[libc][math] Add place-holder implementation for asin to unblock demo examples.

[lntue]

Summary

Add a place-holder implementation for asin to unblock libc demo
examples.

[lntue]

Fix test.

[michaelrj]

LGTM

libc/config/linux/aarch64/entrypoints.txt

set(TARGET_LIBM_ENTRYPOINTS
     libc.src.fenv.fesetexceptflag
     libc.src.fenv.fesetround
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.fenv.feupdateenv
 
     # math.h entrypoints
     libc.src.math.acosf
+    libc.src.math.asin
     libc.src.math.asinf
     libc.src.math.atanf
     libc.src.math.atanhf    
     libc.src.math.copysign
     libc.src.math.copysignf
     libc.src.math.copysignl
     libc.src.math.ceil
     libc.src.math.ceilf

libc/config/linux/x86_64/entrypoints.txt

set(TARGET_LIBM_ENTRYPOINTS
     libc.src.fenv.fesetexceptflag
     libc.src.fenv.fesetround
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.fenv.feupdateenv
 
     # math.h entrypoints
     libc.src.math.acosf
+    libc.src.math.asin
     libc.src.math.asinf
     libc.src.math.atanf
     libc.src.math.atanhf
     libc.src.math.copysign
     libc.src.math.copysignf
     libc.src.math.copysignl
     libc.src.math.ceil
     libc.src.math.ceilf

libc/config/windows/entrypoints.txt

set(TARGET_LIBM_ENTRYPOINTS
     libc.src.fenv.fesetexceptflag
     libc.src.fenv.fesetround
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.fenv.feupdateenv
 
     # math.h entrypoints
     libc.src.math.acosf
+    libc.src.math.asin
     libc.src.math.asinf
     libc.src.math.atanf    
     libc.src.math.atanhf
     libc.src.math.copysign
     libc.src.math.copysignf
     libc.src.math.copysignl
     libc.src.math.ceil
     libc.src.math.ceilf

libc/spec/stdc.td

HeaderSpec Math = HeaderSpec<
           FunctionSpec<"nextafterl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>]>,
 
           FunctionSpec<"coshf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
           FunctionSpec<"sinhf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
           FunctionSpec<"tanhf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
 
           FunctionSpec<"acosf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
           FunctionSpec<"asinf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
+          FunctionSpec<"asin", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
           FunctionSpec<"atanf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
 
           FunctionSpec<"atanhf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
       ]
   >;
 
   HeaderSpec StdIO = HeaderSpec<
       "stdio.h",

libc/src/math/CMakeLists.txt

HDRS
     fma.h
   DEPENDS
     libc.src.__support.FPUtil.fma
   COMPILE_OPTIONS
     -O3
 )
 
 add_math_entrypoint_object(acosf)
+
+add_math_entrypoint_object(asin)
 add_math_entrypoint_object(asinf)
+
 add_math_entrypoint_object(atanf)
 
 add_math_entrypoint_object(atanhf)
 
 add_math_entrypoint_object(ceil)
 add_math_entrypoint_object(ceilf)
 add_math_entrypoint_object(ceill)
 

libc/src/math/asin.h

+//===-- Implementation header for asin --------------------------*- 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_ASIN_H
+#define LLVM_LIBC_SRC_MATH_ASIN_H
+
+namespace __llvm_libc {
+
+double asin(double x);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_MATH_ASIN_H

libc/src/math/generic/CMakeLists.txt

DEPENDS
     libc.src.__support.FPUtil.polyeval
     libc.src.__support.FPUtil.sqrt
     .inv_trigf_utils
   COMPILE_OPTIONS
     -O3
 )
 
 add_entrypoint_object(
+  asin
+  SRCS
+    asin.cpp
+  HDRS
+    ../asin.h
+  DEPENDS
+    .asinf
+  COMPILE_OPTIONS
+    -O3
+)
+
+add_entrypoint_object(
   acosf
   SRCS
     acosf.cpp
   HDRS
     ../acosf.h
   DEPENDS
     libc.src.__support.FPUtil.except_value_utils
     libc.src.__support.FPUtil.fp_bits

libc/src/math/generic/asin.cpp

+//===-- Double-precision asin 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/asin.h"
+#include "src/math/asinf.h"
+
+#include "src/__support/common.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(double, asin, (double x)) {
+  // Place-holder implementation for double precision asin function.
+  // TODO: Implement correctly rounded asin function for double precision.
+  return static_cast<double>(asinf(static_cast<float>(x)));
+}
+
+} // namespace __llvm_libc

libc/test/src/math/CMakeLists.txt

add_fp_unittest(
   DEPENDS
     libc.include.errno
     libc.src.errno.errno
     libc.src.math.asinf
     libc.src.__support.FPUtil.fp_bits
 )
 
 add_fp_unittest(
+  asin_test
+  NEED_MPFR
+  SUITE
+    libc_math_unittests
+  SRCS
+    asin_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.src.errno.errno
+    libc.src.math.asin
+)
+
+add_fp_unittest(
   acosf_test
   NEED_MPFR
   SUITE
     libc_math_unittests
   SRCS
     acosf_test.cpp
   DEPENDS
     libc.include.errno

libc/test/src/math/asin_test.cpp

+//===-- Unittests for asin ------------------------------------------------===//
+//
+// 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/asin.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<double>;
+
+namespace mpfr = __llvm_libc::testing::mpfr;
+
+DECLARE_SPECIAL_CONSTANTS(double)
+
+TEST(LlvmLibcAsinTest, SpecialNumbers) {
+  errno = 0;
+
+  EXPECT_FP_EQ(aNaN, __llvm_libc::asin(aNaN));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(0.0, __llvm_libc::asin(0.0));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(-0.0, __llvm_libc::asin(-0.0));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(aNaN, __llvm_libc::asin(inf));
+  EXPECT_MATH_ERRNO(EDOM);
+
+  EXPECT_FP_EQ(aNaN, __llvm_libc::asin(neg_inf));
+  EXPECT_MATH_ERRNO(EDOM);
+}