1 //===---- LatencyPriorityQueue.h - A latency-oriented priority queue ------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares the LatencyPriorityQueue class, which is a
11 // SchedulingPriorityQueue that schedules using latency information to
12 // reduce the length of the critical path through the basic block.
14 //===----------------------------------------------------------------------===//
16 #ifndef LATENCY_PRIORITY_QUEUE_H
17 #define LATENCY_PRIORITY_QUEUE_H
19 #include "llvm/CodeGen/ScheduleDAG.h"
20 #include "llvm/ADT/PriorityQueue.h"
23 class LatencyPriorityQueue;
25 /// Sorting functions for the Available queue.
26 struct latency_sort : public std::binary_function<SUnit*, SUnit*, bool> {
27 LatencyPriorityQueue *PQ;
28 explicit latency_sort(LatencyPriorityQueue *pq) : PQ(pq) {}
30 bool operator()(const SUnit* left, const SUnit* right) const;
33 class LatencyPriorityQueue : public SchedulingPriorityQueue {
34 // SUnits - The SUnits for the current graph.
35 std::vector<SUnit> *SUnits;
37 // Latencies - The latency (max of latency from this node to the bb exit)
39 std::vector<int> Latencies;
41 /// NumNodesSolelyBlocking - This vector contains, for every node in the
42 /// Queue, the number of nodes that the node is the sole unscheduled
43 /// predecessor for. This is used as a tie-breaker heuristic for better
45 std::vector<unsigned> NumNodesSolelyBlocking;
47 PriorityQueue<SUnit*, std::vector<SUnit*>, latency_sort> Queue;
49 LatencyPriorityQueue() : Queue(latency_sort(this)) {
52 void initNodes(std::vector<SUnit> &sunits) {
54 // Calculate node priorities.
55 CalculatePriorities();
58 void addNode(const SUnit *SU) {
59 Latencies.resize(SUnits->size(), -1);
60 NumNodesSolelyBlocking.resize(SUnits->size(), 0);
64 void updateNode(const SUnit *SU) {
65 Latencies[SU->NodeNum] = -1;
74 unsigned getLatency(unsigned NodeNum) const {
75 assert(NodeNum < Latencies.size());
76 return Latencies[NodeNum];
79 unsigned getNumSolelyBlockNodes(unsigned NodeNum) const {
80 assert(NodeNum < NumNodesSolelyBlocking.size());
81 return NumNodesSolelyBlocking[NodeNum];
84 unsigned size() const { return Queue.size(); }
86 bool empty() const { return Queue.empty(); }
88 virtual void push(SUnit *U) {
91 void push_impl(SUnit *U);
93 void push_all(const std::vector<SUnit *> &Nodes) {
94 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
99 if (empty()) return NULL;
100 SUnit *V = Queue.top();
105 void remove(SUnit *SU) {
106 assert(!Queue.empty() && "Not in queue!");
110 // ScheduledNode - As nodes are scheduled, we look to see if there are any
111 // successor nodes that have a single unscheduled predecessor. If so, that
112 // single predecessor has a higher priority, since scheduling it will make
113 // the node available.
114 void ScheduledNode(SUnit *Node);
117 void CalculatePriorities();
118 int CalcLatency(const SUnit &SU);
119 void AdjustPriorityOfUnscheduledPreds(SUnit *SU);
120 SUnit *getSingleUnscheduledPred(SUnit *SU);