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// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <ostream> // NOLINT(readability/streams)
#include "src/base/compiler-specific.h"
#include "src/base/flags.h"
#include "src/base/functional.h"
#include "src/common/globals.h"
#include "src/handles/handles.h"
#include "src/objects/feedback-cell.h"
#include "src/zone/zone.h"
namespace v8 {
namespace internal {
namespace compiler {
// An operator represents description of the "computation" of a node in the
// compiler IR. A computation takes values (i.e. data) as input and produces
// zero or more values as output. The side-effects of a computation must be
// captured by additional control and data dependencies which are part of the
// IR graph.
// Operators are immutable and describe the statically-known parts of a
// computation. Thus they can be safely shared by many different nodes in the
// IR graph, or even globally between graphs. Operators can have "static
// parameters" which are compile-time constant parameters to the operator, such
// as the name for a named field access, the ID of a runtime function, etc.
// Static parameters are private to the operator and only semantically
// meaningful to the operator itself.
class V8_EXPORT_PRIVATE Operator : public NON_EXPORTED_BASE(ZoneObject) {
using Opcode = uint16_t;
// Properties inform the operator-independent optimizer about legal
// transformations for nodes that have this operator.
enum Property {
kNoProperties = 0,
kCommutative = 1 << 0, // OP(a, b) == OP(b, a) for all inputs.
kAssociative = 1 << 1, // OP(a, OP(b,c)) == OP(OP(a,b), c) for all inputs.
kIdempotent = 1 << 2, // OP(a); OP(a) == OP(a).
kNoRead = 1 << 3, // Has no scheduling dependency on Effects
kNoWrite = 1 << 4, // Does not modify any Effects and thereby
// create new scheduling dependencies.
kNoThrow = 1 << 5, // Can never generate an exception.
kNoDeopt = 1 << 6, // Can never generate an eager deoptimization exit.
kFoldable = kNoRead | kNoWrite,
kEliminatable = kNoDeopt | kNoWrite | kNoThrow,
kKontrol = kNoDeopt | kFoldable | kNoThrow,
kPure = kKontrol | kIdempotent
// List of all bits, for the visualizer.
V(Commutative) \
V(Associative) V(Idempotent) V(NoRead) V(NoWrite) V(NoThrow) V(NoDeopt)
using Properties = base::Flags<Property, uint8_t>;
enum class PrintVerbosity { kVerbose, kSilent };
// Constructor.
Operator(Opcode opcode, Properties properties, const char* mnemonic,
size_t value_in, size_t effect_in, size_t control_in,
size_t value_out, size_t effect_out, size_t control_out);
Operator(const Operator&) = delete;
Operator& operator=(const Operator&) = delete;
// A small integer unique to all instances of a particular kind of operator,
// useful for quick matching for specific kinds of operators. For fast access
// the opcode is stored directly in the operator object.
Opcode opcode() const { return opcode_; }
// Returns a constant string representing the mnemonic of the operator,
// without the static parameters. Useful for debugging.
const char* mnemonic() const { return mnemonic_; }
// Check if this operator equals another operator. Equivalent operators can
// be merged, and nodes with equivalent operators and equivalent inputs
// can be merged.
virtual bool Equals(const Operator* that) const {
return this->opcode() == that->opcode();
// Compute a hashcode to speed up equivalence-set checking.
// Equal operators should always have equal hashcodes, and unequal operators
// should have unequal hashcodes with high probability.
virtual size_t HashCode() const { return base::hash<Opcode>()(opcode()); }
// Check whether this operator has the given property.
bool HasProperty(Property property) const {
return (properties() & property) == property;
Properties properties() const { return properties_; }
// TODO(titzer): convert return values here to size_t.
int ValueInputCount() const { return value_in_; }
int EffectInputCount() const { return effect_in_; }
int ControlInputCount() const { return control_in_; }
int ValueOutputCount() const { return value_out_; }
int EffectOutputCount() const { return effect_out_; }
int ControlOutputCount() const { return control_out_; }
static size_t ZeroIfEliminatable(Properties properties) {
return (properties & kEliminatable) == kEliminatable ? 0 : 1;
static size_t ZeroIfNoThrow(Properties properties) {
return (properties & kNoThrow) == kNoThrow ? 0 : 2;
static size_t ZeroIfPure(Properties properties) {
return (properties & kPure) == kPure ? 0 : 1;
// TODO(titzer): API for input and output types, for typechecking graph.
// Print the full operator into the given stream, including any
// static parameters. Useful for debugging and visualizing the IR.
void PrintTo(std::ostream& os,
PrintVerbosity verbose = PrintVerbosity::kVerbose) const {
// We cannot make PrintTo virtual, because default arguments to virtual
// methods are banned in the style guide.
return PrintToImpl(os, verbose);
void PrintPropsTo(std::ostream& os) const;
virtual void PrintToImpl(std::ostream& os, PrintVerbosity verbose) const;
const char* mnemonic_;
Opcode opcode_;
Properties properties_;
uint32_t value_in_;
uint32_t effect_in_;
uint32_t control_in_;
uint32_t value_out_;
uint8_t effect_out_;
uint32_t control_out_;
V8_EXPORT_PRIVATE std::ostream& operator<<(std::ostream& os,
const Operator& op);
// Default equality function for below Operator1<*> class.
template <typename T>
struct OpEqualTo : public std::equal_to<T> {};
// Default hashing function for below Operator1<*> class.
template <typename T>
struct OpHash : public base::hash<T> {};
// A templatized implementation of Operator that has one static parameter of
// type {T} with the proper default equality and hashing functions.
template <typename T, typename Pred = OpEqualTo<T>, typename Hash = OpHash<T>>
class Operator1 : public Operator {
Operator1(Opcode opcode, Properties properties, const char* mnemonic,
size_t value_in, size_t effect_in, size_t control_in,
size_t value_out, size_t effect_out, size_t control_out,
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),
hash_(hash) {}
T const& parameter() const { return parameter_; }
bool Equals(const Operator* other) const final {
if (opcode() != other->opcode()) return false;
const Operator1<T, Pred, Hash>* that =
reinterpret_cast<const Operator1<T, Pred, Hash>*>(other);
return this->pred_(this->parameter(), that->parameter());
size_t HashCode() const final {
return base::hash_combine(this->opcode(), this->hash_(this->parameter()));
// For most parameter types, we have only a verbose way to print them, namely
// ostream << parameter. But for some types it is particularly useful to have
// a shorter way to print them for the node labels in Turbolizer. The
// following method can be overridden to provide a concise and a verbose
// printing of a parameter.
virtual void PrintParameter(std::ostream& os, PrintVerbosity verbose) const {
os << "[" << parameter() << "]";
void PrintToImpl(std::ostream& os, PrintVerbosity verbose) const override {
os << mnemonic();
PrintParameter(os, verbose);
T const parameter_;
Pred const pred_;
Hash const hash_;
// Helper to extract parameters from Operator1<*> operator.
template <typename T>
inline T const& OpParameter(const Operator* op) {
return reinterpret_cast<const Operator1<T, OpEqualTo<T>, OpHash<T>>*>(op)
// NOTE: We have to be careful to use the right equal/hash functions below, for
// float/double we always use the ones operating on the bit level, for Handle<>
// we always use the ones operating on the location level.
template <>
struct OpEqualTo<float> : public base::bit_equal_to<float> {};
template <>
struct OpHash<float> : public base::bit_hash<float> {};
template <>
struct OpEqualTo<double> : public base::bit_equal_to<double> {};
template <>
struct OpHash<double> : public base::bit_hash<double> {};
template <class T>
struct OpEqualTo<Handle<T>> : public Handle<T>::equal_to {};
template <class T>
struct OpHash<Handle<T>> : public Handle<T>::hash {};
} // namespace compiler
} // namespace internal
} // namespace v8