1//===-- llvm/CodeGen/TargetSchedule.h - Sched Machine Model -----*- 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 defines a wrapper around MCSchedModel that allows the interface to
11// benefit from information currently only available in TargetInstrInfo.
12// Ideally, the scheduling interface would be fully defined in the MC layer.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_CODEGEN_TARGETSCHEDULE_H
17#define LLVM_CODEGEN_TARGETSCHEDULE_H
18
19#include "llvm/ADT/SmallVector.h"
20#include "llvm/MC/MCInstrItineraries.h"
21#include "llvm/MC/MCSchedule.h"
22#include "llvm/Target/TargetSubtargetInfo.h"
23
24namespace llvm {
25
26class TargetRegisterInfo;
27class TargetSubtargetInfo;
28class TargetInstrInfo;
29class MachineInstr;
30
31/// Provide an instruction scheduling machine model to CodeGen passes.
32class TargetSchedModel {
33  // For efficiency, hold a copy of the statically defined MCSchedModel for this
34  // processor.
35  MCSchedModel SchedModel;
36  InstrItineraryData InstrItins;
37  const TargetSubtargetInfo *STI;
38  const TargetInstrInfo *TII;
39
40  SmallVector<unsigned, 16> ResourceFactors;
41  unsigned MicroOpFactor; // Multiply to normalize microops to resource units.
42  unsigned ResourceLCM;   // Resource units per cycle. Latency normalization factor.
43public:
44  TargetSchedModel(): STI(0), TII(0) {}
45
46  /// \brief Initialize the machine model for instruction scheduling.
47  ///
48  /// The machine model API keeps a copy of the top-level MCSchedModel table
49  /// indices and may query TargetSubtargetInfo and TargetInstrInfo to resolve
50  /// dynamic properties.
51  void init(const MCSchedModel &sm, const TargetSubtargetInfo *sti,
52            const TargetInstrInfo *tii);
53
54  /// Return the MCSchedClassDesc for this instruction.
55  const MCSchedClassDesc *resolveSchedClass(const MachineInstr *MI) const;
56
57  /// \brief TargetInstrInfo getter.
58  const TargetInstrInfo *getInstrInfo() const { return TII; }
59
60  /// \brief Return true if this machine model includes an instruction-level
61  /// scheduling model.
62  ///
63  /// This is more detailed than the course grain IssueWidth and default
64  /// latency properties, but separate from the per-cycle itinerary data.
65  bool hasInstrSchedModel() const;
66
67  const MCSchedModel *getMCSchedModel() const { return &SchedModel; }
68
69  /// \brief Return true if this machine model includes cycle-to-cycle itinerary
70  /// data.
71  ///
72  /// This models scheduling at each stage in the processor pipeline.
73  bool hasInstrItineraries() const;
74
75  const InstrItineraryData *getInstrItineraries() const {
76    if (hasInstrItineraries())
77      return &InstrItins;
78    return 0;
79  }
80
81  /// \brief Identify the processor corresponding to the current subtarget.
82  unsigned getProcessorID() const { return SchedModel.getProcessorID(); }
83
84  /// \brief Maximum number of micro-ops that may be scheduled per cycle.
85  unsigned getIssueWidth() const { return SchedModel.IssueWidth; }
86
87  /// \brief Number of cycles the OOO processor is expected to hide.
88  unsigned getILPWindow() const { return SchedModel.ILPWindow; }
89
90  /// \brief Return the number of issue slots required for this MI.
91  unsigned getNumMicroOps(const MachineInstr *MI,
92                          const MCSchedClassDesc *SC = 0) const;
93
94  /// \brief Get the number of kinds of resources for this target.
95  unsigned getNumProcResourceKinds() const {
96    return SchedModel.getNumProcResourceKinds();
97  }
98
99  /// \brief Get a processor resource by ID for convenience.
100  const MCProcResourceDesc *getProcResource(unsigned PIdx) const {
101    return SchedModel.getProcResource(PIdx);
102  }
103
104  typedef const MCWriteProcResEntry *ProcResIter;
105
106  // \brief Get an iterator into the processor resources consumed by this
107  // scheduling class.
108  ProcResIter getWriteProcResBegin(const MCSchedClassDesc *SC) const {
109    // The subtarget holds a single resource table for all processors.
110    return STI->getWriteProcResBegin(SC);
111  }
112  ProcResIter getWriteProcResEnd(const MCSchedClassDesc *SC) const {
113    return STI->getWriteProcResEnd(SC);
114  }
115
116  /// \brief Multiply the number of units consumed for a resource by this factor
117  /// to normalize it relative to other resources.
118  unsigned getResourceFactor(unsigned ResIdx) const {
119    return ResourceFactors[ResIdx];
120  }
121
122  /// \brief Multiply number of micro-ops by this factor to normalize it
123  /// relative to other resources.
124  unsigned getMicroOpFactor() const {
125    return MicroOpFactor;
126  }
127
128  /// \brief Multiply cycle count by this factor to normalize it relative to
129  /// other resources. This is the number of resource units per cycle.
130  unsigned getLatencyFactor() const {
131    return ResourceLCM;
132  }
133
134  /// \brief Compute operand latency based on the available machine model.
135  ///
136  /// Computes and return the latency of the given data dependent def and use
137  /// when the operand indices are already known. UseMI may be NULL for an
138  /// unknown user.
139  ///
140  /// FindMin may be set to get the minimum vs. expected latency. Minimum
141  /// latency is used for scheduling groups, while expected latency is for
142  /// instruction cost and critical path.
143  unsigned computeOperandLatency(const MachineInstr *DefMI, unsigned DefOperIdx,
144                                 const MachineInstr *UseMI, unsigned UseOperIdx,
145                                 bool FindMin) const;
146
147  /// \brief Compute the instruction latency based on the available machine
148  /// model.
149  ///
150  /// Compute and return the expected latency of this instruction independent of
151  /// a particular use. computeOperandLatency is the prefered API, but this is
152  /// occasionally useful to help estimate instruction cost.
153  unsigned computeInstrLatency(const MachineInstr *MI) const;
154
155  /// \brief Output dependency latency of a pair of defs of the same register.
156  ///
157  /// This is typically one cycle.
158  unsigned computeOutputLatency(const MachineInstr *DefMI, unsigned DefIdx,
159                                const MachineInstr *DepMI) const;
160
161private:
162  /// getDefLatency is a helper for computeOperandLatency. Return the
163  /// instruction's latency if operand lookup is not required.
164  /// Otherwise return -1.
165  int getDefLatency(const MachineInstr *DefMI, bool FindMin) const;
166};
167
168} // namespace llvm
169
170#endif
171