Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame^] | 1 | // Copyright 2013 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef V8_COMPILER_OPERATOR_H_ |
| 6 | #define V8_COMPILER_OPERATOR_H_ |
| 7 | |
| 8 | #include "src/base/flags.h" |
| 9 | #include "src/ostreams.h" |
| 10 | #include "src/unique.h" |
| 11 | |
| 12 | namespace v8 { |
| 13 | namespace internal { |
| 14 | namespace compiler { |
| 15 | |
| 16 | // An operator represents description of the "computation" of a node in the |
| 17 | // compiler IR. A computation takes values (i.e. data) as input and produces |
| 18 | // zero or more values as output. The side-effects of a computation must be |
| 19 | // captured by additional control and data dependencies which are part of the |
| 20 | // IR graph. |
| 21 | // Operators are immutable and describe the statically-known parts of a |
| 22 | // computation. Thus they can be safely shared by many different nodes in the |
| 23 | // IR graph, or even globally between graphs. Operators can have "static |
| 24 | // parameters" which are compile-time constant parameters to the operator, such |
| 25 | // as the name for a named field access, the ID of a runtime function, etc. |
| 26 | // Static parameters are private to the operator and only semantically |
| 27 | // meaningful to the operator itself. |
| 28 | class Operator : public ZoneObject { |
| 29 | public: |
| 30 | typedef uint8_t Opcode; |
| 31 | |
| 32 | // Properties inform the operator-independent optimizer about legal |
| 33 | // transformations for nodes that have this operator. |
| 34 | enum Property { |
| 35 | kNoProperties = 0, |
| 36 | kReducible = 1 << 0, // Participates in strength reduction. |
| 37 | kCommutative = 1 << 1, // OP(a, b) == OP(b, a) for all inputs. |
| 38 | kAssociative = 1 << 2, // OP(a, OP(b,c)) == OP(OP(a,b), c) for all inputs. |
| 39 | kIdempotent = 1 << 3, // OP(a); OP(a) == OP(a). |
| 40 | kNoRead = 1 << 4, // Has no scheduling dependency on Effects |
| 41 | kNoWrite = 1 << 5, // Does not modify any Effects and thereby |
| 42 | // create new scheduling dependencies. |
| 43 | kNoThrow = 1 << 6, // Can never generate an exception. |
| 44 | kFoldable = kNoRead | kNoWrite, |
| 45 | kEliminatable = kNoWrite | kNoThrow, |
| 46 | kPure = kNoRead | kNoWrite | kNoThrow | kIdempotent |
| 47 | }; |
| 48 | typedef base::Flags<Property, uint8_t> Properties; |
| 49 | |
| 50 | Operator(Opcode opcode, Properties properties, const char* mnemonic) |
| 51 | : opcode_(opcode), properties_(properties), mnemonic_(mnemonic) {} |
| 52 | virtual ~Operator(); |
| 53 | |
| 54 | // A small integer unique to all instances of a particular kind of operator, |
| 55 | // useful for quick matching for specific kinds of operators. For fast access |
| 56 | // the opcode is stored directly in the operator object. |
| 57 | Opcode opcode() const { return opcode_; } |
| 58 | |
| 59 | // Returns a constant string representing the mnemonic of the operator, |
| 60 | // without the static parameters. Useful for debugging. |
| 61 | const char* mnemonic() const { return mnemonic_; } |
| 62 | |
| 63 | // Check if this operator equals another operator. Equivalent operators can |
| 64 | // be merged, and nodes with equivalent operators and equivalent inputs |
| 65 | // can be merged. |
| 66 | virtual bool Equals(const Operator* other) const = 0; |
| 67 | |
| 68 | // Compute a hashcode to speed up equivalence-set checking. |
| 69 | // Equal operators should always have equal hashcodes, and unequal operators |
| 70 | // should have unequal hashcodes with high probability. |
| 71 | virtual int HashCode() const = 0; |
| 72 | |
| 73 | // Check whether this operator has the given property. |
| 74 | bool HasProperty(Property property) const { |
| 75 | return (properties() & property) == property; |
| 76 | } |
| 77 | |
| 78 | // Number of data inputs to the operator, for verifying graph structure. |
| 79 | virtual int InputCount() const = 0; |
| 80 | |
| 81 | // Number of data outputs from the operator, for verifying graph structure. |
| 82 | virtual int OutputCount() const = 0; |
| 83 | |
| 84 | Properties properties() const { return properties_; } |
| 85 | |
| 86 | // TODO(titzer): API for input and output types, for typechecking graph. |
| 87 | protected: |
| 88 | // Print the full operator into the given stream, including any |
| 89 | // static parameters. Useful for debugging and visualizing the IR. |
| 90 | virtual OStream& PrintTo(OStream& os) const = 0; // NOLINT |
| 91 | friend OStream& operator<<(OStream& os, const Operator& op); |
| 92 | |
| 93 | private: |
| 94 | Opcode opcode_; |
| 95 | Properties properties_; |
| 96 | const char* mnemonic_; |
| 97 | |
| 98 | DISALLOW_COPY_AND_ASSIGN(Operator); |
| 99 | }; |
| 100 | |
| 101 | DEFINE_OPERATORS_FOR_FLAGS(Operator::Properties) |
| 102 | |
| 103 | OStream& operator<<(OStream& os, const Operator& op); |
| 104 | |
| 105 | // An implementation of Operator that has no static parameters. Such operators |
| 106 | // have just a name, an opcode, and a fixed number of inputs and outputs. |
| 107 | // They can represented by singletons and shared globally. |
| 108 | class SimpleOperator : public Operator { |
| 109 | public: |
| 110 | SimpleOperator(Opcode opcode, Properties properties, int input_count, |
| 111 | int output_count, const char* mnemonic); |
| 112 | ~SimpleOperator(); |
| 113 | |
| 114 | virtual bool Equals(const Operator* that) const FINAL { |
| 115 | return opcode() == that->opcode(); |
| 116 | } |
| 117 | virtual int HashCode() const FINAL { return opcode(); } |
| 118 | virtual int InputCount() const FINAL { return input_count_; } |
| 119 | virtual int OutputCount() const FINAL { return output_count_; } |
| 120 | |
| 121 | private: |
| 122 | virtual OStream& PrintTo(OStream& os) const FINAL { // NOLINT |
| 123 | return os << mnemonic(); |
| 124 | } |
| 125 | |
| 126 | int input_count_; |
| 127 | int output_count_; |
| 128 | |
| 129 | DISALLOW_COPY_AND_ASSIGN(SimpleOperator); |
| 130 | }; |
| 131 | |
| 132 | // Template specialization implements a kind of type class for dealing with the |
| 133 | // static parameters of Operator1 automatically. |
| 134 | template <typename T> |
| 135 | struct StaticParameterTraits { |
| 136 | static OStream& PrintTo(OStream& os, T val) { // NOLINT |
| 137 | return os << "??"; |
| 138 | } |
| 139 | static int HashCode(T a) { return 0; } |
| 140 | static bool Equals(T a, T b) { |
| 141 | return false; // Not every T has a ==. By default, be conservative. |
| 142 | } |
| 143 | }; |
| 144 | |
| 145 | // Specialization for static parameters of type {int}. |
| 146 | template <> |
| 147 | struct StaticParameterTraits<int> { |
| 148 | static OStream& PrintTo(OStream& os, int val) { // NOLINT |
| 149 | return os << val; |
| 150 | } |
| 151 | static int HashCode(int a) { return a; } |
| 152 | static bool Equals(int a, int b) { return a == b; } |
| 153 | }; |
| 154 | |
| 155 | // Specialization for static parameters of type {double}. |
| 156 | template <> |
| 157 | struct StaticParameterTraits<double> { |
| 158 | static OStream& PrintTo(OStream& os, double val) { // NOLINT |
| 159 | return os << val; |
| 160 | } |
| 161 | static int HashCode(double a) { |
| 162 | return static_cast<int>(bit_cast<int64_t>(a)); |
| 163 | } |
| 164 | static bool Equals(double a, double b) { |
| 165 | return bit_cast<int64_t>(a) == bit_cast<int64_t>(b); |
| 166 | } |
| 167 | }; |
| 168 | |
| 169 | // Specialization for static parameters of type {Unique<Object>}. |
| 170 | template <> |
| 171 | struct StaticParameterTraits<Unique<Object> > { |
| 172 | static OStream& PrintTo(OStream& os, Unique<Object> val) { // NOLINT |
| 173 | return os << Brief(*val.handle()); |
| 174 | } |
| 175 | static int HashCode(Unique<Object> a) { |
| 176 | return static_cast<int>(a.Hashcode()); |
| 177 | } |
| 178 | static bool Equals(Unique<Object> a, Unique<Object> b) { return a == b; } |
| 179 | }; |
| 180 | |
| 181 | // Specialization for static parameters of type {Unique<Name>}. |
| 182 | template <> |
| 183 | struct StaticParameterTraits<Unique<Name> > { |
| 184 | static OStream& PrintTo(OStream& os, Unique<Name> val) { // NOLINT |
| 185 | return os << Brief(*val.handle()); |
| 186 | } |
| 187 | static int HashCode(Unique<Name> a) { return static_cast<int>(a.Hashcode()); } |
| 188 | static bool Equals(Unique<Name> a, Unique<Name> b) { return a == b; } |
| 189 | }; |
| 190 | |
| 191 | #if DEBUG |
| 192 | // Specialization for static parameters of type {Handle<Object>} to prevent any |
| 193 | // direct usage of Handles in constants. |
| 194 | template <> |
| 195 | struct StaticParameterTraits<Handle<Object> > { |
| 196 | static OStream& PrintTo(OStream& os, Handle<Object> val) { // NOLINT |
| 197 | UNREACHABLE(); // Should use Unique<Object> instead |
| 198 | return os; |
| 199 | } |
| 200 | static int HashCode(Handle<Object> a) { |
| 201 | UNREACHABLE(); // Should use Unique<Object> instead |
| 202 | return 0; |
| 203 | } |
| 204 | static bool Equals(Handle<Object> a, Handle<Object> b) { |
| 205 | UNREACHABLE(); // Should use Unique<Object> instead |
| 206 | return false; |
| 207 | } |
| 208 | }; |
| 209 | #endif |
| 210 | |
| 211 | // A templatized implementation of Operator that has one static parameter of |
| 212 | // type {T}. If a specialization of StaticParameterTraits<{T}> exists, then |
| 213 | // operators of this kind can automatically be hashed, compared, and printed. |
| 214 | template <typename T> |
| 215 | class Operator1 : public Operator { |
| 216 | public: |
| 217 | Operator1(Opcode opcode, Properties properties, int input_count, |
| 218 | int output_count, const char* mnemonic, T parameter) |
| 219 | : Operator(opcode, properties, mnemonic), |
| 220 | input_count_(input_count), |
| 221 | output_count_(output_count), |
| 222 | parameter_(parameter) {} |
| 223 | |
| 224 | const T& parameter() const { return parameter_; } |
| 225 | |
| 226 | virtual bool Equals(const Operator* other) const OVERRIDE { |
| 227 | if (opcode() != other->opcode()) return false; |
| 228 | const Operator1<T>* that = static_cast<const Operator1<T>*>(other); |
| 229 | return StaticParameterTraits<T>::Equals(this->parameter_, that->parameter_); |
| 230 | } |
| 231 | virtual int HashCode() const OVERRIDE { |
| 232 | return opcode() + 33 * StaticParameterTraits<T>::HashCode(this->parameter_); |
| 233 | } |
| 234 | virtual int InputCount() const OVERRIDE { return input_count_; } |
| 235 | virtual int OutputCount() const OVERRIDE { return output_count_; } |
| 236 | virtual OStream& PrintParameter(OStream& os) const { // NOLINT |
| 237 | return StaticParameterTraits<T>::PrintTo(os << "[", parameter_) << "]"; |
| 238 | } |
| 239 | |
| 240 | protected: |
| 241 | virtual OStream& PrintTo(OStream& os) const FINAL { // NOLINT |
| 242 | return PrintParameter(os << mnemonic()); |
| 243 | } |
| 244 | |
| 245 | private: |
| 246 | int input_count_; |
| 247 | int output_count_; |
| 248 | T parameter_; |
| 249 | }; |
| 250 | |
| 251 | |
| 252 | // Helper to extract parameters from Operator1<*> operator. |
| 253 | template <typename T> |
| 254 | static inline const T& OpParameter(const Operator* op) { |
| 255 | return reinterpret_cast<const Operator1<T>*>(op)->parameter(); |
| 256 | } |
| 257 | |
| 258 | } // namespace compiler |
| 259 | } // namespace internal |
| 260 | } // namespace v8 |
| 261 | |
| 262 | #endif // V8_COMPILER_OPERATOR_H_ |