LatencyPriorityQueue.h revision 208954 
1//===---- LatencyPriorityQueue.h - A latency-oriented priority queue ------===//
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//
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.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LATENCY_PRIORITY_QUEUE_H
17#define LATENCY_PRIORITY_QUEUE_H
18
19#include "llvm/CodeGen/ScheduleDAG.h"
20
21namespace llvm {
22  class LatencyPriorityQueue;
23
24  /// Sorting functions for the Available queue.
25  struct latency_sort : public std::binary_function<SUnit*, SUnit*, bool> {
26    LatencyPriorityQueue *PQ;
27    explicit latency_sort(LatencyPriorityQueue *pq) : PQ(pq) {}
28
29    bool operator()(const SUnit* left, const SUnit* right) const;
30  };
31
32  class LatencyPriorityQueue : public SchedulingPriorityQueue {
33    // SUnits - The SUnits for the current graph.
34    std::vector<SUnit> *SUnits;
35
36    /// NumNodesSolelyBlocking - This vector contains, for every node in the
37    /// Queue, the number of nodes that the node is the sole unscheduled
38    /// predecessor for.  This is used as a tie-breaker heuristic for better
39    /// mobility.
40    std::vector<unsigned> NumNodesSolelyBlocking;
41
42    /// Queue - The queue.
43    std::vector<SUnit*> Queue;
44    latency_sort Picker;
45
46  public:
47    LatencyPriorityQueue() : Picker(this) {
48    }
49
50    void initNodes(std::vector<SUnit> &sunits) {
51      SUnits = &sunits;
52      NumNodesSolelyBlocking.resize(SUnits->size(), 0);
53    }
54
55    void addNode(const SUnit *SU) {
56      NumNodesSolelyBlocking.resize(SUnits->size(), 0);
57    }
58
59    void updateNode(const SUnit *SU) {
60    }
61
62    void releaseState() {
63      SUnits = 0;
64    }
65
66    unsigned getLatency(unsigned NodeNum) const {
67      assert(NodeNum < (*SUnits).size());
68      return (*SUnits)[NodeNum].getHeight();
69    }
70
71    unsigned getNumSolelyBlockNodes(unsigned NodeNum) const {
72      assert(NodeNum < NumNodesSolelyBlocking.size());
73      return NumNodesSolelyBlocking[NodeNum];
74    }
75
76    bool empty() const { return Queue.empty(); }
77
78    virtual void push(SUnit *U);
79
80    virtual SUnit *pop();
81
82    virtual void remove(SUnit *SU);
83
84    // ScheduledNode - As nodes are scheduled, we look to see if there are any
85    // successor nodes that have a single unscheduled predecessor.  If so, that
86    // single predecessor has a higher priority, since scheduling it will make
87    // the node available.
88    void ScheduledNode(SUnit *Node);
89
90private:
91    void AdjustPriorityOfUnscheduledPreds(SUnit *SU);
92    SUnit *getSingleUnscheduledPred(SUnit *SU);
93  };
94}
95
96#endif
97