[libc][math] Implement double precision cbrt correctly rounded to all rounding modes.

libc/config/darwin/arm/entrypoints.txt

@@ -123,6 +123,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.atan2f
     libc.src.math.atanf
     libc.src.math.atanhf
+    libc.src.math.cbrt
     libc.src.math.cbrtf
     libc.src.math.copysign
     libc.src.math.copysignf

libc/config/gpu/entrypoints.txt

@@ -245,6 +245,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.atanf
     libc.src.math.atanh
     libc.src.math.atanhf
+    libc.src.math.cbrt
     libc.src.math.cbrtf
     libc.src.math.ceil
     libc.src.math.ceilf

libc/config/linux/aarch64/entrypoints.txt

@@ -345,6 +345,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.atan2f
     libc.src.math.atanf
     libc.src.math.atanhf
+    libc.src.math.cbrt
     libc.src.math.cbrtf
     libc.src.math.ceil
     libc.src.math.ceilf

libc/config/linux/arm/entrypoints.txt

@@ -216,6 +216,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.atan2f
     libc.src.math.atanf
     libc.src.math.atanhf
+    libc.src.math.cbrt
     libc.src.math.cbrtf
     libc.src.math.ceil
     libc.src.math.ceilf

libc/config/linux/riscv/entrypoints.txt

@@ -347,6 +347,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.atan2f
     libc.src.math.atanf
     libc.src.math.atanhf
+    libc.src.math.cbrt
     libc.src.math.cbrtf
     libc.src.math.ceil
     libc.src.math.ceilf

libc/config/linux/x86_64/entrypoints.txt

@@ -370,6 +370,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.canonicalize
     libc.src.math.canonicalizef
     libc.src.math.canonicalizel
+    libc.src.math.cbrt
     libc.src.math.cbrtf
     libc.src.math.ceil
     libc.src.math.ceilf

libc/config/windows/entrypoints.txt

@@ -121,6 +121,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.atan2f
     libc.src.math.atanf
     libc.src.math.atanhf
+    libc.src.math.cbrt
     libc.src.math.cbrtf
     libc.src.math.copysign
     libc.src.math.copysignf

libc/docs/math/index.rst

@@ -266,7 +266,7 @@ Higher Math Functions
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | atanpi    |                  |                 |                        |                      |                        | 7.12.4.10              | F.10.1.10                  |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| cbrt      | |check|          |                 |                        |                      |                        | 7.12.7.1               | F.10.4.1                   |
+| cbrt      | |check|          | |check|         |                        |                      |                        | 7.12.7.1               | F.10.4.1                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | compoundn |                  |                 |                        |                      |                        | 7.12.7.2               | F.10.4.2                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+

libc/spec/stdc.td

@@ -382,6 +382,7 @@ def StdC : StandardSpec<"stdc"> {
       ],
       [], // Enumerations
       [
+          FunctionSpec<"cbrt", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
           FunctionSpec<"cbrtf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
 
           FunctionSpec<"copysign", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,

libc/src/math/CMakeLists.txt

@@ -65,6 +65,7 @@ add_math_entrypoint_object(canonicalizel)
 add_math_entrypoint_object(canonicalizef16)
 add_math_entrypoint_object(canonicalizef128)
 
+add_math_entrypoint_object(cbrt)
 add_math_entrypoint_object(cbrtf)
 
 add_math_entrypoint_object(ceil)

libc/src/math/cbrt.h

@@ -0,0 +1,18 @@
+//===-- Implementation header for cbrt --------------------------*- 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_CBRT_H
+#define LLVM_LIBC_SRC_MATH_CBRT_H
+
+namespace LIBC_NAMESPACE {
+
+double cbrt(double x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_CBRT_H

libc/src/math/generic/CMakeLists.txt

@@ -4180,3 +4180,23 @@ add_entrypoint_object(
     libc.src.__support.FPUtil.multiply_add
     libc.src.__support.macros.optimization
 )
+
+add_entrypoint_object(
+  cbrt
+  SRCS
+    cbrt.cpp
+  HDRS
+    ../cbrt.h
+  COMPILE_OPTIONS
+    -O3
+  DEPENDS
+    libc.hdr.fenv_macros
+    libc.src.__support.FPUtil.double_double
+    libc.src.__support.FPUtil.dyadic_float
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.multiply_add
+    libc.src.__support.FPUtil.polyeval
+    libc.src.__support.macros.optimization
+    libc.src.__support.integer_literals
+)