ScheduleDAGSDNodes.h revision 92e946630d5f9bb092853b93501387dd216899b9 
1//===---- ScheduleDAGSDNodes.h - SDNode Scheduling --------------*- C++ -*-===//
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 implements the ScheduleDAGSDNodes class, which implements
11// scheduling for an SDNode-based dependency graph.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef SCHEDULEDAGSDNODES_H
16#define SCHEDULEDAGSDNODES_H
17
18#include "llvm/CodeGen/ScheduleDAG.h"
19#include "llvm/CodeGen/SelectionDAG.h"
20
21namespace llvm {
22  /// ScheduleDAGSDNodes - A ScheduleDAG for scheduling SDNode-based DAGs.
23  ///
24  /// Edges between SUnits are initially based on edges in the SelectionDAG,
25  /// and additional edges can be added by the schedulers as heuristics.
26  /// SDNodes such as Constants, Registers, and a few others that are not
27  /// interesting to schedulers are not allocated SUnits.
28  ///
29  /// SDNodes with MVT::Glue operands are grouped along with the flagged
30  /// nodes into a single SUnit so that they are scheduled together.
31  ///
32  /// SDNode-based scheduling graphs do not use SDep::Anti or SDep::Output
33  /// edges.  Physical register dependence information is not carried in
34  /// the DAG and must be handled explicitly by schedulers.
35  ///
36  class ScheduleDAGSDNodes : public ScheduleDAG {
37  public:
38    SelectionDAG *DAG;                    // DAG of the current basic block
39    const InstrItineraryData *InstrItins;
40
41    explicit ScheduleDAGSDNodes(MachineFunction &mf);
42
43    virtual ~ScheduleDAGSDNodes() {}
44
45    /// Run - perform scheduling.
46    ///
47    void Run(SelectionDAG *dag, MachineBasicBlock *bb,
48             MachineBasicBlock::iterator insertPos);
49
50    /// isPassiveNode - Return true if the node is a non-scheduled leaf.
51    ///
52    static bool isPassiveNode(SDNode *Node) {
53      if (isa<ConstantSDNode>(Node))       return true;
54      if (isa<ConstantFPSDNode>(Node))     return true;
55      if (isa<RegisterSDNode>(Node))       return true;
56      if (isa<GlobalAddressSDNode>(Node))  return true;
57      if (isa<BasicBlockSDNode>(Node))     return true;
58      if (isa<FrameIndexSDNode>(Node))     return true;
59      if (isa<ConstantPoolSDNode>(Node))   return true;
60      if (isa<JumpTableSDNode>(Node))      return true;
61      if (isa<ExternalSymbolSDNode>(Node)) return true;
62      if (isa<BlockAddressSDNode>(Node))   return true;
63      if (Node->getOpcode() == ISD::EntryToken ||
64          isa<MDNodeSDNode>(Node)) return true;
65      return false;
66    }
67
68    /// NewSUnit - Creates a new SUnit and return a ptr to it.
69    ///
70    SUnit *NewSUnit(SDNode *N);
71
72    /// Clone - Creates a clone of the specified SUnit. It does not copy the
73    /// predecessors / successors info nor the temporary scheduling states.
74    ///
75    SUnit *Clone(SUnit *N);
76
77    /// BuildSchedGraph - Build the SUnit graph from the selection dag that we
78    /// are input.  This SUnit graph is similar to the SelectionDAG, but
79    /// excludes nodes that aren't interesting to scheduling, and represents
80    /// flagged together nodes with a single SUnit.
81    virtual void BuildSchedGraph(AliasAnalysis *AA);
82
83    /// InitNumRegDefsLeft - Determine the # of regs defined by this node.
84    ///
85    void InitNumRegDefsLeft(SUnit *SU);
86
87    /// ComputeLatency - Compute node latency.
88    ///
89    virtual void ComputeLatency(SUnit *SU);
90
91    /// ComputeOperandLatency - Override dependence edge latency using
92    /// operand use/def information
93    ///
94    virtual void ComputeOperandLatency(SUnit *Def, SUnit *Use,
95                                       SDep& dep) const { }
96
97    virtual void ComputeOperandLatency(SDNode *Def, SDNode *Use,
98                                       unsigned OpIdx, SDep& dep) const;
99
100    virtual MachineBasicBlock *EmitSchedule();
101
102    /// Schedule - Order nodes according to selected style, filling
103    /// in the Sequence member.
104    ///
105    virtual void Schedule() = 0;
106
107    virtual void dumpNode(const SUnit *SU) const;
108
109    virtual std::string getGraphNodeLabel(const SUnit *SU) const;
110
111    virtual void getCustomGraphFeatures(GraphWriter<ScheduleDAG*> &GW) const;
112
113    /// RegDefIter - In place iteration over the values defined by an
114    /// SUnit. This does not need copies of the iterator or any other STLisms.
115    /// The iterator creates itself, rather than being provided by the SchedDAG.
116    class RegDefIter {
117      const ScheduleDAGSDNodes *SchedDAG;
118      const SDNode *Node;
119      unsigned DefIdx;
120      unsigned NodeNumDefs;
121      EVT ValueType;
122    public:
123      RegDefIter(const SUnit *SU, const ScheduleDAGSDNodes *SD);
124
125      bool IsValid() const { return Node != NULL; }
126
127      EVT GetValue() const {
128        assert(IsValid() && "bad iterator");
129        return ValueType;
130      }
131
132      void Advance();
133    private:
134      void InitNodeNumDefs();
135    };
136
137  private:
138    /// ClusterNeighboringLoads - Cluster loads from "near" addresses into
139    /// combined SUnits.
140    void ClusterNeighboringLoads(SDNode *Node);
141    /// ClusterNodes - Cluster certain nodes which should be scheduled together.
142    ///
143    void ClusterNodes();
144
145    /// BuildSchedUnits, AddSchedEdges - Helper functions for BuildSchedGraph.
146    void BuildSchedUnits();
147    void AddSchedEdges();
148  };
149}
150
151#endif
152