mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-11-25 12:12:47 +01:00
c127d68e31
No functionality change (intended), but this seems to make the code a bit clearer for the compiler and maybe for human readers too.
108 lines
4.0 KiB
C++
108 lines
4.0 KiB
C++
//===--------------------- DfaEmitter.h -----------------------------------===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
// Defines a generic automaton builder. This takes a set of transitions and
|
|
// states that represent a nondeterministic finite state automaton (NFA) and
|
|
// emits a determinized DFA in a form that include/llvm/Support/Automaton.h can
|
|
// drive.
|
|
//
|
|
// See file llvm/TableGen/Automaton.td for the TableGen API definition.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_UTILS_TABLEGEN_DFAEMITTER_H
|
|
#define LLVM_UTILS_TABLEGEN_DFAEMITTER_H
|
|
|
|
#include "llvm/ADT/StringRef.h"
|
|
#include "llvm/ADT/UniqueVector.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include "llvm/TableGen/Record.h"
|
|
#include <set>
|
|
#include <unordered_map>
|
|
|
|
namespace llvm {
|
|
|
|
class raw_ostream;
|
|
/// Construct a deterministic finite state automaton from possible
|
|
/// nondeterministic state and transition data.
|
|
///
|
|
/// The state type is a 64-bit unsigned integer. The generated automaton is
|
|
/// invariant to the sparsity of the state representation - its size is only
|
|
/// a function of the cardinality of the set of states.
|
|
///
|
|
/// The inputs to this emitter are considered to define a nondeterministic
|
|
/// finite state automaton (NFA). This is then converted to a DFA during
|
|
/// emission. The emitted tables can be used to by
|
|
/// include/llvm/Support/Automaton.h.
|
|
class DfaEmitter {
|
|
public:
|
|
// The type of an NFA state. The initial state is always zero.
|
|
using state_type = uint64_t;
|
|
// The type of an action.
|
|
using action_type = uint64_t;
|
|
|
|
DfaEmitter() = default;
|
|
virtual ~DfaEmitter() = default;
|
|
|
|
void addTransition(state_type From, state_type To, action_type A);
|
|
void emit(StringRef Name, raw_ostream &OS);
|
|
|
|
protected:
|
|
/// Emit the C++ type of an action to OS.
|
|
virtual void printActionType(raw_ostream &OS);
|
|
/// Emit the C++ value of an action A to OS.
|
|
virtual void printActionValue(action_type A, raw_ostream &OS);
|
|
|
|
private:
|
|
/// The state type of deterministic states. These are only used internally to
|
|
/// this class. This is an ID into the DfaStates UniqueVector.
|
|
using dfa_state_type = unsigned;
|
|
|
|
/// The actual representation of a DFA state, which is a union of one or more
|
|
/// NFA states.
|
|
using DfaState = SmallVector<state_type, 4>;
|
|
|
|
/// A DFA transition consists of a set of NFA states transitioning to a
|
|
/// new set of NFA states. The DfaTransitionInfo tracks, for every
|
|
/// transitioned-from NFA state, a set of valid transitioned-to states.
|
|
///
|
|
/// Emission of this transition relation allows algorithmic determination of
|
|
/// the possible candidate NFA paths taken under a given input sequence to
|
|
/// reach a given DFA state.
|
|
using DfaTransitionInfo = SmallVector<std::pair<state_type, state_type>, 4>;
|
|
|
|
/// The set of all possible actions.
|
|
std::set<action_type> Actions;
|
|
|
|
/// The set of nondeterministic transitions. A state-action pair can
|
|
/// transition to multiple target states.
|
|
std::map<std::pair<state_type, action_type>, std::vector<state_type>>
|
|
NfaTransitions;
|
|
std::set<state_type> NfaStates;
|
|
unsigned NumNfaTransitions = 0;
|
|
|
|
/// The set of deterministic states. DfaStates.getId(DfaState) returns an ID,
|
|
/// which is dfa_state_type. Note that because UniqueVector reserves state
|
|
/// zero, the initial DFA state is always 1.
|
|
UniqueVector<DfaState> DfaStates;
|
|
/// The set of deterministic transitions. A state-action pair has only a
|
|
/// single target state.
|
|
std::map<std::pair<dfa_state_type, action_type>,
|
|
std::pair<dfa_state_type, DfaTransitionInfo>>
|
|
DfaTransitions;
|
|
|
|
/// Visit all NFA states and construct the DFA.
|
|
void constructDfa();
|
|
/// Visit a single DFA state and construct all possible transitions to new DFA
|
|
/// states.
|
|
void visitDfaState(const DfaState &DS);
|
|
};
|
|
|
|
} // namespace llvm
|
|
|
|
#endif
|