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 <ostream> // NOLINT(readability/streams)
9
10 #include "src/base/compiler-specific.h"
11 #include "src/base/flags.h"
12 #include "src/base/functional.h"
13 #include "src/globals.h"
14 #include "src/handles.h"
15 #include "src/zone/zone.h"
16
17 namespace v8 {
18 namespace internal {
19 namespace compiler {
20
21 // An operator represents description of the "computation" of a node in the
22 // compiler IR. A computation takes values (i.e. data) as input and produces
23 // zero or more values as output. The side-effects of a computation must be
24 // captured by additional control and data dependencies which are part of the
25 // IR graph.
26 // Operators are immutable and describe the statically-known parts of a
27 // computation. Thus they can be safely shared by many different nodes in the
28 // IR graph, or even globally between graphs. Operators can have "static
29 // parameters" which are compile-time constant parameters to the operator, such
30 // as the name for a named field access, the ID of a runtime function, etc.
31 // Static parameters are private to the operator and only semantically
32 // meaningful to the operator itself.
NON_EXPORTED_BASE(ZoneObject)33 class V8_EXPORT_PRIVATE Operator : public NON_EXPORTED_BASE(ZoneObject) {
34 public:
35 typedef uint16_t Opcode;
36
37 // Properties inform the operator-independent optimizer about legal
38 // transformations for nodes that have this operator.
39 enum Property {
40 kNoProperties = 0,
41 kCommutative = 1 << 0, // OP(a, b) == OP(b, a) for all inputs.
42 kAssociative = 1 << 1, // OP(a, OP(b,c)) == OP(OP(a,b), c) for all inputs.
43 kIdempotent = 1 << 2, // OP(a); OP(a) == OP(a).
44 kNoRead = 1 << 3, // Has no scheduling dependency on Effects
45 kNoWrite = 1 << 4, // Does not modify any Effects and thereby
46 // create new scheduling dependencies.
47 kNoThrow = 1 << 5, // Can never generate an exception.
48 kNoDeopt = 1 << 6, // Can never generate an eager deoptimization exit.
49 kFoldable = kNoRead | kNoWrite,
50 kKontrol = kNoDeopt | kFoldable | kNoThrow,
51 kEliminatable = kNoDeopt | kNoWrite | kNoThrow,
52 kPure = kNoDeopt | kNoRead | kNoWrite | kNoThrow | kIdempotent
53 };
54
55 // List of all bits, for the visualizer.
56 #define OPERATOR_PROPERTY_LIST(V) \
57 V(Commutative) \
58 V(Associative) V(Idempotent) V(NoRead) V(NoWrite) V(NoThrow) V(NoDeopt)
59
60 typedef base::Flags<Property, uint8_t> Properties;
61 enum class PrintVerbosity { kVerbose, kSilent };
62
63 // Constructor.
64 Operator(Opcode opcode, Properties properties, const char* mnemonic,
65 size_t value_in, size_t effect_in, size_t control_in,
66 size_t value_out, size_t effect_out, size_t control_out);
67
68 virtual ~Operator() {}
69
70 // A small integer unique to all instances of a particular kind of operator,
71 // useful for quick matching for specific kinds of operators. For fast access
72 // the opcode is stored directly in the operator object.
73 Opcode opcode() const { return opcode_; }
74
75 // Returns a constant string representing the mnemonic of the operator,
76 // without the static parameters. Useful for debugging.
77 const char* mnemonic() const { return mnemonic_; }
78
79 // Check if this operator equals another operator. Equivalent operators can
80 // be merged, and nodes with equivalent operators and equivalent inputs
81 // can be merged.
82 virtual bool Equals(const Operator* that) const {
83 return this->opcode() == that->opcode();
84 }
85
86 // Compute a hashcode to speed up equivalence-set checking.
87 // Equal operators should always have equal hashcodes, and unequal operators
88 // should have unequal hashcodes with high probability.
89 virtual size_t HashCode() const { return base::hash<Opcode>()(opcode()); }
90
91 // Check whether this operator has the given property.
92 bool HasProperty(Property property) const {
93 return (properties() & property) == property;
94 }
95
96 Properties properties() const { return properties_; }
97
98 // TODO(bmeurer): Use bit fields below?
99 static const size_t kMaxControlOutputCount = (1u << 16) - 1;
100
101 // TODO(titzer): convert return values here to size_t.
102 int ValueInputCount() const { return value_in_; }
103 int EffectInputCount() const { return effect_in_; }
104 int ControlInputCount() const { return control_in_; }
105
106 int ValueOutputCount() const { return value_out_; }
107 int EffectOutputCount() const { return effect_out_; }
108 int ControlOutputCount() const { return control_out_; }
109
110 static size_t ZeroIfEliminatable(Properties properties) {
111 return (properties & kEliminatable) == kEliminatable ? 0 : 1;
112 }
113
114 static size_t ZeroIfNoThrow(Properties properties) {
115 return (properties & kNoThrow) == kNoThrow ? 0 : 2;
116 }
117
118 static size_t ZeroIfPure(Properties properties) {
119 return (properties & kPure) == kPure ? 0 : 1;
120 }
121
122 // TODO(titzer): API for input and output types, for typechecking graph.
123
124 // Print the full operator into the given stream, including any
125 // static parameters. Useful for debugging and visualizing the IR.
126 void PrintTo(std::ostream& os,
127 PrintVerbosity verbose = PrintVerbosity::kVerbose) const {
128 // We cannot make PrintTo virtual, because default arguments to virtual
129 // methods are banned in the style guide.
130 return PrintToImpl(os, verbose);
131 }
132
133 void PrintPropsTo(std::ostream& os) const;
134
135 protected:
136 virtual void PrintToImpl(std::ostream& os, PrintVerbosity verbose) const;
137
138 private:
139 Opcode opcode_;
140 Properties properties_;
141 const char* mnemonic_;
142 uint32_t value_in_;
143 uint16_t effect_in_;
144 uint16_t control_in_;
145 uint16_t value_out_;
146 uint8_t effect_out_;
147 uint32_t control_out_;
148
149 DISALLOW_COPY_AND_ASSIGN(Operator);
150 };
151
152 DEFINE_OPERATORS_FOR_FLAGS(Operator::Properties)
153
154 std::ostream& operator<<(std::ostream& os, const Operator& op);
155
156
157 // Default equality function for below Operator1<*> class.
158 template <typename T>
159 struct OpEqualTo : public std::equal_to<T> {};
160
161
162 // Default hashing function for below Operator1<*> class.
163 template <typename T>
164 struct OpHash : public base::hash<T> {};
165
166
167 // A templatized implementation of Operator that has one static parameter of
168 // type {T} with the proper default equality and hashing functions.
169 template <typename T, typename Pred = OpEqualTo<T>, typename Hash = OpHash<T>>
170 class Operator1 : public Operator {
171 public:
172 Operator1(Opcode opcode, Properties properties, const char* mnemonic,
173 size_t value_in, size_t effect_in, size_t control_in,
174 size_t value_out, size_t effect_out, size_t control_out,
175 T parameter, Pred const& pred = Pred(), Hash const& hash = Hash())
Operator(opcode,properties,mnemonic,value_in,effect_in,control_in,value_out,effect_out,control_out)176 : Operator(opcode, properties, mnemonic, value_in, effect_in, control_in,
177 value_out, effect_out, control_out),
178 parameter_(parameter),
179 pred_(pred),
180 hash_(hash) {}
181
parameter()182 T const& parameter() const { return parameter_; }
183
Equals(const Operator * other)184 bool Equals(const Operator* other) const final {
185 if (opcode() != other->opcode()) return false;
186 const Operator1<T, Pred, Hash>* that =
187 reinterpret_cast<const Operator1<T, Pred, Hash>*>(other);
188 return this->pred_(this->parameter(), that->parameter());
189 }
HashCode()190 size_t HashCode() const final {
191 return base::hash_combine(this->opcode(), this->hash_(this->parameter()));
192 }
193 // For most parameter types, we have only a verbose way to print them, namely
194 // ostream << parameter. But for some types it is particularly useful to have
195 // a shorter way to print them for the node labels in Turbolizer. The
196 // following method can be overridden to provide a concise and a verbose
197 // printing of a parameter.
198
PrintParameter(std::ostream & os,PrintVerbosity verbose)199 virtual void PrintParameter(std::ostream& os, PrintVerbosity verbose) const {
200 os << "[" << parameter() << "]";
201 }
202
PrintToImpl(std::ostream & os,PrintVerbosity verbose)203 virtual void PrintToImpl(std::ostream& os, PrintVerbosity verbose) const {
204 os << mnemonic();
205 PrintParameter(os, verbose);
206 }
207
208 private:
209 T const parameter_;
210 Pred const pred_;
211 Hash const hash_;
212 };
213
214
215 // Helper to extract parameters from Operator1<*> operator.
216 template <typename T>
OpParameter(const Operator * op)217 inline T const& OpParameter(const Operator* op) {
218 return reinterpret_cast<const Operator1<T, OpEqualTo<T>, OpHash<T>>*>(op)
219 ->parameter();
220 }
221
222
223 // NOTE: We have to be careful to use the right equal/hash functions below, for
224 // float/double we always use the ones operating on the bit level, for Handle<>
225 // we always use the ones operating on the location level.
226 template <>
227 struct OpEqualTo<float> : public base::bit_equal_to<float> {};
228 template <>
229 struct OpHash<float> : public base::bit_hash<float> {};
230
231 template <>
232 struct OpEqualTo<double> : public base::bit_equal_to<double> {};
233 template <>
234 struct OpHash<double> : public base::bit_hash<double> {};
235
236 template <>
237 struct OpEqualTo<Handle<HeapObject>> : public Handle<HeapObject>::equal_to {};
238 template <>
239 struct OpHash<Handle<HeapObject>> : public Handle<HeapObject>::hash {};
240
241 template <>
242 struct OpEqualTo<Handle<String>> : public Handle<String>::equal_to {};
243 template <>
244 struct OpHash<Handle<String>> : public Handle<String>::hash {};
245
246 template <>
247 struct OpEqualTo<Handle<ScopeInfo>> : public Handle<ScopeInfo>::equal_to {};
248 template <>
249 struct OpHash<Handle<ScopeInfo>> : public Handle<ScopeInfo>::hash {};
250
251 } // namespace compiler
252 } // namespace internal
253 } // namespace v8
254
255 #endif // V8_COMPILER_OPERATOR_H_
256