[libc][math][c23] Add fabsf16 C23 math function #93567

overmighty · 2024-05-28T16:02:33Z

cc @lntue

llvmbot · 2024-05-28T16:03:08Z

@llvm/pr-subscribers-libc

Author: OverMighty (overmighty)

Changes

cc @lntue

Full diff: https://github.com/llvm/llvm-project/pull/93567.diff

16 Files Affected:

(modified) libc/cmake/modules/CheckCompilerFeatures.cmake (+4-2)
(added) libc/cmake/modules/compiler_features/check_float16.cpp (+5)
(modified) libc/config/linux/x86_64/entrypoints.txt (+7)
(modified) libc/include/llvm-libc-types/CMakeLists.txt (+1)
(added) libc/include/llvm-libc-types/float16.h (+38)
(modified) libc/spec/spec.td (+1)
(modified) libc/spec/stdc.td (+2)
(modified) libc/src/__support/CPP/type_traits/is_floating_point.h (+8-1)
(modified) libc/src/__support/FPUtil/FPBits.h (+1-1)
(modified) libc/src/__support/macros/properties/types.h (+3-22)
(modified) libc/src/math/CMakeLists.txt (+1)
(added) libc/src/math/fabsf16.h (+20)
(modified) libc/src/math/generic/CMakeLists.txt (+13)
(added) libc/src/math/generic/fabsf16.cpp (+17)
(modified) libc/test/src/math/smoke/CMakeLists.txt (+13)
(added) libc/test/src/math/smoke/fabsf16_test.cpp (+13)

diff --git a/libc/cmake/modules/CheckCompilerFeatures.cmake b/libc/cmake/modules/CheckCompilerFeatures.cmake
index 3a9e1e3b1cf8b..17806588550eb 100644
--- 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
new file mode 100644
index 0000000000000..133c559eed219
--- /dev/null
+++ b/libc/cmake/modules/compiler_features/check_float16.cpp
@@ -0,0 +1,5 @@
+#include "src/__support/macros/properties/types.h"
+
+#ifndef LIBC_TYPES_HAS_FLOAT16
+#error unsupported
+#endif
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 5e3ddd34fb4dc..03cd17a8090cb 100644
--- 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/include/llvm-libc-types/CMakeLists.txt b/libc/include/llvm-libc-types/CMakeLists.txt
index 018b6c58316c3..6f3e123f78d8f 100644
--- a/libc/include/llvm-libc-types/CMakeLists.txt
+++ b/libc/include/llvm-libc-types/CMakeLists.txt
@@ -119,6 +119,7 @@ add_header(ENTRY HDR ENTRY.h)
 add_header(struct_hsearch_data HDR struct_hsearch_data.h)
 add_header(struct_epoll_event HDR struct_epoll_event.h)
 add_header(struct_epoll_data HDR struct_epoll_data.h)
+add_header(float16 HDR float16.h)
 add_header(
   float128
   HDR
diff --git a/libc/include/llvm-libc-types/float16.h b/libc/include/llvm-libc-types/float16.h
new file mode 100644
index 0000000000000..671d9c1b97b7f
--- /dev/null
+++ b/libc/include/llvm-libc-types/float16.h
@@ -0,0 +1,38 @@
+//===-- Definition of float16 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_TYPES_FLOAT16_H
+#define LLVM_LIBC_TYPES_FLOAT16_H
+
+#include "src/__support/macros/properties/architectures.h"
+#include "src/__support/macros/properties/compiler.h"
+#include "src/__support/macros/properties/cpu_features.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
+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 // LLVM_LIBC_TYPES_FLOAT16_H
diff --git a/libc/spec/spec.td b/libc/spec/spec.td
index ea8fa4cd373cf..966e1f5df47c1 100644
--- 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
index eb67c9b0b009b..6034a6e1aa703 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -378,6 +378,7 @@ def StdC : StandardSpec<"stdc"> {
       [
           NamedType<"float_t">,
           NamedType<"double_t">,
+          Float16Type,
           NamedType<"float128">,
       ],
       [], // Enumerations
@@ -395,6 +396,7 @@ 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
index 4c8f50f4e91f9..39150d64b7876 100644
--- a/libc/src/__support/CPP/type_traits/is_floating_point.h
+++ b/libc/src/__support/CPP/type_traits/is_floating_point.h
@@ -24,7 +24,14 @@ template <typename T> struct is_floating_point {
   }
 
 public:
-#if defined(LIBC_TYPES_HAS_FLOAT128)
+#if defined(LIBC_TYPES_HAS_FLOAT16) && defined(LIBC_TYPES_HAS_FLOAT128)
+  LIBC_INLINE_VAR static constexpr bool value =
+      __is_unqualified_any_of<T, float, double, long double, float16,
+                              float128>();
+#elif defined(LIBC_TYPES_HAS_FLOAT16)
+  LIBC_INLINE_VAR static constexpr bool value =
+      __is_unqualified_any_of<T, float, double, long double, float16>();
+#elif defined(LIBC_TYPES_HAS_FLOAT128)
   LIBC_INLINE_VAR static constexpr bool value =
       __is_unqualified_any_of<T, float, double, long double, float128>();
 #else
diff --git a/libc/src/__support/FPUtil/FPBits.h b/libc/src/__support/FPUtil/FPBits.h
index ab050360c353b..d3c96d2d613d6 100644
--- 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/types.h b/libc/src/__support/macros/properties/types.h
index d43cf99e6859b..4baf9fae36f7f 100644
--- a/libc/src/__support/macros/properties/types.h
+++ b/libc/src/__support/macros/properties/types.h
@@ -12,6 +12,7 @@
 
 #include "include/llvm-libc-macros/float-macros.h" // LDBL_MANT_DIG
 #include "include/llvm-libc-types/float128.h"      // float128
+#include "include/llvm-libc-types/float16.h"       // float16
 #include "src/__support/macros/properties/architectures.h"
 #include "src/__support/macros/properties/compiler.h"
 #include "src/__support/macros/properties/cpu_features.h"
@@ -39,28 +40,8 @@
 #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
-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
+// LIBC_TYPES_HAS_FLOAT16 and 'float16' type are provided by
+// "include/llvm-libc-types/float16.h"
 
 // -- 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
index c34c58575441d..31df5d0ab8809 100644
--- 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
new file mode 100644
index 0000000000000..532662a77e9a6
--- /dev/null
+++ 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
index daaf505008ca1..2a4dcdcf7ddde 100644
--- 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
new file mode 100644
index 0000000000000..4de84f35da302
--- /dev/null
+++ 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
index 112b2985829ca..c74f68daeb082 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -92,6 +92,19 @@ 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
+    libc.src.__support.FPUtil.fp_bits
+)
+
 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
new file mode 100644
index 0000000000000..c43bd5090f90b
--- /dev/null
+++ 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)

overmighty

Should we #include "src/__support/macros/properties/types.h" for float16, like we do for float128, or should we #include "llvm-libc-types/float16.h"?

libc/include/llvm-libc-types/float16.h

libc/spec/stdc.td

nickdesaulniers · 2024-05-28T16:37:20Z

Should we #include "src/__support/macros/properties/types.h" for float16, like we do for float128, or should we #include "llvm-libc-types/float16.h"?

I think it's nice to be as specific as possible. To me, long include lists that are precise are a feature, not a bug.

libc/src/__support/CPP/type_traits/is_floating_point.h

libc/spec/stdc.td

libc/config/linux/api.td

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

libc/include/llvm-libc-types/float16.h

libc/src/__support/macros/properties/types.h

libc/include/llvm-libc-types/float16.h

Fix usage of internal float16 alias in generated headers.

Add check mark for fabsf16 in docs.

Fix missing include in generated math.h public header.

Replace includes for float16 alias with "include/llvm-libc-types/float16.h".

Simplify cpp::is_floating_point.

Simplify check for _Float16 support.

Fix llvm-libc-types/float16.h including internal header and exposing internal C++ using float16 stmt.

Remove unused direct dependency from fabsf16_test target.

Move _Float16 detection header to llvm-libc-macros/float16-macros.h.

overmighty · 2024-05-29T17:31:36Z

Rebased and fixed the merge conflict.

Enable fabsf16 entrypoint on linux/aarch64.

Delete libc/include/llvm-libc-types/float16.h.

llvmbot added the libc label May 28, 2024

overmighty commented May 28, 2024

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overmighty mentioned this pull request May 29, 2024

[gsoc2024][libc][math][c23] Implement _Float16 basic operations #93566

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overmighty added 10 commits May 29, 2024 19:25

[libc][math][c23] Add fabsf16 C23 math function

f5f64f9

fixup! [libc][math][c23] Add fabsf16 C23 math function

e2ec1d5

Fix usage of internal float16 alias in generated headers.

fixup! [libc][math][c23] Add fabsf16 C23 math function

04c701c

Add check mark for fabsf16 in docs.

fixup! [libc][math][c23] Add fabsf16 C23 math function

e1c6035

Fix missing include in generated math.h public header.

fixup! [libc][math][c23] Add fabsf16 C23 math function

079c7ad

Replace includes for float16 alias with "include/llvm-libc-types/float16.h".

fixup! [libc][math][c23] Add fabsf16 C23 math function

304f7d7

Simplify cpp::is_floating_point.

fixup! [libc][math][c23] Add fabsf16 C23 math function

c651c80

Simplify check for _Float16 support.

fixup! [libc][math][c23] Add fabsf16 C23 math function

d5d24c6

Fix llvm-libc-types/float16.h including internal header and exposing internal C++ using float16 stmt.

fixup! [libc][math][c23] Add fabsf16 C23 math function

41220f5

Remove unused direct dependency from fabsf16_test target.

fixup! [libc][math][c23] Add fabsf16 C23 math function

8931477

Move _Float16 detection header to llvm-libc-macros/float16-macros.h.

overmighty force-pushed the libc-math-fabsf16 branch from de04a24 to 8931477 Compare May 29, 2024 17:31

overmighty added 2 commits May 30, 2024 19:29

fixup! [libc][math][c23] Add fabsf16 C23 math function

c4dc50e

Enable fabsf16 entrypoint on linux/aarch64.

fixup! [libc][math][c23] Add fabsf16 C23 math function

9e1b138

Delete libc/include/llvm-libc-types/float16.h.

lntue approved these changes May 30, 2024

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lntue merged commit 0eb9e02 into llvm:main May 30, 2024
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keith added a commit that referenced this pull request May 30, 2024

[bazel] Port #93567 (#93877)

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[libc][math][c23] Add fabsf16 C23 math function #93567

[libc][math][c23] Add fabsf16 C23 math function #93567

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overmighty commented May 29, 2024

[libc][math][c23] Add fabsf16 C23 math function #93567

[libc][math][c23] Add fabsf16 C23 math function #93567

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