1 //===- ScheduleDAGILP.h - ILP metric for ScheduleDAGInstrs ------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Definition of an ILP metric for machine level instruction scheduling.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_SCHEDULEDFS_H
15 #define LLVM_CODEGEN_SCHEDULEDFS_H
17 #include "llvm/CodeGen/ScheduleDAG.h"
18 #include "llvm/Support/DataTypes.h"
25 class ScheduleDAGInstrs;
28 /// \brief Represent the ILP of the subDAG rooted at a DAG node.
30 /// ILPValues summarize the DAG subtree rooted at each node. ILPValues are
31 /// valid for all nodes regardless of their subtree membership.
33 /// When computed using bottom-up DFS, this metric assumes that the DAG is a
34 /// forest of trees with roots at the bottom of the schedule branching upward.
37 /// Length may either correspond to depth or height, depending on direction,
38 /// and cycles or nodes depending on context.
41 ILPValue(unsigned count, unsigned length):
42 InstrCount(count), Length(length) {}
44 // Order by the ILP metric's value.
45 bool operator<(ILPValue RHS) const {
46 return (uint64_t)InstrCount * RHS.Length
47 < (uint64_t)Length * RHS.InstrCount;
49 bool operator>(ILPValue RHS) const {
52 bool operator<=(ILPValue RHS) const {
53 return (uint64_t)InstrCount * RHS.Length
54 <= (uint64_t)Length * RHS.InstrCount;
56 bool operator>=(ILPValue RHS) const {
60 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
61 void print(raw_ostream &OS) const;
67 /// \brief Compute the values of each DAG node for various metrics during DFS.
68 class SchedDFSResult {
69 friend class SchedDFSImpl;
71 static const unsigned InvalidSubtreeID = ~0u;
73 /// \brief Per-SUnit data computed during DFS for various metrics.
75 /// A node's SubtreeID is set to itself when it is visited to indicate that it
76 /// is the root of a subtree. Later it is set to its parent to indicate an
77 /// interior node. Finally, it is set to a representative subtree ID during
81 unsigned SubInstrCount;
84 NodeData(): InstrCount(0), SubInstrCount(0), SubtreeID(InvalidSubtreeID) {}
87 /// \brief Record a connection between subtrees and the connection level.
92 Connection(unsigned tree, unsigned level): TreeID(tree), Level(level) {}
96 unsigned SubtreeLimit;
97 /// DFS results for each SUnit in this DAG.
98 std::vector<NodeData> DFSData;
100 // For each subtree discovered during DFS, record its connections to other
102 std::vector<SmallVector<Connection, 4> > SubtreeConnections;
104 /// Cache the current connection level of each subtree.
105 /// This mutable array is updated during scheduling.
106 std::vector<unsigned> SubtreeConnectLevels;
109 SchedDFSResult(bool IsBU, unsigned lim)
110 : IsBottomUp(IsBU), SubtreeLimit(lim) {}
112 /// \brief Return true if this DFSResult is uninitialized.
114 /// resize() initializes DFSResult, while compute() populates it.
115 bool empty() const { return DFSData.empty(); }
117 /// \brief Clear the results.
120 SubtreeConnections.clear();
121 SubtreeConnectLevels.clear();
124 /// \brief Initialize the result data with the size of the DAG.
125 void resize(unsigned NumSUnits) {
126 DFSData.resize(NumSUnits);
129 /// \brief Compute various metrics for the DAG with given roots.
130 void compute(ArrayRef<SUnit> SUnits);
132 /// \brief Get the ILP value for a DAG node.
134 /// A leaf node has an ILP of 1/1.
135 ILPValue getILP(const SUnit *SU) const {
136 return ILPValue(DFSData[SU->NodeNum].InstrCount, 1 + SU->getDepth());
139 /// \brief The number of subtrees detected in this DAG.
140 unsigned getNumSubtrees() const { return SubtreeConnectLevels.size(); }
142 /// \brief Get the ID of the subtree the given DAG node belongs to.
144 /// For convenience, if DFSResults have not been computed yet, give everything
146 unsigned getSubtreeID(const SUnit *SU) const {
149 assert(SU->NodeNum < DFSData.size() && "New Node");
150 return DFSData[SU->NodeNum].SubtreeID;
153 /// \brief Get the connection level of a subtree.
155 /// For bottom-up trees, the connection level is the latency depth (in cycles)
156 /// of the deepest connection to another subtree.
157 unsigned getSubtreeLevel(unsigned SubtreeID) const {
158 return SubtreeConnectLevels[SubtreeID];
161 /// \brief Scheduler callback to update SubtreeConnectLevels when a tree is
162 /// initially scheduled.
163 void scheduleTree(unsigned SubtreeID);
166 raw_ostream &operator<<(raw_ostream &OS, const ILPValue &Val);