[libc-commits] [libc] [libc][math] Add Generic Comparison Operations for floating point types (PR #144983)

[Krishna Pandey via libc-commits]

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@@ -0,0 +1,113 @@
+//===-- Comparison operations on floating point numbers ---------*- 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___SUPPORT_FPUTIL_COMPARISONOPERATIONS_H
+#define LLVM_LIBC_SRC___SUPPORT_FPUTIL_COMPARISONOPERATIONS_H
+
+#include "FEnvImpl.h"                      // raise_except_if_required
+#include "FPBits.h"                        // FPBits<T>
+#include "src/__support/CPP/type_traits.h" // enable_if, is_floating_point
+#include "src/__support/macros/config.h"   // LIBC_NAMESPACE_DECL
+
+namespace LIBC_NAMESPACE_DECL {
+namespace fputil {
+
+// IEEE Standard 754-2019. Section 5.11
+// Rules for comparison within the same floating point type
+// 1. +0 = −0
+// 2. (i)   +inf  = +inf
+//    (ii)  -inf  = -inf
+//    (iii) -inf != +inf
+// 3. Any comparison with NaN return false except (NaN != NaN => true)
+template <typename T>
+LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<T>, bool> equals(T x,
+                                                                       T y) {
+  using FPBits = FPBits<T>;
+  FPBits x_bits(x);
+  FPBits y_bits(y);
+
+  if (x_bits.is_signaling_nan() || y_bits.is_signaling_nan())
+    fputil::raise_except_if_required(FE_INVALID);
+
+  // NaN == x returns false for every x
+  if (x_bits.is_nan() || y_bits.is_nan())
+    return false;
+
+  // +/- 0 == +/- 0
+  if (x_bits.is_zero() && y_bits.is_zero())
+    return true;
+
+  // should also work for comparisons of different signs
+  return x_bits.uintval() == y_bits.uintval();
+}
+
+// Rules:
+// 1. -inf < x (x != -inf)
+// 2. x < +inf (x != +inf)
+// 3. Any comparison with NaN return false
+template <typename T>
+LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<T>, bool> less_than(T x,
+                                                                          T y) {
+  using FPBits = FPBits<T>;
+  FPBits x_bits(x);
+  FPBits y_bits(y);
+
+  if (x_bits.is_signaling_nan() || y_bits.is_signaling_nan() ||
+      x_bits.is_quiet_nan() || y_bits.is_quiet_nan())
+    fputil::raise_except_if_required(FE_INVALID);
+
+  // Any comparison with NaN returns false
+  if (x_bits.is_nan() || y_bits.is_nan())
+    return false;
----------------
krishna2803 wrote:

updated, as of [4a69dc51](https://github.com/llvm/llvm-project/pull/144983/commits/4a69dc512d328e66b094b10ad0a0aad95766230c)

https://github.com/llvm/llvm-project/pull/144983