1//===----- ResourcePriorityQueue.h - A DFA-oriented priority queue -------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the ResourcePriorityQueue class, which is a
10// SchedulingPriorityQueue that schedules using DFA state to
11// reduce the length of the critical path through the basic block
12// on VLIW platforms.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_CODEGEN_RESOURCEPRIORITYQUEUE_H
17#define LLVM_CODEGEN_RESOURCEPRIORITYQUEUE_H
18
19#include "llvm/CodeGen/ScheduleDAG.h"
20
21namespace llvm {
22  class DFAPacketizer;
23  class InstrItineraryData;
24  class ResourcePriorityQueue;
25  class SelectionDAGISel;
26  class TargetInstrInfo;
27  class TargetRegisterInfo;
28
29  /// Sorting functions for the Available queue.
30  struct resource_sort {
31    ResourcePriorityQueue *PQ;
32    explicit resource_sort(ResourcePriorityQueue *pq) : PQ(pq) {}
33
34    bool operator()(const SUnit* LHS, const SUnit* RHS) const;
35  };
36
37  class ResourcePriorityQueue : public SchedulingPriorityQueue {
38    /// SUnits - The SUnits for the current graph.
39    std::vector<SUnit> *SUnits;
40
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
44    /// mobility.
45    std::vector<unsigned> NumNodesSolelyBlocking;
46
47    /// Queue - The queue.
48    std::vector<SUnit*> Queue;
49
50    /// RegPressure - Tracking current reg pressure per register class.
51    ///
52    std::vector<unsigned> RegPressure;
53
54    /// RegLimit - Tracking the number of allocatable registers per register
55    /// class.
56    std::vector<unsigned> RegLimit;
57
58    resource_sort Picker;
59    const TargetRegisterInfo *TRI;
60    const TargetLowering *TLI;
61    const TargetInstrInfo *TII;
62    const InstrItineraryData* InstrItins;
63    /// ResourcesModel - Represents VLIW state.
64    /// Not limited to VLIW targets per say, but assumes
65    /// definition of DFA by a target.
66    std::unique_ptr<DFAPacketizer> ResourcesModel;
67
68    /// Resource model - packet/bundle model. Purely
69    /// internal at the time.
70    std::vector<SUnit*> Packet;
71
72    /// Heuristics for estimating register pressure.
73    unsigned ParallelLiveRanges;
74    int HorizontalVerticalBalance;
75
76  public:
77    ResourcePriorityQueue(SelectionDAGISel *IS);
78
79    bool isBottomUp() const override { return false; }
80
81    void initNodes(std::vector<SUnit> &sunits) override;
82
83    void addNode(const SUnit *SU) override {
84      NumNodesSolelyBlocking.resize(SUnits->size(), 0);
85    }
86
87    void updateNode(const SUnit *SU) override {}
88
89    void releaseState() override {
90      SUnits = nullptr;
91    }
92
93    unsigned getLatency(unsigned NodeNum) const {
94      assert(NodeNum < (*SUnits).size());
95      return (*SUnits)[NodeNum].getHeight();
96    }
97
98    unsigned getNumSolelyBlockNodes(unsigned NodeNum) const {
99      assert(NodeNum < NumNodesSolelyBlocking.size());
100      return NumNodesSolelyBlocking[NodeNum];
101    }
102
103    /// Single cost function reflecting benefit of scheduling SU
104    /// in the current cycle.
105    int SUSchedulingCost (SUnit *SU);
106
107    /// InitNumRegDefsLeft - Determine the # of regs defined by this node.
108    ///
109    void initNumRegDefsLeft(SUnit *SU);
110    void updateNumRegDefsLeft(SUnit *SU);
111    int regPressureDelta(SUnit *SU, bool RawPressure = false);
112    int rawRegPressureDelta (SUnit *SU, unsigned RCId);
113
114    bool empty() const override { return Queue.empty(); }
115
116    void push(SUnit *U) override;
117
118    SUnit *pop() override;
119
120    void remove(SUnit *SU) override;
121
122    /// scheduledNode - Main resource tracking point.
123    void scheduledNode(SUnit *SU) override;
124    bool isResourceAvailable(SUnit *SU);
125    void reserveResources(SUnit *SU);
126
127private:
128    void adjustPriorityOfUnscheduledPreds(SUnit *SU);
129    SUnit *getSingleUnscheduledPred(SUnit *SU);
130    unsigned numberRCValPredInSU (SUnit *SU, unsigned RCId);
131    unsigned numberRCValSuccInSU (SUnit *SU, unsigned RCId);
132  };
133}
134
135#endif
136