1 //==- ScheduleDAGInstrs.h - MachineInstr Scheduling --------------*- 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 // This file implements the ScheduleDAGInstrs class, which implements
11 // scheduling for a MachineInstr-based dependency graph.
13 //===----------------------------------------------------------------------===//
15 #ifndef SCHEDULEDAGINSTRS_H
16 #define SCHEDULEDAGINSTRS_H
18 #include "llvm/CodeGen/MachineDominators.h"
19 #include "llvm/CodeGen/MachineLoopInfo.h"
20 #include "llvm/CodeGen/ScheduleDAG.h"
21 #include "llvm/Support/Compiler.h"
22 #include "llvm/Target/TargetRegisterInfo.h"
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/ADT/SmallSet.h"
28 class MachineLoopInfo;
29 class MachineDominatorTree;
31 /// LoopDependencies - This class analyzes loop-oriented register
32 /// dependencies, which are used to guide scheduling decisions.
33 /// For example, loop induction variable increments should be
34 /// scheduled as soon as possible after the variable's last use.
36 class VISIBILITY_HIDDEN LoopDependencies {
37 const MachineLoopInfo &MLI;
38 const MachineDominatorTree &MDT;
41 typedef std::map<unsigned, std::pair<const MachineOperand *, unsigned> >
45 LoopDependencies(const MachineLoopInfo &mli,
46 const MachineDominatorTree &mdt) :
49 /// VisitLoop - Clear out any previous state and analyze the given loop.
51 void VisitLoop(const MachineLoop *Loop) {
53 MachineBasicBlock *Header = Loop->getHeader();
54 SmallSet<unsigned, 8> LoopLiveIns;
55 for (MachineBasicBlock::livein_iterator LI = Header->livein_begin(),
56 LE = Header->livein_end(); LI != LE; ++LI)
57 LoopLiveIns.insert(*LI);
59 const MachineDomTreeNode *Node = MDT.getNode(Header);
60 const MachineBasicBlock *MBB = Node->getBlock();
61 assert(Loop->contains(MBB) &&
62 "Loop does not contain header!");
63 VisitRegion(Node, MBB, Loop, LoopLiveIns);
67 void VisitRegion(const MachineDomTreeNode *Node,
68 const MachineBasicBlock *MBB,
69 const MachineLoop *Loop,
70 const SmallSet<unsigned, 8> &LoopLiveIns) {
72 for (MachineBasicBlock::const_iterator I = MBB->begin(), E = MBB->end();
73 I != E; ++I, ++Count) {
74 const MachineInstr *MI = I;
75 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
76 const MachineOperand &MO = MI->getOperand(i);
77 if (!MO.isReg() || !MO.isUse())
79 unsigned MOReg = MO.getReg();
80 if (LoopLiveIns.count(MOReg))
81 Deps.insert(std::make_pair(MOReg, std::make_pair(&MO, Count)));
85 const std::vector<MachineDomTreeNode*> &Children = Node->getChildren();
86 for (std::vector<MachineDomTreeNode*>::const_iterator I =
87 Children.begin(), E = Children.end(); I != E; ++I) {
88 const MachineDomTreeNode *ChildNode = *I;
89 MachineBasicBlock *ChildBlock = ChildNode->getBlock();
90 if (Loop->contains(ChildBlock))
91 VisitRegion(ChildNode, ChildBlock, Loop, LoopLiveIns);
96 /// ScheduleDAGInstrs - A ScheduleDAG subclass for scheduling lists of
98 class VISIBILITY_HIDDEN ScheduleDAGInstrs : public ScheduleDAG {
99 const MachineLoopInfo &MLI;
100 const MachineDominatorTree &MDT;
101 const MachineFrameInfo *MFI;
103 /// Defs, Uses - Remember where defs and uses of each physical register
104 /// are as we iterate upward through the instructions. This is allocated
105 /// here instead of inside BuildSchedGraph to avoid the need for it to be
106 /// initialized and destructed for each block.
107 std::vector<SUnit *> Defs[TargetRegisterInfo::FirstVirtualRegister];
108 std::vector<SUnit *> Uses[TargetRegisterInfo::FirstVirtualRegister];
110 /// DbgValueVec - Remember DBG_VALUEs that refer to a particular
112 std::vector<MachineInstr *>DbgValueVec;
114 /// PendingLoads - Remember where unknown loads are after the most recent
115 /// unknown store, as we iterate. As with Defs and Uses, this is here
116 /// to minimize construction/destruction.
117 std::vector<SUnit *> PendingLoads;
119 /// LoopRegs - Track which registers are used for loop-carried dependencies.
121 LoopDependencies LoopRegs;
123 /// LoopLiveInRegs - Track which regs are live into a loop, to help guide
124 /// back-edge-aware scheduling.
126 SmallSet<unsigned, 8> LoopLiveInRegs;
129 MachineBasicBlock::iterator Begin; // The beginning of the range to
130 // be scheduled. The range extends
132 unsigned InsertPosIndex; // The index in BB of InsertPos.
134 explicit ScheduleDAGInstrs(MachineFunction &mf,
135 const MachineLoopInfo &mli,
136 const MachineDominatorTree &mdt);
138 virtual ~ScheduleDAGInstrs() {}
140 /// NewSUnit - Creates a new SUnit and return a ptr to it.
142 SUnit *NewSUnit(MachineInstr *MI) {
144 const SUnit *Addr = SUnits.empty() ? 0 : &SUnits[0];
146 SUnits.push_back(SUnit(MI, (unsigned)SUnits.size()));
147 assert((Addr == 0 || Addr == &SUnits[0]) &&
148 "SUnits std::vector reallocated on the fly!");
149 SUnits.back().OrigNode = &SUnits.back();
150 return &SUnits.back();
153 /// Run - perform scheduling.
155 void Run(MachineBasicBlock *bb,
156 MachineBasicBlock::iterator begin,
157 MachineBasicBlock::iterator end,
160 /// BuildSchedGraph - Build SUnits from the MachineBasicBlock that we are
162 virtual void BuildSchedGraph(AliasAnalysis *AA);
164 /// ComputeLatency - Compute node latency.
166 virtual void ComputeLatency(SUnit *SU);
168 /// ComputeOperandLatency - Override dependence edge latency using
169 /// operand use/def information
171 virtual void ComputeOperandLatency(SUnit *Def, SUnit *Use,
174 virtual MachineBasicBlock*
175 EmitSchedule(DenseMap<MachineBasicBlock*, MachineBasicBlock*>*);
177 /// StartBlock - Prepare to perform scheduling in the given block.
179 virtual void StartBlock(MachineBasicBlock *BB);
181 /// Schedule - Order nodes according to selected style, filling
182 /// in the Sequence member.
184 virtual void Schedule() = 0;
186 /// FinishBlock - Clean up after scheduling in the given block.
188 virtual void FinishBlock();
190 virtual void dumpNode(const SUnit *SU) const;
192 virtual std::string getGraphNodeLabel(const SUnit *SU) const;