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(titzer): convert return values here to size_t.
99 int ValueInputCount() const { return value_in_; }
100 int EffectInputCount() const { return effect_in_; }
101 int ControlInputCount() const { return control_in_; }
102
103 int ValueOutputCount() const { return value_out_; }
104 int EffectOutputCount() const { return effect_out_; }
105 int ControlOutputCount() const { return control_out_; }
106
107 static size_t ZeroIfEliminatable(Properties properties) {
108 return (properties & kEliminatable) == kEliminatable ? 0 : 1;
109 }
110
111 static size_t ZeroIfNoThrow(Properties properties) {
112 return (properties & kNoThrow) == kNoThrow ? 0 : 2;
113 }
114
115 static size_t ZeroIfPure(Properties properties) {
116 return (properties & kPure) == kPure ? 0 : 1;
117 }
118
119 // TODO(titzer): API for input and output types, for typechecking graph.
120
121 // Print the full operator into the given stream, including any
122 // static parameters. Useful for debugging and visualizing the IR.
123 void PrintTo(std::ostream& os,
124 PrintVerbosity verbose = PrintVerbosity::kVerbose) const {
125 // We cannot make PrintTo virtual, because default arguments to virtual
126 // methods are banned in the style guide.
127 return PrintToImpl(os, verbose);
128 }
129
130 void PrintPropsTo(std::ostream& os) const;
131
132 protected:
133 virtual void PrintToImpl(std::ostream& os, PrintVerbosity verbose) const;
134
135 private:
136 const char* mnemonic_;
137 Opcode opcode_;
138 Properties properties_;
139 uint32_t value_in_;
140 uint32_t effect_in_;
141 uint32_t control_in_;
142 uint32_t value_out_;
143 uint8_t effect_out_;
144 uint32_t control_out_;
145
146 DISALLOW_COPY_AND_ASSIGN(Operator);
147 };
148
149 DEFINE_OPERATORS_FOR_FLAGS(Operator::Properties)
150
151 std::ostream& operator<<(std::ostream& os, const Operator& op);
152
153
154 // Default equality function for below Operator1<*> class.
155 template <typename T>
156 struct OpEqualTo : public std::equal_to<T> {};
157
158
159 // Default hashing function for below Operator1<*> class.
160 template <typename T>
161 struct OpHash : public base::hash<T> {};
162
163
164 // A templatized implementation of Operator that has one static parameter of
165 // type {T} with the proper default equality and hashing functions.
166 template <typename T, typename Pred = OpEqualTo<T>, typename Hash = OpHash<T>>
167 class Operator1 : public Operator {
168 public:
169 Operator1(Opcode opcode, Properties properties, const char* mnemonic,
170 size_t value_in, size_t effect_in, size_t control_in,
171 size_t value_out, size_t effect_out, size_t control_out,
172 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)173 : Operator(opcode, properties, mnemonic, value_in, effect_in, control_in,
174 value_out, effect_out, control_out),
175 parameter_(parameter),
176 pred_(pred),
177 hash_(hash) {}
178
parameter()179 T const& parameter() const { return parameter_; }
180
Equals(const Operator * other)181 bool Equals(const Operator* other) const final {
182 if (opcode() != other->opcode()) return false;
183 const Operator1<T, Pred, Hash>* that =
184 reinterpret_cast<const Operator1<T, Pred, Hash>*>(other);
185 return this->pred_(this->parameter(), that->parameter());
186 }
HashCode()187 size_t HashCode() const final {
188 return base::hash_combine(this->opcode(), this->hash_(this->parameter()));
189 }
190 // For most parameter types, we have only a verbose way to print them, namely
191 // ostream << parameter. But for some types it is particularly useful to have
192 // a shorter way to print them for the node labels in Turbolizer. The
193 // following method can be overridden to provide a concise and a verbose
194 // printing of a parameter.
195
PrintParameter(std::ostream & os,PrintVerbosity verbose)196 virtual void PrintParameter(std::ostream& os, PrintVerbosity verbose) const {
197 os << "[" << parameter() << "]";
198 }
199
PrintToImpl(std::ostream & os,PrintVerbosity verbose)200 virtual void PrintToImpl(std::ostream& os, PrintVerbosity verbose) const {
201 os << mnemonic();
202 PrintParameter(os, verbose);
203 }
204
205 private:
206 T const parameter_;
207 Pred const pred_;
208 Hash const hash_;
209 };
210
211
212 // Helper to extract parameters from Operator1<*> operator.
213 template <typename T>
OpParameter(const Operator * op)214 inline T const& OpParameter(const Operator* op) {
215 return reinterpret_cast<const Operator1<T, OpEqualTo<T>, OpHash<T>>*>(op)
216 ->parameter();
217 }
218
219
220 // NOTE: We have to be careful to use the right equal/hash functions below, for
221 // float/double we always use the ones operating on the bit level, for Handle<>
222 // we always use the ones operating on the location level.
223 template <>
224 struct OpEqualTo<float> : public base::bit_equal_to<float> {};
225 template <>
226 struct OpHash<float> : public base::bit_hash<float> {};
227
228 template <>
229 struct OpEqualTo<double> : public base::bit_equal_to<double> {};
230 template <>
231 struct OpHash<double> : public base::bit_hash<double> {};
232
233 template <>
234 struct OpEqualTo<Handle<HeapObject>> : public Handle<HeapObject>::equal_to {};
235 template <>
236 struct OpHash<Handle<HeapObject>> : public Handle<HeapObject>::hash {};
237
238 template <>
239 struct OpEqualTo<Handle<String>> : public Handle<String>::equal_to {};
240 template <>
241 struct OpHash<Handle<String>> : public Handle<String>::hash {};
242
243 template <>
244 struct OpEqualTo<Handle<ScopeInfo>> : public Handle<ScopeInfo>::equal_to {};
245 template <>
246 struct OpHash<Handle<ScopeInfo>> : public Handle<ScopeInfo>::hash {};
247
248 } // namespace compiler
249 } // namespace internal
250 } // namespace v8
251
252 #endif // V8_COMPILER_OPERATOR_H_
253