[libc][math][c23] Add nextup{,f,f128} and nextdown{,f,f128} functions (#85431)

See #85283.

I had a test for `nextdownl` that was failing and I thought I should add
`nextupl` and `nextdownl` later and first make a PR for the other
functions.

cc @lntue

Author: overmighty

libc/config/linux/x86_64/entrypoints.txt

@@ -429,6 +429,10 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.nexttoward
     libc.src.math.nexttowardf
     libc.src.math.nexttowardl
+    libc.src.math.nextdown
+    libc.src.math.nextdownf
+    libc.src.math.nextup
+    libc.src.math.nextupf
     libc.src.math.powf
     libc.src.math.remainderf
     libc.src.math.remainder
@@ -483,6 +487,8 @@ if(LIBC_TYPES_HAS_FLOAT128)
     libc.src.math.modff128
     libc.src.math.nanf128
     libc.src.math.nextafterf128
+    libc.src.math.nextdownf128
+    libc.src.math.nextupf128
     libc.src.math.rintf128
     libc.src.math.roundf128
     libc.src.math.sqrtf128

libc/spec/stdc.td

@@ -536,6 +536,14 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"nexttoward", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<LongDoubleType>]>,
           FunctionSpec<"nexttowardl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>]>,
 
+          FunctionSpec<"nextdown", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
+          FunctionSpec<"nextdownf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
+          GuardedFunctionSpec<"nextdownf128", RetValSpec<Float128Type>, [ArgSpec<Float128Type>], "LIBC_TYPES_HAS_FLOAT128">,
+
+          FunctionSpec<"nextup", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
+          FunctionSpec<"nextupf", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
+          GuardedFunctionSpec<"nextupf128", RetValSpec<Float128Type>, [ArgSpec<Float128Type>], "LIBC_TYPES_HAS_FLOAT128">,
+
           FunctionSpec<"powf", RetValSpec<FloatType>, [ArgSpec<FloatType>, ArgSpec<FloatType>]>,
           FunctionSpec<"pow", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,
 

libc/src/__support/FPUtil/ManipulationFunctions.h

@@ -230,6 +230,30 @@ LIBC_INLINE T nextafter(T from, U to) {
   return from_bits.get_val();
 }
 
+template <bool IsDown, typename T,
+          cpp::enable_if_t<cpp::is_floating_point_v<T>, int> = 0>
+LIBC_INLINE constexpr T nextupdown(T x) {
+  constexpr Sign sign = IsDown ? Sign::NEG : Sign::POS;
+
+  FPBits<T> xbits(x);
+  if (xbits.is_nan() || xbits == FPBits<T>::max_normal(sign) ||
+      xbits == FPBits<T>::inf(sign))
+    return x;
+
+  using StorageType = typename FPBits<T>::StorageType;
+  if (x != T(0)) {
+    if (xbits.sign() == sign) {
+      xbits = FPBits<T>(StorageType(xbits.uintval() + 1));
+    } else {
+      xbits = FPBits<T>(StorageType(xbits.uintval() - 1));
+    }
+  } else {
+    xbits = FPBits<T>::min_subnormal(sign);
+  }
+
+  return xbits.get_val();
+}
+
 } // namespace fputil
 } // namespace LIBC_NAMESPACE
 

libc/src/math/CMakeLists.txt

@@ -205,6 +205,14 @@ add_math_entrypoint_object(nexttoward)
 add_math_entrypoint_object(nexttowardf)
 add_math_entrypoint_object(nexttowardl)
 
+add_math_entrypoint_object(nextdown)
+add_math_entrypoint_object(nextdownf)
+add_math_entrypoint_object(nextdownf128)
+
+add_math_entrypoint_object(nextup)
+add_math_entrypoint_object(nextupf)
+add_math_entrypoint_object(nextupf128)
+
 add_math_entrypoint_object(pow)
 add_math_entrypoint_object(powf)
 

libc/src/math/generic/CMakeLists.txt

@@ -1878,6 +1878,80 @@ add_entrypoint_object(
     -O3
 )
 
+add_entrypoint_object(
+  nextdown
+  SRCS
+    nextdown.cpp
+  HDRS
+    ../nextdown.h
+  DEPENDS
+    libc.src.__support.FPUtil.manipulation_functions
+  COMPILE_OPTIONS
+    -O3
+)
+
+add_entrypoint_object(
+  nextdownf
+  SRCS
+    nextdownf.cpp
+  HDRS
+    ../nextdownf.h
+  DEPENDS
+    libc.src.__support.FPUtil.manipulation_functions
+  COMPILE_OPTIONS
+    -O3
+)
+
+add_entrypoint_object(
+  nextdownf128
+  SRCS
+    nextdownf128.cpp
+  HDRS
+    ../nextdownf128.h
+  DEPENDS
+    libc.src.__support.macros.properties.types
+    libc.src.__support.FPUtil.manipulation_functions
+  COMPILE_OPTIONS
+    -O3
+)
+
+add_entrypoint_object(
+  nextup
+  SRCS
+    nextup.cpp
+  HDRS
+    ../nextup.h
+  DEPENDS
+    libc.src.__support.FPUtil.manipulation_functions
+  COMPILE_OPTIONS
+    -O3
+)
+
+add_entrypoint_object(
+  nextupf
+  SRCS
+    nextupf.cpp
+  HDRS
+    ../nextupf.h
+  DEPENDS
+    libc.src.__support.FPUtil.manipulation_functions
+  COMPILE_OPTIONS
+    -O3
+)
+
+add_entrypoint_object(
+  nextupf128
+  SRCS
+    nextupf128.cpp
+  HDRS
+    ../nextupf128.h
+  DEPENDS
+    libc.src.__support.macros.properties.types
+    libc.src.__support.FPUtil.manipulation_functions
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   fmod
   SRCS

libc/src/math/generic/nextdown.cpp

@@ -0,0 +1,19 @@
+//===-- Implementation of nextdown 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/nextdown.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(double, nextdown, (double x)) {
+  return fputil::nextupdown</*IsDown=*/true>(x);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/math/generic/nextdownf.cpp

@@ -0,0 +1,19 @@
+//===-- Implementation of nextdownf 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/nextdownf.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float, nextdownf, (float x)) {
+  return fputil::nextupdown</*IsDown=*/true>(x);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/math/generic/nextdownf128.cpp

@@ -0,0 +1,19 @@
+//===-- Implementation of nextdownf128 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/nextdownf128.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float128, nextdownf128, (float128 x)) {
+  return fputil::nextupdown</*IsDown=*/true>(x);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/math/generic/nextup.cpp

@@ -0,0 +1,19 @@
+//===-- Implementation of nextup 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/nextup.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(double, nextup, (double x)) {
+  return fputil::nextupdown</*IsDown=*/false>(x);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/math/generic/nextupf.cpp

@@ -0,0 +1,19 @@
+//===-- Implementation of nextupf 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/nextupf.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float, nextupf, (float x)) {
+  return fputil::nextupdown</*IsDown=*/false>(x);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/math/generic/nextupf128.cpp

@@ -0,0 +1,19 @@
+//===-- Implementation of nextupf128 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/nextupf128.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float128, nextupf128, (float128 x)) {
+  return fputil::nextupdown</*IsDown=*/false>(x);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/math/nextdown.h

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

libc/src/math/nextdownf.h

@@ -0,0 +1,18 @@
+//===-- Implementation header for nextdownf ---------------------*- 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_NEXTDOWNF_H
+#define LLVM_LIBC_SRC_MATH_NEXTDOWNF_H
+
+namespace LIBC_NAMESPACE {
+
+float nextdownf(float x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_NEXTDOWNF_H

libc/src/math/nextdownf128.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for nextdownf128 ------------------*- 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_NEXTDOWNF128_H
+#define LLVM_LIBC_SRC_MATH_NEXTDOWNF128_H
+
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE {
+
+float128 nextdownf128(float128 x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_NEXTDOWNF128_H

libc/src/math/nextup.h

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

libc/src/math/nextupf.h

@@ -0,0 +1,18 @@
+//===-- Implementation header for nextupf -----------------------*- 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_NEXTUPF_H
+#define LLVM_LIBC_SRC_MATH_NEXTUPF_H
+
+namespace LIBC_NAMESPACE {
+
+float nextupf(float x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_NEXTUPF_H

libc/src/math/nextupf128.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for nextupf128 --------------------*- 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_NEXTUPF128_H
+#define LLVM_LIBC_SRC_MATH_NEXTUPF128_H
+
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE {
+
+float128 nextupf128(float128 x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_NEXTUPF128_H