ScheduleDAGSDNodes.h revision 4c727204271067f3dbf50bd23098b2df8e1cc47a 
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<RegisterMaskSDNode>(Node))   return true;
57      if (isa<GlobalAddressSDNode>(Node))  return true;
58      if (isa<BasicBlockSDNode>(Node))     return true;
59      if (isa<FrameIndexSDNode>(Node))     return true;
60      if (isa<ConstantPoolSDNode>(Node))   return true;
61      if (isa<JumpTableSDNode>(Node))      return true;
62      if (isa<ExternalSymbolSDNode>(Node)) return true;
63      if (isa<BlockAddressSDNode>(Node))   return true;
64      if (Node->getOpcode() == ISD::EntryToken ||
65          isa<MDNodeSDNode>(Node)) return true;
66      return false;
67    }
68
69    /// NewSUnit - Creates a new SUnit and return a ptr to it.
70    ///
71    SUnit *NewSUnit(SDNode *N);
72
73    /// Clone - Creates a clone of the specified SUnit. It does not copy the
74    /// predecessors / successors info nor the temporary scheduling states.
75    ///
76    SUnit *Clone(SUnit *N);
77
78    /// BuildSchedGraph - Build the SUnit graph from the selection dag that we
79    /// are input.  This SUnit graph is similar to the SelectionDAG, but
80    /// excludes nodes that aren't interesting to scheduling, and represents
81    /// flagged together nodes with a single SUnit.
82    void BuildSchedGraph(AliasAnalysis *AA);
83
84    /// InitVRegCycleFlag - Set isVRegCycle if this node's single use is
85    /// CopyToReg and its only active data operands are CopyFromReg within a
86    /// single block loop.
87    ///
88    void InitVRegCycleFlag(SUnit *SU);
89
90    /// InitNumRegDefsLeft - Determine the # of regs defined by this node.
91    ///
92    void InitNumRegDefsLeft(SUnit *SU);
93
94    /// ComputeLatency - Compute node latency.
95    ///
96    virtual void ComputeLatency(SUnit *SU);
97
98    /// ComputeOperandLatency - Override dependence edge latency using
99    /// operand use/def information
100    ///
101    virtual void ComputeOperandLatency(SUnit *Def, SUnit *Use,
102                                       SDep& dep) const { }
103
104    virtual void ComputeOperandLatency(SDNode *Def, SDNode *Use,
105                                       unsigned OpIdx, SDep& dep) const;
106
107    virtual MachineBasicBlock *EmitSchedule();
108
109    /// Schedule - Order nodes according to selected style, filling
110    /// in the Sequence member.
111    ///
112    virtual void Schedule() = 0;
113
114    /// VerifyScheduledSequence - Verify that all SUnits are scheduled and
115    /// consistent with the Sequence of scheduled instructions.
116    void VerifyScheduledSequence(bool isBottomUp);
117
118    virtual void dumpNode(const SUnit *SU) const;
119
120    virtual std::string getGraphNodeLabel(const SUnit *SU) const;
121
122    virtual std::string getDAGName() const;
123
124    virtual void getCustomGraphFeatures(GraphWriter<ScheduleDAG*> &GW) const;
125
126    /// RegDefIter - In place iteration over the values defined by an
127    /// SUnit. This does not need copies of the iterator or any other STLisms.
128    /// The iterator creates itself, rather than being provided by the SchedDAG.
129    class RegDefIter {
130      const ScheduleDAGSDNodes *SchedDAG;
131      const SDNode *Node;
132      unsigned DefIdx;
133      unsigned NodeNumDefs;
134      EVT ValueType;
135    public:
136      RegDefIter(const SUnit *SU, const ScheduleDAGSDNodes *SD);
137
138      bool IsValid() const { return Node != NULL; }
139
140      EVT GetValue() const {
141        assert(IsValid() && "bad iterator");
142        return ValueType;
143      }
144
145      const SDNode *GetNode() const {
146        return Node;
147      }
148
149      unsigned GetIdx() const {
150        return DefIdx-1;
151      }
152
153      void Advance();
154    private:
155      void InitNodeNumDefs();
156    };
157
158  private:
159    /// ClusterNeighboringLoads - Cluster loads from "near" addresses into
160    /// combined SUnits.
161    void ClusterNeighboringLoads(SDNode *Node);
162    /// ClusterNodes - Cluster certain nodes which should be scheduled together.
163    ///
164    void ClusterNodes();
165
166    /// BuildSchedUnits, AddSchedEdges - Helper functions for BuildSchedGraph.
167    void BuildSchedUnits();
168    void AddSchedEdges();
169  };
170}
171
172#endif
173