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1 | //=- llvm/CodeGen/DFAPacketizer.h - DFA Packetizer for VLIW ---*- C++ -*-=====// |
2 | // | |
3 | // The LLVM Compiler Infrastructure | |
4 | // | |
5 | // This file is distributed under the University of Illinois Open Source | |
6 | // License. See LICENSE.TXT for details. | |
7 | // | |
8 | //===----------------------------------------------------------------------===// | |
9 | // This class implements a deterministic finite automaton (DFA) based | |
10 | // packetizing mechanism for VLIW architectures. It provides APIs to | |
11 | // determine whether there exists a legal mapping of instructions to | |
12 | // functional unit assignments in a packet. The DFA is auto-generated from | |
13 | // the target's Schedule.td file. | |
14 | // | |
15 | // A DFA consists of 3 major elements: states, inputs, and transitions. For | |
16 | // the packetizing mechanism, the input is the set of instruction classes for | |
17 | // a target. The state models all possible combinations of functional unit | |
18 | // consumption for a given set of instructions in a packet. A transition | |
19 | // models the addition of an instruction to a packet. In the DFA constructed | |
20 | // by this class, if an instruction can be added to a packet, then a valid | |
21 | // transition exists from the corresponding state. Invalid transitions | |
22 | // indicate that the instruction cannot be added to the current packet. | |
23 | // | |
24 | //===----------------------------------------------------------------------===// | |
25 | ||
26 | #ifndef LLVM_CODEGEN_DFAPACKETIZER_H | |
27 | #define LLVM_CODEGEN_DFAPACKETIZER_H | |
28 | ||
223e47cc | 29 | #include "llvm/ADT/DenseMap.h" |
970d7e83 | 30 | #include "llvm/CodeGen/MachineBasicBlock.h" |
223e47cc LB |
31 | #include <map> |
32 | ||
33 | namespace llvm { | |
34 | ||
35 | class MCInstrDesc; | |
36 | class MachineInstr; | |
37 | class MachineLoopInfo; | |
38 | class MachineDominatorTree; | |
39 | class InstrItineraryData; | |
40 | class DefaultVLIWScheduler; | |
41 | class SUnit; | |
42 | ||
43 | class DFAPacketizer { | |
44 | private: | |
45 | typedef std::pair<unsigned, unsigned> UnsignPair; | |
46 | const InstrItineraryData *InstrItins; | |
47 | int CurrentState; | |
48 | const int (*DFAStateInputTable)[2]; | |
49 | const unsigned *DFAStateEntryTable; | |
50 | ||
51 | // CachedTable is a map from <FromState, Input> to ToState. | |
52 | DenseMap<UnsignPair, unsigned> CachedTable; | |
53 | ||
54 | // ReadTable - Read the DFA transition table and update CachedTable. | |
55 | void ReadTable(unsigned int state); | |
56 | ||
57 | public: | |
58 | DFAPacketizer(const InstrItineraryData *I, const int (*SIT)[2], | |
59 | const unsigned *SET); | |
60 | ||
61 | // Reset the current state to make all resources available. | |
62 | void clearResources() { | |
63 | CurrentState = 0; | |
64 | } | |
65 | ||
66 | // canReserveResources - Check if the resources occupied by a MCInstrDesc | |
67 | // are available in the current state. | |
68 | bool canReserveResources(const llvm::MCInstrDesc *MID); | |
69 | ||
70 | // reserveResources - Reserve the resources occupied by a MCInstrDesc and | |
71 | // change the current state to reflect that change. | |
72 | void reserveResources(const llvm::MCInstrDesc *MID); | |
73 | ||
74 | // canReserveResources - Check if the resources occupied by a machine | |
75 | // instruction are available in the current state. | |
76 | bool canReserveResources(llvm::MachineInstr *MI); | |
77 | ||
78 | // reserveResources - Reserve the resources occupied by a machine | |
79 | // instruction and change the current state to reflect that change. | |
80 | void reserveResources(llvm::MachineInstr *MI); | |
81 | ||
82 | const InstrItineraryData *getInstrItins() const { return InstrItins; } | |
83 | }; | |
84 | ||
85 | // VLIWPacketizerList - Implements a simple VLIW packetizer using DFA. The | |
86 | // packetizer works on machine basic blocks. For each instruction I in BB, the | |
87 | // packetizer consults the DFA to see if machine resources are available to | |
88 | // execute I. If so, the packetizer checks if I depends on any instruction J in | |
89 | // the current packet. If no dependency is found, I is added to current packet | |
90 | // and machine resource is marked as taken. If any dependency is found, a target | |
91 | // API call is made to prune the dependence. | |
92 | class VLIWPacketizerList { | |
93 | protected: | |
223e47cc LB |
94 | const MachineFunction &MF; |
95 | const TargetInstrInfo *TII; | |
96 | ||
97 | // The VLIW Scheduler. | |
98 | DefaultVLIWScheduler *VLIWScheduler; | |
99 | ||
100 | // Vector of instructions assigned to the current packet. | |
101 | std::vector<MachineInstr*> CurrentPacketMIs; | |
102 | // DFA resource tracker. | |
103 | DFAPacketizer *ResourceTracker; | |
104 | ||
105 | // Generate MI -> SU map. | |
106 | std::map<MachineInstr*, SUnit*> MIToSUnit; | |
107 | ||
108 | public: | |
1a4d82fc | 109 | VLIWPacketizerList(MachineFunction &MF, MachineLoopInfo &MLI, bool IsPostRA); |
223e47cc LB |
110 | |
111 | virtual ~VLIWPacketizerList(); | |
112 | ||
113 | // PacketizeMIs - Implement this API in the backend to bundle instructions. | |
114 | void PacketizeMIs(MachineBasicBlock *MBB, | |
115 | MachineBasicBlock::iterator BeginItr, | |
116 | MachineBasicBlock::iterator EndItr); | |
117 | ||
118 | // getResourceTracker - return ResourceTracker | |
119 | DFAPacketizer *getResourceTracker() {return ResourceTracker;} | |
120 | ||
121 | // addToPacket - Add MI to the current packet. | |
122 | virtual MachineBasicBlock::iterator addToPacket(MachineInstr *MI) { | |
123 | MachineBasicBlock::iterator MII = MI; | |
124 | CurrentPacketMIs.push_back(MI); | |
125 | ResourceTracker->reserveResources(MI); | |
126 | return MII; | |
127 | } | |
128 | ||
129 | // endPacket - End the current packet. | |
130 | void endPacket(MachineBasicBlock *MBB, MachineInstr *MI); | |
131 | ||
132 | // initPacketizerState - perform initialization before packetizing | |
133 | // an instruction. This function is supposed to be overrided by | |
134 | // the target dependent packetizer. | |
970d7e83 | 135 | virtual void initPacketizerState() { return; } |
223e47cc LB |
136 | |
137 | // ignorePseudoInstruction - Ignore bundling of pseudo instructions. | |
138 | virtual bool ignorePseudoInstruction(MachineInstr *I, | |
139 | MachineBasicBlock *MBB) { | |
140 | return false; | |
141 | } | |
142 | ||
143 | // isSoloInstruction - return true if instruction MI can not be packetized | |
144 | // with any other instruction, which means that MI itself is a packet. | |
145 | virtual bool isSoloInstruction(MachineInstr *MI) { | |
146 | return true; | |
147 | } | |
148 | ||
149 | // isLegalToPacketizeTogether - Is it legal to packetize SUI and SUJ | |
150 | // together. | |
151 | virtual bool isLegalToPacketizeTogether(SUnit *SUI, SUnit *SUJ) { | |
152 | return false; | |
153 | } | |
154 | ||
155 | // isLegalToPruneDependencies - Is it legal to prune dependece between SUI | |
156 | // and SUJ. | |
157 | virtual bool isLegalToPruneDependencies(SUnit *SUI, SUnit *SUJ) { | |
158 | return false; | |
159 | } | |
160 | ||
161 | }; | |
162 | } | |
163 | ||
164 | #endif |