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 
21 namespace 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 
~ScheduleDAGSDNodes()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     ///
isPassiveNode(SDNode * Node)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     /// InitVRegCycleFlag - Set isVRegCycle if this node's single use is
84     /// CopyToReg and its only active data operands are CopyFromReg within a
85     /// single block loop.
86     ///
87     void InitVRegCycleFlag(SUnit *SU);
88 
89     /// InitNumRegDefsLeft - Determine the # of regs defined by this node.
90     ///
91     void InitNumRegDefsLeft(SUnit *SU);
92 
93     /// ComputeLatency - Compute node latency.
94     ///
95     virtual void ComputeLatency(SUnit *SU);
96 
97     /// ComputeOperandLatency - Override dependence edge latency using
98     /// operand use/def information
99     ///
ComputeOperandLatency(SUnit * Def,SUnit * Use,SDep & dep)100     virtual void ComputeOperandLatency(SUnit *Def, SUnit *Use,
101                                        SDep& dep) const { }
102 
103     virtual void ComputeOperandLatency(SDNode *Def, SDNode *Use,
104                                        unsigned OpIdx, SDep& dep) const;
105 
106     virtual MachineBasicBlock *EmitSchedule();
107 
108     /// Schedule - Order nodes according to selected style, filling
109     /// in the Sequence member.
110     ///
111     virtual void Schedule() = 0;
112 
113     virtual void dumpNode(const SUnit *SU) const;
114 
115     virtual std::string getGraphNodeLabel(const SUnit *SU) const;
116 
117     virtual void getCustomGraphFeatures(GraphWriter<ScheduleDAG*> &GW) const;
118 
119     /// RegDefIter - In place iteration over the values defined by an
120     /// SUnit. This does not need copies of the iterator or any other STLisms.
121     /// The iterator creates itself, rather than being provided by the SchedDAG.
122     class RegDefIter {
123       const ScheduleDAGSDNodes *SchedDAG;
124       const SDNode *Node;
125       unsigned DefIdx;
126       unsigned NodeNumDefs;
127       EVT ValueType;
128     public:
129       RegDefIter(const SUnit *SU, const ScheduleDAGSDNodes *SD);
130 
IsValid()131       bool IsValid() const { return Node != NULL; }
132 
GetValue()133       EVT GetValue() const {
134         assert(IsValid() && "bad iterator");
135         return ValueType;
136       }
137 
GetNode()138       const SDNode *GetNode() const {
139         return Node;
140       }
141 
GetIdx()142       unsigned GetIdx() const {
143         return DefIdx-1;
144       }
145 
146       void Advance();
147     private:
148       void InitNodeNumDefs();
149     };
150 
151   private:
152     /// ClusterNeighboringLoads - Cluster loads from "near" addresses into
153     /// combined SUnits.
154     void ClusterNeighboringLoads(SDNode *Node);
155     /// ClusterNodes - Cluster certain nodes which should be scheduled together.
156     ///
157     void ClusterNodes();
158 
159     /// BuildSchedUnits, AddSchedEdges - Helper functions for BuildSchedGraph.
160     void BuildSchedUnits();
161     void AddSchedEdges();
162   };
163 }
164 
165 #endif
166