[libc][math][c23] Add llogbf16 C23 math function

Author: overmighty

libc/config/linux/aarch64/entrypoints.txt

@@ -521,6 +521,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.fromfpxf16
     libc.src.math.ilogbf16
     libc.src.math.ldexpf16
+    libc.src.math.llogbf16
     libc.src.math.llrintf16
     libc.src.math.llroundf16
     libc.src.math.lrintf16

libc/config/linux/x86_64/entrypoints.txt

@@ -554,6 +554,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.fromfpxf16
     libc.src.math.ilogbf16
     libc.src.math.ldexpf16
+    libc.src.math.llogbf16
     libc.src.math.llrintf16
     libc.src.math.llroundf16
     libc.src.math.lrintf16

libc/docs/c23.rst

@@ -50,7 +50,7 @@ Additions:
   * issignaling
   * issubnormal
   * iszero
-  * llogb*
+  * llogb* |check|
   * pown*
   * powr*
   * rootn*

libc/docs/math/index.rst

@@ -172,7 +172,7 @@ Basic Operations
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | ldexp            | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.6.9               | F.10.3.9                   |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| llogb            | |check|          | |check|         | |check|                |                      | |check|                | 7.12.6.10              | F.10.3.10                  |
+| llogb            | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.6.10              | F.10.3.10                  |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | llrint           | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.9.5               | F.10.6.5                   |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+

libc/spec/stdc.td

@@ -526,6 +526,7 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"llogb", RetValSpec<LongType>, [ArgSpec<DoubleType>]>,
           FunctionSpec<"llogbf", RetValSpec<LongType>, [ArgSpec<FloatType>]>,
           FunctionSpec<"llogbl", RetValSpec<LongType>, [ArgSpec<LongDoubleType>]>,
+          GuardedFunctionSpec<"llogbf16", RetValSpec<LongType>, [ArgSpec<Float16Type>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"llogbf128", RetValSpec<LongType>, [ArgSpec<Float128Type>], "LIBC_TYPES_HAS_FLOAT128">,
 
           FunctionSpec<"ldexp", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<IntType>]>,

libc/src/math/CMakeLists.txt

@@ -218,6 +218,7 @@ add_math_entrypoint_object(ilogbf128)
 add_math_entrypoint_object(llogb)
 add_math_entrypoint_object(llogbf)
 add_math_entrypoint_object(llogbl)
+add_math_entrypoint_object(llogbf16)
 add_math_entrypoint_object(llogbf128)
 
 add_math_entrypoint_object(ldexp)

libc/src/math/generic/CMakeLists.txt

@@ -1425,6 +1425,19 @@ add_entrypoint_object(
     libc.src.__support.FPUtil.manipulation_functions
 )
 
+add_entrypoint_object(
+  llogbf16
+  SRCS
+    llogbf16.cpp
+  HDRS
+    ../llogbf16.h
+  COMPILE_OPTIONS
+    -O3
+  DEPENDS
+    libc.src.__support.macros.properties.types
+    libc.src.__support.FPUtil.manipulation_functions
+)
+
 add_entrypoint_object(
   llogbf128
   SRCS

libc/src/math/generic/llogbf16.cpp

@@ -0,0 +1,19 @@
+//===-- Implementation of llogbf16 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/llogbf16.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(long, llogbf16, (float16 x)) {
+  return fputil::intlogb<long>(x);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/math/llogbf16.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for llogbf16 ----------------------*- 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_LLOGBF16_H
+#define LLVM_LIBC_SRC_MATH_LLOGBF16_H
+
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE {
+
+long llogbf16(float16 x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_LLOGBF16_H

libc/test/src/math/smoke/CMakeLists.txt

@@ -1475,6 +1475,21 @@ add_fp_unittest(
     libc.src.__support.FPUtil.manipulation_functions
 )
 
+add_fp_unittest(
+  llogbf16_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    llogbf16_test.cpp
+  HDRS
+    ILogbTest.h
+  DEPENDS
+    libc.src.math.llogbf16
+    libc.src.__support.CPP.limits
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.manipulation_functions
+)
+
 add_fp_unittest(
   llogbf128_test
   SUITE

libc/test/src/math/smoke/llogbf16_test.cpp

@@ -0,0 +1,13 @@
+//===-- Unittests for llogbf16 --------------------------------------------===//
+//
+// 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 "ILogbTest.h"
+
+#include "src/math/llogbf16.h"
+
+LIST_INTLOGB_TESTS(long, float16, LIBC_NAMESPACE::llogbf16);