llvm-6502/include/llvm/CodeGen/ScheduleDAGInstrs.h
Benjamin Kramer a7542d5f87 Remove unused private fields found by clang's new -Wunused-private-field.
There are some that I didn't remove this round because they looked like
obvious stubs. There are dead variables in gtest too, they should be
fixed upstream.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158090 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-06 18:25:08 +00:00

350 lines
13 KiB
C++

//==- 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 "llvm/ADT/SparseSet.h"
#include <map>
namespace llvm {
class MachineLoopInfo;
class MachineDominatorTree;
class LiveIntervals;
class RegPressureTracker;
/// 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 LoopDependencies {
const MachineDominatorTree &MDT;
public:
typedef std::map<unsigned, std::pair<const MachineOperand *, unsigned> >
LoopDeps;
LoopDeps Deps;
LoopDependencies(const MachineDominatorTree &mdt) : 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);
}
}
};
/// An individual mapping from virtual register number to SUnit.
struct VReg2SUnit {
unsigned VirtReg;
SUnit *SU;
VReg2SUnit(unsigned reg, SUnit *su): VirtReg(reg), SU(su) {}
unsigned getSparseSetIndex() const {
return TargetRegisterInfo::virtReg2Index(VirtReg);
}
};
/// Combine a SparseSet with a 1x1 vector to track physical registers.
/// The SparseSet allows iterating over the (few) live registers for quickly
/// comparing against a regmask or clearing the set.
///
/// Storage for the map is allocated once for the pass. The map can be
/// cleared between scheduling regions without freeing unused entries.
class Reg2SUnitsMap {
SparseSet<unsigned> PhysRegSet;
std::vector<std::vector<SUnit*> > SUnits;
public:
typedef SparseSet<unsigned>::const_iterator const_iterator;
// Allow iteration over register numbers (keys) in the map. If needed, we
// can provide an iterator over SUnits (values) as well.
const_iterator reg_begin() const { return PhysRegSet.begin(); }
const_iterator reg_end() const { return PhysRegSet.end(); }
/// Initialize the map with the number of registers.
/// If the map is already large enough, no allocation occurs.
/// For simplicity we expect the map to be empty().
void setRegLimit(unsigned Limit);
/// Returns true if the map is empty.
bool empty() const { return PhysRegSet.empty(); }
/// Clear the map without deallocating storage.
void clear();
bool contains(unsigned Reg) const { return PhysRegSet.count(Reg); }
/// If this register is mapped, return its existing SUnits vector.
/// Otherwise map the register and return an empty SUnits vector.
std::vector<SUnit *> &operator[](unsigned Reg) {
bool New = PhysRegSet.insert(Reg).second;
assert((!New || SUnits[Reg].empty()) && "stale SUnits vector");
(void)New;
return SUnits[Reg];
}
/// Erase an existing element without freeing memory.
void erase(unsigned Reg) {
PhysRegSet.erase(Reg);
SUnits[Reg].clear();
}
};
/// Use SparseSet as a SparseMap by relying on the fact that it never
/// compares ValueT's, only unsigned keys. This allows the set to be cleared
/// between scheduling regions in constant time as long as ValueT does not
/// require a destructor.
typedef SparseSet<VReg2SUnit, VirtReg2IndexFunctor> VReg2SUnitMap;
/// ScheduleDAGInstrs - A ScheduleDAG subclass for scheduling lists of
/// MachineInstrs.
class ScheduleDAGInstrs : public ScheduleDAG {
protected:
const MachineLoopInfo &MLI;
const MachineDominatorTree &MDT;
const MachineFrameInfo *MFI;
const InstrItineraryData *InstrItins;
/// Live Intervals provides reaching defs in preRA scheduling.
LiveIntervals *LIS;
/// isPostRA flag indicates vregs cannot be present.
bool IsPostRA;
/// UnitLatencies (misnamed) flag avoids computing def-use latencies, using
/// the def-side latency only.
bool UnitLatencies;
/// The standard DAG builder does not normally include terminators as DAG
/// nodes because it does not create the necessary dependencies to prevent
/// reordering. A specialized scheduler can overide
/// TargetInstrInfo::isSchedulingBoundary then enable this flag to indicate
/// it has taken responsibility for scheduling the terminator correctly.
bool CanHandleTerminators;
/// State specific to the current scheduling region.
/// ------------------------------------------------
/// The block in which to insert instructions
MachineBasicBlock *BB;
/// The beginning of the range to be scheduled.
MachineBasicBlock::iterator RegionBegin;
/// The end of the range to be scheduled.
MachineBasicBlock::iterator RegionEnd;
/// The index in BB of RegionEnd.
unsigned EndIndex;
/// After calling BuildSchedGraph, each machine instruction in the current
/// scheduling region is mapped to an SUnit.
DenseMap<MachineInstr*, SUnit*> MISUnitMap;
/// State internal to DAG building.
/// -------------------------------
/// Defs, Uses - Remember where defs and uses of each 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.
Reg2SUnitsMap Defs;
Reg2SUnitsMap Uses;
/// Track the last instructon in this region defining each virtual register.
VReg2SUnitMap VRegDefs;
/// 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;
/// DbgValues - Remember instruction that precedes DBG_VALUE.
/// These are generated by buildSchedGraph but persist so they can be
/// referenced when emitting the final schedule.
typedef std::vector<std::pair<MachineInstr *, MachineInstr *> >
DbgValueVector;
DbgValueVector DbgValues;
MachineInstr *FirstDbgValue;
public:
explicit ScheduleDAGInstrs(MachineFunction &mf,
const MachineLoopInfo &mli,
const MachineDominatorTree &mdt,
bool IsPostRAFlag,
LiveIntervals *LIS = 0);
virtual ~ScheduleDAGInstrs() {}
/// begin - Return an iterator to the top of the current scheduling region.
MachineBasicBlock::iterator begin() const { return RegionBegin; }
/// end - Return an iterator to the bottom of the current scheduling region.
MachineBasicBlock::iterator end() const { return RegionEnd; }
/// newSUnit - Creates a new SUnit and return a ptr to it.
SUnit *newSUnit(MachineInstr *MI);
/// getSUnit - Return an existing SUnit for this MI, or NULL.
SUnit *getSUnit(MachineInstr *MI) const;
/// startBlock - Prepare to perform scheduling in the given block.
virtual void startBlock(MachineBasicBlock *BB);
/// finishBlock - Clean up after scheduling in the given block.
virtual void finishBlock();
/// Initialize the scheduler state for the next scheduling region.
virtual void enterRegion(MachineBasicBlock *bb,
MachineBasicBlock::iterator begin,
MachineBasicBlock::iterator end,
unsigned endcount);
/// Notify that the scheduler has finished scheduling the current region.
virtual void exitRegion();
/// buildSchedGraph - Build SUnits from the MachineBasicBlock that we are
/// input.
void buildSchedGraph(AliasAnalysis *AA, RegPressureTracker *RPTracker = 0);
/// 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 - Return dependence edge latency using
/// operand use/def information
///
/// FindMin may be set to get the minimum vs. expected latency. Minimum
/// latency is used for scheduling groups, while expected latency is for
/// instruction cost and critical path.
virtual unsigned computeOperandLatency(SUnit *Def, SUnit *Use,
const SDep& dep,
bool FindMin = false) const;
/// schedule - Order nodes according to selected style, filling
/// in the Sequence member.
///
/// Typically, a scheduling algorithm will implement schedule() without
/// overriding enterRegion() or exitRegion().
virtual void schedule() = 0;
/// finalizeSchedule - Allow targets to perform final scheduling actions at
/// the level of the whole MachineFunction. By default does nothing.
virtual void finalizeSchedule() {}
virtual void dumpNode(const SUnit *SU) const;
/// Return a label for a DAG node that points to an instruction.
virtual std::string getGraphNodeLabel(const SUnit *SU) const;
/// Return a label for the region of code covered by the DAG.
virtual std::string getDAGName() const;
protected:
void initSUnits();
void addPhysRegDataDeps(SUnit *SU, const MachineOperand &MO);
void addPhysRegDeps(SUnit *SU, unsigned OperIdx);
void addVRegDefDeps(SUnit *SU, unsigned OperIdx);
void addVRegUseDeps(SUnit *SU, unsigned OperIdx);
};
/// newSUnit - Creates a new SUnit and return a ptr to it.
inline SUnit *ScheduleDAGInstrs::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();
}
/// getSUnit - Return an existing SUnit for this MI, or NULL.
inline SUnit *ScheduleDAGInstrs::getSUnit(MachineInstr *MI) const {
DenseMap<MachineInstr*, SUnit*>::const_iterator I = MISUnitMap.find(MI);
if (I == MISUnitMap.end())
return 0;
return I->second;
}
} // namespace llvm
#endif