1 //===- llvm/Support/FloatingPointMode.h -------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Utilities for dealing with flags related to floating point mode controls. 10 // 11 //===----------------------------------------------------------------------===/ 12 13 #ifndef LLVM_FLOATINGPOINTMODE_H 14 #define LLVM_FLOATINGPOINTMODE_H 15 16 #include "llvm/ADT/StringSwitch.h" 17 #include "llvm/Support/raw_ostream.h" 18 19 namespace llvm { 20 21 /// Rounding mode. 22 /// 23 /// Enumerates supported rounding modes, as well as some special values. The set 24 /// of the modes must agree with IEEE-754, 4.3.1 and 4.3.2. The constants 25 /// assigned to the IEEE rounding modes must agree with the values used by 26 /// FLT_ROUNDS (C11, 5.2.4.2.2p8). 27 /// 28 /// This value is packed into bitfield in some cases, including \c FPOptions, so 29 /// the rounding mode values and the special value \c Dynamic must fit into the 30 /// the bit field (now - 3 bits). The value \c Invalid is used only in values 31 /// returned by intrinsics to indicate errors, it should never be stored as 32 /// rounding mode value, so it does not need to fit the bit fields. 33 /// 34 enum class RoundingMode : int8_t { 35 // Rounding mode defined in IEEE-754. 36 TowardZero = 0, ///< roundTowardZero. 37 NearestTiesToEven = 1, ///< roundTiesToEven. 38 TowardPositive = 2, ///< roundTowardPositive. 39 TowardNegative = 3, ///< roundTowardNegative. 40 NearestTiesToAway = 4, ///< roundTiesToAway. 41 42 // Special values. 43 Dynamic = 7, ///< Denotes mode unknown at compile time. 44 Invalid = -1 ///< Denotes invalid value. 45 }; 46 47 /// Represent subnormal handling kind for floating point instruction inputs and 48 /// outputs. 49 struct DenormalMode { 50 /// Represent handled modes for denormal (aka subnormal) modes in the floating 51 /// point environment. 52 enum DenormalModeKind : int8_t { 53 Invalid = -1, 54 55 /// IEEE-754 denormal numbers preserved. 56 IEEE, 57 58 /// The sign of a flushed-to-zero number is preserved in the sign of 0 59 PreserveSign, 60 61 /// Denormals are flushed to positive zero. 62 PositiveZero 63 }; 64 65 /// Denormal flushing mode for floating point instruction results in the 66 /// default floating point environment. 67 DenormalModeKind Output = DenormalModeKind::Invalid; 68 69 /// Denormal treatment kind for floating point instruction inputs in the 70 /// default floating-point environment. If this is not DenormalModeKind::IEEE, 71 /// floating-point instructions implicitly treat the input value as 0. 72 DenormalModeKind Input = DenormalModeKind::Invalid; 73 74 constexpr DenormalMode() = default; 75 constexpr DenormalMode(DenormalModeKind Out, DenormalModeKind In) : 76 Output(Out), Input(In) {} 77 78 79 static constexpr DenormalMode getInvalid() { 80 return DenormalMode(DenormalModeKind::Invalid, DenormalModeKind::Invalid); 81 } 82 83 static constexpr DenormalMode getIEEE() { 84 return DenormalMode(DenormalModeKind::IEEE, DenormalModeKind::IEEE); 85 } 86 87 static constexpr DenormalMode getPreserveSign() { 88 return DenormalMode(DenormalModeKind::PreserveSign, 89 DenormalModeKind::PreserveSign); 90 } 91 92 static constexpr DenormalMode getPositiveZero() { 93 return DenormalMode(DenormalModeKind::PositiveZero, 94 DenormalModeKind::PositiveZero); 95 } 96 97 bool operator==(DenormalMode Other) const { 98 return Output == Other.Output && Input == Other.Input; 99 } 100 101 bool operator!=(DenormalMode Other) const { 102 return !(*this == Other); 103 } 104 105 bool isSimple() const { 106 return Input == Output; 107 } 108 109 bool isValid() const { 110 return Output != DenormalModeKind::Invalid && 111 Input != DenormalModeKind::Invalid; 112 } 113 114 inline void print(raw_ostream &OS) const; 115 116 inline std::string str() const { 117 std::string storage; 118 raw_string_ostream OS(storage); 119 print(OS); 120 return OS.str(); 121 } 122 }; 123 124 inline raw_ostream& operator<<(raw_ostream &OS, DenormalMode Mode) { 125 Mode.print(OS); 126 return OS; 127 } 128 129 /// Parse the expected names from the denormal-fp-math attribute. 130 inline DenormalMode::DenormalModeKind 131 parseDenormalFPAttributeComponent(StringRef Str) { 132 // Assume ieee on unspecified attribute. 133 return StringSwitch<DenormalMode::DenormalModeKind>(Str) 134 .Cases("", "ieee", DenormalMode::IEEE) 135 .Case("preserve-sign", DenormalMode::PreserveSign) 136 .Case("positive-zero", DenormalMode::PositiveZero) 137 .Default(DenormalMode::Invalid); 138 } 139 140 /// Return the name used for the denormal handling mode used by the the 141 /// expected names from the denormal-fp-math attribute. 142 inline StringRef denormalModeKindName(DenormalMode::DenormalModeKind Mode) { 143 switch (Mode) { 144 case DenormalMode::IEEE: 145 return "ieee"; 146 case DenormalMode::PreserveSign: 147 return "preserve-sign"; 148 case DenormalMode::PositiveZero: 149 return "positive-zero"; 150 default: 151 return ""; 152 } 153 } 154 155 /// Returns the denormal mode to use for inputs and outputs. 156 inline DenormalMode parseDenormalFPAttribute(StringRef Str) { 157 StringRef OutputStr, InputStr; 158 std::tie(OutputStr, InputStr) = Str.split(','); 159 160 DenormalMode Mode; 161 Mode.Output = parseDenormalFPAttributeComponent(OutputStr); 162 163 // Maintain compatability with old form of the attribute which only specified 164 // one component. 165 Mode.Input = InputStr.empty() ? Mode.Output : 166 parseDenormalFPAttributeComponent(InputStr); 167 168 return Mode; 169 } 170 171 void DenormalMode::print(raw_ostream &OS) const { 172 OS << denormalModeKindName(Output) << ',' << denormalModeKindName(Input); 173 } 174 175 } 176 177 #endif // LLVM_FLOATINGPOINTMODE_H 178