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79 lines
2.9 KiB
C++
79 lines
2.9 KiB
C++
//=- llvm/CodeGen/DFAPacketizer.h - DFA Packetizer for VLIW ---*- C++ -*-=====//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// This class implements a deterministic finite automaton (DFA) based
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// packetizing mechanism for VLIW architectures. It provides APIs to
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// determine whether there exists a legal mapping of instructions to
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// functional unit assignments in a packet. The DFA is auto-generated from
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// the target's Schedule.td file.
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//
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// A DFA consists of 3 major elements: states, inputs, and transitions. For
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// the packetizing mechanism, the input is the set of instruction classes for
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// a target. The state models all possible combinations of functional unit
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// consumption for a given set of instructions in a packet. A transition
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// models the addition of an instruction to a packet. In the DFA constructed
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// by this class, if an instruction can be added to a packet, then a valid
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// transition exists from the corresponding state. Invalid transitions
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// indicate that the instruction cannot be added to the current packet.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_DFAPACKETIZER_H
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#define LLVM_CODEGEN_DFAPACKETIZER_H
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#include "llvm/ADT/DenseMap.h"
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namespace llvm {
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class MCInstrDesc;
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class MachineInstr;
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class InstrItineraryData;
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class DFAPacketizer {
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private:
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typedef std::pair<unsigned, unsigned> UnsignPair;
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const InstrItineraryData *InstrItins;
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int CurrentState;
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const int (*DFAStateInputTable)[2];
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const unsigned *DFAStateEntryTable;
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// CachedTable is a map from <FromState, Input> to ToState.
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DenseMap<UnsignPair, unsigned> CachedTable;
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// ReadTable - Read the DFA transition table and update CachedTable.
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void ReadTable(unsigned int state);
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public:
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DFAPacketizer(const InstrItineraryData *I, const int (*SIT)[2],
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const unsigned *SET);
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// Reset the current state to make all resources available.
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void clearResources() {
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CurrentState = 0;
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}
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// canReserveResources - Check if the resources occupied by a MCInstrDesc
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// are available in the current state.
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bool canReserveResources(const llvm::MCInstrDesc *MID);
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// reserveResources - Reserve the resources occupied by a MCInstrDesc and
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// change the current state to reflect that change.
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void reserveResources(const llvm::MCInstrDesc *MID);
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// canReserveResources - Check if the resources occupied by a machine
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// instruction are available in the current state.
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bool canReserveResources(llvm::MachineInstr *MI);
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// reserveResources - Reserve the resources occupied by a machine
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// instruction and change the current state to reflect that change.
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void reserveResources(llvm::MachineInstr *MI);
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};
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}
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#endif
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