBits(0x17800000U));
+  float result = __llvm_libc::coshf(x);
+  EXPECT_MPFR_MATCH(mpfr::Operation::Cosh, x, result, 0.5);
+  EXPECT_FP_EQ(1.0f, result);
+
+  x = float(FPBits(0x0040000U));
+  result = __llvm_libc::coshf(x);
+  EXPECT_MPFR_MATCH(mpfr::Operation::Cosh, x, result, 0.5);
+  EXPECT_FP_EQ(1.0f, result);
+}
diff --git a/libc/test/src/math/exhaustive/CMakeLists.txt b/libc/test/src/math/exhaustive/CMakeLists.txt
@@ -201,3 +201,21 @@ add_fp_unittest(
     libc.src.__support.FPUtil.fputil
     libc.src.__support.FPUtil.generic.fmod
 )
+
+add_fp_unittest(
+  coshf_test
+  NO_RUN_POSTBUILD
+  NEED_MPFR
+  SUITE
+    libc_math_exhaustive_tests
+  SRCS
+    coshf_test.cpp
+  DEPENDS
+    .exhaustive_test
+    libc.include.math
+    libc.src.math.coshf
+    libc.src.__support.FPUtil.fputil
+  LINK_LIBRARIES
+    -lpthread
+)
+
diff --git a/libc/test/src/math/exhaustive/coshf_test.cpp b/libc/test/src/math/exhaustive/coshf_test.cpp
@@ -0,0 +1,55 @@
+//===-- Exhaustive test for coshf -----------------------------------------===//
+//
+// 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 "exhaustive_test.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/math/coshf.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+#include "utils/UnitTest/FPMatcher.h"
+
+#include <thread>
+
+using FPBits = __llvm_libc::fputil::FPBits<float>;
+
+namespace mpfr = __llvm_libc::testing::mpfr;
+
+struct LlvmLibcCoshfExhaustiveTest : public LlvmLibcExhaustiveTest<uint32_t> {
+  bool check(uint32_t start, uint32_t stop,
+             mpfr::RoundingMode rounding) override {
+    mpfr::ForceRoundingMode r(rounding);
+    uint32_t bits = start;
+    bool result = true;
+    do {
+      FPBits xbits(bits);
+      float x = float(xbits);
+      result &= EXPECT_MPFR_MATCH(mpfr::Operation::Cosh, x,
+                                  __llvm_libc::coshf(x), 0.5, rounding);
+    } while (bits++ < stop);
+    return result;
+  }
+};
+
+// Range: [0, 90];
+static constexpr uint32_t POS_START = 0x0000'0000U;
+static constexpr uint32_t POS_STOP = 0x42b4'0000U;
+
+TEST_F(LlvmLibcCoshfExhaustiveTest, PostiveRangeRoundNearestTieToEven) {
+  test_full_range(POS_START, POS_STOP, mpfr::RoundingMode::Nearest);
+}
+
+TEST_F(LlvmLibcCoshfExhaustiveTest, PostiveRangeRoundUp) {
+  test_full_range(POS_START, POS_STOP, mpfr::RoundingMode::Upward);
+}
+
+TEST_F(LlvmLibcCoshfExhaustiveTest, PostiveRangeRoundDown) {
+  test_full_range(POS_START, POS_STOP, mpfr::RoundingMode::Downward);
+}
+
+TEST_F(LlvmLibcCoshfExhaustiveTest, PostiveRangeRoundTowardZero) {
+  test_full_range(POS_START, POS_STOP, mpfr::RoundingMode::TowardZero);
+}
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -194,6 +194,12 @@ class MPFRNumber {
     return result;
   }
 
+  MPFRNumber cosh() const {
+    MPFRNumber result(*this);
+    mpfr_cosh(result.value, value, mpfr_rounding);
+    return result;
+  }
+
   MPFRNumber exp() const {
     MPFRNumber result(*this);
     mpfr_exp(result.value, value, mpfr_rounding);
@@ -481,6 +487,8 @@ unary_operation(Operation op, InputType input, unsigned int precision,
     return mpfrInput.ceil();
   case Operation::Cos:
     return mpfrInput.cos();
+  case Operation::Cosh:
+    return mpfrInput.cosh();
   case Operation::Exp:
     return mpfrInput.exp();
   case Operation::Exp2:
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.h b/libc/utils/MPFRWrapper/MPFRUtils.h
@@ -27,6 +27,7 @@ enum class Operation : int {
   Abs,
   Ceil,
   Cos,
+  Cosh,
   Exp,
   Exp2,
   Expm1,

Original file line number	Diff line number	Diff line change
`@@ -470,6 +470,8 @@ def StdC : StandardSpec<"stdc"> {`
`470`	`470`	`FunctionSpec<"nextafterf", RetValSpec<FloatType>, [ArgSpec<FloatType>, ArgSpec<FloatType>]>,`
`471`	`471`	`FunctionSpec<"nextafter", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,`
`472`	`472`	`FunctionSpec<"nextafterl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>]>,`
	`473`	`+`
	`474`	`+ FunctionSpec<"coshf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,`
`473`	`475`	`]`
`474`	`476`	`>;`
`475`	`477`
Original file line number	Diff line number	Diff line change
`@@ -153,8 +153,8 @@ template <typename T> struct FPBits {`
`153`	`153`
`154`	`154`	`static constexpr FPBits<T> neg_zero() { return zero(true); }`
`155`	`155`
`156`		`- static constexpr FPBits<T> inf() {`
`157`		`- FPBits<T> bits;`
	`156`	`+ static constexpr FPBits<T> inf(bool sign = false) {`
	`157`	`+ FPBits<T> bits(sign ? FloatProp::SIGN_MASK : UIntType(0));`
`158`	`158`	`bits.set_unbiased_exponent(MAX_EXPONENT);`
`159`	`159`	`return bits;`
`160`	`160`	`}`
-Original file line number
+Diff line change
   Abs,
   Ceil,
   Cos,
 +  Cosh,
   Exp,
   Exp2,
   Expm1,