2 //***************************************************************************
7 // Encapsulate heuristics for instruction scheduling.
10 // Priority ordering rules:
11 // (1) Max delay, which is the order of the heap S.candsAsHeap.
12 // (2) Instruction that frees up a register.
13 // (3) Instruction that has the maximum number of dependent instructions.
14 // Note that rules 2 and 3 are only used if issue conflicts prevent
15 // choosing a higher priority instruction by rule 1.
18 // 7/30/01 - Vikram Adve - Created
19 //**************************************************************************/
21 #ifndef LLVM_CODEGEN_SCHEDPRIORITIES_H
22 #define LLVM_CODEGEN_SCHEDPRIORITIES_H
24 #include "SchedGraph.h"
25 #include "llvm/CodeGen/InstrScheduling.h"
26 #include "llvm/Target/MachineSchedInfo.h"
27 #include "Support/CommandLine.h"
29 #include <ext/hash_set>
33 class SchedulingManager;
34 class MethodLiveVarInfo;
36 //---------------------------------------------------------------------------
37 // Debug option levels for instruction scheduling
39 enum SchedDebugLevel_t {
41 Sched_PrintMachineCode,
42 Sched_PrintSchedTrace,
43 Sched_PrintSchedGraphs,
46 extern cl::Enum<SchedDebugLevel_t> SchedDebugLevel;
48 //---------------------------------------------------------------------------
49 // Function: instrIsFeasible
52 // Used by the priority analysis to filter out instructions
53 // that are not feasible to issue in the current cycle.
54 // Should only be used during schedule construction..
55 //---------------------------------------------------------------------------
57 bool instrIsFeasible(const SchedulingManager &S, MachineOpCode opCode);
61 struct NodeDelayPair {
62 const SchedGraphNode* node;
64 NodeDelayPair(const SchedGraphNode* n, cycles_t d) : node(n), delay(d) {}
65 inline bool operator<(const NodeDelayPair& np) { return delay < np.delay; }
69 NDPLessThan(const NodeDelayPair* np1, const NodeDelayPair* np2)
71 return np1->delay < np2->delay;
74 class NodeHeap: public std::list<NodeDelayPair*>, public NonCopyable {
76 typedef std::list<NodeDelayPair*>::iterator iterator;
77 typedef std::list<NodeDelayPair*>::const_iterator const_iterator;
80 NodeHeap() : _size(0) {}
82 inline unsigned size() const { return _size; }
84 const SchedGraphNode* getNode (const_iterator i) const { return (*i)->node; }
85 cycles_t getDelay(const_iterator i) const { return (*i)->delay;}
87 inline void makeHeap() {
88 // make_heap(begin(), end(), NDPLessThan);
91 inline iterator findNode(const SchedGraphNode* node) {
92 for (iterator I=begin(); I != end(); ++I)
93 if (getNode(I) == node)
98 inline void removeNode (const SchedGraphNode* node) {
99 iterator ndpPtr = findNode(node);
108 void insert(const SchedGraphNode* node, cycles_t delay) {
109 NodeDelayPair* ndp = new NodeDelayPair(node, delay);
110 if (_size == 0 || front()->delay < delay)
115 for ( ; I != end() && getDelay(I) >= delay; ++I)
117 std::list<NodeDelayPair*>::insert(I, ndp);
126 class SchedPriorities: public NonCopyable {
128 SchedPriorities(const Function *F, const SchedGraph *G,
129 MethodLiveVarInfo &LVI);
132 // This must be called before scheduling begins.
135 cycles_t getTime () const { return curTime; }
136 cycles_t getEarliestReadyTime () const { return earliestReadyTime; }
137 unsigned getNumReady () const { return candsAsHeap.size(); }
138 bool nodeIsReady (const SchedGraphNode* node) const {
139 return (candsAsSet.find(node) != candsAsSet.end());
142 void issuedReadyNodeAt (cycles_t curTime,
143 const SchedGraphNode* node);
145 void insertReady (const SchedGraphNode* node);
147 void updateTime (cycles_t /*unused*/);
149 const SchedGraphNode* getNextHighest (const SchedulingManager& S,
151 // choose next highest priority instr
154 typedef NodeHeap::iterator candIndex;
158 const SchedGraph* graph;
159 MethodLiveVarInfo &methodLiveVarInfo;
160 std::hash_map<const MachineInstr*, bool> lastUseMap;
161 std::vector<cycles_t> nodeDelayVec;
162 std::vector<cycles_t> earliestForNode;
163 cycles_t earliestReadyTime;
164 NodeHeap candsAsHeap; // candidate nodes, ready to go
165 std::hash_set<const SchedGraphNode*> candsAsSet;//same entries as candsAsHeap,
166 // but as set for fast lookup
167 std::vector<candIndex> mcands; // holds pointers into cands
168 candIndex nextToTry; // next cand after the last
169 // one tried in this cycle
171 int chooseByRule1 (std::vector<candIndex>& mcands);
172 int chooseByRule2 (std::vector<candIndex>& mcands);
173 int chooseByRule3 (std::vector<candIndex>& mcands);
175 void findSetWithMaxDelay (std::vector<candIndex>& mcands,
176 const SchedulingManager& S);
178 void computeDelays (const SchedGraph* graph);
180 void initializeReadyHeap (const SchedGraph* graph);
182 bool instructionHasLastUse (MethodLiveVarInfo& methodLiveVarInfo,
183 const SchedGraphNode* graphNode);
185 // NOTE: The next two return references to the actual vector entries.
187 cycles_t& getNodeDelayRef (const SchedGraphNode* node) {
188 assert(node->getNodeId() < nodeDelayVec.size());
189 return nodeDelayVec[node->getNodeId()];
191 cycles_t& getEarliestForNodeRef (const SchedGraphNode* node) {
192 assert(node->getNodeId() < earliestForNode.size());
193 return earliestForNode[node->getNodeId()];
198 inline void SchedPriorities::updateTime(cycles_t c) {
200 nextToTry = candsAsHeap.begin();
204 inline std::ostream &operator<<(std::ostream &os, const NodeDelayPair* nd) {
205 return os << "Delay for node " << nd->node->getNodeId()
206 << " = " << (long)nd->delay << "\n";