[libc][math][c23] Add fabsf16 C23 math function (llvm#93567)

overmighty · web-flow · commit 0eb9e021b15f · 2024-05-30T15:37:15.000-04:00
cc @lntue
diff --git a/libc/cmake/modules/CheckCompilerFeatures.cmake b/libc/cmake/modules/CheckCompilerFeatures.cmake
@@ -2,7 +2,7 @@
 # Compiler features definition and flags
 # ------------------------------------------------------------------------------
 
-set(ALL_COMPILER_FEATURES "float128" "fixed_point")
+set(ALL_COMPILER_FEATURES "float16" "float128" "fixed_point")
 
 # Making sure ALL_COMPILER_FEATURES is sorted.
 list(SORT ALL_COMPILER_FEATURES)
@@ -54,7 +54,9 @@ foreach(feature IN LISTS ALL_COMPILER_FEATURES)
   )
   if(has_feature)
     list(APPEND AVAILABLE_COMPILER_FEATURES ${feature})
-    if(${feature} STREQUAL "float128")
+    if(${feature} STREQUAL "float16")
+      set(LIBC_TYPES_HAS_FLOAT16 TRUE)
+    elseif(${feature} STREQUAL "float128")
       set(LIBC_TYPES_HAS_FLOAT128 TRUE)
     elseif(${feature} STREQUAL "fixed_point")
       set(LIBC_COMPILER_HAS_FIXED_POINT TRUE)
diff --git a/libc/cmake/modules/compiler_features/check_float16.cpp b/libc/cmake/modules/compiler_features/check_float16.cpp
@@ -0,0 +1,5 @@
+#include "include/llvm-libc-macros/float16-macros.h"
+
+#ifndef LIBC_TYPES_HAS_FLOAT16
+#error unsupported
+#endif
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
@@ -496,6 +496,13 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.ufromfpxl
 )
 
+if(LIBC_TYPES_HAS_FLOAT16)
+  list(APPEND TARGET_LIBM_ENTRYPOINTS
+    # math.h C23 _Float16 entrypoints
+    libc.src.math.fabsf16
+  )
+endif()
+
 if(LIBC_TYPES_HAS_FLOAT128)
   list(APPEND TARGET_LIBM_ENTRYPOINTS
     # math.h C23 _Float128 entrypoints
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
@@ -528,6 +528,13 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.ufromfpxl
 )
 
+if(LIBC_TYPES_HAS_FLOAT16)
+  list(APPEND TARGET_LIBM_ENTRYPOINTS
+    # math.h C23 _Float16 entrypoints
+    libc.src.math.fabsf16
+  )
+endif()
+
 if(LIBC_TYPES_HAS_FLOAT128)
   list(APPEND TARGET_LIBM_ENTRYPOINTS
     # math.h C23 _Float128 entrypoints
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
@@ -124,7 +124,7 @@ Basic Operations
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | dsub             | N/A              | N/A             |                        | N/A                  |                        | 7.12.14.2              | F.10.11                    |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| fabs             | |check|          | |check|         | |check|                |                      | |check|                | 7.12.7.3               | F.10.4.3                   |
+| fabs             | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.7.3               | F.10.4.3                   |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | fadd             | N/A              |                 |                        | N/A                  |                        | 7.12.14.1              | F.10.11                    |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
@@ -111,6 +111,7 @@ add_gen_header(
   GEN_HDR math.h
   DEPENDS
     .llvm_libc_common_h
+    .llvm-libc-macros.float16_macros
     .llvm-libc-macros.math_macros
     .llvm-libc-types.double_t
     .llvm-libc-types.float_t
diff --git a/libc/include/llvm-libc-macros/CMakeLists.txt b/libc/include/llvm-libc-macros/CMakeLists.txt
@@ -91,6 +91,12 @@ add_macro_header(
     float-macros.h
 )
 
+add_macro_header(
+  float16_macros
+  HDR
+    float16-macros.h
+)
+
 add_macro_header(
   limits_macros
   HDR
diff --git a/libc/include/llvm-libc-macros/float16-macros.h b/libc/include/llvm-libc-macros/float16-macros.h
@@ -0,0 +1,17 @@
+//===-- Detection of _Float16 compiler builtin type -----------------------===//
+//
+// 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_MACROS_FLOAT16_MACROS_H
+#define LLVM_LIBC_MACROS_FLOAT16_MACROS_H
+
+#if defined(__FLT16_MANT_DIG__) &&                                             \
+    (!defined(__GNUC__) || __GNUC__ >= 13 || defined(__clang__))
+#define LIBC_TYPES_HAS_FLOAT16
+#endif
+
+#endif // LLVM_LIBC_MACROS_FLOAT16_MACROS_H
diff --git a/libc/include/math.h.def b/libc/include/math.h.def
@@ -10,6 +10,7 @@
 #define LLVM_LIBC_MATH_H
 
 #include "__llvm-libc-common.h"
+#include "llvm-libc-macros/float16-macros.h"
 #include "llvm-libc-macros/math-macros.h"
 #include "llvm-libc-types/float128.h"
 
diff --git a/libc/spec/spec.td b/libc/spec/spec.td
@@ -53,6 +53,7 @@ def UnsignedCharType : NamedType<"unsigned char">;
 def UnsignedShortType : NamedType<"unsigned short">;
 def BoolType : NamedType<"bool">;
 
+def Float16Type : NamedType<"_Float16">;
 def Float128Type : NamedType<"float128">;
 
 // Common types
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
@@ -395,6 +395,7 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"fabs", RetValSpec<DoubleType>, [ArgSpec<DoubleType>], [ConstAttr]>,
           FunctionSpec<"fabsf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
           FunctionSpec<"fabsl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>]>,
+          GuardedFunctionSpec<"fabsf16", RetValSpec<Float16Type>, [ArgSpec<Float16Type>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"fabsf128", RetValSpec<Float128Type>, [ArgSpec<Float128Type>], "LIBC_TYPES_HAS_FLOAT128">,
 
           FunctionSpec<"fdim", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,
diff --git a/libc/src/__support/CPP/type_traits/is_floating_point.h b/libc/src/__support/CPP/type_traits/is_floating_point.h
@@ -24,13 +24,17 @@ template <typename T> struct is_floating_point {
   }
 
 public:
-#if defined(LIBC_TYPES_HAS_FLOAT128)
   LIBC_INLINE_VAR static constexpr bool value =
-      __is_unqualified_any_of<T, float, double, long double, float128>();
-#else
-  LIBC_INLINE_VAR static constexpr bool value =
-      __is_unqualified_any_of<T, float, double, long double>();
-#endif // LIBC_TYPES_HAS_FLOAT128
+      __is_unqualified_any_of<T, float, double, long double
+#ifdef LIBC_TYPES_HAS_FLOAT16
+                              ,
+                              float16
+#endif
+#ifdef LIBC_TYPES_HAS_FLOAT128
+                              ,
+                              float128
+#endif
+                              >();
 };
 template <typename T>
 LIBC_INLINE_VAR constexpr bool is_floating_point_v =
diff --git a/libc/src/__support/FPUtil/FPBits.h b/libc/src/__support/FPUtil/FPBits.h
@@ -651,7 +651,7 @@ struct FPRepImpl : public FPRepSem<fp_type, RetT> {
 
   // Modifiers
   LIBC_INLINE constexpr RetT abs() const {
-    return RetT(bits & UP::EXP_SIG_MASK);
+    return RetT(static_cast<StorageType>(bits & UP::EXP_SIG_MASK));
   }
 
   // Observers
diff --git a/libc/src/__support/macros/properties/CMakeLists.txt b/libc/src/__support/macros/properties/CMakeLists.txt
@@ -34,5 +34,6 @@ add_header_library(
     .cpu_features
     .os
     libc.hdr.float_macros
+    libc.include.llvm-libc-macros.float16_macros
     libc.include.llvm-libc-types.float128
 )
diff --git a/libc/src/__support/macros/properties/types.h b/libc/src/__support/macros/properties/types.h
@@ -11,7 +11,8 @@
 #define LLVM_LIBC_SRC___SUPPORT_MACROS_PROPERTIES_TYPES_H
 
 #include "hdr/float_macros.h"                      // LDBL_MANT_DIG
-#include "include/llvm-libc-types/float128.h"      // float128
+#include "include/llvm-libc-macros/float16-macros.h" // LIBC_TYPES_HAS_FLOAT16
+#include "include/llvm-libc-types/float128.h"        // float128
 #include "src/__support/macros/properties/architectures.h"
 #include "src/__support/macros/properties/compiler.h"
 #include "src/__support/macros/properties/cpu_features.h"
@@ -39,28 +40,12 @@
 #endif // defined(__SIZEOF_INT128__)
 
 // -- float16 support ---------------------------------------------------------
-// TODO: move this logic to "llvm-libc-types/float16.h"
-#if defined(LIBC_TARGET_ARCH_IS_X86_64) && defined(LIBC_TARGET_CPU_HAS_SSE2)
-#if (defined(LIBC_COMPILER_CLANG_VER) && (LIBC_COMPILER_CLANG_VER >= 1500)) || \
-    (defined(LIBC_COMPILER_GCC_VER) && (LIBC_COMPILER_GCC_VER >= 1201))
-#define LIBC_TYPES_HAS_FLOAT16
+// LIBC_TYPES_HAS_FLOAT16 is provided by
+// "include/llvm-libc-macros/float16-macros.h"
+#ifdef LIBC_TYPES_HAS_FLOAT16
+// Type alias for internal use.
 using float16 = _Float16;
-#endif
-#endif
-#if defined(LIBC_TARGET_ARCH_IS_AARCH64)
-#if (defined(LIBC_COMPILER_CLANG_VER) && (LIBC_COMPILER_CLANG_VER >= 900)) ||  \
-    (defined(LIBC_COMPILER_GCC_VER) && (LIBC_COMPILER_GCC_VER >= 1301))
-#define LIBC_TYPES_HAS_FLOAT16
-using float16 = _Float16;
-#endif
-#endif
-#if defined(LIBC_TARGET_ARCH_IS_ANY_RISCV)
-#if (defined(LIBC_COMPILER_CLANG_VER) && (LIBC_COMPILER_CLANG_VER >= 1300)) || \
-    (defined(LIBC_COMPILER_GCC_VER) && (LIBC_COMPILER_GCC_VER >= 1301))
-#define LIBC_TYPES_HAS_FLOAT16
-using float16 = _Float16;
-#endif
-#endif
+#endif // LIBC_TYPES_HAS_FLOAT16
 
 // -- float128 support --------------------------------------------------------
 // LIBC_TYPES_HAS_FLOAT128 and 'float128' type are provided by
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
@@ -99,6 +99,7 @@ add_math_entrypoint_object(expm1f)
 add_math_entrypoint_object(fabs)
 add_math_entrypoint_object(fabsf)
 add_math_entrypoint_object(fabsl)
+add_math_entrypoint_object(fabsf16)
 add_math_entrypoint_object(fabsf128)
 
 add_math_entrypoint_object(fdim)
diff --git a/libc/src/math/fabsf16.h b/libc/src/math/fabsf16.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for fabsf16 -----------------------*- 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_FABSF16_H
+#define LLVM_LIBC_SRC_MATH_FABSF16_H
+
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE {
+
+float16 fabsf16(float16 x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_FABSF16_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
@@ -241,6 +241,19 @@ add_entrypoint_object(
     -O2
 )
 
+add_entrypoint_object(
+  fabsf16
+  SRCS
+    fabsf16.cpp
+  HDRS
+    ../fabsf16.h
+  DEPENDS
+    libc.src.__support.macros.properties.types
+    libc.src.__support.FPUtil.basic_operations
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   fabsf128
   SRCS
diff --git a/libc/src/math/generic/fabsf16.cpp b/libc/src/math/generic/fabsf16.cpp
@@ -0,0 +1,17 @@
+//===-- Implementation of fabsf16 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/fabsf16.h"
+#include "src/__support/FPUtil/BasicOperations.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float16, fabsf16, (float16 x)) { return fputil::abs(x); }
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
@@ -92,6 +92,18 @@ add_fp_unittest(
     libc.src.__support.FPUtil.fp_bits
 )
 
+add_fp_unittest(
+  fabsf16_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    fabsf16_test.cpp
+  HDRS
+    FAbsTest.h
+  DEPENDS
+    libc.src.math.fabsf16
+)
+
 add_fp_unittest(
   fabsf128_test
   SUITE
diff --git a/libc/test/src/math/smoke/fabsf16_test.cpp b/libc/test/src/math/smoke/fabsf16_test.cpp
@@ -0,0 +1,13 @@
+//===-- Unittests for fabsf16 ---------------------------------------------===//
+//
+// 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 "FAbsTest.h"
+
+#include "src/math/fabsf16.h"
+
+LIST_FABS_TESTS(float16, LIBC_NAMESPACE::fabsf16)
