[llvm] [LLVM][IR] Add constant range support for floating-point types (PR #86483)

[Matt Arsenault via llvm-commits]

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+//===- ConstantFPRange.h - Represent a range for floating-point -*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Represent a range of possible values that may occur when the program is run
+// for a floating-point value. This keeps track of a lower and upper bound for
+// the constant.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_CONSTANTFPRANGE_H
+#define LLVM_IR_CONSTANTFPRANGE_H
+
+#include "llvm/ADT/APFloat.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/Support/Compiler.h"
+#include <optional>
+
+namespace llvm {
+
+class raw_ostream;
+struct KnownFPClass;
+
+/// This class represents a range of floating-point values.
+class [[nodiscard]] ConstantFPRange {
+  APFloat Lower, Upper;
+  bool MaybeQNaN : 1;
+  bool MaybeSNaN : 1;
+  bool SignBitMaybeZero : 1;
+  bool SignBitMaybeOne : 1;
+
+  /// Create empty constant range with same semantics.
+  ConstantFPRange getEmpty() const {
+    return ConstantFPRange(getSemantics(), /*IsFullSet=*/false);
+  }
+
+  /// Create full constant range with same semantics.
+  ConstantFPRange getFull() const {
+    return ConstantFPRange(getSemantics(), /*IsFullSet=*/true);
+  }
+
+public:
+  /// Initialize a full or empty set for the specified semantics.
+  explicit ConstantFPRange(const fltSemantics &FloatSema, bool IsFullSet);
+
+  /// Initialize a range to hold the single specified value.
+  ConstantFPRange(const APFloat &Value);
+
+  /// Initialize a range of values explicitly.
+  ConstantFPRange(APFloat Lower, APFloat Upper, bool MaybeQNaN, bool MaybeSNaN,
+                  bool SignBitMaybeZero, bool SignBitMaybeOne);
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arsenm wrote:

Default values for the nan/sign params 

https://github.com/llvm/llvm-project/pull/86483