[libc][math][c23] Add modff128 C23 math function.

libc/config/linux/aarch64/entrypoints.txt

@@ -434,6 +434,7 @@ if(LIBC_TYPES_HAS_FLOAT128)
     libc.src.math.llroundf128
     libc.src.math.lrintf128
     libc.src.math.lroundf128
+    libc.src.math.modff128
     libc.src.math.rintf128
     libc.src.math.roundf128
     libc.src.math.sqrtf128

libc/config/linux/riscv/entrypoints.txt

@@ -442,6 +442,7 @@ if(LIBC_TYPES_HAS_FLOAT128)
     libc.src.math.llroundf128
     libc.src.math.lrintf128
     libc.src.math.lroundf128
+    libc.src.math.modff128
     libc.src.math.rintf128
     libc.src.math.roundf128
     libc.src.math.sqrtf128

libc/config/linux/x86_64/entrypoints.txt

@@ -472,6 +472,7 @@ if(LIBC_TYPES_HAS_FLOAT128)
     libc.src.math.llroundf128
     libc.src.math.lrintf128
     libc.src.math.lroundf128
+    libc.src.math.modff128
     libc.src.math.rintf128
     libc.src.math.roundf128
     libc.src.math.sqrtf128

libc/docs/math/index.rst

@@ -249,6 +249,8 @@ Basic Operations
 +--------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
 | modfl        | |check| | |check| | |check| | |check| | |check| |         |         | |check| | |check| | |check| |         |         |
 +--------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
+| modff128     | |check| | |check| |         | |check| |         |         |         |         |         |         |         |         |
++--------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
 | nan          | |check| | |check| | |check| | |check| | |check| |         |         | |check| | |check| | |check| |         |         |
 +--------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
 | nanf         | |check| | |check| | |check| | |check| | |check| |         |         | |check| | |check| | |check| |         |         |

libc/spec/spec.td

@@ -111,6 +111,7 @@ def IntPtr : PtrType<IntType>;
 def RestrictedIntPtr : RestrictedPtrType<IntType>;
 def FloatPtr : PtrType<FloatType>;
 def DoublePtr : PtrType<DoubleType>;
+def Float128Ptr : PtrType<Float128Type>;
 def UnsignedCharPtr : PtrType<UnsignedCharType>;
 
 def SigHandlerT : NamedType<"__sighandler_t">;

libc/spec/stdc.td

@@ -451,6 +451,7 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"modf", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoublePtr>]>,
           FunctionSpec<"modff", RetValSpec<FloatType>, [ArgSpec<FloatType>, ArgSpec<FloatPtr>]>,
           FunctionSpec<"modfl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoublePtr>]>,
+          GuardedFunctionSpec<"modff128", RetValSpec<Float128Type>, [ArgSpec<Float128Type>, ArgSpec<Float128Ptr>], "LIBC_TYPES_HAS_FLOAT128">,
 
           FunctionSpec<"cos", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
           FunctionSpec<"cosf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,

libc/src/math/CMakeLists.txt

@@ -183,6 +183,7 @@ add_math_entrypoint_object(lroundf128)
 add_math_entrypoint_object(modf)
 add_math_entrypoint_object(modff)
 add_math_entrypoint_object(modfl)
+add_math_entrypoint_object(modff128)
 
 add_math_entrypoint_object(nan)
 add_math_entrypoint_object(nanf)

libc/src/math/generic/CMakeLists.txt

@@ -1407,7 +1407,7 @@ add_entrypoint_object(
   DEPENDS
     libc.src.__support.FPUtil.manipulation_functions
   COMPILE_OPTIONS
-    -O2
+    -O3
 )
 
 add_entrypoint_object(
@@ -1419,7 +1419,7 @@ add_entrypoint_object(
   DEPENDS
     libc.src.__support.FPUtil.manipulation_functions
   COMPILE_OPTIONS
-    -O2
+    -O3
 )
 
 add_entrypoint_object(
@@ -1431,7 +1431,20 @@ add_entrypoint_object(
   DEPENDS
     libc.src.__support.FPUtil.manipulation_functions
   COMPILE_OPTIONS
-    -O2
+    -O3
+)
+
+add_entrypoint_object(
+  modff128
+  SRCS
+    modff128.cpp
+  HDRS
+    ../modff128.h
+  DEPENDS
+    libc.src.__support.macros.properties.types
+    libc.src.__support.FPUtil.manipulation_functions
+  COMPILE_OPTIONS
+    -O3
 )
 
 add_entrypoint_object(

libc/src/math/generic/modff128.cpp

@@ -0,0 +1,19 @@
+//===-- Implementation of modff128 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/modff128.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float128, modff128, (float128 x, float128 *iptr)) {
+  return fputil::modf(x, *iptr);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/math/modff128.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for modff128 -----------------------*- 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_MODFF128_H
+#define LLVM_LIBC_SRC_MATH_MODFF128_H
+
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE {
+
+float128 modff128(float128 x, float128 *iptr);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_MODFF128_H

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

@@ -1078,8 +1078,6 @@ add_fp_unittest(
     libc.src.math.modf
     libc.src.__support.FPUtil.basic_operations
     libc.src.__support.FPUtil.nearest_integer_operations
-  # Requires C++ limits.
-  UNIT_TEST_ONLY
 )
 
 add_fp_unittest(
@@ -1095,8 +1093,6 @@ add_fp_unittest(
     libc.src.math.modff
     libc.src.__support.FPUtil.basic_operations
     libc.src.__support.FPUtil.nearest_integer_operations
-  # Requires C++ limits.
-  UNIT_TEST_ONLY
 )
 
 add_fp_unittest(
@@ -1114,6 +1110,21 @@ add_fp_unittest(
     libc.src.__support.FPUtil.nearest_integer_operations
 )
 
+add_fp_unittest(
+  modff128_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    modff128_test.cpp
+  HDRS
+    ModfTest.h
+  DEPENDS
+    libc.include.math
+    libc.src.math.modff128
+    libc.src.__support.FPUtil.basic_operations
+    libc.src.__support.FPUtil.nearest_integer_operations
+)
+
 add_fp_unittest(
   fdimf_test
   SUITE

libc/test/src/math/smoke/ModfTest.h

@@ -84,10 +84,12 @@ template <typename T> class ModfTest : public LIBC_NAMESPACE::testing::Test {
     constexpr StorageType COUNT = 100'000;
     constexpr StorageType STEP = STORAGE_MAX / COUNT;
     for (StorageType i = 0, v = 0; i <= COUNT; ++i, v += STEP) {
-      T x = FPBits(v).get_val();
-      if (isnan(x) || isinf(x) || x == T(0.0))
+      FPBits x_bits = FPBits(v);
+      if (x_bits.is_zero() || x_bits.is_inf_or_nan())
         continue;
 
+      T x = x_bits.get_val();
+
       T integral;
       T frac = func(x, &integral);
       ASSERT_TRUE(LIBC_NAMESPACE::fputil::abs(frac) < 1.0l);

libc/test/src/math/smoke/modff128_test.cpp

@@ -0,0 +1,13 @@
+//===-- Unittests for modff128 --------------------------------------------===//
+//
+// 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 "ModfTest.h"
+
+#include "src/math/modff128.h"
+
+LIST_MODF_TESTS(float128, LIBC_NAMESPACE::modff128)