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 LLVM_CODEGEN_LATENCYPRIORITYQUEUE_H
17#define LLVM_CODEGEN_LATENCYPRIORITYQUEUE_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    bool isBottomUp() const override { return false; }
51
52    void initNodes(std::vector<SUnit> &sunits) override {
53      SUnits = &sunits;
54      NumNodesSolelyBlocking.resize(SUnits->size(), 0);
55    }
56
57    void addNode(const SUnit *SU) override {
58      NumNodesSolelyBlocking.resize(SUnits->size(), 0);
59    }
60
61    void updateNode(const SUnit *SU) override {
62    }
63
64    void releaseState() override {
65      SUnits = nullptr;
66    }
67
68    unsigned getLatency(unsigned NodeNum) const {
69      assert(NodeNum < (*SUnits).size());
70      return (*SUnits)[NodeNum].getHeight();
71    }
72
73    unsigned getNumSolelyBlockNodes(unsigned NodeNum) const {
74      assert(NodeNum < NumNodesSolelyBlocking.size());
75      return NumNodesSolelyBlocking[NodeNum];
76    }
77
78    bool empty() const override { return Queue.empty(); }
79
80    void push(SUnit *U) override;
81
82    SUnit *pop() override;
83
84    void remove(SUnit *SU) override;
85
86    void dump(ScheduleDAG* DAG) const override;
87
88    // scheduledNode - As nodes are scheduled, we look to see if there are any
89    // successor nodes that have a single unscheduled predecessor.  If so, that
90    // single predecessor has a higher priority, since scheduling it will make
91    // the node available.
92    void scheduledNode(SUnit *Node) override;
93
94private:
95    void AdjustPriorityOfUnscheduledPreds(SUnit *SU);
96    SUnit *getSingleUnscheduledPred(SUnit *SU);
97  };
98}
99
100#endif
101