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

Yingwei Zheng via llvm-commits llvm-commits at lists.llvm.org
Fri Jun 21 23:22:06 PDT 2024


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

>From 9928b1408e5cb949de0eb2ef705c62b85286a85c Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Tue, 27 Feb 2024 01:47:23 +0800
Subject: [PATCH 1/3] tmp

---
 llvm/include/llvm/IR/ConstantFPRange.h | 139 +++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 llvm/include/llvm/IR/ConstantFPRange.h

diff --git a/llvm/include/llvm/IR/ConstantFPRange.h b/llvm/include/llvm/IR/ConstantFPRange.h
new file mode 100644
index 0000000000000..89b0cd0b7763b
--- /dev/null
+++ b/llvm/include/llvm/IR/ConstantFPRange.h
@@ -0,0 +1,139 @@
+//===- 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);
+
+  /// Create empty constant range with the given semantics.
+  static ConstantFPRange getEmpty(const fltSemantics &FloatSema) {
+    return ConstantFPRange(FloatSema, /*IsFullSet=*/false);
+  }
+
+  /// Create full constant range with the given semantics.
+  static ConstantFPRange getFull(const fltSemantics &FloatSema) {
+    return ConstantFPRange(FloatSema, /*IsFullSet=*/true);
+  }
+
+  /// Initialize a range based on a known floating-point classes constraint.
+  static ConstantFPRange fromKnownFPClass(const KnownFPClass &Known);
+
+  /// Produce the exact range such that all values in the returned range satisfy
+  /// the given predicate with any value contained within Other. Formally, this
+  /// returns the exact answer when the superset of 'union over all y in Other
+  /// is exactly same as the subset of intersection over all y in Other.
+  /// { x : fcmp op x y is true}'.
+  ///
+  /// Example: Pred = olt and Other = float 3 returns [-inf, 3)
+  static ConstantFPRange makeExactFCmpRegion(FCmpInst::Predicate Pred,
+                                             const APFloat &Other);
+
+  /// Does the predicate \p Pred hold between ranges this and \p Other?
+  /// NOTE: false does not mean that inverse predicate holds!
+  bool fcmp(FCmpInst::Predicate Pred, const ConstantFPRange &Other) const;
+
+  /// Return the lower value for this range.
+  const APFloat &getLower() const { return Lower; }
+
+  /// Return the upper value for this range.
+  const APFloat &getUpper() const { return Upper; }
+
+  /// Get the semantics of this ConstantFPRange.
+  const fltSemantics &getSemantics() const { return Lower.getSemantics(); }
+
+  /// Return true if this set contains all of the elements possible
+  /// for this data-type.
+  bool isFullSet() const;
+
+  /// Return true if this set contains no members.
+  bool isEmptySet() const;
+
+  /// Return true if the specified value is in the set.
+  bool contains(const APFloat &Val) const;
+
+  /// Return true if the other range is a subset of this one.
+  bool contains(const ConstantFPRange &CR) const;
+
+  /// If this set contains a single element, return it, otherwise return null.
+  const APFloat *getSingleElement() const;
+
+  /// Return true if this set contains exactly one member.
+  bool isSingleElement() const { return getSingleElement() != nullptr; }
+
+  /// Return true if the sign bit of all values in this range is 1.
+  /// Return false if the sign bit of all values in this range is 0.
+  /// Otherwise, return std::nullopt.
+  std::optional<bool> getSignBit();
+
+  /// Return true if this range is equal to another range.
+  bool operator==(const ConstantFPRange &CR) const;
+  bool operator!=(const ConstantFPRange &CR) const { return !operator==(CR); }
+
+  /// Return known floating-point classes for values in this range.
+  KnownFPClass toKnownFPClass();
+
+  /// Print out the bounds to a stream.
+  void print(raw_ostream &OS) const;
+
+  /// Allow printing from a debugger easily.
+  void dump() const;
+};
+
+inline raw_ostream &operator<<(raw_ostream &OS, const ConstantFPRange &CR) {
+  CR.print(OS);
+  return OS;
+}
+
+} // end namespace llvm
+
+#endif // LLVM_IR_CONSTANTFPRANGE_H

>From 6491a81ec25f32819244021315dcc98af1407b78 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Fri, 21 Jun 2024 22:05:04 +0800
Subject: [PATCH 2/3] add basic implementation

---
 llvm/include/llvm/IR/ConstantFPRange.h |  79 ++++++--
 llvm/lib/IR/CMakeLists.txt             |   1 +
 llvm/lib/IR/ConstantFPRange.cpp        | 253 +++++++++++++++++++++++++
 3 files changed, 315 insertions(+), 18 deletions(-)
 create mode 100644 llvm/lib/IR/ConstantFPRange.cpp

diff --git a/llvm/include/llvm/IR/ConstantFPRange.h b/llvm/include/llvm/IR/ConstantFPRange.h
index 89b0cd0b7763b..3cfc6f362f2b8 100644
--- a/llvm/include/llvm/IR/ConstantFPRange.h
+++ b/llvm/include/llvm/IR/ConstantFPRange.h
@@ -10,15 +10,18 @@
 // for a floating-point value. This keeps track of a lower and upper bound for
 // the constant.
 //
+// Range = [Lower, Upper] U (MayBeQNaN ? QNaN : {}) U (MayBeSNaN ? SNaN : {})
+// Specifically, [inf, -inf] represents an empty set.
+// Note: -0 is considered to be less than 0. That is, range [0, 0] doesn't
+// contain -0.
+//
 //===----------------------------------------------------------------------===//
 
 #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 "llvm/IR/Instructions.h"
 #include <optional>
 
 namespace llvm {
@@ -29,10 +32,8 @@ 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;
+  bool MayBeQNaN : 1;
+  bool MayBeSNaN : 1;
 
   /// Create empty constant range with same semantics.
   ConstantFPRange getEmpty() const {
@@ -44,29 +45,55 @@ class [[nodiscard]] ConstantFPRange {
     return ConstantFPRange(getSemantics(), /*IsFullSet=*/true);
   }
 
+  void makeEmpty();
+  void makeFull();
+  bool isNaNOnly() const;
+
 public:
+  /// Return true if the floating point format is supported.
+  static bool isSupportedSemantics(const fltSemantics &Sem);
+
   /// Initialize a full or empty set for the specified semantics.
-  explicit ConstantFPRange(const fltSemantics &FloatSema, bool IsFullSet);
+  explicit ConstantFPRange(const fltSemantics &Sem, 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);
+  ConstantFPRange(APFloat LowerVal, APFloat UpperVal, bool MayBeQNaN = true,
+                  bool MaybeSNaN = true);
 
   /// Create empty constant range with the given semantics.
-  static ConstantFPRange getEmpty(const fltSemantics &FloatSema) {
-    return ConstantFPRange(FloatSema, /*IsFullSet=*/false);
+  static ConstantFPRange getEmpty(const fltSemantics &Sem) {
+    return ConstantFPRange(Sem, /*IsFullSet=*/false);
   }
 
   /// Create full constant range with the given semantics.
-  static ConstantFPRange getFull(const fltSemantics &FloatSema) {
-    return ConstantFPRange(FloatSema, /*IsFullSet=*/true);
+  static ConstantFPRange getFull(const fltSemantics &Sem) {
+    return ConstantFPRange(Sem, /*IsFullSet=*/true);
   }
 
-  /// Initialize a range based on a known floating-point classes constraint.
-  static ConstantFPRange fromKnownFPClass(const KnownFPClass &Known);
+  /// Produce the smallest range such that all values that may satisfy the given
+  /// predicate with any value contained within Other is contained in the
+  /// returned range.  Formally, this returns a superset of
+  /// 'union over all y in Other . { x : fcmp op x y is true }'.  If the exact
+  /// answer is not representable as a ConstantRange, the return value will be a
+  /// proper superset of the above.
+  ///
+  /// Example: Pred = ole and Other = float [2, 5] returns Result = [-inf, 5]
+  static ConstantFPRange makeAllowedFCmpRegion(FCmpInst::Predicate Pred,
+                                               const ConstantFPRange &Other);
+
+  /// Produce the largest range such that all values in the returned range
+  /// satisfy the given predicate with all values contained within Other.
+  /// Formally, this returns a subset of
+  /// 'intersection over all y in Other . { x : fcmp op x y is true }'.  If the
+  /// exact answer is not representable as a ConstantRange, the return value
+  /// will be a proper subset of the above.
+  ///
+  /// Example: Pred = ole and Other = float [2, 5] returns [-inf, 2]
+  static ConstantFPRange makeSatisfyingFCmpRegion(FCmpInst::Predicate Pred,
+                                                  const ConstantFPRange &Other);
 
   /// Produce the exact range such that all values in the returned range satisfy
   /// the given predicate with any value contained within Other. Formally, this
@@ -113,20 +140,36 @@ class [[nodiscard]] ConstantFPRange {
   /// Return true if the sign bit of all values in this range is 1.
   /// Return false if the sign bit of all values in this range is 0.
   /// Otherwise, return std::nullopt.
-  std::optional<bool> getSignBit();
+  std::optional<bool> getSignBit() const;
 
   /// Return true if this range is equal to another range.
   bool operator==(const ConstantFPRange &CR) const;
+  /// Return true if this range is not equal to another range.
   bool operator!=(const ConstantFPRange &CR) const { return !operator==(CR); }
 
+  /// Return the FPClassTest which will return true for the value.
+  FPClassTest classify() const;
+
   /// Return known floating-point classes for values in this range.
-  KnownFPClass toKnownFPClass();
+  KnownFPClass toKnownFPClass() const;
 
   /// Print out the bounds to a stream.
   void print(raw_ostream &OS) const;
 
   /// Allow printing from a debugger easily.
   void dump() const;
+
+  /// Return the range that results from the intersection of this range with
+  /// another range.
+  ConstantFPRange intersectWith(const ConstantFPRange &CR) const;
+
+  /// Return the range that results from the union of this range
+  /// with another range.  The resultant range is guaranteed to include the
+  /// elements of both sets, but may contain more.
+  ConstantFPRange unionWith(const ConstantFPRange &CR) const;
+
+  /// Return a new range that is the logical not of the current set.
+  ConstantFPRange inverse() const;
 };
 
 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantFPRange &CR) {
diff --git a/llvm/lib/IR/CMakeLists.txt b/llvm/lib/IR/CMakeLists.txt
index 20f169913087a..ca237156d8237 100644
--- a/llvm/lib/IR/CMakeLists.txt
+++ b/llvm/lib/IR/CMakeLists.txt
@@ -8,6 +8,7 @@ add_llvm_component_library(LLVMCore
   BuiltinGCs.cpp
   Comdat.cpp
   ConstantFold.cpp
+  ConstantFPRange.cpp
   ConstantRange.cpp
   Constants.cpp
   ConvergenceVerifier.cpp
diff --git a/llvm/lib/IR/ConstantFPRange.cpp b/llvm/lib/IR/ConstantFPRange.cpp
new file mode 100644
index 0000000000000..1576da4fc0b3e
--- /dev/null
+++ b/llvm/lib/IR/ConstantFPRange.cpp
@@ -0,0 +1,253 @@
+//===- ConstantFPRange.cpp - ConstantFPRange implementation ---------------===//
+//
+// 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.
+//
+// Range = [Lower, Upper] U (MayBeQNaN ? QNaN : {}) U (MayBeSNaN ? SNaN : {})
+// Specifically, [inf, -inf] represents an empty set.
+// Note: -0 is considered to be less than 0. That is, range [0, 0] doesn't
+// contain -0.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/ConstantFPRange.h"
+#include "llvm/ADT/APFloat.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cassert>
+
+using namespace llvm;
+
+// A floating point format must supports NaN, Inf and -0.
+bool ConstantFPRange::isSupportedSemantics(const fltSemantics &Sem) {
+  switch (APFloat::SemanticsToEnum(Sem)) {
+  default:
+    return false;
+  case APFloat::S_IEEEhalf:
+  case APFloat::S_BFloat:
+  case APFloat::S_IEEEsingle:
+  case APFloat::S_IEEEdouble:
+  case APFloat::S_IEEEquad:
+    return true;
+  }
+}
+
+void ConstantFPRange::makeEmpty() {
+  auto &Sem = Lower.getSemantics();
+  Lower = APFloat::getInf(Sem, /*Negative=*/false);
+  Upper = APFloat::getInf(Sem, /*Negative=*/true);
+  MayBeQNaN = false;
+  MayBeSNaN = false;
+}
+
+void ConstantFPRange::makeFull() {
+  auto &Sem = Lower.getSemantics();
+  Lower = APFloat::getInf(Sem, /*Negative=*/true);
+  Upper = APFloat::getInf(Sem, /*Negative=*/false);
+  MayBeQNaN = true;
+  MayBeSNaN = true;
+}
+
+bool ConstantFPRange::isNaNOnly() const {
+  return Lower.isPosInfinity() && Upper.isNegInfinity();
+}
+
+ConstantFPRange::ConstantFPRange(const fltSemantics &Sem, bool IsFullSet)
+    : Lower(Sem, APFloat::uninitialized), Upper(Sem, APFloat::uninitialized) {
+  assert(isSupportedSemantics(Sem) && "Unsupported fp format");
+  Lower = APFloat::getInf(Sem, /*Negative=*/IsFullSet);
+  Upper = APFloat::getInf(Sem, /*Negative=*/!IsFullSet);
+  MayBeQNaN = IsFullSet;
+  MayBeSNaN = IsFullSet;
+}
+
+ConstantFPRange::ConstantFPRange(const APFloat &Value)
+    : Lower(Value.getSemantics(), APFloat::uninitialized),
+      Upper(Value.getSemantics(), APFloat::uninitialized) {
+  assert(isSupportedSemantics(getSemantics()) && "Unsupported fp format");
+
+  if (Value.isNaN()) {
+    makeEmpty();
+    bool isSNaN = Value.isSignaling();
+    MayBeQNaN = !isSNaN;
+    MayBeSNaN = isSNaN;
+  } else {
+    Lower = Upper = Value;
+    MayBeQNaN = MayBeSNaN = false;
+  }
+}
+
+// We treat that -0 is less than 0 here.
+static APFloat::cmpResult strictCompare(const APFloat &LHS,
+                                        const APFloat &RHS) {
+  assert(!LHS.isNaN() && !RHS.isNaN() && "Unordered compare");
+  if (LHS.isZero() && RHS.isZero()) {
+    if (LHS.isNegative() == RHS.isNegative())
+      return APFloat::cmpEqual;
+    return LHS.isNegative() ? APFloat::cmpLessThan : APFloat::cmpGreaterThan;
+  }
+  return LHS.compare(RHS);
+}
+
+ConstantFPRange::ConstantFPRange(APFloat LowerVal, APFloat UpperVal,
+                                 bool MayBeQNaN, bool MaybeSNaN)
+    : Lower(std::move(LowerVal)), Upper(std::move(UpperVal)) {
+  assert(isSupportedSemantics(getSemantics()) && "Unsupported fp format");
+
+  // Canonicalize empty set into [Inf, -Inf].
+  if (strictCompare(Lower, Upper) == APFloat::cmpGreaterThan &&
+      !(Lower.isInfinity() && Upper.isInfinity()))
+    makeEmpty();
+  this->MayBeQNaN = MayBeQNaN;
+  this->MayBeSNaN = MayBeSNaN;
+}
+
+ConstantFPRange
+ConstantFPRange::makeAllowedFCmpRegion(FCmpInst::Predicate Pred,
+                                       const ConstantFPRange &Other) {
+  // TODO
+  return getFull(Other.getSemantics());
+}
+
+ConstantFPRange
+ConstantFPRange::makeSatisfyingFCmpRegion(FCmpInst::Predicate Pred,
+                                          const ConstantFPRange &Other) {
+  // TODO
+  return getEmpty(Other.getSemantics());
+}
+
+ConstantFPRange ConstantFPRange::makeExactFCmpRegion(FCmpInst::Predicate Pred,
+                                                     const APFloat &Other) {
+  return makeAllowedFCmpRegion(Pred, Other);
+}
+
+bool ConstantFPRange::fcmp(FCmpInst::Predicate Pred,
+                           const ConstantFPRange &Other) const {
+  return makeSatisfyingFCmpRegion(Pred, Other).contains(*this);
+}
+
+bool ConstantFPRange::isFullSet() const {
+  return Lower.isNegInfinity() && Upper.isPosInfinity() && MayBeQNaN &&
+         MayBeSNaN;
+}
+
+bool ConstantFPRange::isEmptySet() const {
+  return Lower.isPosInfinity() && Upper.isNegInfinity() && !MayBeQNaN &&
+         !MayBeSNaN;
+}
+
+bool ConstantFPRange::contains(const APFloat &Val) const {
+  assert(&getSemantics() == &Val.getSemantics() &&
+         "Should only use the same semantics");
+
+  if (Val.isNaN())
+    return Val.isSignaling() ? MayBeSNaN : MayBeQNaN;
+  return strictCompare(Lower, Val) != APFloat::cmpGreaterThan &&
+         strictCompare(Val, Upper) != APFloat::cmpGreaterThan;
+}
+
+bool ConstantFPRange::contains(const ConstantFPRange &CR) const {
+  assert(&getSemantics() == &CR.getSemantics() &&
+         "Should only use the same semantics");
+
+  if (CR.MayBeQNaN && !MayBeQNaN)
+    return false;
+
+  if (CR.MayBeSNaN && !MayBeSNaN)
+    return false;
+
+  return strictCompare(Lower, CR.Lower) != APFloat::cmpGreaterThan &&
+         strictCompare(CR.Upper, Upper) != APFloat::cmpGreaterThan;
+}
+
+const APFloat *ConstantFPRange::getSingleElement() const {
+  if (MayBeSNaN || MayBeQNaN)
+    return nullptr;
+  return Lower.bitwiseIsEqual(Upper) ? &Lower : nullptr;
+}
+
+std::optional<bool> ConstantFPRange::getSignBit() const {
+  if (!MayBeSNaN && !MayBeQNaN && Lower.isNegative() == Upper.isNegative())
+    return Lower.isNegative();
+  return std::nullopt;
+}
+
+bool ConstantFPRange::operator==(const ConstantFPRange &CR) const {
+  if (MayBeSNaN != CR.MayBeSNaN || MayBeQNaN != CR.MayBeQNaN)
+    return false;
+  return Lower.bitwiseIsEqual(CR.Lower) && Upper.bitwiseIsEqual(CR.Upper);
+}
+
+FPClassTest ConstantFPRange::classify() const {
+  uint32_t Mask = fcNone;
+  if (MayBeSNaN)
+    Mask |= fcSNan;
+  if (MayBeQNaN)
+    Mask |= fcQNan;
+  if (!isNaNOnly()) {
+    FPClassTest LowerMask = Lower.classify();
+    FPClassTest UpperMask = Upper.classify();
+    assert(LowerMask <= UpperMask && "Range is nan-only.");
+    for (uint32_t I = LowerMask; I <= UpperMask; I <<= 1)
+      Mask |= I;
+  }
+  return static_cast<FPClassTest>(Mask);
+}
+
+KnownFPClass ConstantFPRange::toKnownFPClass() const {
+  KnownFPClass Result;
+  Result.KnownFPClasses = classify();
+  Result.SignBit = getSignBit();
+  return Result;
+}
+
+void ConstantFPRange::print(raw_ostream &OS) const {
+  if (isFullSet())
+    OS << "full-set";
+  else if (isEmptySet())
+    OS << "empty-set";
+  else {
+    bool NaNOnly = isNaNOnly();
+    if (!NaNOnly) {
+      OS << '[';
+      Lower.print(OS);
+      OS << ", ";
+      Upper.print(OS);
+      OS << ']';
+    }
+
+    if (MayBeSNaN || MayBeQNaN) {
+      if (!NaNOnly)
+        OS << " with ";
+      if (MayBeSNaN && MayBeQNaN)
+        OS << "NaN";
+      else if (MayBeSNaN)
+        OS << "SNaN";
+      else if (MayBeQNaN)
+        OS << "QNaN";
+    }
+  }
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD void ConstantFPRange::dump() const { print(dbgs()); }
+#endif
+
+ConstantFPRange
+ConstantFPRange::intersectWith(const ConstantFPRange &CR) const {
+  return ConstantFPRange(maxnum(Lower, CR.Lower), minnum(Upper, CR.Upper),
+                         MayBeQNaN & CR.MayBeQNaN, MayBeSNaN & CR.MayBeSNaN);
+}
+
+ConstantFPRange ConstantFPRange::unionWith(const ConstantFPRange &CR) const {
+  return ConstantFPRange(minnum(Lower, CR.Lower), maxnum(Upper, CR.Upper),
+                         MayBeQNaN | CR.MayBeQNaN, MayBeSNaN | CR.MayBeSNaN);
+}

>From 661dc2876f018c06e626b03368bdf2cf0bd19bce Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Sat, 22 Jun 2024 14:21:31 +0800
Subject: [PATCH 3/3] [LLVM][IR] Remove comments. NFC.

---
 llvm/lib/IR/ConstantFPRange.cpp | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/llvm/lib/IR/ConstantFPRange.cpp b/llvm/lib/IR/ConstantFPRange.cpp
index 1576da4fc0b3e..10462968fbea9 100644
--- a/llvm/lib/IR/ConstantFPRange.cpp
+++ b/llvm/lib/IR/ConstantFPRange.cpp
@@ -5,17 +5,6 @@
 // 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.
-//
-// Range = [Lower, Upper] U (MayBeQNaN ? QNaN : {}) U (MayBeSNaN ? SNaN : {})
-// Specifically, [inf, -inf] represents an empty set.
-// Note: -0 is considered to be less than 0. That is, range [0, 0] doesn't
-// contain -0.
-//
-//===----------------------------------------------------------------------===//
 
 #include "llvm/IR/ConstantFPRange.h"
 #include "llvm/ADT/APFloat.h"



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