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//==- ScheduleDAGInstrs.h - MachineInstr Scheduling --------------*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the ScheduleDAGInstrs class, which implements
// scheduling for a MachineInstr-based dependency graph.
//
//===----------------------------------------------------------------------===//
#ifndef SCHEDULEDAGINSTRS_H
#define SCHEDULEDAGINSTRS_H
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/ADT/SmallSet.h"
#include <map>
namespace llvm {
class MachineLoopInfo;
class MachineDominatorTree;
/// LoopDependencies - This class analyzes loop-oriented register
/// dependencies, which are used to guide scheduling decisions.
/// For example, loop induction variable increments should be
/// scheduled as soon as possible after the variable's last use.
///
class LLVM_LIBRARY_VISIBILITY LoopDependencies {
const MachineLoopInfo &MLI;
const MachineDominatorTree &MDT;
public:
typedef std::map<unsigned, std::pair<const MachineOperand *, unsigned> >
LoopDeps;
LoopDeps Deps;
LoopDependencies(const MachineLoopInfo &mli,
const MachineDominatorTree &mdt) :
MLI(mli), MDT(mdt) {}
/// VisitLoop - Clear out any previous state and analyze the given loop.
///
void VisitLoop(const MachineLoop *Loop) {
assert(Deps.empty() && "stale loop dependencies");
MachineBasicBlock *Header = Loop->getHeader();
SmallSet<unsigned, 8> LoopLiveIns;
for (MachineBasicBlock::livein_iterator LI = Header->livein_begin(),
LE = Header->livein_end(); LI != LE; ++LI)
LoopLiveIns.insert(*LI);
const MachineDomTreeNode *Node = MDT.getNode(Header);
const MachineBasicBlock *MBB = Node->getBlock();
assert(Loop->contains(MBB) &&
"Loop does not contain header!");
VisitRegion(Node, MBB, Loop, LoopLiveIns);
}
private:
void VisitRegion(const MachineDomTreeNode *Node,
const MachineBasicBlock *MBB,
const MachineLoop *Loop,
const SmallSet<unsigned, 8> &LoopLiveIns) {
unsigned Count = 0;
for (MachineBasicBlock::const_iterator I = MBB->begin(), E = MBB->end();
I != E; ++I) {
const MachineInstr *MI = I;
if (MI->isDebugValue())
continue;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || !MO.isUse())
continue;
unsigned MOReg = MO.getReg();
if (LoopLiveIns.count(MOReg))
Deps.insert(std::make_pair(MOReg, std::make_pair(&MO, Count)));
}
++Count; // Not every iteration due to dbg_value above.
}
const std::vector<MachineDomTreeNode*> &Children = Node->getChildren();
for (std::vector<MachineDomTreeNode*>::const_iterator I =
Children.begin(), E = Children.end(); I != E; ++I) {
const MachineDomTreeNode *ChildNode = *I;
MachineBasicBlock *ChildBlock = ChildNode->getBlock();
if (Loop->contains(ChildBlock))
VisitRegion(ChildNode, ChildBlock, Loop, LoopLiveIns);
}
}
};
/// ScheduleDAGInstrs - A ScheduleDAG subclass for scheduling lists of
/// MachineInstrs.
class LLVM_LIBRARY_VISIBILITY ScheduleDAGInstrs : public ScheduleDAG {
const MachineLoopInfo &MLI;
const MachineDominatorTree &MDT;
const MachineFrameInfo *MFI;
const InstrItineraryData *InstrItins;
/// Defs, Uses - Remember where defs and uses of each physical register
/// are as we iterate upward through the instructions. This is allocated
/// here instead of inside BuildSchedGraph to avoid the need for it to be
/// initialized and destructed for each block.
std::vector<std::vector<SUnit *> > Defs;
std::vector<std::vector<SUnit *> > Uses;
/// PendingLoads - Remember where unknown loads are after the most recent
/// unknown store, as we iterate. As with Defs and Uses, this is here
/// to minimize construction/destruction.
std::vector<SUnit *> PendingLoads;
/// LoopRegs - Track which registers are used for loop-carried dependencies.
///
LoopDependencies LoopRegs;
/// LoopLiveInRegs - Track which regs are live into a loop, to help guide
/// back-edge-aware scheduling.
///
SmallSet<unsigned, 8> LoopLiveInRegs;
protected:
/// DbgValues - Remember instruction that preceeds DBG_VALUE.
typedef std::vector<std::pair<MachineInstr *, MachineInstr *> >
DbgValueVector;
DbgValueVector DbgValues;
MachineInstr *FirstDbgValue;
public:
MachineBasicBlock::iterator Begin; // The beginning of the range to
// be scheduled. The range extends
// to InsertPos.
unsigned InsertPosIndex; // The index in BB of InsertPos.
explicit ScheduleDAGInstrs(MachineFunction &mf,
const MachineLoopInfo &mli,
const MachineDominatorTree &mdt);
virtual ~ScheduleDAGInstrs() {}
/// NewSUnit - Creates a new SUnit and return a ptr to it.
///
SUnit *NewSUnit(MachineInstr *MI) {
#ifndef NDEBUG
const SUnit *Addr = SUnits.empty() ? 0 : &SUnits[0];
#endif
SUnits.push_back(SUnit(MI, (unsigned)SUnits.size()));
assert((Addr == 0 || Addr == &SUnits[0]) &&
"SUnits std::vector reallocated on the fly!");
SUnits.back().OrigNode = &SUnits.back();
return &SUnits.back();
}
/// Run - perform scheduling.
///
void Run(MachineBasicBlock *bb,
MachineBasicBlock::iterator begin,
MachineBasicBlock::iterator end,
unsigned endindex);
/// BuildSchedGraph - Build SUnits from the MachineBasicBlock that we are
/// input.
virtual void BuildSchedGraph(AliasAnalysis *AA);
/// AddSchedBarrierDeps - Add dependencies from instructions in the current
/// list of instructions being scheduled to scheduling barrier. We want to
/// make sure instructions which define registers that are either used by
/// the terminator or are live-out are properly scheduled. This is
/// especially important when the definition latency of the return value(s)
/// are too high to be hidden by the branch or when the liveout registers
/// used by instructions in the fallthrough block.
void AddSchedBarrierDeps();
/// ComputeLatency - Compute node latency.
///
virtual void ComputeLatency(SUnit *SU);
/// ComputeOperandLatency - Override dependence edge latency using
/// operand use/def information
///
virtual void ComputeOperandLatency(SUnit *Def, SUnit *Use,
SDep& dep) const;
virtual MachineBasicBlock *EmitSchedule();
/// StartBlock - Prepare to perform scheduling in the given block.
///
virtual void StartBlock(MachineBasicBlock *BB);
/// Schedule - Order nodes according to selected style, filling
/// in the Sequence member.
///
virtual void Schedule() = 0;
/// FinishBlock - Clean up after scheduling in the given block.
///
virtual void FinishBlock();
virtual void dumpNode(const SUnit *SU) const;
virtual std::string getGraphNodeLabel(const SUnit *SU) const;
};
}
#endif
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