forked from OSchip/llvm-project
4212 lines
157 KiB
C++
4212 lines
157 KiB
C++
//===- MachinePipeliner.cpp - Machine Software Pipeliner Pass -------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// An implementation of the Swing Modulo Scheduling (SMS) software pipeliner.
|
|
//
|
|
// Software pipelining (SWP) is an instruction scheduling technique for loops
|
|
// that overlap loop iterations and exploits ILP via a compiler transformation.
|
|
//
|
|
// Swing Modulo Scheduling is an implementation of software pipelining
|
|
// that generates schedules that are near optimal in terms of initiation
|
|
// interval, register requirements, and stage count. See the papers:
|
|
//
|
|
// "Swing Modulo Scheduling: A Lifetime-Sensitive Approach", by J. Llosa,
|
|
// A. Gonzalez, E. Ayguade, and M. Valero. In PACT '96 Proceedings of the 1996
|
|
// Conference on Parallel Architectures and Compilation Techiniques.
|
|
//
|
|
// "Lifetime-Sensitive Modulo Scheduling in a Production Environment", by J.
|
|
// Llosa, E. Ayguade, A. Gonzalez, M. Valero, and J. Eckhardt. In IEEE
|
|
// Transactions on Computers, Vol. 50, No. 3, 2001.
|
|
//
|
|
// "An Implementation of Swing Modulo Scheduling With Extensions for
|
|
// Superblocks", by T. Lattner, Master's Thesis, University of Illinois at
|
|
// Urbana-Chambpain, 2005.
|
|
//
|
|
//
|
|
// The SMS algorithm consists of three main steps after computing the minimal
|
|
// initiation interval (MII).
|
|
// 1) Analyze the dependence graph and compute information about each
|
|
// instruction in the graph.
|
|
// 2) Order the nodes (instructions) by priority based upon the heuristics
|
|
// described in the algorithm.
|
|
// 3) Attempt to schedule the nodes in the specified order using the MII.
|
|
//
|
|
// This SMS implementation is a target-independent back-end pass. When enabled,
|
|
// the pass runs just prior to the register allocation pass, while the machine
|
|
// IR is in SSA form. If software pipelining is successful, then the original
|
|
// loop is replaced by the optimized loop. The optimized loop contains one or
|
|
// more prolog blocks, the pipelined kernel, and one or more epilog blocks. If
|
|
// the instructions cannot be scheduled in a given MII, we increase the MII by
|
|
// one and try again.
|
|
//
|
|
// The SMS implementation is an extension of the ScheduleDAGInstrs class. We
|
|
// represent loop carried dependences in the DAG as order edges to the Phi
|
|
// nodes. We also perform several passes over the DAG to eliminate unnecessary
|
|
// edges that inhibit the ability to pipeline. The implementation uses the
|
|
// DFAPacketizer class to compute the minimum initiation interval and the check
|
|
// where an instruction may be inserted in the pipelined schedule.
|
|
//
|
|
// In order for the SMS pass to work, several target specific hooks need to be
|
|
// implemented to get information about the loop structure and to rewrite
|
|
// instructions.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/ADT/ArrayRef.h"
|
|
#include "llvm/ADT/BitVector.h"
|
|
#include "llvm/ADT/DenseMap.h"
|
|
#include "llvm/ADT/MapVector.h"
|
|
#include "llvm/ADT/PriorityQueue.h"
|
|
#include "llvm/ADT/SetVector.h"
|
|
#include "llvm/ADT/SmallPtrSet.h"
|
|
#include "llvm/ADT/SmallSet.h"
|
|
#include "llvm/ADT/SmallVector.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/ADT/iterator_range.h"
|
|
#include "llvm/Analysis/AliasAnalysis.h"
|
|
#include "llvm/Analysis/MemoryLocation.h"
|
|
#include "llvm/Analysis/ValueTracking.h"
|
|
#include "llvm/CodeGen/DFAPacketizer.h"
|
|
#include "llvm/CodeGen/LiveIntervals.h"
|
|
#include "llvm/CodeGen/MachineBasicBlock.h"
|
|
#include "llvm/CodeGen/MachineDominators.h"
|
|
#include "llvm/CodeGen/MachineFunction.h"
|
|
#include "llvm/CodeGen/MachineFunctionPass.h"
|
|
#include "llvm/CodeGen/MachineInstr.h"
|
|
#include "llvm/CodeGen/MachineInstrBuilder.h"
|
|
#include "llvm/CodeGen/MachineLoopInfo.h"
|
|
#include "llvm/CodeGen/MachineMemOperand.h"
|
|
#include "llvm/CodeGen/MachineOperand.h"
|
|
#include "llvm/CodeGen/MachineRegisterInfo.h"
|
|
#include "llvm/CodeGen/RegisterClassInfo.h"
|
|
#include "llvm/CodeGen/RegisterPressure.h"
|
|
#include "llvm/CodeGen/ScheduleDAG.h"
|
|
#include "llvm/CodeGen/ScheduleDAGInstrs.h"
|
|
#include "llvm/CodeGen/ScheduleDAGMutation.h"
|
|
#include "llvm/CodeGen/TargetInstrInfo.h"
|
|
#include "llvm/CodeGen/TargetOpcodes.h"
|
|
#include "llvm/CodeGen/TargetRegisterInfo.h"
|
|
#include "llvm/CodeGen/TargetSubtargetInfo.h"
|
|
#include "llvm/Config/llvm-config.h"
|
|
#include "llvm/IR/Attributes.h"
|
|
#include "llvm/IR/DebugLoc.h"
|
|
#include "llvm/IR/Function.h"
|
|
#include "llvm/MC/LaneBitmask.h"
|
|
#include "llvm/MC/MCInstrDesc.h"
|
|
#include "llvm/MC/MCInstrItineraries.h"
|
|
#include "llvm/MC/MCRegisterInfo.h"
|
|
#include "llvm/Pass.h"
|
|
#include "llvm/Support/CommandLine.h"
|
|
#include "llvm/Support/Compiler.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/MathExtras.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include <algorithm>
|
|
#include <cassert>
|
|
#include <climits>
|
|
#include <cstdint>
|
|
#include <deque>
|
|
#include <functional>
|
|
#include <iterator>
|
|
#include <map>
|
|
#include <memory>
|
|
#include <tuple>
|
|
#include <utility>
|
|
#include <vector>
|
|
|
|
using namespace llvm;
|
|
|
|
#define DEBUG_TYPE "pipeliner"
|
|
|
|
STATISTIC(NumTrytoPipeline, "Number of loops that we attempt to pipeline");
|
|
STATISTIC(NumPipelined, "Number of loops software pipelined");
|
|
STATISTIC(NumNodeOrderIssues, "Number of node order issues found");
|
|
|
|
/// A command line option to turn software pipelining on or off.
|
|
static cl::opt<bool> EnableSWP("enable-pipeliner", cl::Hidden, cl::init(true),
|
|
cl::ZeroOrMore,
|
|
cl::desc("Enable Software Pipelining"));
|
|
|
|
/// A command line option to enable SWP at -Os.
|
|
static cl::opt<bool> EnableSWPOptSize("enable-pipeliner-opt-size",
|
|
cl::desc("Enable SWP at Os."), cl::Hidden,
|
|
cl::init(false));
|
|
|
|
/// A command line argument to limit minimum initial interval for pipelining.
|
|
static cl::opt<int> SwpMaxMii("pipeliner-max-mii",
|
|
cl::desc("Size limit for the MII."),
|
|
cl::Hidden, cl::init(27));
|
|
|
|
/// A command line argument to limit the number of stages in the pipeline.
|
|
static cl::opt<int>
|
|
SwpMaxStages("pipeliner-max-stages",
|
|
cl::desc("Maximum stages allowed in the generated scheduled."),
|
|
cl::Hidden, cl::init(3));
|
|
|
|
/// A command line option to disable the pruning of chain dependences due to
|
|
/// an unrelated Phi.
|
|
static cl::opt<bool>
|
|
SwpPruneDeps("pipeliner-prune-deps",
|
|
cl::desc("Prune dependences between unrelated Phi nodes."),
|
|
cl::Hidden, cl::init(true));
|
|
|
|
/// A command line option to disable the pruning of loop carried order
|
|
/// dependences.
|
|
static cl::opt<bool>
|
|
SwpPruneLoopCarried("pipeliner-prune-loop-carried",
|
|
cl::desc("Prune loop carried order dependences."),
|
|
cl::Hidden, cl::init(true));
|
|
|
|
#ifndef NDEBUG
|
|
static cl::opt<int> SwpLoopLimit("pipeliner-max", cl::Hidden, cl::init(-1));
|
|
#endif
|
|
|
|
static cl::opt<bool> SwpIgnoreRecMII("pipeliner-ignore-recmii",
|
|
cl::ReallyHidden, cl::init(false),
|
|
cl::ZeroOrMore, cl::desc("Ignore RecMII"));
|
|
|
|
namespace {
|
|
|
|
class NodeSet;
|
|
class SMSchedule;
|
|
|
|
/// The main class in the implementation of the target independent
|
|
/// software pipeliner pass.
|
|
class MachinePipeliner : public MachineFunctionPass {
|
|
public:
|
|
MachineFunction *MF = nullptr;
|
|
const MachineLoopInfo *MLI = nullptr;
|
|
const MachineDominatorTree *MDT = nullptr;
|
|
const InstrItineraryData *InstrItins;
|
|
const TargetInstrInfo *TII = nullptr;
|
|
RegisterClassInfo RegClassInfo;
|
|
|
|
#ifndef NDEBUG
|
|
static int NumTries;
|
|
#endif
|
|
|
|
/// Cache the target analysis information about the loop.
|
|
struct LoopInfo {
|
|
MachineBasicBlock *TBB = nullptr;
|
|
MachineBasicBlock *FBB = nullptr;
|
|
SmallVector<MachineOperand, 4> BrCond;
|
|
MachineInstr *LoopInductionVar = nullptr;
|
|
MachineInstr *LoopCompare = nullptr;
|
|
};
|
|
LoopInfo LI;
|
|
|
|
static char ID;
|
|
|
|
MachinePipeliner() : MachineFunctionPass(ID) {
|
|
initializeMachinePipelinerPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
bool runOnMachineFunction(MachineFunction &MF) override;
|
|
|
|
void getAnalysisUsage(AnalysisUsage &AU) const override {
|
|
AU.addRequired<AAResultsWrapperPass>();
|
|
AU.addPreserved<AAResultsWrapperPass>();
|
|
AU.addRequired<MachineLoopInfo>();
|
|
AU.addRequired<MachineDominatorTree>();
|
|
AU.addRequired<LiveIntervals>();
|
|
MachineFunctionPass::getAnalysisUsage(AU);
|
|
}
|
|
|
|
private:
|
|
void preprocessPhiNodes(MachineBasicBlock &B);
|
|
bool canPipelineLoop(MachineLoop &L);
|
|
bool scheduleLoop(MachineLoop &L);
|
|
bool swingModuloScheduler(MachineLoop &L);
|
|
};
|
|
|
|
/// This class builds the dependence graph for the instructions in a loop,
|
|
/// and attempts to schedule the instructions using the SMS algorithm.
|
|
class SwingSchedulerDAG : public ScheduleDAGInstrs {
|
|
MachinePipeliner &Pass;
|
|
/// The minimum initiation interval between iterations for this schedule.
|
|
unsigned MII = 0;
|
|
/// Set to true if a valid pipelined schedule is found for the loop.
|
|
bool Scheduled = false;
|
|
MachineLoop &Loop;
|
|
LiveIntervals &LIS;
|
|
const RegisterClassInfo &RegClassInfo;
|
|
|
|
/// A toplogical ordering of the SUnits, which is needed for changing
|
|
/// dependences and iterating over the SUnits.
|
|
ScheduleDAGTopologicalSort Topo;
|
|
|
|
struct NodeInfo {
|
|
int ASAP = 0;
|
|
int ALAP = 0;
|
|
int ZeroLatencyDepth = 0;
|
|
int ZeroLatencyHeight = 0;
|
|
|
|
NodeInfo() = default;
|
|
};
|
|
/// Computed properties for each node in the graph.
|
|
std::vector<NodeInfo> ScheduleInfo;
|
|
|
|
enum OrderKind { BottomUp = 0, TopDown = 1 };
|
|
/// Computed node ordering for scheduling.
|
|
SetVector<SUnit *> NodeOrder;
|
|
|
|
using NodeSetType = SmallVector<NodeSet, 8>;
|
|
using ValueMapTy = DenseMap<unsigned, unsigned>;
|
|
using MBBVectorTy = SmallVectorImpl<MachineBasicBlock *>;
|
|
using InstrMapTy = DenseMap<MachineInstr *, MachineInstr *>;
|
|
|
|
/// Instructions to change when emitting the final schedule.
|
|
DenseMap<SUnit *, std::pair<unsigned, int64_t>> InstrChanges;
|
|
|
|
/// We may create a new instruction, so remember it because it
|
|
/// must be deleted when the pass is finished.
|
|
SmallPtrSet<MachineInstr *, 4> NewMIs;
|
|
|
|
/// Ordered list of DAG postprocessing steps.
|
|
std::vector<std::unique_ptr<ScheduleDAGMutation>> Mutations;
|
|
|
|
/// Helper class to implement Johnson's circuit finding algorithm.
|
|
class Circuits {
|
|
std::vector<SUnit> &SUnits;
|
|
SetVector<SUnit *> Stack;
|
|
BitVector Blocked;
|
|
SmallVector<SmallPtrSet<SUnit *, 4>, 10> B;
|
|
SmallVector<SmallVector<int, 4>, 16> AdjK;
|
|
unsigned NumPaths;
|
|
static unsigned MaxPaths;
|
|
|
|
public:
|
|
Circuits(std::vector<SUnit> &SUs)
|
|
: SUnits(SUs), Blocked(SUs.size()), B(SUs.size()), AdjK(SUs.size()) {}
|
|
|
|
/// Reset the data structures used in the circuit algorithm.
|
|
void reset() {
|
|
Stack.clear();
|
|
Blocked.reset();
|
|
B.assign(SUnits.size(), SmallPtrSet<SUnit *, 4>());
|
|
NumPaths = 0;
|
|
}
|
|
|
|
void createAdjacencyStructure(SwingSchedulerDAG *DAG);
|
|
bool circuit(int V, int S, NodeSetType &NodeSets, bool HasBackedge = false);
|
|
void unblock(int U);
|
|
};
|
|
|
|
public:
|
|
SwingSchedulerDAG(MachinePipeliner &P, MachineLoop &L, LiveIntervals &lis,
|
|
const RegisterClassInfo &rci)
|
|
: ScheduleDAGInstrs(*P.MF, P.MLI, false), Pass(P), Loop(L), LIS(lis),
|
|
RegClassInfo(rci), Topo(SUnits, &ExitSU) {
|
|
P.MF->getSubtarget().getSMSMutations(Mutations);
|
|
}
|
|
|
|
void schedule() override;
|
|
void finishBlock() override;
|
|
|
|
/// Return true if the loop kernel has been scheduled.
|
|
bool hasNewSchedule() { return Scheduled; }
|
|
|
|
/// Return the earliest time an instruction may be scheduled.
|
|
int getASAP(SUnit *Node) { return ScheduleInfo[Node->NodeNum].ASAP; }
|
|
|
|
/// Return the latest time an instruction my be scheduled.
|
|
int getALAP(SUnit *Node) { return ScheduleInfo[Node->NodeNum].ALAP; }
|
|
|
|
/// The mobility function, which the number of slots in which
|
|
/// an instruction may be scheduled.
|
|
int getMOV(SUnit *Node) { return getALAP(Node) - getASAP(Node); }
|
|
|
|
/// The depth, in the dependence graph, for a node.
|
|
unsigned getDepth(SUnit *Node) { return Node->getDepth(); }
|
|
|
|
/// The maximum unweighted length of a path from an arbitrary node to the
|
|
/// given node in which each edge has latency 0
|
|
int getZeroLatencyDepth(SUnit *Node) {
|
|
return ScheduleInfo[Node->NodeNum].ZeroLatencyDepth;
|
|
}
|
|
|
|
/// The height, in the dependence graph, for a node.
|
|
unsigned getHeight(SUnit *Node) { return Node->getHeight(); }
|
|
|
|
/// The maximum unweighted length of a path from the given node to an
|
|
/// arbitrary node in which each edge has latency 0
|
|
int getZeroLatencyHeight(SUnit *Node) {
|
|
return ScheduleInfo[Node->NodeNum].ZeroLatencyHeight;
|
|
}
|
|
|
|
/// Return true if the dependence is a back-edge in the data dependence graph.
|
|
/// Since the DAG doesn't contain cycles, we represent a cycle in the graph
|
|
/// using an anti dependence from a Phi to an instruction.
|
|
bool isBackedge(SUnit *Source, const SDep &Dep) {
|
|
if (Dep.getKind() != SDep::Anti)
|
|
return false;
|
|
return Source->getInstr()->isPHI() || Dep.getSUnit()->getInstr()->isPHI();
|
|
}
|
|
|
|
bool isLoopCarriedDep(SUnit *Source, const SDep &Dep, bool isSucc = true);
|
|
|
|
/// The distance function, which indicates that operation V of iteration I
|
|
/// depends on operations U of iteration I-distance.
|
|
unsigned getDistance(SUnit *U, SUnit *V, const SDep &Dep) {
|
|
// Instructions that feed a Phi have a distance of 1. Computing larger
|
|
// values for arrays requires data dependence information.
|
|
if (V->getInstr()->isPHI() && Dep.getKind() == SDep::Anti)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
/// Set the Minimum Initiation Interval for this schedule attempt.
|
|
void setMII(unsigned mii) { MII = mii; }
|
|
|
|
void applyInstrChange(MachineInstr *MI, SMSchedule &Schedule);
|
|
|
|
void fixupRegisterOverlaps(std::deque<SUnit *> &Instrs);
|
|
|
|
/// Return the new base register that was stored away for the changed
|
|
/// instruction.
|
|
unsigned getInstrBaseReg(SUnit *SU) {
|
|
DenseMap<SUnit *, std::pair<unsigned, int64_t>>::iterator It =
|
|
InstrChanges.find(SU);
|
|
if (It != InstrChanges.end())
|
|
return It->second.first;
|
|
return 0;
|
|
}
|
|
|
|
void addMutation(std::unique_ptr<ScheduleDAGMutation> Mutation) {
|
|
Mutations.push_back(std::move(Mutation));
|
|
}
|
|
|
|
private:
|
|
void addLoopCarriedDependences(AliasAnalysis *AA);
|
|
void updatePhiDependences();
|
|
void changeDependences();
|
|
unsigned calculateResMII();
|
|
unsigned calculateRecMII(NodeSetType &RecNodeSets);
|
|
void findCircuits(NodeSetType &NodeSets);
|
|
void fuseRecs(NodeSetType &NodeSets);
|
|
void removeDuplicateNodes(NodeSetType &NodeSets);
|
|
void computeNodeFunctions(NodeSetType &NodeSets);
|
|
void registerPressureFilter(NodeSetType &NodeSets);
|
|
void colocateNodeSets(NodeSetType &NodeSets);
|
|
void checkNodeSets(NodeSetType &NodeSets);
|
|
void groupRemainingNodes(NodeSetType &NodeSets);
|
|
void addConnectedNodes(SUnit *SU, NodeSet &NewSet,
|
|
SetVector<SUnit *> &NodesAdded);
|
|
void computeNodeOrder(NodeSetType &NodeSets);
|
|
void checkValidNodeOrder(const NodeSetType &Circuits) const;
|
|
bool schedulePipeline(SMSchedule &Schedule);
|
|
void generatePipelinedLoop(SMSchedule &Schedule);
|
|
void generateProlog(SMSchedule &Schedule, unsigned LastStage,
|
|
MachineBasicBlock *KernelBB, ValueMapTy *VRMap,
|
|
MBBVectorTy &PrologBBs);
|
|
void generateEpilog(SMSchedule &Schedule, unsigned LastStage,
|
|
MachineBasicBlock *KernelBB, ValueMapTy *VRMap,
|
|
MBBVectorTy &EpilogBBs, MBBVectorTy &PrologBBs);
|
|
void generateExistingPhis(MachineBasicBlock *NewBB, MachineBasicBlock *BB1,
|
|
MachineBasicBlock *BB2, MachineBasicBlock *KernelBB,
|
|
SMSchedule &Schedule, ValueMapTy *VRMap,
|
|
InstrMapTy &InstrMap, unsigned LastStageNum,
|
|
unsigned CurStageNum, bool IsLast);
|
|
void generatePhis(MachineBasicBlock *NewBB, MachineBasicBlock *BB1,
|
|
MachineBasicBlock *BB2, MachineBasicBlock *KernelBB,
|
|
SMSchedule &Schedule, ValueMapTy *VRMap,
|
|
InstrMapTy &InstrMap, unsigned LastStageNum,
|
|
unsigned CurStageNum, bool IsLast);
|
|
void removeDeadInstructions(MachineBasicBlock *KernelBB,
|
|
MBBVectorTy &EpilogBBs);
|
|
void splitLifetimes(MachineBasicBlock *KernelBB, MBBVectorTy &EpilogBBs,
|
|
SMSchedule &Schedule);
|
|
void addBranches(MBBVectorTy &PrologBBs, MachineBasicBlock *KernelBB,
|
|
MBBVectorTy &EpilogBBs, SMSchedule &Schedule,
|
|
ValueMapTy *VRMap);
|
|
bool computeDelta(MachineInstr &MI, unsigned &Delta);
|
|
void updateMemOperands(MachineInstr &NewMI, MachineInstr &OldMI,
|
|
unsigned Num);
|
|
MachineInstr *cloneInstr(MachineInstr *OldMI, unsigned CurStageNum,
|
|
unsigned InstStageNum);
|
|
MachineInstr *cloneAndChangeInstr(MachineInstr *OldMI, unsigned CurStageNum,
|
|
unsigned InstStageNum,
|
|
SMSchedule &Schedule);
|
|
void updateInstruction(MachineInstr *NewMI, bool LastDef,
|
|
unsigned CurStageNum, unsigned InstrStageNum,
|
|
SMSchedule &Schedule, ValueMapTy *VRMap);
|
|
MachineInstr *findDefInLoop(unsigned Reg);
|
|
unsigned getPrevMapVal(unsigned StageNum, unsigned PhiStage, unsigned LoopVal,
|
|
unsigned LoopStage, ValueMapTy *VRMap,
|
|
MachineBasicBlock *BB);
|
|
void rewritePhiValues(MachineBasicBlock *NewBB, unsigned StageNum,
|
|
SMSchedule &Schedule, ValueMapTy *VRMap,
|
|
InstrMapTy &InstrMap);
|
|
void rewriteScheduledInstr(MachineBasicBlock *BB, SMSchedule &Schedule,
|
|
InstrMapTy &InstrMap, unsigned CurStageNum,
|
|
unsigned PhiNum, MachineInstr *Phi,
|
|
unsigned OldReg, unsigned NewReg,
|
|
unsigned PrevReg = 0);
|
|
bool canUseLastOffsetValue(MachineInstr *MI, unsigned &BasePos,
|
|
unsigned &OffsetPos, unsigned &NewBase,
|
|
int64_t &NewOffset);
|
|
void postprocessDAG();
|
|
};
|
|
|
|
/// A NodeSet contains a set of SUnit DAG nodes with additional information
|
|
/// that assigns a priority to the set.
|
|
class NodeSet {
|
|
SetVector<SUnit *> Nodes;
|
|
bool HasRecurrence = false;
|
|
unsigned RecMII = 0;
|
|
int MaxMOV = 0;
|
|
unsigned MaxDepth = 0;
|
|
unsigned Colocate = 0;
|
|
SUnit *ExceedPressure = nullptr;
|
|
unsigned Latency = 0;
|
|
|
|
public:
|
|
using iterator = SetVector<SUnit *>::const_iterator;
|
|
|
|
NodeSet() = default;
|
|
NodeSet(iterator S, iterator E) : Nodes(S, E), HasRecurrence(true) {
|
|
Latency = 0;
|
|
for (unsigned i = 0, e = Nodes.size(); i < e; ++i)
|
|
for (const SDep &Succ : Nodes[i]->Succs)
|
|
if (Nodes.count(Succ.getSUnit()))
|
|
Latency += Succ.getLatency();
|
|
}
|
|
|
|
bool insert(SUnit *SU) { return Nodes.insert(SU); }
|
|
|
|
void insert(iterator S, iterator E) { Nodes.insert(S, E); }
|
|
|
|
template <typename UnaryPredicate> bool remove_if(UnaryPredicate P) {
|
|
return Nodes.remove_if(P);
|
|
}
|
|
|
|
unsigned count(SUnit *SU) const { return Nodes.count(SU); }
|
|
|
|
bool hasRecurrence() { return HasRecurrence; };
|
|
|
|
unsigned size() const { return Nodes.size(); }
|
|
|
|
bool empty() const { return Nodes.empty(); }
|
|
|
|
SUnit *getNode(unsigned i) const { return Nodes[i]; };
|
|
|
|
void setRecMII(unsigned mii) { RecMII = mii; };
|
|
|
|
void setColocate(unsigned c) { Colocate = c; };
|
|
|
|
void setExceedPressure(SUnit *SU) { ExceedPressure = SU; }
|
|
|
|
bool isExceedSU(SUnit *SU) { return ExceedPressure == SU; }
|
|
|
|
int compareRecMII(NodeSet &RHS) { return RecMII - RHS.RecMII; }
|
|
|
|
int getRecMII() { return RecMII; }
|
|
|
|
/// Summarize node functions for the entire node set.
|
|
void computeNodeSetInfo(SwingSchedulerDAG *SSD) {
|
|
for (SUnit *SU : *this) {
|
|
MaxMOV = std::max(MaxMOV, SSD->getMOV(SU));
|
|
MaxDepth = std::max(MaxDepth, SSD->getDepth(SU));
|
|
}
|
|
}
|
|
|
|
unsigned getLatency() { return Latency; }
|
|
|
|
unsigned getMaxDepth() { return MaxDepth; }
|
|
|
|
void clear() {
|
|
Nodes.clear();
|
|
RecMII = 0;
|
|
HasRecurrence = false;
|
|
MaxMOV = 0;
|
|
MaxDepth = 0;
|
|
Colocate = 0;
|
|
ExceedPressure = nullptr;
|
|
}
|
|
|
|
operator SetVector<SUnit *> &() { return Nodes; }
|
|
|
|
/// Sort the node sets by importance. First, rank them by recurrence MII,
|
|
/// then by mobility (least mobile done first), and finally by depth.
|
|
/// Each node set may contain a colocate value which is used as the first
|
|
/// tie breaker, if it's set.
|
|
bool operator>(const NodeSet &RHS) const {
|
|
if (RecMII == RHS.RecMII) {
|
|
if (Colocate != 0 && RHS.Colocate != 0 && Colocate != RHS.Colocate)
|
|
return Colocate < RHS.Colocate;
|
|
if (MaxMOV == RHS.MaxMOV)
|
|
return MaxDepth > RHS.MaxDepth;
|
|
return MaxMOV < RHS.MaxMOV;
|
|
}
|
|
return RecMII > RHS.RecMII;
|
|
}
|
|
|
|
bool operator==(const NodeSet &RHS) const {
|
|
return RecMII == RHS.RecMII && MaxMOV == RHS.MaxMOV &&
|
|
MaxDepth == RHS.MaxDepth;
|
|
}
|
|
|
|
bool operator!=(const NodeSet &RHS) const { return !operator==(RHS); }
|
|
|
|
iterator begin() { return Nodes.begin(); }
|
|
iterator end() { return Nodes.end(); }
|
|
|
|
void print(raw_ostream &os) const {
|
|
os << "Num nodes " << size() << " rec " << RecMII << " mov " << MaxMOV
|
|
<< " depth " << MaxDepth << " col " << Colocate << "\n";
|
|
for (const auto &I : Nodes)
|
|
os << " SU(" << I->NodeNum << ") " << *(I->getInstr());
|
|
os << "\n";
|
|
}
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
|
|
#endif
|
|
};
|
|
|
|
/// This class represents the scheduled code. The main data structure is a
|
|
/// map from scheduled cycle to instructions. During scheduling, the
|
|
/// data structure explicitly represents all stages/iterations. When
|
|
/// the algorithm finshes, the schedule is collapsed into a single stage,
|
|
/// which represents instructions from different loop iterations.
|
|
///
|
|
/// The SMS algorithm allows negative values for cycles, so the first cycle
|
|
/// in the schedule is the smallest cycle value.
|
|
class SMSchedule {
|
|
private:
|
|
/// Map from execution cycle to instructions.
|
|
DenseMap<int, std::deque<SUnit *>> ScheduledInstrs;
|
|
|
|
/// Map from instruction to execution cycle.
|
|
std::map<SUnit *, int> InstrToCycle;
|
|
|
|
/// Map for each register and the max difference between its uses and def.
|
|
/// The first element in the pair is the max difference in stages. The
|
|
/// second is true if the register defines a Phi value and loop value is
|
|
/// scheduled before the Phi.
|
|
std::map<unsigned, std::pair<unsigned, bool>> RegToStageDiff;
|
|
|
|
/// Keep track of the first cycle value in the schedule. It starts
|
|
/// as zero, but the algorithm allows negative values.
|
|
int FirstCycle = 0;
|
|
|
|
/// Keep track of the last cycle value in the schedule.
|
|
int LastCycle = 0;
|
|
|
|
/// The initiation interval (II) for the schedule.
|
|
int InitiationInterval = 0;
|
|
|
|
/// Target machine information.
|
|
const TargetSubtargetInfo &ST;
|
|
|
|
/// Virtual register information.
|
|
MachineRegisterInfo &MRI;
|
|
|
|
std::unique_ptr<DFAPacketizer> Resources;
|
|
|
|
public:
|
|
SMSchedule(MachineFunction *mf)
|
|
: ST(mf->getSubtarget()), MRI(mf->getRegInfo()),
|
|
Resources(ST.getInstrInfo()->CreateTargetScheduleState(ST)) {}
|
|
|
|
void reset() {
|
|
ScheduledInstrs.clear();
|
|
InstrToCycle.clear();
|
|
RegToStageDiff.clear();
|
|
FirstCycle = 0;
|
|
LastCycle = 0;
|
|
InitiationInterval = 0;
|
|
}
|
|
|
|
/// Set the initiation interval for this schedule.
|
|
void setInitiationInterval(int ii) { InitiationInterval = ii; }
|
|
|
|
/// Return the first cycle in the completed schedule. This
|
|
/// can be a negative value.
|
|
int getFirstCycle() const { return FirstCycle; }
|
|
|
|
/// Return the last cycle in the finalized schedule.
|
|
int getFinalCycle() const { return FirstCycle + InitiationInterval - 1; }
|
|
|
|
/// Return the cycle of the earliest scheduled instruction in the dependence
|
|
/// chain.
|
|
int earliestCycleInChain(const SDep &Dep);
|
|
|
|
/// Return the cycle of the latest scheduled instruction in the dependence
|
|
/// chain.
|
|
int latestCycleInChain(const SDep &Dep);
|
|
|
|
void computeStart(SUnit *SU, int *MaxEarlyStart, int *MinLateStart,
|
|
int *MinEnd, int *MaxStart, int II, SwingSchedulerDAG *DAG);
|
|
bool insert(SUnit *SU, int StartCycle, int EndCycle, int II);
|
|
|
|
/// Iterators for the cycle to instruction map.
|
|
using sched_iterator = DenseMap<int, std::deque<SUnit *>>::iterator;
|
|
using const_sched_iterator =
|
|
DenseMap<int, std::deque<SUnit *>>::const_iterator;
|
|
|
|
/// Return true if the instruction is scheduled at the specified stage.
|
|
bool isScheduledAtStage(SUnit *SU, unsigned StageNum) {
|
|
return (stageScheduled(SU) == (int)StageNum);
|
|
}
|
|
|
|
/// Return the stage for a scheduled instruction. Return -1 if
|
|
/// the instruction has not been scheduled.
|
|
int stageScheduled(SUnit *SU) const {
|
|
std::map<SUnit *, int>::const_iterator it = InstrToCycle.find(SU);
|
|
if (it == InstrToCycle.end())
|
|
return -1;
|
|
return (it->second - FirstCycle) / InitiationInterval;
|
|
}
|
|
|
|
/// Return the cycle for a scheduled instruction. This function normalizes
|
|
/// the first cycle to be 0.
|
|
unsigned cycleScheduled(SUnit *SU) const {
|
|
std::map<SUnit *, int>::const_iterator it = InstrToCycle.find(SU);
|
|
assert(it != InstrToCycle.end() && "Instruction hasn't been scheduled.");
|
|
return (it->second - FirstCycle) % InitiationInterval;
|
|
}
|
|
|
|
/// Return the maximum stage count needed for this schedule.
|
|
unsigned getMaxStageCount() {
|
|
return (LastCycle - FirstCycle) / InitiationInterval;
|
|
}
|
|
|
|
/// Return the max. number of stages/iterations that can occur between a
|
|
/// register definition and its uses.
|
|
unsigned getStagesForReg(int Reg, unsigned CurStage) {
|
|
std::pair<unsigned, bool> Stages = RegToStageDiff[Reg];
|
|
if (CurStage > getMaxStageCount() && Stages.first == 0 && Stages.second)
|
|
return 1;
|
|
return Stages.first;
|
|
}
|
|
|
|
/// The number of stages for a Phi is a little different than other
|
|
/// instructions. The minimum value computed in RegToStageDiff is 1
|
|
/// because we assume the Phi is needed for at least 1 iteration.
|
|
/// This is not the case if the loop value is scheduled prior to the
|
|
/// Phi in the same stage. This function returns the number of stages
|
|
/// or iterations needed between the Phi definition and any uses.
|
|
unsigned getStagesForPhi(int Reg) {
|
|
std::pair<unsigned, bool> Stages = RegToStageDiff[Reg];
|
|
if (Stages.second)
|
|
return Stages.first;
|
|
return Stages.first - 1;
|
|
}
|
|
|
|
/// Return the instructions that are scheduled at the specified cycle.
|
|
std::deque<SUnit *> &getInstructions(int cycle) {
|
|
return ScheduledInstrs[cycle];
|
|
}
|
|
|
|
bool isValidSchedule(SwingSchedulerDAG *SSD);
|
|
void finalizeSchedule(SwingSchedulerDAG *SSD);
|
|
void orderDependence(SwingSchedulerDAG *SSD, SUnit *SU,
|
|
std::deque<SUnit *> &Insts);
|
|
bool isLoopCarried(SwingSchedulerDAG *SSD, MachineInstr &Phi);
|
|
bool isLoopCarriedDefOfUse(SwingSchedulerDAG *SSD, MachineInstr *Def,
|
|
MachineOperand &MO);
|
|
void print(raw_ostream &os) const;
|
|
void dump() const;
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
unsigned SwingSchedulerDAG::Circuits::MaxPaths = 5;
|
|
char MachinePipeliner::ID = 0;
|
|
#ifndef NDEBUG
|
|
int MachinePipeliner::NumTries = 0;
|
|
#endif
|
|
char &llvm::MachinePipelinerID = MachinePipeliner::ID;
|
|
|
|
INITIALIZE_PASS_BEGIN(MachinePipeliner, DEBUG_TYPE,
|
|
"Modulo Software Pipelining", false, false)
|
|
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
|
|
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
|
|
INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
|
|
INITIALIZE_PASS_END(MachinePipeliner, DEBUG_TYPE,
|
|
"Modulo Software Pipelining", false, false)
|
|
|
|
/// The "main" function for implementing Swing Modulo Scheduling.
|
|
bool MachinePipeliner::runOnMachineFunction(MachineFunction &mf) {
|
|
if (skipFunction(mf.getFunction()))
|
|
return false;
|
|
|
|
if (!EnableSWP)
|
|
return false;
|
|
|
|
if (mf.getFunction().getAttributes().hasAttribute(
|
|
AttributeList::FunctionIndex, Attribute::OptimizeForSize) &&
|
|
!EnableSWPOptSize.getPosition())
|
|
return false;
|
|
|
|
MF = &mf;
|
|
MLI = &getAnalysis<MachineLoopInfo>();
|
|
MDT = &getAnalysis<MachineDominatorTree>();
|
|
TII = MF->getSubtarget().getInstrInfo();
|
|
RegClassInfo.runOnMachineFunction(*MF);
|
|
|
|
for (auto &L : *MLI)
|
|
scheduleLoop(*L);
|
|
|
|
return false;
|
|
}
|
|
|
|
/// Attempt to perform the SMS algorithm on the specified loop. This function is
|
|
/// the main entry point for the algorithm. The function identifies candidate
|
|
/// loops, calculates the minimum initiation interval, and attempts to schedule
|
|
/// the loop.
|
|
bool MachinePipeliner::scheduleLoop(MachineLoop &L) {
|
|
bool Changed = false;
|
|
for (auto &InnerLoop : L)
|
|
Changed |= scheduleLoop(*InnerLoop);
|
|
|
|
#ifndef NDEBUG
|
|
// Stop trying after reaching the limit (if any).
|
|
int Limit = SwpLoopLimit;
|
|
if (Limit >= 0) {
|
|
if (NumTries >= SwpLoopLimit)
|
|
return Changed;
|
|
NumTries++;
|
|
}
|
|
#endif
|
|
|
|
if (!canPipelineLoop(L))
|
|
return Changed;
|
|
|
|
++NumTrytoPipeline;
|
|
|
|
Changed = swingModuloScheduler(L);
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// Return true if the loop can be software pipelined. The algorithm is
|
|
/// restricted to loops with a single basic block. Make sure that the
|
|
/// branch in the loop can be analyzed.
|
|
bool MachinePipeliner::canPipelineLoop(MachineLoop &L) {
|
|
if (L.getNumBlocks() != 1)
|
|
return false;
|
|
|
|
// Check if the branch can't be understood because we can't do pipelining
|
|
// if that's the case.
|
|
LI.TBB = nullptr;
|
|
LI.FBB = nullptr;
|
|
LI.BrCond.clear();
|
|
if (TII->analyzeBranch(*L.getHeader(), LI.TBB, LI.FBB, LI.BrCond))
|
|
return false;
|
|
|
|
LI.LoopInductionVar = nullptr;
|
|
LI.LoopCompare = nullptr;
|
|
if (TII->analyzeLoop(L, LI.LoopInductionVar, LI.LoopCompare))
|
|
return false;
|
|
|
|
if (!L.getLoopPreheader())
|
|
return false;
|
|
|
|
// Remove any subregisters from inputs to phi nodes.
|
|
preprocessPhiNodes(*L.getHeader());
|
|
return true;
|
|
}
|
|
|
|
void MachinePipeliner::preprocessPhiNodes(MachineBasicBlock &B) {
|
|
MachineRegisterInfo &MRI = MF->getRegInfo();
|
|
SlotIndexes &Slots = *getAnalysis<LiveIntervals>().getSlotIndexes();
|
|
|
|
for (MachineInstr &PI : make_range(B.begin(), B.getFirstNonPHI())) {
|
|
MachineOperand &DefOp = PI.getOperand(0);
|
|
assert(DefOp.getSubReg() == 0);
|
|
auto *RC = MRI.getRegClass(DefOp.getReg());
|
|
|
|
for (unsigned i = 1, n = PI.getNumOperands(); i != n; i += 2) {
|
|
MachineOperand &RegOp = PI.getOperand(i);
|
|
if (RegOp.getSubReg() == 0)
|
|
continue;
|
|
|
|
// If the operand uses a subregister, replace it with a new register
|
|
// without subregisters, and generate a copy to the new register.
|
|
unsigned NewReg = MRI.createVirtualRegister(RC);
|
|
MachineBasicBlock &PredB = *PI.getOperand(i+1).getMBB();
|
|
MachineBasicBlock::iterator At = PredB.getFirstTerminator();
|
|
const DebugLoc &DL = PredB.findDebugLoc(At);
|
|
auto Copy = BuildMI(PredB, At, DL, TII->get(TargetOpcode::COPY), NewReg)
|
|
.addReg(RegOp.getReg(), getRegState(RegOp),
|
|
RegOp.getSubReg());
|
|
Slots.insertMachineInstrInMaps(*Copy);
|
|
RegOp.setReg(NewReg);
|
|
RegOp.setSubReg(0);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// The SMS algorithm consists of the following main steps:
|
|
/// 1. Computation and analysis of the dependence graph.
|
|
/// 2. Ordering of the nodes (instructions).
|
|
/// 3. Attempt to Schedule the loop.
|
|
bool MachinePipeliner::swingModuloScheduler(MachineLoop &L) {
|
|
assert(L.getBlocks().size() == 1 && "SMS works on single blocks only.");
|
|
|
|
SwingSchedulerDAG SMS(*this, L, getAnalysis<LiveIntervals>(), RegClassInfo);
|
|
|
|
MachineBasicBlock *MBB = L.getHeader();
|
|
// The kernel should not include any terminator instructions. These
|
|
// will be added back later.
|
|
SMS.startBlock(MBB);
|
|
|
|
// Compute the number of 'real' instructions in the basic block by
|
|
// ignoring terminators.
|
|
unsigned size = MBB->size();
|
|
for (MachineBasicBlock::iterator I = MBB->getFirstTerminator(),
|
|
E = MBB->instr_end();
|
|
I != E; ++I, --size)
|
|
;
|
|
|
|
SMS.enterRegion(MBB, MBB->begin(), MBB->getFirstTerminator(), size);
|
|
SMS.schedule();
|
|
SMS.exitRegion();
|
|
|
|
SMS.finishBlock();
|
|
return SMS.hasNewSchedule();
|
|
}
|
|
|
|
/// We override the schedule function in ScheduleDAGInstrs to implement the
|
|
/// scheduling part of the Swing Modulo Scheduling algorithm.
|
|
void SwingSchedulerDAG::schedule() {
|
|
AliasAnalysis *AA = &Pass.getAnalysis<AAResultsWrapperPass>().getAAResults();
|
|
buildSchedGraph(AA);
|
|
addLoopCarriedDependences(AA);
|
|
updatePhiDependences();
|
|
Topo.InitDAGTopologicalSorting();
|
|
postprocessDAG();
|
|
changeDependences();
|
|
LLVM_DEBUG(dump());
|
|
|
|
NodeSetType NodeSets;
|
|
findCircuits(NodeSets);
|
|
NodeSetType Circuits = NodeSets;
|
|
|
|
// Calculate the MII.
|
|
unsigned ResMII = calculateResMII();
|
|
unsigned RecMII = calculateRecMII(NodeSets);
|
|
|
|
fuseRecs(NodeSets);
|
|
|
|
// This flag is used for testing and can cause correctness problems.
|
|
if (SwpIgnoreRecMII)
|
|
RecMII = 0;
|
|
|
|
MII = std::max(ResMII, RecMII);
|
|
LLVM_DEBUG(dbgs() << "MII = " << MII << " (rec=" << RecMII
|
|
<< ", res=" << ResMII << ")\n");
|
|
|
|
// Can't schedule a loop without a valid MII.
|
|
if (MII == 0)
|
|
return;
|
|
|
|
// Don't pipeline large loops.
|
|
if (SwpMaxMii != -1 && (int)MII > SwpMaxMii)
|
|
return;
|
|
|
|
computeNodeFunctions(NodeSets);
|
|
|
|
registerPressureFilter(NodeSets);
|
|
|
|
colocateNodeSets(NodeSets);
|
|
|
|
checkNodeSets(NodeSets);
|
|
|
|
LLVM_DEBUG({
|
|
for (auto &I : NodeSets) {
|
|
dbgs() << " Rec NodeSet ";
|
|
I.dump();
|
|
}
|
|
});
|
|
|
|
std::stable_sort(NodeSets.begin(), NodeSets.end(), std::greater<NodeSet>());
|
|
|
|
groupRemainingNodes(NodeSets);
|
|
|
|
removeDuplicateNodes(NodeSets);
|
|
|
|
LLVM_DEBUG({
|
|
for (auto &I : NodeSets) {
|
|
dbgs() << " NodeSet ";
|
|
I.dump();
|
|
}
|
|
});
|
|
|
|
computeNodeOrder(NodeSets);
|
|
|
|
// check for node order issues
|
|
checkValidNodeOrder(Circuits);
|
|
|
|
SMSchedule Schedule(Pass.MF);
|
|
Scheduled = schedulePipeline(Schedule);
|
|
|
|
if (!Scheduled)
|
|
return;
|
|
|
|
unsigned numStages = Schedule.getMaxStageCount();
|
|
// No need to generate pipeline if there are no overlapped iterations.
|
|
if (numStages == 0)
|
|
return;
|
|
|
|
// Check that the maximum stage count is less than user-defined limit.
|
|
if (SwpMaxStages > -1 && (int)numStages > SwpMaxStages)
|
|
return;
|
|
|
|
generatePipelinedLoop(Schedule);
|
|
++NumPipelined;
|
|
}
|
|
|
|
/// Clean up after the software pipeliner runs.
|
|
void SwingSchedulerDAG::finishBlock() {
|
|
for (MachineInstr *I : NewMIs)
|
|
MF.DeleteMachineInstr(I);
|
|
NewMIs.clear();
|
|
|
|
// Call the superclass.
|
|
ScheduleDAGInstrs::finishBlock();
|
|
}
|
|
|
|
/// Return the register values for the operands of a Phi instruction.
|
|
/// This function assume the instruction is a Phi.
|
|
static void getPhiRegs(MachineInstr &Phi, MachineBasicBlock *Loop,
|
|
unsigned &InitVal, unsigned &LoopVal) {
|
|
assert(Phi.isPHI() && "Expecting a Phi.");
|
|
|
|
InitVal = 0;
|
|
LoopVal = 0;
|
|
for (unsigned i = 1, e = Phi.getNumOperands(); i != e; i += 2)
|
|
if (Phi.getOperand(i + 1).getMBB() != Loop)
|
|
InitVal = Phi.getOperand(i).getReg();
|
|
else
|
|
LoopVal = Phi.getOperand(i).getReg();
|
|
|
|
assert(InitVal != 0 && LoopVal != 0 && "Unexpected Phi structure.");
|
|
}
|
|
|
|
/// Return the Phi register value that comes from the incoming block.
|
|
static unsigned getInitPhiReg(MachineInstr &Phi, MachineBasicBlock *LoopBB) {
|
|
for (unsigned i = 1, e = Phi.getNumOperands(); i != e; i += 2)
|
|
if (Phi.getOperand(i + 1).getMBB() != LoopBB)
|
|
return Phi.getOperand(i).getReg();
|
|
return 0;
|
|
}
|
|
|
|
/// Return the Phi register value that comes the loop block.
|
|
static unsigned getLoopPhiReg(MachineInstr &Phi, MachineBasicBlock *LoopBB) {
|
|
for (unsigned i = 1, e = Phi.getNumOperands(); i != e; i += 2)
|
|
if (Phi.getOperand(i + 1).getMBB() == LoopBB)
|
|
return Phi.getOperand(i).getReg();
|
|
return 0;
|
|
}
|
|
|
|
/// Return true if SUb can be reached from SUa following the chain edges.
|
|
static bool isSuccOrder(SUnit *SUa, SUnit *SUb) {
|
|
SmallPtrSet<SUnit *, 8> Visited;
|
|
SmallVector<SUnit *, 8> Worklist;
|
|
Worklist.push_back(SUa);
|
|
while (!Worklist.empty()) {
|
|
const SUnit *SU = Worklist.pop_back_val();
|
|
for (auto &SI : SU->Succs) {
|
|
SUnit *SuccSU = SI.getSUnit();
|
|
if (SI.getKind() == SDep::Order) {
|
|
if (Visited.count(SuccSU))
|
|
continue;
|
|
if (SuccSU == SUb)
|
|
return true;
|
|
Worklist.push_back(SuccSU);
|
|
Visited.insert(SuccSU);
|
|
}
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// Return true if the instruction causes a chain between memory
|
|
/// references before and after it.
|
|
static bool isDependenceBarrier(MachineInstr &MI, AliasAnalysis *AA) {
|
|
return MI.isCall() || MI.hasUnmodeledSideEffects() ||
|
|
(MI.hasOrderedMemoryRef() &&
|
|
(!MI.mayLoad() || !MI.isDereferenceableInvariantLoad(AA)));
|
|
}
|
|
|
|
/// Return the underlying objects for the memory references of an instruction.
|
|
/// This function calls the code in ValueTracking, but first checks that the
|
|
/// instruction has a memory operand.
|
|
static void getUnderlyingObjects(MachineInstr *MI,
|
|
SmallVectorImpl<Value *> &Objs,
|
|
const DataLayout &DL) {
|
|
if (!MI->hasOneMemOperand())
|
|
return;
|
|
MachineMemOperand *MM = *MI->memoperands_begin();
|
|
if (!MM->getValue())
|
|
return;
|
|
GetUnderlyingObjects(const_cast<Value *>(MM->getValue()), Objs, DL);
|
|
for (Value *V : Objs) {
|
|
if (!isIdentifiedObject(V)) {
|
|
Objs.clear();
|
|
return;
|
|
}
|
|
Objs.push_back(V);
|
|
}
|
|
}
|
|
|
|
/// Add a chain edge between a load and store if the store can be an
|
|
/// alias of the load on a subsequent iteration, i.e., a loop carried
|
|
/// dependence. This code is very similar to the code in ScheduleDAGInstrs
|
|
/// but that code doesn't create loop carried dependences.
|
|
void SwingSchedulerDAG::addLoopCarriedDependences(AliasAnalysis *AA) {
|
|
MapVector<Value *, SmallVector<SUnit *, 4>> PendingLoads;
|
|
Value *UnknownValue =
|
|
UndefValue::get(Type::getVoidTy(MF.getFunction().getContext()));
|
|
for (auto &SU : SUnits) {
|
|
MachineInstr &MI = *SU.getInstr();
|
|
if (isDependenceBarrier(MI, AA))
|
|
PendingLoads.clear();
|
|
else if (MI.mayLoad()) {
|
|
SmallVector<Value *, 4> Objs;
|
|
getUnderlyingObjects(&MI, Objs, MF.getDataLayout());
|
|
if (Objs.empty())
|
|
Objs.push_back(UnknownValue);
|
|
for (auto V : Objs) {
|
|
SmallVector<SUnit *, 4> &SUs = PendingLoads[V];
|
|
SUs.push_back(&SU);
|
|
}
|
|
} else if (MI.mayStore()) {
|
|
SmallVector<Value *, 4> Objs;
|
|
getUnderlyingObjects(&MI, Objs, MF.getDataLayout());
|
|
if (Objs.empty())
|
|
Objs.push_back(UnknownValue);
|
|
for (auto V : Objs) {
|
|
MapVector<Value *, SmallVector<SUnit *, 4>>::iterator I =
|
|
PendingLoads.find(V);
|
|
if (I == PendingLoads.end())
|
|
continue;
|
|
for (auto Load : I->second) {
|
|
if (isSuccOrder(Load, &SU))
|
|
continue;
|
|
MachineInstr &LdMI = *Load->getInstr();
|
|
// First, perform the cheaper check that compares the base register.
|
|
// If they are the same and the load offset is less than the store
|
|
// offset, then mark the dependence as loop carried potentially.
|
|
unsigned BaseReg1, BaseReg2;
|
|
int64_t Offset1, Offset2;
|
|
if (TII->getMemOpBaseRegImmOfs(LdMI, BaseReg1, Offset1, TRI) &&
|
|
TII->getMemOpBaseRegImmOfs(MI, BaseReg2, Offset2, TRI)) {
|
|
if (BaseReg1 == BaseReg2 && (int)Offset1 < (int)Offset2) {
|
|
assert(TII->areMemAccessesTriviallyDisjoint(LdMI, MI, AA) &&
|
|
"What happened to the chain edge?");
|
|
SDep Dep(Load, SDep::Barrier);
|
|
Dep.setLatency(1);
|
|
SU.addPred(Dep);
|
|
continue;
|
|
}
|
|
}
|
|
// Second, the more expensive check that uses alias analysis on the
|
|
// base registers. If they alias, and the load offset is less than
|
|
// the store offset, the mark the dependence as loop carried.
|
|
if (!AA) {
|
|
SDep Dep(Load, SDep::Barrier);
|
|
Dep.setLatency(1);
|
|
SU.addPred(Dep);
|
|
continue;
|
|
}
|
|
MachineMemOperand *MMO1 = *LdMI.memoperands_begin();
|
|
MachineMemOperand *MMO2 = *MI.memoperands_begin();
|
|
if (!MMO1->getValue() || !MMO2->getValue()) {
|
|
SDep Dep(Load, SDep::Barrier);
|
|
Dep.setLatency(1);
|
|
SU.addPred(Dep);
|
|
continue;
|
|
}
|
|
if (MMO1->getValue() == MMO2->getValue() &&
|
|
MMO1->getOffset() <= MMO2->getOffset()) {
|
|
SDep Dep(Load, SDep::Barrier);
|
|
Dep.setLatency(1);
|
|
SU.addPred(Dep);
|
|
continue;
|
|
}
|
|
AliasResult AAResult = AA->alias(
|
|
MemoryLocation(MMO1->getValue(), MemoryLocation::UnknownSize,
|
|
MMO1->getAAInfo()),
|
|
MemoryLocation(MMO2->getValue(), MemoryLocation::UnknownSize,
|
|
MMO2->getAAInfo()));
|
|
|
|
if (AAResult != NoAlias) {
|
|
SDep Dep(Load, SDep::Barrier);
|
|
Dep.setLatency(1);
|
|
SU.addPred(Dep);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Update the phi dependences to the DAG because ScheduleDAGInstrs no longer
|
|
/// processes dependences for PHIs. This function adds true dependences
|
|
/// from a PHI to a use, and a loop carried dependence from the use to the
|
|
/// PHI. The loop carried dependence is represented as an anti dependence
|
|
/// edge. This function also removes chain dependences between unrelated
|
|
/// PHIs.
|
|
void SwingSchedulerDAG::updatePhiDependences() {
|
|
SmallVector<SDep, 4> RemoveDeps;
|
|
const TargetSubtargetInfo &ST = MF.getSubtarget<TargetSubtargetInfo>();
|
|
|
|
// Iterate over each DAG node.
|
|
for (SUnit &I : SUnits) {
|
|
RemoveDeps.clear();
|
|
// Set to true if the instruction has an operand defined by a Phi.
|
|
unsigned HasPhiUse = 0;
|
|
unsigned HasPhiDef = 0;
|
|
MachineInstr *MI = I.getInstr();
|
|
// Iterate over each operand, and we process the definitions.
|
|
for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
|
|
MOE = MI->operands_end();
|
|
MOI != MOE; ++MOI) {
|
|
if (!MOI->isReg())
|
|
continue;
|
|
unsigned Reg = MOI->getReg();
|
|
if (MOI->isDef()) {
|
|
// If the register is used by a Phi, then create an anti dependence.
|
|
for (MachineRegisterInfo::use_instr_iterator
|
|
UI = MRI.use_instr_begin(Reg),
|
|
UE = MRI.use_instr_end();
|
|
UI != UE; ++UI) {
|
|
MachineInstr *UseMI = &*UI;
|
|
SUnit *SU = getSUnit(UseMI);
|
|
if (SU != nullptr && UseMI->isPHI()) {
|
|
if (!MI->isPHI()) {
|
|
SDep Dep(SU, SDep::Anti, Reg);
|
|
Dep.setLatency(1);
|
|
I.addPred(Dep);
|
|
} else {
|
|
HasPhiDef = Reg;
|
|
// Add a chain edge to a dependent Phi that isn't an existing
|
|
// predecessor.
|
|
if (SU->NodeNum < I.NodeNum && !I.isPred(SU))
|
|
I.addPred(SDep(SU, SDep::Barrier));
|
|
}
|
|
}
|
|
}
|
|
} else if (MOI->isUse()) {
|
|
// If the register is defined by a Phi, then create a true dependence.
|
|
MachineInstr *DefMI = MRI.getUniqueVRegDef(Reg);
|
|
if (DefMI == nullptr)
|
|
continue;
|
|
SUnit *SU = getSUnit(DefMI);
|
|
if (SU != nullptr && DefMI->isPHI()) {
|
|
if (!MI->isPHI()) {
|
|
SDep Dep(SU, SDep::Data, Reg);
|
|
Dep.setLatency(0);
|
|
ST.adjustSchedDependency(SU, &I, Dep);
|
|
I.addPred(Dep);
|
|
} else {
|
|
HasPhiUse = Reg;
|
|
// Add a chain edge to a dependent Phi that isn't an existing
|
|
// predecessor.
|
|
if (SU->NodeNum < I.NodeNum && !I.isPred(SU))
|
|
I.addPred(SDep(SU, SDep::Barrier));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
// Remove order dependences from an unrelated Phi.
|
|
if (!SwpPruneDeps)
|
|
continue;
|
|
for (auto &PI : I.Preds) {
|
|
MachineInstr *PMI = PI.getSUnit()->getInstr();
|
|
if (PMI->isPHI() && PI.getKind() == SDep::Order) {
|
|
if (I.getInstr()->isPHI()) {
|
|
if (PMI->getOperand(0).getReg() == HasPhiUse)
|
|
continue;
|
|
if (getLoopPhiReg(*PMI, PMI->getParent()) == HasPhiDef)
|
|
continue;
|
|
}
|
|
RemoveDeps.push_back(PI);
|
|
}
|
|
}
|
|
for (int i = 0, e = RemoveDeps.size(); i != e; ++i)
|
|
I.removePred(RemoveDeps[i]);
|
|
}
|
|
}
|
|
|
|
/// Iterate over each DAG node and see if we can change any dependences
|
|
/// in order to reduce the recurrence MII.
|
|
void SwingSchedulerDAG::changeDependences() {
|
|
// See if an instruction can use a value from the previous iteration.
|
|
// If so, we update the base and offset of the instruction and change
|
|
// the dependences.
|
|
for (SUnit &I : SUnits) {
|
|
unsigned BasePos = 0, OffsetPos = 0, NewBase = 0;
|
|
int64_t NewOffset = 0;
|
|
if (!canUseLastOffsetValue(I.getInstr(), BasePos, OffsetPos, NewBase,
|
|
NewOffset))
|
|
continue;
|
|
|
|
// Get the MI and SUnit for the instruction that defines the original base.
|
|
unsigned OrigBase = I.getInstr()->getOperand(BasePos).getReg();
|
|
MachineInstr *DefMI = MRI.getUniqueVRegDef(OrigBase);
|
|
if (!DefMI)
|
|
continue;
|
|
SUnit *DefSU = getSUnit(DefMI);
|
|
if (!DefSU)
|
|
continue;
|
|
// Get the MI and SUnit for the instruction that defins the new base.
|
|
MachineInstr *LastMI = MRI.getUniqueVRegDef(NewBase);
|
|
if (!LastMI)
|
|
continue;
|
|
SUnit *LastSU = getSUnit(LastMI);
|
|
if (!LastSU)
|
|
continue;
|
|
|
|
if (Topo.IsReachable(&I, LastSU))
|
|
continue;
|
|
|
|
// Remove the dependence. The value now depends on a prior iteration.
|
|
SmallVector<SDep, 4> Deps;
|
|
for (SUnit::pred_iterator P = I.Preds.begin(), E = I.Preds.end(); P != E;
|
|
++P)
|
|
if (P->getSUnit() == DefSU)
|
|
Deps.push_back(*P);
|
|
for (int i = 0, e = Deps.size(); i != e; i++) {
|
|
Topo.RemovePred(&I, Deps[i].getSUnit());
|
|
I.removePred(Deps[i]);
|
|
}
|
|
// Remove the chain dependence between the instructions.
|
|
Deps.clear();
|
|
for (auto &P : LastSU->Preds)
|
|
if (P.getSUnit() == &I && P.getKind() == SDep::Order)
|
|
Deps.push_back(P);
|
|
for (int i = 0, e = Deps.size(); i != e; i++) {
|
|
Topo.RemovePred(LastSU, Deps[i].getSUnit());
|
|
LastSU->removePred(Deps[i]);
|
|
}
|
|
|
|
// Add a dependence between the new instruction and the instruction
|
|
// that defines the new base.
|
|
SDep Dep(&I, SDep::Anti, NewBase);
|
|
LastSU->addPred(Dep);
|
|
|
|
// Remember the base and offset information so that we can update the
|
|
// instruction during code generation.
|
|
InstrChanges[&I] = std::make_pair(NewBase, NewOffset);
|
|
}
|
|
}
|
|
|
|
namespace {
|
|
|
|
// FuncUnitSorter - Comparison operator used to sort instructions by
|
|
// the number of functional unit choices.
|
|
struct FuncUnitSorter {
|
|
const InstrItineraryData *InstrItins;
|
|
DenseMap<unsigned, unsigned> Resources;
|
|
|
|
FuncUnitSorter(const InstrItineraryData *IID) : InstrItins(IID) {}
|
|
|
|
// Compute the number of functional unit alternatives needed
|
|
// at each stage, and take the minimum value. We prioritize the
|
|
// instructions by the least number of choices first.
|
|
unsigned minFuncUnits(const MachineInstr *Inst, unsigned &F) const {
|
|
unsigned schedClass = Inst->getDesc().getSchedClass();
|
|
unsigned min = UINT_MAX;
|
|
for (const InstrStage *IS = InstrItins->beginStage(schedClass),
|
|
*IE = InstrItins->endStage(schedClass);
|
|
IS != IE; ++IS) {
|
|
unsigned funcUnits = IS->getUnits();
|
|
unsigned numAlternatives = countPopulation(funcUnits);
|
|
if (numAlternatives < min) {
|
|
min = numAlternatives;
|
|
F = funcUnits;
|
|
}
|
|
}
|
|
return min;
|
|
}
|
|
|
|
// Compute the critical resources needed by the instruction. This
|
|
// function records the functional units needed by instructions that
|
|
// must use only one functional unit. We use this as a tie breaker
|
|
// for computing the resource MII. The instrutions that require
|
|
// the same, highly used, functional unit have high priority.
|
|
void calcCriticalResources(MachineInstr &MI) {
|
|
unsigned SchedClass = MI.getDesc().getSchedClass();
|
|
for (const InstrStage *IS = InstrItins->beginStage(SchedClass),
|
|
*IE = InstrItins->endStage(SchedClass);
|
|
IS != IE; ++IS) {
|
|
unsigned FuncUnits = IS->getUnits();
|
|
if (countPopulation(FuncUnits) == 1)
|
|
Resources[FuncUnits]++;
|
|
}
|
|
}
|
|
|
|
/// Return true if IS1 has less priority than IS2.
|
|
bool operator()(const MachineInstr *IS1, const MachineInstr *IS2) const {
|
|
unsigned F1 = 0, F2 = 0;
|
|
unsigned MFUs1 = minFuncUnits(IS1, F1);
|
|
unsigned MFUs2 = minFuncUnits(IS2, F2);
|
|
if (MFUs1 == 1 && MFUs2 == 1)
|
|
return Resources.lookup(F1) < Resources.lookup(F2);
|
|
return MFUs1 > MFUs2;
|
|
}
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
/// Calculate the resource constrained minimum initiation interval for the
|
|
/// specified loop. We use the DFA to model the resources needed for
|
|
/// each instruction, and we ignore dependences. A different DFA is created
|
|
/// for each cycle that is required. When adding a new instruction, we attempt
|
|
/// to add it to each existing DFA, until a legal space is found. If the
|
|
/// instruction cannot be reserved in an existing DFA, we create a new one.
|
|
unsigned SwingSchedulerDAG::calculateResMII() {
|
|
SmallVector<DFAPacketizer *, 8> Resources;
|
|
MachineBasicBlock *MBB = Loop.getHeader();
|
|
Resources.push_back(TII->CreateTargetScheduleState(MF.getSubtarget()));
|
|
|
|
// Sort the instructions by the number of available choices for scheduling,
|
|
// least to most. Use the number of critical resources as the tie breaker.
|
|
FuncUnitSorter FUS =
|
|
FuncUnitSorter(MF.getSubtarget().getInstrItineraryData());
|
|
for (MachineBasicBlock::iterator I = MBB->getFirstNonPHI(),
|
|
E = MBB->getFirstTerminator();
|
|
I != E; ++I)
|
|
FUS.calcCriticalResources(*I);
|
|
PriorityQueue<MachineInstr *, std::vector<MachineInstr *>, FuncUnitSorter>
|
|
FuncUnitOrder(FUS);
|
|
|
|
for (MachineBasicBlock::iterator I = MBB->getFirstNonPHI(),
|
|
E = MBB->getFirstTerminator();
|
|
I != E; ++I)
|
|
FuncUnitOrder.push(&*I);
|
|
|
|
while (!FuncUnitOrder.empty()) {
|
|
MachineInstr *MI = FuncUnitOrder.top();
|
|
FuncUnitOrder.pop();
|
|
if (TII->isZeroCost(MI->getOpcode()))
|
|
continue;
|
|
// Attempt to reserve the instruction in an existing DFA. At least one
|
|
// DFA is needed for each cycle.
|
|
unsigned NumCycles = getSUnit(MI)->Latency;
|
|
unsigned ReservedCycles = 0;
|
|
SmallVectorImpl<DFAPacketizer *>::iterator RI = Resources.begin();
|
|
SmallVectorImpl<DFAPacketizer *>::iterator RE = Resources.end();
|
|
for (unsigned C = 0; C < NumCycles; ++C)
|
|
while (RI != RE) {
|
|
if ((*RI++)->canReserveResources(*MI)) {
|
|
++ReservedCycles;
|
|
break;
|
|
}
|
|
}
|
|
// Start reserving resources using existing DFAs.
|
|
for (unsigned C = 0; C < ReservedCycles; ++C) {
|
|
--RI;
|
|
(*RI)->reserveResources(*MI);
|
|
}
|
|
// Add new DFAs, if needed, to reserve resources.
|
|
for (unsigned C = ReservedCycles; C < NumCycles; ++C) {
|
|
DFAPacketizer *NewResource =
|
|
TII->CreateTargetScheduleState(MF.getSubtarget());
|
|
assert(NewResource->canReserveResources(*MI) && "Reserve error.");
|
|
NewResource->reserveResources(*MI);
|
|
Resources.push_back(NewResource);
|
|
}
|
|
}
|
|
int Resmii = Resources.size();
|
|
// Delete the memory for each of the DFAs that were created earlier.
|
|
for (DFAPacketizer *RI : Resources) {
|
|
DFAPacketizer *D = RI;
|
|
delete D;
|
|
}
|
|
Resources.clear();
|
|
return Resmii;
|
|
}
|
|
|
|
/// Calculate the recurrence-constrainted minimum initiation interval.
|
|
/// Iterate over each circuit. Compute the delay(c) and distance(c)
|
|
/// for each circuit. The II needs to satisfy the inequality
|
|
/// delay(c) - II*distance(c) <= 0. For each circuit, choose the smallest
|
|
/// II that satisfies the inequality, and the RecMII is the maximum
|
|
/// of those values.
|
|
unsigned SwingSchedulerDAG::calculateRecMII(NodeSetType &NodeSets) {
|
|
unsigned RecMII = 0;
|
|
|
|
for (NodeSet &Nodes : NodeSets) {
|
|
if (Nodes.empty())
|
|
continue;
|
|
|
|
unsigned Delay = Nodes.getLatency();
|
|
unsigned Distance = 1;
|
|
|
|
// ii = ceil(delay / distance)
|
|
unsigned CurMII = (Delay + Distance - 1) / Distance;
|
|
Nodes.setRecMII(CurMII);
|
|
if (CurMII > RecMII)
|
|
RecMII = CurMII;
|
|
}
|
|
|
|
return RecMII;
|
|
}
|
|
|
|
/// Swap all the anti dependences in the DAG. That means it is no longer a DAG,
|
|
/// but we do this to find the circuits, and then change them back.
|
|
static void swapAntiDependences(std::vector<SUnit> &SUnits) {
|
|
SmallVector<std::pair<SUnit *, SDep>, 8> DepsAdded;
|
|
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
|
|
SUnit *SU = &SUnits[i];
|
|
for (SUnit::pred_iterator IP = SU->Preds.begin(), EP = SU->Preds.end();
|
|
IP != EP; ++IP) {
|
|
if (IP->getKind() != SDep::Anti)
|
|
continue;
|
|
DepsAdded.push_back(std::make_pair(SU, *IP));
|
|
}
|
|
}
|
|
for (SmallVector<std::pair<SUnit *, SDep>, 8>::iterator I = DepsAdded.begin(),
|
|
E = DepsAdded.end();
|
|
I != E; ++I) {
|
|
// Remove this anti dependency and add one in the reverse direction.
|
|
SUnit *SU = I->first;
|
|
SDep &D = I->second;
|
|
SUnit *TargetSU = D.getSUnit();
|
|
unsigned Reg = D.getReg();
|
|
unsigned Lat = D.getLatency();
|
|
SU->removePred(D);
|
|
SDep Dep(SU, SDep::Anti, Reg);
|
|
Dep.setLatency(Lat);
|
|
TargetSU->addPred(Dep);
|
|
}
|
|
}
|
|
|
|
/// Create the adjacency structure of the nodes in the graph.
|
|
void SwingSchedulerDAG::Circuits::createAdjacencyStructure(
|
|
SwingSchedulerDAG *DAG) {
|
|
BitVector Added(SUnits.size());
|
|
DenseMap<int, int> OutputDeps;
|
|
for (int i = 0, e = SUnits.size(); i != e; ++i) {
|
|
Added.reset();
|
|
// Add any successor to the adjacency matrix and exclude duplicates.
|
|
for (auto &SI : SUnits[i].Succs) {
|
|
// Only create a back-edge on the first and last nodes of a dependence
|
|
// chain. This records any chains and adds them later.
|
|
if (SI.getKind() == SDep::Output) {
|
|
int N = SI.getSUnit()->NodeNum;
|
|
int BackEdge = i;
|
|
auto Dep = OutputDeps.find(BackEdge);
|
|
if (Dep != OutputDeps.end()) {
|
|
BackEdge = Dep->second;
|
|
OutputDeps.erase(Dep);
|
|
}
|
|
OutputDeps[N] = BackEdge;
|
|
}
|
|
// Do not process a boundary node and a back-edge is processed only
|
|
// if it goes to a Phi.
|
|
if (SI.getSUnit()->isBoundaryNode() ||
|
|
(SI.getKind() == SDep::Anti && !SI.getSUnit()->getInstr()->isPHI()))
|
|
continue;
|
|
int N = SI.getSUnit()->NodeNum;
|
|
if (!Added.test(N)) {
|
|
AdjK[i].push_back(N);
|
|
Added.set(N);
|
|
}
|
|
}
|
|
// A chain edge between a store and a load is treated as a back-edge in the
|
|
// adjacency matrix.
|
|
for (auto &PI : SUnits[i].Preds) {
|
|
if (!SUnits[i].getInstr()->mayStore() ||
|
|
!DAG->isLoopCarriedDep(&SUnits[i], PI, false))
|
|
continue;
|
|
if (PI.getKind() == SDep::Order && PI.getSUnit()->getInstr()->mayLoad()) {
|
|
int N = PI.getSUnit()->NodeNum;
|
|
if (!Added.test(N)) {
|
|
AdjK[i].push_back(N);
|
|
Added.set(N);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
// Add back-eges in the adjacency matrix for the output dependences.
|
|
for (auto &OD : OutputDeps)
|
|
if (!Added.test(OD.second)) {
|
|
AdjK[OD.first].push_back(OD.second);
|
|
Added.set(OD.second);
|
|
}
|
|
}
|
|
|
|
/// Identify an elementary circuit in the dependence graph starting at the
|
|
/// specified node.
|
|
bool SwingSchedulerDAG::Circuits::circuit(int V, int S, NodeSetType &NodeSets,
|
|
bool HasBackedge) {
|
|
SUnit *SV = &SUnits[V];
|
|
bool F = false;
|
|
Stack.insert(SV);
|
|
Blocked.set(V);
|
|
|
|
for (auto W : AdjK[V]) {
|
|
if (NumPaths > MaxPaths)
|
|
break;
|
|
if (W < S)
|
|
continue;
|
|
if (W == S) {
|
|
if (!HasBackedge)
|
|
NodeSets.push_back(NodeSet(Stack.begin(), Stack.end()));
|
|
F = true;
|
|
++NumPaths;
|
|
break;
|
|
} else if (!Blocked.test(W)) {
|
|
if (circuit(W, S, NodeSets, W < V ? true : HasBackedge))
|
|
F = true;
|
|
}
|
|
}
|
|
|
|
if (F)
|
|
unblock(V);
|
|
else {
|
|
for (auto W : AdjK[V]) {
|
|
if (W < S)
|
|
continue;
|
|
if (B[W].count(SV) == 0)
|
|
B[W].insert(SV);
|
|
}
|
|
}
|
|
Stack.pop_back();
|
|
return F;
|
|
}
|
|
|
|
/// Unblock a node in the circuit finding algorithm.
|
|
void SwingSchedulerDAG::Circuits::unblock(int U) {
|
|
Blocked.reset(U);
|
|
SmallPtrSet<SUnit *, 4> &BU = B[U];
|
|
while (!BU.empty()) {
|
|
SmallPtrSet<SUnit *, 4>::iterator SI = BU.begin();
|
|
assert(SI != BU.end() && "Invalid B set.");
|
|
SUnit *W = *SI;
|
|
BU.erase(W);
|
|
if (Blocked.test(W->NodeNum))
|
|
unblock(W->NodeNum);
|
|
}
|
|
}
|
|
|
|
/// Identify all the elementary circuits in the dependence graph using
|
|
/// Johnson's circuit algorithm.
|
|
void SwingSchedulerDAG::findCircuits(NodeSetType &NodeSets) {
|
|
// Swap all the anti dependences in the DAG. That means it is no longer a DAG,
|
|
// but we do this to find the circuits, and then change them back.
|
|
swapAntiDependences(SUnits);
|
|
|
|
Circuits Cir(SUnits);
|
|
// Create the adjacency structure.
|
|
Cir.createAdjacencyStructure(this);
|
|
for (int i = 0, e = SUnits.size(); i != e; ++i) {
|
|
Cir.reset();
|
|
Cir.circuit(i, i, NodeSets);
|
|
}
|
|
|
|
// Change the dependences back so that we've created a DAG again.
|
|
swapAntiDependences(SUnits);
|
|
}
|
|
|
|
/// Return true for DAG nodes that we ignore when computing the cost functions.
|
|
/// We ignore the back-edge recurrence in order to avoid unbounded recursion
|
|
/// in the calculation of the ASAP, ALAP, etc functions.
|
|
static bool ignoreDependence(const SDep &D, bool isPred) {
|
|
if (D.isArtificial())
|
|
return true;
|
|
return D.getKind() == SDep::Anti && isPred;
|
|
}
|
|
|
|
/// Compute several functions need to order the nodes for scheduling.
|
|
/// ASAP - Earliest time to schedule a node.
|
|
/// ALAP - Latest time to schedule a node.
|
|
/// MOV - Mobility function, difference between ALAP and ASAP.
|
|
/// D - Depth of each node.
|
|
/// H - Height of each node.
|
|
void SwingSchedulerDAG::computeNodeFunctions(NodeSetType &NodeSets) {
|
|
ScheduleInfo.resize(SUnits.size());
|
|
|
|
LLVM_DEBUG({
|
|
for (ScheduleDAGTopologicalSort::const_iterator I = Topo.begin(),
|
|
E = Topo.end();
|
|
I != E; ++I) {
|
|
const SUnit &SU = SUnits[*I];
|
|
dumpNode(SU);
|
|
}
|
|
});
|
|
|
|
int maxASAP = 0;
|
|
// Compute ASAP and ZeroLatencyDepth.
|
|
for (ScheduleDAGTopologicalSort::const_iterator I = Topo.begin(),
|
|
E = Topo.end();
|
|
I != E; ++I) {
|
|
int asap = 0;
|
|
int zeroLatencyDepth = 0;
|
|
SUnit *SU = &SUnits[*I];
|
|
for (SUnit::const_pred_iterator IP = SU->Preds.begin(),
|
|
EP = SU->Preds.end();
|
|
IP != EP; ++IP) {
|
|
SUnit *pred = IP->getSUnit();
|
|
if (IP->getLatency() == 0)
|
|
zeroLatencyDepth =
|
|
std::max(zeroLatencyDepth, getZeroLatencyDepth(pred) + 1);
|
|
if (ignoreDependence(*IP, true))
|
|
continue;
|
|
asap = std::max(asap, (int)(getASAP(pred) + IP->getLatency() -
|
|
getDistance(pred, SU, *IP) * MII));
|
|
}
|
|
maxASAP = std::max(maxASAP, asap);
|
|
ScheduleInfo[*I].ASAP = asap;
|
|
ScheduleInfo[*I].ZeroLatencyDepth = zeroLatencyDepth;
|
|
}
|
|
|
|
// Compute ALAP, ZeroLatencyHeight, and MOV.
|
|
for (ScheduleDAGTopologicalSort::const_reverse_iterator I = Topo.rbegin(),
|
|
E = Topo.rend();
|
|
I != E; ++I) {
|
|
int alap = maxASAP;
|
|
int zeroLatencyHeight = 0;
|
|
SUnit *SU = &SUnits[*I];
|
|
for (SUnit::const_succ_iterator IS = SU->Succs.begin(),
|
|
ES = SU->Succs.end();
|
|
IS != ES; ++IS) {
|
|
SUnit *succ = IS->getSUnit();
|
|
if (IS->getLatency() == 0)
|
|
zeroLatencyHeight =
|
|
std::max(zeroLatencyHeight, getZeroLatencyHeight(succ) + 1);
|
|
if (ignoreDependence(*IS, true))
|
|
continue;
|
|
alap = std::min(alap, (int)(getALAP(succ) - IS->getLatency() +
|
|
getDistance(SU, succ, *IS) * MII));
|
|
}
|
|
|
|
ScheduleInfo[*I].ALAP = alap;
|
|
ScheduleInfo[*I].ZeroLatencyHeight = zeroLatencyHeight;
|
|
}
|
|
|
|
// After computing the node functions, compute the summary for each node set.
|
|
for (NodeSet &I : NodeSets)
|
|
I.computeNodeSetInfo(this);
|
|
|
|
LLVM_DEBUG({
|
|
for (unsigned i = 0; i < SUnits.size(); i++) {
|
|
dbgs() << "\tNode " << i << ":\n";
|
|
dbgs() << "\t ASAP = " << getASAP(&SUnits[i]) << "\n";
|
|
dbgs() << "\t ALAP = " << getALAP(&SUnits[i]) << "\n";
|
|
dbgs() << "\t MOV = " << getMOV(&SUnits[i]) << "\n";
|
|
dbgs() << "\t D = " << getDepth(&SUnits[i]) << "\n";
|
|
dbgs() << "\t H = " << getHeight(&SUnits[i]) << "\n";
|
|
dbgs() << "\t ZLD = " << getZeroLatencyDepth(&SUnits[i]) << "\n";
|
|
dbgs() << "\t ZLH = " << getZeroLatencyHeight(&SUnits[i]) << "\n";
|
|
}
|
|
});
|
|
}
|
|
|
|
/// Compute the Pred_L(O) set, as defined in the paper. The set is defined
|
|
/// as the predecessors of the elements of NodeOrder that are not also in
|
|
/// NodeOrder.
|
|
static bool pred_L(SetVector<SUnit *> &NodeOrder,
|
|
SmallSetVector<SUnit *, 8> &Preds,
|
|
const NodeSet *S = nullptr) {
|
|
Preds.clear();
|
|
for (SetVector<SUnit *>::iterator I = NodeOrder.begin(), E = NodeOrder.end();
|
|
I != E; ++I) {
|
|
for (SUnit::pred_iterator PI = (*I)->Preds.begin(), PE = (*I)->Preds.end();
|
|
PI != PE; ++PI) {
|
|
if (S && S->count(PI->getSUnit()) == 0)
|
|
continue;
|
|
if (ignoreDependence(*PI, true))
|
|
continue;
|
|
if (NodeOrder.count(PI->getSUnit()) == 0)
|
|
Preds.insert(PI->getSUnit());
|
|
}
|
|
// Back-edges are predecessors with an anti-dependence.
|
|
for (SUnit::const_succ_iterator IS = (*I)->Succs.begin(),
|
|
ES = (*I)->Succs.end();
|
|
IS != ES; ++IS) {
|
|
if (IS->getKind() != SDep::Anti)
|
|
continue;
|
|
if (S && S->count(IS->getSUnit()) == 0)
|
|
continue;
|
|
if (NodeOrder.count(IS->getSUnit()) == 0)
|
|
Preds.insert(IS->getSUnit());
|
|
}
|
|
}
|
|
return !Preds.empty();
|
|
}
|
|
|
|
/// Compute the Succ_L(O) set, as defined in the paper. The set is defined
|
|
/// as the successors of the elements of NodeOrder that are not also in
|
|
/// NodeOrder.
|
|
static bool succ_L(SetVector<SUnit *> &NodeOrder,
|
|
SmallSetVector<SUnit *, 8> &Succs,
|
|
const NodeSet *S = nullptr) {
|
|
Succs.clear();
|
|
for (SetVector<SUnit *>::iterator I = NodeOrder.begin(), E = NodeOrder.end();
|
|
I != E; ++I) {
|
|
for (SUnit::succ_iterator SI = (*I)->Succs.begin(), SE = (*I)->Succs.end();
|
|
SI != SE; ++SI) {
|
|
if (S && S->count(SI->getSUnit()) == 0)
|
|
continue;
|
|
if (ignoreDependence(*SI, false))
|
|
continue;
|
|
if (NodeOrder.count(SI->getSUnit()) == 0)
|
|
Succs.insert(SI->getSUnit());
|
|
}
|
|
for (SUnit::const_pred_iterator PI = (*I)->Preds.begin(),
|
|
PE = (*I)->Preds.end();
|
|
PI != PE; ++PI) {
|
|
if (PI->getKind() != SDep::Anti)
|
|
continue;
|
|
if (S && S->count(PI->getSUnit()) == 0)
|
|
continue;
|
|
if (NodeOrder.count(PI->getSUnit()) == 0)
|
|
Succs.insert(PI->getSUnit());
|
|
}
|
|
}
|
|
return !Succs.empty();
|
|
}
|
|
|
|
/// Return true if there is a path from the specified node to any of the nodes
|
|
/// in DestNodes. Keep track and return the nodes in any path.
|
|
static bool computePath(SUnit *Cur, SetVector<SUnit *> &Path,
|
|
SetVector<SUnit *> &DestNodes,
|
|
SetVector<SUnit *> &Exclude,
|
|
SmallPtrSet<SUnit *, 8> &Visited) {
|
|
if (Cur->isBoundaryNode())
|
|
return false;
|
|
if (Exclude.count(Cur) != 0)
|
|
return false;
|
|
if (DestNodes.count(Cur) != 0)
|
|
return true;
|
|
if (!Visited.insert(Cur).second)
|
|
return Path.count(Cur) != 0;
|
|
bool FoundPath = false;
|
|
for (auto &SI : Cur->Succs)
|
|
FoundPath |= computePath(SI.getSUnit(), Path, DestNodes, Exclude, Visited);
|
|
for (auto &PI : Cur->Preds)
|
|
if (PI.getKind() == SDep::Anti)
|
|
FoundPath |=
|
|
computePath(PI.getSUnit(), Path, DestNodes, Exclude, Visited);
|
|
if (FoundPath)
|
|
Path.insert(Cur);
|
|
return FoundPath;
|
|
}
|
|
|
|
/// Return true if Set1 is a subset of Set2.
|
|
template <class S1Ty, class S2Ty> static bool isSubset(S1Ty &Set1, S2Ty &Set2) {
|
|
for (typename S1Ty::iterator I = Set1.begin(), E = Set1.end(); I != E; ++I)
|
|
if (Set2.count(*I) == 0)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/// Compute the live-out registers for the instructions in a node-set.
|
|
/// The live-out registers are those that are defined in the node-set,
|
|
/// but not used. Except for use operands of Phis.
|
|
static void computeLiveOuts(MachineFunction &MF, RegPressureTracker &RPTracker,
|
|
NodeSet &NS) {
|
|
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
|
|
MachineRegisterInfo &MRI = MF.getRegInfo();
|
|
SmallVector<RegisterMaskPair, 8> LiveOutRegs;
|
|
SmallSet<unsigned, 4> Uses;
|
|
for (SUnit *SU : NS) {
|
|
const MachineInstr *MI = SU->getInstr();
|
|
if (MI->isPHI())
|
|
continue;
|
|
for (const MachineOperand &MO : MI->operands())
|
|
if (MO.isReg() && MO.isUse()) {
|
|
unsigned Reg = MO.getReg();
|
|
if (TargetRegisterInfo::isVirtualRegister(Reg))
|
|
Uses.insert(Reg);
|
|
else if (MRI.isAllocatable(Reg))
|
|
for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units)
|
|
Uses.insert(*Units);
|
|
}
|
|
}
|
|
for (SUnit *SU : NS)
|
|
for (const MachineOperand &MO : SU->getInstr()->operands())
|
|
if (MO.isReg() && MO.isDef() && !MO.isDead()) {
|
|
unsigned Reg = MO.getReg();
|
|
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
|
|
if (!Uses.count(Reg))
|
|
LiveOutRegs.push_back(RegisterMaskPair(Reg,
|
|
LaneBitmask::getNone()));
|
|
} else if (MRI.isAllocatable(Reg)) {
|
|
for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units)
|
|
if (!Uses.count(*Units))
|
|
LiveOutRegs.push_back(RegisterMaskPair(*Units,
|
|
LaneBitmask::getNone()));
|
|
}
|
|
}
|
|
RPTracker.addLiveRegs(LiveOutRegs);
|
|
}
|
|
|
|
/// A heuristic to filter nodes in recurrent node-sets if the register
|
|
/// pressure of a set is too high.
|
|
void SwingSchedulerDAG::registerPressureFilter(NodeSetType &NodeSets) {
|
|
for (auto &NS : NodeSets) {
|
|
// Skip small node-sets since they won't cause register pressure problems.
|
|
if (NS.size() <= 2)
|
|
continue;
|
|
IntervalPressure RecRegPressure;
|
|
RegPressureTracker RecRPTracker(RecRegPressure);
|
|
RecRPTracker.init(&MF, &RegClassInfo, &LIS, BB, BB->end(), false, true);
|
|
computeLiveOuts(MF, RecRPTracker, NS);
|
|
RecRPTracker.closeBottom();
|
|
|
|
std::vector<SUnit *> SUnits(NS.begin(), NS.end());
|
|
llvm::sort(SUnits, [](const SUnit *A, const SUnit *B) {
|
|
return A->NodeNum > B->NodeNum;
|
|
});
|
|
|
|
for (auto &SU : SUnits) {
|
|
// Since we're computing the register pressure for a subset of the
|
|
// instructions in a block, we need to set the tracker for each
|
|
// instruction in the node-set. The tracker is set to the instruction
|
|
// just after the one we're interested in.
|
|
MachineBasicBlock::const_iterator CurInstI = SU->getInstr();
|
|
RecRPTracker.setPos(std::next(CurInstI));
|
|
|
|
RegPressureDelta RPDelta;
|
|
ArrayRef<PressureChange> CriticalPSets;
|
|
RecRPTracker.getMaxUpwardPressureDelta(SU->getInstr(), nullptr, RPDelta,
|
|
CriticalPSets,
|
|
RecRegPressure.MaxSetPressure);
|
|
if (RPDelta.Excess.isValid()) {
|
|
LLVM_DEBUG(
|
|
dbgs() << "Excess register pressure: SU(" << SU->NodeNum << ") "
|
|
<< TRI->getRegPressureSetName(RPDelta.Excess.getPSet())
|
|
<< ":" << RPDelta.Excess.getUnitInc());
|
|
NS.setExceedPressure(SU);
|
|
break;
|
|
}
|
|
RecRPTracker.recede();
|
|
}
|
|
}
|
|
}
|
|
|
|
/// A heuristic to colocate node sets that have the same set of
|
|
/// successors.
|
|
void SwingSchedulerDAG::colocateNodeSets(NodeSetType &NodeSets) {
|
|
unsigned Colocate = 0;
|
|
for (int i = 0, e = NodeSets.size(); i < e; ++i) {
|
|
NodeSet &N1 = NodeSets[i];
|
|
SmallSetVector<SUnit *, 8> S1;
|
|
if (N1.empty() || !succ_L(N1, S1))
|
|
continue;
|
|
for (int j = i + 1; j < e; ++j) {
|
|
NodeSet &N2 = NodeSets[j];
|
|
if (N1.compareRecMII(N2) != 0)
|
|
continue;
|
|
SmallSetVector<SUnit *, 8> S2;
|
|
if (N2.empty() || !succ_L(N2, S2))
|
|
continue;
|
|
if (isSubset(S1, S2) && S1.size() == S2.size()) {
|
|
N1.setColocate(++Colocate);
|
|
N2.setColocate(Colocate);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Check if the existing node-sets are profitable. If not, then ignore the
|
|
/// recurrent node-sets, and attempt to schedule all nodes together. This is
|
|
/// a heuristic. If the MII is large and all the recurrent node-sets are small,
|
|
/// then it's best to try to schedule all instructions together instead of
|
|
/// starting with the recurrent node-sets.
|
|
void SwingSchedulerDAG::checkNodeSets(NodeSetType &NodeSets) {
|
|
// Look for loops with a large MII.
|
|
if (MII < 17)
|
|
return;
|
|
// Check if the node-set contains only a simple add recurrence.
|
|
for (auto &NS : NodeSets) {
|
|
if (NS.getRecMII() > 2)
|
|
return;
|
|
if (NS.getMaxDepth() > MII)
|
|
return;
|
|
}
|
|
NodeSets.clear();
|
|
LLVM_DEBUG(dbgs() << "Clear recurrence node-sets\n");
|
|
return;
|
|
}
|
|
|
|
/// Add the nodes that do not belong to a recurrence set into groups
|
|
/// based upon connected componenets.
|
|
void SwingSchedulerDAG::groupRemainingNodes(NodeSetType &NodeSets) {
|
|
SetVector<SUnit *> NodesAdded;
|
|
SmallPtrSet<SUnit *, 8> Visited;
|
|
// Add the nodes that are on a path between the previous node sets and
|
|
// the current node set.
|
|
for (NodeSet &I : NodeSets) {
|
|
SmallSetVector<SUnit *, 8> N;
|
|
// Add the nodes from the current node set to the previous node set.
|
|
if (succ_L(I, N)) {
|
|
SetVector<SUnit *> Path;
|
|
for (SUnit *NI : N) {
|
|
Visited.clear();
|
|
computePath(NI, Path, NodesAdded, I, Visited);
|
|
}
|
|
if (!Path.empty())
|
|
I.insert(Path.begin(), Path.end());
|
|
}
|
|
// Add the nodes from the previous node set to the current node set.
|
|
N.clear();
|
|
if (succ_L(NodesAdded, N)) {
|
|
SetVector<SUnit *> Path;
|
|
for (SUnit *NI : N) {
|
|
Visited.clear();
|
|
computePath(NI, Path, I, NodesAdded, Visited);
|
|
}
|
|
if (!Path.empty())
|
|
I.insert(Path.begin(), Path.end());
|
|
}
|
|
NodesAdded.insert(I.begin(), I.end());
|
|
}
|
|
|
|
// Create a new node set with the connected nodes of any successor of a node
|
|
// in a recurrent set.
|
|
NodeSet NewSet;
|
|
SmallSetVector<SUnit *, 8> N;
|
|
if (succ_L(NodesAdded, N))
|
|
for (SUnit *I : N)
|
|
addConnectedNodes(I, NewSet, NodesAdded);
|
|
if (!NewSet.empty())
|
|
NodeSets.push_back(NewSet);
|
|
|
|
// Create a new node set with the connected nodes of any predecessor of a node
|
|
// in a recurrent set.
|
|
NewSet.clear();
|
|
if (pred_L(NodesAdded, N))
|
|
for (SUnit *I : N)
|
|
addConnectedNodes(I, NewSet, NodesAdded);
|
|
if (!NewSet.empty())
|
|
NodeSets.push_back(NewSet);
|
|
|
|
// Create new nodes sets with the connected nodes any remaining node that
|
|
// has no predecessor.
|
|
for (unsigned i = 0; i < SUnits.size(); ++i) {
|
|
SUnit *SU = &SUnits[i];
|
|
if (NodesAdded.count(SU) == 0) {
|
|
NewSet.clear();
|
|
addConnectedNodes(SU, NewSet, NodesAdded);
|
|
if (!NewSet.empty())
|
|
NodeSets.push_back(NewSet);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Add the node to the set, and add all is its connected nodes to the set.
|
|
void SwingSchedulerDAG::addConnectedNodes(SUnit *SU, NodeSet &NewSet,
|
|
SetVector<SUnit *> &NodesAdded) {
|
|
NewSet.insert(SU);
|
|
NodesAdded.insert(SU);
|
|
for (auto &SI : SU->Succs) {
|
|
SUnit *Successor = SI.getSUnit();
|
|
if (!SI.isArtificial() && NodesAdded.count(Successor) == 0)
|
|
addConnectedNodes(Successor, NewSet, NodesAdded);
|
|
}
|
|
for (auto &PI : SU->Preds) {
|
|
SUnit *Predecessor = PI.getSUnit();
|
|
if (!PI.isArtificial() && NodesAdded.count(Predecessor) == 0)
|
|
addConnectedNodes(Predecessor, NewSet, NodesAdded);
|
|
}
|
|
}
|
|
|
|
/// Return true if Set1 contains elements in Set2. The elements in common
|
|
/// are returned in a different container.
|
|
static bool isIntersect(SmallSetVector<SUnit *, 8> &Set1, const NodeSet &Set2,
|
|
SmallSetVector<SUnit *, 8> &Result) {
|
|
Result.clear();
|
|
for (unsigned i = 0, e = Set1.size(); i != e; ++i) {
|
|
SUnit *SU = Set1[i];
|
|
if (Set2.count(SU) != 0)
|
|
Result.insert(SU);
|
|
}
|
|
return !Result.empty();
|
|
}
|
|
|
|
/// Merge the recurrence node sets that have the same initial node.
|
|
void SwingSchedulerDAG::fuseRecs(NodeSetType &NodeSets) {
|
|
for (NodeSetType::iterator I = NodeSets.begin(), E = NodeSets.end(); I != E;
|
|
++I) {
|
|
NodeSet &NI = *I;
|
|
for (NodeSetType::iterator J = I + 1; J != E;) {
|
|
NodeSet &NJ = *J;
|
|
if (NI.getNode(0)->NodeNum == NJ.getNode(0)->NodeNum) {
|
|
if (NJ.compareRecMII(NI) > 0)
|
|
NI.setRecMII(NJ.getRecMII());
|
|
for (NodeSet::iterator NII = J->begin(), ENI = J->end(); NII != ENI;
|
|
++NII)
|
|
I->insert(*NII);
|
|
NodeSets.erase(J);
|
|
E = NodeSets.end();
|
|
} else {
|
|
++J;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Remove nodes that have been scheduled in previous NodeSets.
|
|
void SwingSchedulerDAG::removeDuplicateNodes(NodeSetType &NodeSets) {
|
|
for (NodeSetType::iterator I = NodeSets.begin(), E = NodeSets.end(); I != E;
|
|
++I)
|
|
for (NodeSetType::iterator J = I + 1; J != E;) {
|
|
J->remove_if([&](SUnit *SUJ) { return I->count(SUJ); });
|
|
|
|
if (J->empty()) {
|
|
NodeSets.erase(J);
|
|
E = NodeSets.end();
|
|
} else {
|
|
++J;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Compute an ordered list of the dependence graph nodes, which
|
|
/// indicates the order that the nodes will be scheduled. This is a
|
|
/// two-level algorithm. First, a partial order is created, which
|
|
/// consists of a list of sets ordered from highest to lowest priority.
|
|
void SwingSchedulerDAG::computeNodeOrder(NodeSetType &NodeSets) {
|
|
SmallSetVector<SUnit *, 8> R;
|
|
NodeOrder.clear();
|
|
|
|
for (auto &Nodes : NodeSets) {
|
|
LLVM_DEBUG(dbgs() << "NodeSet size " << Nodes.size() << "\n");
|
|
OrderKind Order;
|
|
SmallSetVector<SUnit *, 8> N;
|
|
if (pred_L(NodeOrder, N) && isSubset(N, Nodes)) {
|
|
R.insert(N.begin(), N.end());
|
|
Order = BottomUp;
|
|
LLVM_DEBUG(dbgs() << " Bottom up (preds) ");
|
|
} else if (succ_L(NodeOrder, N) && isSubset(N, Nodes)) {
|
|
R.insert(N.begin(), N.end());
|
|
Order = TopDown;
|
|
LLVM_DEBUG(dbgs() << " Top down (succs) ");
|
|
} else if (isIntersect(N, Nodes, R)) {
|
|
// If some of the successors are in the existing node-set, then use the
|
|
// top-down ordering.
|
|
Order = TopDown;
|
|
LLVM_DEBUG(dbgs() << " Top down (intersect) ");
|
|
} else if (NodeSets.size() == 1) {
|
|
for (auto &N : Nodes)
|
|
if (N->Succs.size() == 0)
|
|
R.insert(N);
|
|
Order = BottomUp;
|
|
LLVM_DEBUG(dbgs() << " Bottom up (all) ");
|
|
} else {
|
|
// Find the node with the highest ASAP.
|
|
SUnit *maxASAP = nullptr;
|
|
for (SUnit *SU : Nodes) {
|
|
if (maxASAP == nullptr || getASAP(SU) > getASAP(maxASAP) ||
|
|
(getASAP(SU) == getASAP(maxASAP) && SU->NodeNum > maxASAP->NodeNum))
|
|
maxASAP = SU;
|
|
}
|
|
R.insert(maxASAP);
|
|
Order = BottomUp;
|
|
LLVM_DEBUG(dbgs() << " Bottom up (default) ");
|
|
}
|
|
|
|
while (!R.empty()) {
|
|
if (Order == TopDown) {
|
|
// Choose the node with the maximum height. If more than one, choose
|
|
// the node wiTH the maximum ZeroLatencyHeight. If still more than one,
|
|
// choose the node with the lowest MOV.
|
|
while (!R.empty()) {
|
|
SUnit *maxHeight = nullptr;
|
|
for (SUnit *I : R) {
|
|
if (maxHeight == nullptr || getHeight(I) > getHeight(maxHeight))
|
|
maxHeight = I;
|
|
else if (getHeight(I) == getHeight(maxHeight) &&
|
|
getZeroLatencyHeight(I) > getZeroLatencyHeight(maxHeight))
|
|
maxHeight = I;
|
|
else if (getHeight(I) == getHeight(maxHeight) &&
|
|
getZeroLatencyHeight(I) ==
|
|
getZeroLatencyHeight(maxHeight) &&
|
|
getMOV(I) < getMOV(maxHeight))
|
|
maxHeight = I;
|
|
}
|
|
NodeOrder.insert(maxHeight);
|
|
LLVM_DEBUG(dbgs() << maxHeight->NodeNum << " ");
|
|
R.remove(maxHeight);
|
|
for (const auto &I : maxHeight->Succs) {
|
|
if (Nodes.count(I.getSUnit()) == 0)
|
|
continue;
|
|
if (NodeOrder.count(I.getSUnit()) != 0)
|
|
continue;
|
|
if (ignoreDependence(I, false))
|
|
continue;
|
|
R.insert(I.getSUnit());
|
|
}
|
|
// Back-edges are predecessors with an anti-dependence.
|
|
for (const auto &I : maxHeight->Preds) {
|
|
if (I.getKind() != SDep::Anti)
|
|
continue;
|
|
if (Nodes.count(I.getSUnit()) == 0)
|
|
continue;
|
|
if (NodeOrder.count(I.getSUnit()) != 0)
|
|
continue;
|
|
R.insert(I.getSUnit());
|
|
}
|
|
}
|
|
Order = BottomUp;
|
|
LLVM_DEBUG(dbgs() << "\n Switching order to bottom up ");
|
|
SmallSetVector<SUnit *, 8> N;
|
|
if (pred_L(NodeOrder, N, &Nodes))
|
|
R.insert(N.begin(), N.end());
|
|
} else {
|
|
// Choose the node with the maximum depth. If more than one, choose
|
|
// the node with the maximum ZeroLatencyDepth. If still more than one,
|
|
// choose the node with the lowest MOV.
|
|
while (!R.empty()) {
|
|
SUnit *maxDepth = nullptr;
|
|
for (SUnit *I : R) {
|
|
if (maxDepth == nullptr || getDepth(I) > getDepth(maxDepth))
|
|
maxDepth = I;
|
|
else if (getDepth(I) == getDepth(maxDepth) &&
|
|
getZeroLatencyDepth(I) > getZeroLatencyDepth(maxDepth))
|
|
maxDepth = I;
|
|
else if (getDepth(I) == getDepth(maxDepth) &&
|
|
getZeroLatencyDepth(I) == getZeroLatencyDepth(maxDepth) &&
|
|
getMOV(I) < getMOV(maxDepth))
|
|
maxDepth = I;
|
|
}
|
|
NodeOrder.insert(maxDepth);
|
|
LLVM_DEBUG(dbgs() << maxDepth->NodeNum << " ");
|
|
R.remove(maxDepth);
|
|
if (Nodes.isExceedSU(maxDepth)) {
|
|
Order = TopDown;
|
|
R.clear();
|
|
R.insert(Nodes.getNode(0));
|
|
break;
|
|
}
|
|
for (const auto &I : maxDepth->Preds) {
|
|
if (Nodes.count(I.getSUnit()) == 0)
|
|
continue;
|
|
if (NodeOrder.count(I.getSUnit()) != 0)
|
|
continue;
|
|
R.insert(I.getSUnit());
|
|
}
|
|
// Back-edges are predecessors with an anti-dependence.
|
|
for (const auto &I : maxDepth->Succs) {
|
|
if (I.getKind() != SDep::Anti)
|
|
continue;
|
|
if (Nodes.count(I.getSUnit()) == 0)
|
|
continue;
|
|
if (NodeOrder.count(I.getSUnit()) != 0)
|
|
continue;
|
|
R.insert(I.getSUnit());
|
|
}
|
|
}
|
|
Order = TopDown;
|
|
LLVM_DEBUG(dbgs() << "\n Switching order to top down ");
|
|
SmallSetVector<SUnit *, 8> N;
|
|
if (succ_L(NodeOrder, N, &Nodes))
|
|
R.insert(N.begin(), N.end());
|
|
}
|
|
}
|
|
LLVM_DEBUG(dbgs() << "\nDone with Nodeset\n");
|
|
}
|
|
|
|
LLVM_DEBUG({
|
|
dbgs() << "Node order: ";
|
|
for (SUnit *I : NodeOrder)
|
|
dbgs() << " " << I->NodeNum << " ";
|
|
dbgs() << "\n";
|
|
});
|
|
}
|
|
|
|
/// Process the nodes in the computed order and create the pipelined schedule
|
|
/// of the instructions, if possible. Return true if a schedule is found.
|
|
bool SwingSchedulerDAG::schedulePipeline(SMSchedule &Schedule) {
|
|
if (NodeOrder.empty())
|
|
return false;
|
|
|
|
bool scheduleFound = false;
|
|
// Keep increasing II until a valid schedule is found.
|
|
for (unsigned II = MII; II < MII + 10 && !scheduleFound; ++II) {
|
|
Schedule.reset();
|
|
Schedule.setInitiationInterval(II);
|
|
LLVM_DEBUG(dbgs() << "Try to schedule with " << II << "\n");
|
|
|
|
SetVector<SUnit *>::iterator NI = NodeOrder.begin();
|
|
SetVector<SUnit *>::iterator NE = NodeOrder.end();
|
|
do {
|
|
SUnit *SU = *NI;
|
|
|
|
// Compute the schedule time for the instruction, which is based
|
|
// upon the scheduled time for any predecessors/successors.
|
|
int EarlyStart = INT_MIN;
|
|
int LateStart = INT_MAX;
|
|
// These values are set when the size of the schedule window is limited
|
|
// due to chain dependences.
|
|
int SchedEnd = INT_MAX;
|
|
int SchedStart = INT_MIN;
|
|
Schedule.computeStart(SU, &EarlyStart, &LateStart, &SchedEnd, &SchedStart,
|
|
II, this);
|
|
LLVM_DEBUG({
|
|
dbgs() << "Inst (" << SU->NodeNum << ") ";
|
|
SU->getInstr()->dump();
|
|
dbgs() << "\n";
|
|
});
|
|
LLVM_DEBUG({
|
|
dbgs() << "\tes: " << EarlyStart << " ls: " << LateStart
|
|
<< " me: " << SchedEnd << " ms: " << SchedStart << "\n";
|
|
});
|
|
|
|
if (EarlyStart > LateStart || SchedEnd < EarlyStart ||
|
|
SchedStart > LateStart)
|
|
scheduleFound = false;
|
|
else if (EarlyStart != INT_MIN && LateStart == INT_MAX) {
|
|
SchedEnd = std::min(SchedEnd, EarlyStart + (int)II - 1);
|
|
scheduleFound = Schedule.insert(SU, EarlyStart, SchedEnd, II);
|
|
} else if (EarlyStart == INT_MIN && LateStart != INT_MAX) {
|
|
SchedStart = std::max(SchedStart, LateStart - (int)II + 1);
|
|
scheduleFound = Schedule.insert(SU, LateStart, SchedStart, II);
|
|
} else if (EarlyStart != INT_MIN && LateStart != INT_MAX) {
|
|
SchedEnd =
|
|
std::min(SchedEnd, std::min(LateStart, EarlyStart + (int)II - 1));
|
|
// When scheduling a Phi it is better to start at the late cycle and go
|
|
// backwards. The default order may insert the Phi too far away from
|
|
// its first dependence.
|
|
if (SU->getInstr()->isPHI())
|
|
scheduleFound = Schedule.insert(SU, SchedEnd, EarlyStart, II);
|
|
else
|
|
scheduleFound = Schedule.insert(SU, EarlyStart, SchedEnd, II);
|
|
} else {
|
|
int FirstCycle = Schedule.getFirstCycle();
|
|
scheduleFound = Schedule.insert(SU, FirstCycle + getASAP(SU),
|
|
FirstCycle + getASAP(SU) + II - 1, II);
|
|
}
|
|
// Even if we find a schedule, make sure the schedule doesn't exceed the
|
|
// allowable number of stages. We keep trying if this happens.
|
|
if (scheduleFound)
|
|
if (SwpMaxStages > -1 &&
|
|
Schedule.getMaxStageCount() > (unsigned)SwpMaxStages)
|
|
scheduleFound = false;
|
|
|
|
LLVM_DEBUG({
|
|
if (!scheduleFound)
|
|
dbgs() << "\tCan't schedule\n";
|
|
});
|
|
} while (++NI != NE && scheduleFound);
|
|
|
|
// If a schedule is found, check if it is a valid schedule too.
|
|
if (scheduleFound)
|
|
scheduleFound = Schedule.isValidSchedule(this);
|
|
}
|
|
|
|
LLVM_DEBUG(dbgs() << "Schedule Found? " << scheduleFound << "\n");
|
|
|
|
if (scheduleFound)
|
|
Schedule.finalizeSchedule(this);
|
|
else
|
|
Schedule.reset();
|
|
|
|
return scheduleFound && Schedule.getMaxStageCount() > 0;
|
|
}
|
|
|
|
/// Given a schedule for the loop, generate a new version of the loop,
|
|
/// and replace the old version. This function generates a prolog
|
|
/// that contains the initial iterations in the pipeline, and kernel
|
|
/// loop, and the epilogue that contains the code for the final
|
|
/// iterations.
|
|
void SwingSchedulerDAG::generatePipelinedLoop(SMSchedule &Schedule) {
|
|
// Create a new basic block for the kernel and add it to the CFG.
|
|
MachineBasicBlock *KernelBB = MF.CreateMachineBasicBlock(BB->getBasicBlock());
|
|
|
|
unsigned MaxStageCount = Schedule.getMaxStageCount();
|
|
|
|
// Remember the registers that are used in different stages. The index is
|
|
// the iteration, or stage, that the instruction is scheduled in. This is
|
|
// a map between register names in the original block and the names created
|
|
// in each stage of the pipelined loop.
|
|
ValueMapTy *VRMap = new ValueMapTy[(MaxStageCount + 1) * 2];
|
|
InstrMapTy InstrMap;
|
|
|
|
SmallVector<MachineBasicBlock *, 4> PrologBBs;
|
|
// Generate the prolog instructions that set up the pipeline.
|
|
generateProlog(Schedule, MaxStageCount, KernelBB, VRMap, PrologBBs);
|
|
MF.insert(BB->getIterator(), KernelBB);
|
|
|
|
// Rearrange the instructions to generate the new, pipelined loop,
|
|
// and update register names as needed.
|
|
for (int Cycle = Schedule.getFirstCycle(),
|
|
LastCycle = Schedule.getFinalCycle();
|
|
Cycle <= LastCycle; ++Cycle) {
|
|
std::deque<SUnit *> &CycleInstrs = Schedule.getInstructions(Cycle);
|
|
// This inner loop schedules each instruction in the cycle.
|
|
for (SUnit *CI : CycleInstrs) {
|
|
if (CI->getInstr()->isPHI())
|
|
continue;
|
|
unsigned StageNum = Schedule.stageScheduled(getSUnit(CI->getInstr()));
|
|
MachineInstr *NewMI = cloneInstr(CI->getInstr(), MaxStageCount, StageNum);
|
|
updateInstruction(NewMI, false, MaxStageCount, StageNum, Schedule, VRMap);
|
|
KernelBB->push_back(NewMI);
|
|
InstrMap[NewMI] = CI->getInstr();
|
|
}
|
|
}
|
|
|
|
// Copy any terminator instructions to the new kernel, and update
|
|
// names as needed.
|
|
for (MachineBasicBlock::iterator I = BB->getFirstTerminator(),
|
|
E = BB->instr_end();
|
|
I != E; ++I) {
|
|
MachineInstr *NewMI = MF.CloneMachineInstr(&*I);
|
|
updateInstruction(NewMI, false, MaxStageCount, 0, Schedule, VRMap);
|
|
KernelBB->push_back(NewMI);
|
|
InstrMap[NewMI] = &*I;
|
|
}
|
|
|
|
KernelBB->transferSuccessors(BB);
|
|
KernelBB->replaceSuccessor(BB, KernelBB);
|
|
|
|
generateExistingPhis(KernelBB, PrologBBs.back(), KernelBB, KernelBB, Schedule,
|
|
VRMap, InstrMap, MaxStageCount, MaxStageCount, false);
|
|
generatePhis(KernelBB, PrologBBs.back(), KernelBB, KernelBB, Schedule, VRMap,
|
|
InstrMap, MaxStageCount, MaxStageCount, false);
|
|
|
|
LLVM_DEBUG(dbgs() << "New block\n"; KernelBB->dump(););
|
|
|
|
SmallVector<MachineBasicBlock *, 4> EpilogBBs;
|
|
// Generate the epilog instructions to complete the pipeline.
|
|
generateEpilog(Schedule, MaxStageCount, KernelBB, VRMap, EpilogBBs,
|
|
PrologBBs);
|
|
|
|
// We need this step because the register allocation doesn't handle some
|
|
// situations well, so we insert copies to help out.
|
|
splitLifetimes(KernelBB, EpilogBBs, Schedule);
|
|
|
|
// Remove dead instructions due to loop induction variables.
|
|
removeDeadInstructions(KernelBB, EpilogBBs);
|
|
|
|
// Add branches between prolog and epilog blocks.
|
|
addBranches(PrologBBs, KernelBB, EpilogBBs, Schedule, VRMap);
|
|
|
|
// Remove the original loop since it's no longer referenced.
|
|
for (auto &I : *BB)
|
|
LIS.RemoveMachineInstrFromMaps(I);
|
|
BB->clear();
|
|
BB->eraseFromParent();
|
|
|
|
delete[] VRMap;
|
|
}
|
|
|
|
/// Generate the pipeline prolog code.
|
|
void SwingSchedulerDAG::generateProlog(SMSchedule &Schedule, unsigned LastStage,
|
|
MachineBasicBlock *KernelBB,
|
|
ValueMapTy *VRMap,
|
|
MBBVectorTy &PrologBBs) {
|
|
MachineBasicBlock *PreheaderBB = MLI->getLoopFor(BB)->getLoopPreheader();
|
|
assert(PreheaderBB != nullptr &&
|
|
"Need to add code to handle loops w/o preheader");
|
|
MachineBasicBlock *PredBB = PreheaderBB;
|
|
InstrMapTy InstrMap;
|
|
|
|
// Generate a basic block for each stage, not including the last stage,
|
|
// which will be generated in the kernel. Each basic block may contain
|
|
// instructions from multiple stages/iterations.
|
|
for (unsigned i = 0; i < LastStage; ++i) {
|
|
// Create and insert the prolog basic block prior to the original loop
|
|
// basic block. The original loop is removed later.
|
|
MachineBasicBlock *NewBB = MF.CreateMachineBasicBlock(BB->getBasicBlock());
|
|
PrologBBs.push_back(NewBB);
|
|
MF.insert(BB->getIterator(), NewBB);
|
|
NewBB->transferSuccessors(PredBB);
|
|
PredBB->addSuccessor(NewBB);
|
|
PredBB = NewBB;
|
|
|
|
// Generate instructions for each appropriate stage. Process instructions
|
|
// in original program order.
|
|
for (int StageNum = i; StageNum >= 0; --StageNum) {
|
|
for (MachineBasicBlock::iterator BBI = BB->instr_begin(),
|
|
BBE = BB->getFirstTerminator();
|
|
BBI != BBE; ++BBI) {
|
|
if (Schedule.isScheduledAtStage(getSUnit(&*BBI), (unsigned)StageNum)) {
|
|
if (BBI->isPHI())
|
|
continue;
|
|
MachineInstr *NewMI =
|
|
cloneAndChangeInstr(&*BBI, i, (unsigned)StageNum, Schedule);
|
|
updateInstruction(NewMI, false, i, (unsigned)StageNum, Schedule,
|
|
VRMap);
|
|
NewBB->push_back(NewMI);
|
|
InstrMap[NewMI] = &*BBI;
|
|
}
|
|
}
|
|
}
|
|
rewritePhiValues(NewBB, i, Schedule, VRMap, InstrMap);
|
|
LLVM_DEBUG({
|
|
dbgs() << "prolog:\n";
|
|
NewBB->dump();
|
|
});
|
|
}
|
|
|
|
PredBB->replaceSuccessor(BB, KernelBB);
|
|
|
|
// Check if we need to remove the branch from the preheader to the original
|
|
// loop, and replace it with a branch to the new loop.
|
|
unsigned numBranches = TII->removeBranch(*PreheaderBB);
|
|
if (numBranches) {
|
|
SmallVector<MachineOperand, 0> Cond;
|
|
TII->insertBranch(*PreheaderBB, PrologBBs[0], nullptr, Cond, DebugLoc());
|
|
}
|
|
}
|
|
|
|
/// Generate the pipeline epilog code. The epilog code finishes the iterations
|
|
/// that were started in either the prolog or the kernel. We create a basic
|
|
/// block for each stage that needs to complete.
|
|
void SwingSchedulerDAG::generateEpilog(SMSchedule &Schedule, unsigned LastStage,
|
|
MachineBasicBlock *KernelBB,
|
|
ValueMapTy *VRMap,
|
|
MBBVectorTy &EpilogBBs,
|
|
MBBVectorTy &PrologBBs) {
|
|
// We need to change the branch from the kernel to the first epilog block, so
|
|
// this call to analyze branch uses the kernel rather than the original BB.
|
|
MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
|
|
SmallVector<MachineOperand, 4> Cond;
|
|
bool checkBranch = TII->analyzeBranch(*KernelBB, TBB, FBB, Cond);
|
|
assert(!checkBranch && "generateEpilog must be able to analyze the branch");
|
|
if (checkBranch)
|
|
return;
|
|
|
|
MachineBasicBlock::succ_iterator LoopExitI = KernelBB->succ_begin();
|
|
if (*LoopExitI == KernelBB)
|
|
++LoopExitI;
|
|
assert(LoopExitI != KernelBB->succ_end() && "Expecting a successor");
|
|
MachineBasicBlock *LoopExitBB = *LoopExitI;
|
|
|
|
MachineBasicBlock *PredBB = KernelBB;
|
|
MachineBasicBlock *EpilogStart = LoopExitBB;
|
|
InstrMapTy InstrMap;
|
|
|
|
// Generate a basic block for each stage, not including the last stage,
|
|
// which was generated for the kernel. Each basic block may contain
|
|
// instructions from multiple stages/iterations.
|
|
int EpilogStage = LastStage + 1;
|
|
for (unsigned i = LastStage; i >= 1; --i, ++EpilogStage) {
|
|
MachineBasicBlock *NewBB = MF.CreateMachineBasicBlock();
|
|
EpilogBBs.push_back(NewBB);
|
|
MF.insert(BB->getIterator(), NewBB);
|
|
|
|
PredBB->replaceSuccessor(LoopExitBB, NewBB);
|
|
NewBB->addSuccessor(LoopExitBB);
|
|
|
|
if (EpilogStart == LoopExitBB)
|
|
EpilogStart = NewBB;
|
|
|
|
// Add instructions to the epilog depending on the current block.
|
|
// Process instructions in original program order.
|
|
for (unsigned StageNum = i; StageNum <= LastStage; ++StageNum) {
|
|
for (auto &BBI : *BB) {
|
|
if (BBI.isPHI())
|
|
continue;
|
|
MachineInstr *In = &BBI;
|
|
if (Schedule.isScheduledAtStage(getSUnit(In), StageNum)) {
|
|
// Instructions with memoperands in the epilog are updated with
|
|
// conservative values.
|
|
MachineInstr *NewMI = cloneInstr(In, UINT_MAX, 0);
|
|
updateInstruction(NewMI, i == 1, EpilogStage, 0, Schedule, VRMap);
|
|
NewBB->push_back(NewMI);
|
|
InstrMap[NewMI] = In;
|
|
}
|
|
}
|
|
}
|
|
generateExistingPhis(NewBB, PrologBBs[i - 1], PredBB, KernelBB, Schedule,
|
|
VRMap, InstrMap, LastStage, EpilogStage, i == 1);
|
|
generatePhis(NewBB, PrologBBs[i - 1], PredBB, KernelBB, Schedule, VRMap,
|
|
InstrMap, LastStage, EpilogStage, i == 1);
|
|
PredBB = NewBB;
|
|
|
|
LLVM_DEBUG({
|
|
dbgs() << "epilog:\n";
|
|
NewBB->dump();
|
|
});
|
|
}
|
|
|
|
// Fix any Phi nodes in the loop exit block.
|
|
for (MachineInstr &MI : *LoopExitBB) {
|
|
if (!MI.isPHI())
|
|
break;
|
|
for (unsigned i = 2, e = MI.getNumOperands() + 1; i != e; i += 2) {
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
if (MO.getMBB() == BB)
|
|
MO.setMBB(PredBB);
|
|
}
|
|
}
|
|
|
|
// Create a branch to the new epilog from the kernel.
|
|
// Remove the original branch and add a new branch to the epilog.
|
|
TII->removeBranch(*KernelBB);
|
|
TII->insertBranch(*KernelBB, KernelBB, EpilogStart, Cond, DebugLoc());
|
|
// Add a branch to the loop exit.
|
|
if (EpilogBBs.size() > 0) {
|
|
MachineBasicBlock *LastEpilogBB = EpilogBBs.back();
|
|
SmallVector<MachineOperand, 4> Cond1;
|
|
TII->insertBranch(*LastEpilogBB, LoopExitBB, nullptr, Cond1, DebugLoc());
|
|
}
|
|
}
|
|
|
|
/// Replace all uses of FromReg that appear outside the specified
|
|
/// basic block with ToReg.
|
|
static void replaceRegUsesAfterLoop(unsigned FromReg, unsigned ToReg,
|
|
MachineBasicBlock *MBB,
|
|
MachineRegisterInfo &MRI,
|
|
LiveIntervals &LIS) {
|
|
for (MachineRegisterInfo::use_iterator I = MRI.use_begin(FromReg),
|
|
E = MRI.use_end();
|
|
I != E;) {
|
|
MachineOperand &O = *I;
|
|
++I;
|
|
if (O.getParent()->getParent() != MBB)
|
|
O.setReg(ToReg);
|
|
}
|
|
if (!LIS.hasInterval(ToReg))
|
|
LIS.createEmptyInterval(ToReg);
|
|
}
|
|
|
|
/// Return true if the register has a use that occurs outside the
|
|
/// specified loop.
|
|
static bool hasUseAfterLoop(unsigned Reg, MachineBasicBlock *BB,
|
|
MachineRegisterInfo &MRI) {
|
|
for (MachineRegisterInfo::use_iterator I = MRI.use_begin(Reg),
|
|
E = MRI.use_end();
|
|
I != E; ++I)
|
|
if (I->getParent()->getParent() != BB)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
/// Generate Phis for the specific block in the generated pipelined code.
|
|
/// This function looks at the Phis from the original code to guide the
|
|
/// creation of new Phis.
|
|
void SwingSchedulerDAG::generateExistingPhis(
|
|
MachineBasicBlock *NewBB, MachineBasicBlock *BB1, MachineBasicBlock *BB2,
|
|
MachineBasicBlock *KernelBB, SMSchedule &Schedule, ValueMapTy *VRMap,
|
|
InstrMapTy &InstrMap, unsigned LastStageNum, unsigned CurStageNum,
|
|
bool IsLast) {
|
|
// Compute the stage number for the initial value of the Phi, which
|
|
// comes from the prolog. The prolog to use depends on to which kernel/
|
|
// epilog that we're adding the Phi.
|
|
unsigned PrologStage = 0;
|
|
unsigned PrevStage = 0;
|
|
bool InKernel = (LastStageNum == CurStageNum);
|
|
if (InKernel) {
|
|
PrologStage = LastStageNum - 1;
|
|
PrevStage = CurStageNum;
|
|
} else {
|
|
PrologStage = LastStageNum - (CurStageNum - LastStageNum);
|
|
PrevStage = LastStageNum + (CurStageNum - LastStageNum) - 1;
|
|
}
|
|
|
|
for (MachineBasicBlock::iterator BBI = BB->instr_begin(),
|
|
BBE = BB->getFirstNonPHI();
|
|
BBI != BBE; ++BBI) {
|
|
unsigned Def = BBI->getOperand(0).getReg();
|
|
|
|
unsigned InitVal = 0;
|
|
unsigned LoopVal = 0;
|
|
getPhiRegs(*BBI, BB, InitVal, LoopVal);
|
|
|
|
unsigned PhiOp1 = 0;
|
|
// The Phi value from the loop body typically is defined in the loop, but
|
|
// not always. So, we need to check if the value is defined in the loop.
|
|
unsigned PhiOp2 = LoopVal;
|
|
if (VRMap[LastStageNum].count(LoopVal))
|
|
PhiOp2 = VRMap[LastStageNum][LoopVal];
|
|
|
|
int StageScheduled = Schedule.stageScheduled(getSUnit(&*BBI));
|
|
int LoopValStage =
|
|
Schedule.stageScheduled(getSUnit(MRI.getVRegDef(LoopVal)));
|
|
unsigned NumStages = Schedule.getStagesForReg(Def, CurStageNum);
|
|
if (NumStages == 0) {
|
|
// We don't need to generate a Phi anymore, but we need to rename any uses
|
|
// of the Phi value.
|
|
unsigned NewReg = VRMap[PrevStage][LoopVal];
|
|
rewriteScheduledInstr(NewBB, Schedule, InstrMap, CurStageNum, 0, &*BBI,
|
|
Def, InitVal, NewReg);
|
|
if (VRMap[CurStageNum].count(LoopVal))
|
|
VRMap[CurStageNum][Def] = VRMap[CurStageNum][LoopVal];
|
|
}
|
|
// Adjust the number of Phis needed depending on the number of prologs left,
|
|
// and the distance from where the Phi is first scheduled. The number of
|
|
// Phis cannot exceed the number of prolog stages. Each stage can
|
|
// potentially define two values.
|
|
unsigned MaxPhis = PrologStage + 2;
|
|
if (!InKernel && (int)PrologStage <= LoopValStage)
|
|
MaxPhis = std::max((int)MaxPhis - (int)LoopValStage, 1);
|
|
unsigned NumPhis = std::min(NumStages, MaxPhis);
|
|
|
|
unsigned NewReg = 0;
|
|
unsigned AccessStage = (LoopValStage != -1) ? LoopValStage : StageScheduled;
|
|
// In the epilog, we may need to look back one stage to get the correct
|
|
// Phi name because the epilog and prolog blocks execute the same stage.
|
|
// The correct name is from the previous block only when the Phi has
|
|
// been completely scheduled prior to the epilog, and Phi value is not
|
|
// needed in multiple stages.
|
|
int StageDiff = 0;
|
|
if (!InKernel && StageScheduled >= LoopValStage && AccessStage == 0 &&
|
|
NumPhis == 1)
|
|
StageDiff = 1;
|
|
// Adjust the computations below when the phi and the loop definition
|
|
// are scheduled in different stages.
|
|
if (InKernel && LoopValStage != -1 && StageScheduled > LoopValStage)
|
|
StageDiff = StageScheduled - LoopValStage;
|
|
for (unsigned np = 0; np < NumPhis; ++np) {
|
|
// If the Phi hasn't been scheduled, then use the initial Phi operand
|
|
// value. Otherwise, use the scheduled version of the instruction. This
|
|
// is a little complicated when a Phi references another Phi.
|
|
if (np > PrologStage || StageScheduled >= (int)LastStageNum)
|
|
PhiOp1 = InitVal;
|
|
// Check if the Phi has already been scheduled in a prolog stage.
|
|
else if (PrologStage >= AccessStage + StageDiff + np &&
|
|
VRMap[PrologStage - StageDiff - np].count(LoopVal) != 0)
|
|
PhiOp1 = VRMap[PrologStage - StageDiff - np][LoopVal];
|
|
// Check if the Phi has already been scheduled, but the loop intruction
|
|
// is either another Phi, or doesn't occur in the loop.
|
|
else if (PrologStage >= AccessStage + StageDiff + np) {
|
|
// If the Phi references another Phi, we need to examine the other
|
|
// Phi to get the correct value.
|
|
PhiOp1 = LoopVal;
|
|
MachineInstr *InstOp1 = MRI.getVRegDef(PhiOp1);
|
|
int Indirects = 1;
|
|
while (InstOp1 && InstOp1->isPHI() && InstOp1->getParent() == BB) {
|
|
int PhiStage = Schedule.stageScheduled(getSUnit(InstOp1));
|
|
if ((int)(PrologStage - StageDiff - np) < PhiStage + Indirects)
|
|
PhiOp1 = getInitPhiReg(*InstOp1, BB);
|
|
else
|
|
PhiOp1 = getLoopPhiReg(*InstOp1, BB);
|
|
InstOp1 = MRI.getVRegDef(PhiOp1);
|
|
int PhiOpStage = Schedule.stageScheduled(getSUnit(InstOp1));
|
|
int StageAdj = (PhiOpStage != -1 ? PhiStage - PhiOpStage : 0);
|
|
if (PhiOpStage != -1 && PrologStage - StageAdj >= Indirects + np &&
|
|
VRMap[PrologStage - StageAdj - Indirects - np].count(PhiOp1)) {
|
|
PhiOp1 = VRMap[PrologStage - StageAdj - Indirects - np][PhiOp1];
|
|
break;
|
|
}
|
|
++Indirects;
|
|
}
|
|
} else
|
|
PhiOp1 = InitVal;
|
|
// If this references a generated Phi in the kernel, get the Phi operand
|
|
// from the incoming block.
|
|
if (MachineInstr *InstOp1 = MRI.getVRegDef(PhiOp1))
|
|
if (InstOp1->isPHI() && InstOp1->getParent() == KernelBB)
|
|
PhiOp1 = getInitPhiReg(*InstOp1, KernelBB);
|
|
|
|
MachineInstr *PhiInst = MRI.getVRegDef(LoopVal);
|
|
bool LoopDefIsPhi = PhiInst && PhiInst->isPHI();
|
|
// In the epilog, a map lookup is needed to get the value from the kernel,
|
|
// or previous epilog block. How is does this depends on if the
|
|
// instruction is scheduled in the previous block.
|
|
if (!InKernel) {
|
|
int StageDiffAdj = 0;
|
|
if (LoopValStage != -1 && StageScheduled > LoopValStage)
|
|
StageDiffAdj = StageScheduled - LoopValStage;
|
|
// Use the loop value defined in the kernel, unless the kernel
|
|
// contains the last definition of the Phi.
|
|
if (np == 0 && PrevStage == LastStageNum &&
|
|
(StageScheduled != 0 || LoopValStage != 0) &&
|
|
VRMap[PrevStage - StageDiffAdj].count(LoopVal))
|
|
PhiOp2 = VRMap[PrevStage - StageDiffAdj][LoopVal];
|
|
// Use the value defined by the Phi. We add one because we switch
|
|
// from looking at the loop value to the Phi definition.
|
|
else if (np > 0 && PrevStage == LastStageNum &&
|
|
VRMap[PrevStage - np + 1].count(Def))
|
|
PhiOp2 = VRMap[PrevStage - np + 1][Def];
|
|
// Use the loop value defined in the kernel.
|
|
else if (static_cast<unsigned>(LoopValStage) > PrologStage + 1 &&
|
|
VRMap[PrevStage - StageDiffAdj - np].count(LoopVal))
|
|
PhiOp2 = VRMap[PrevStage - StageDiffAdj - np][LoopVal];
|
|
// Use the value defined by the Phi, unless we're generating the first
|
|
// epilog and the Phi refers to a Phi in a different stage.
|
|
else if (VRMap[PrevStage - np].count(Def) &&
|
|
(!LoopDefIsPhi || PrevStage != LastStageNum))
|
|
PhiOp2 = VRMap[PrevStage - np][Def];
|
|
}
|
|
|
|
// Check if we can reuse an existing Phi. This occurs when a Phi
|
|
// references another Phi, and the other Phi is scheduled in an
|
|
// earlier stage. We can try to reuse an existing Phi up until the last
|
|
// stage of the current Phi.
|
|
if (LoopDefIsPhi) {
|
|
if (static_cast<int>(PrologStage - np) >= StageScheduled) {
|
|
int LVNumStages = Schedule.getStagesForPhi(LoopVal);
|
|
int StageDiff = (StageScheduled - LoopValStage);
|
|
LVNumStages -= StageDiff;
|
|
// Make sure the loop value Phi has been processed already.
|
|
if (LVNumStages > (int)np && VRMap[CurStageNum].count(LoopVal)) {
|
|
NewReg = PhiOp2;
|
|
unsigned ReuseStage = CurStageNum;
|
|
if (Schedule.isLoopCarried(this, *PhiInst))
|
|
ReuseStage -= LVNumStages;
|
|
// Check if the Phi to reuse has been generated yet. If not, then
|
|
// there is nothing to reuse.
|
|
if (VRMap[ReuseStage - np].count(LoopVal)) {
|
|
NewReg = VRMap[ReuseStage - np][LoopVal];
|
|
|
|
rewriteScheduledInstr(NewBB, Schedule, InstrMap, CurStageNum, np,
|
|
&*BBI, Def, NewReg);
|
|
// Update the map with the new Phi name.
|
|
VRMap[CurStageNum - np][Def] = NewReg;
|
|
PhiOp2 = NewReg;
|
|
if (VRMap[LastStageNum - np - 1].count(LoopVal))
|
|
PhiOp2 = VRMap[LastStageNum - np - 1][LoopVal];
|
|
|
|
if (IsLast && np == NumPhis - 1)
|
|
replaceRegUsesAfterLoop(Def, NewReg, BB, MRI, LIS);
|
|
continue;
|
|
}
|
|
}
|
|
}
|
|
if (InKernel && StageDiff > 0 &&
|
|
VRMap[CurStageNum - StageDiff - np].count(LoopVal))
|
|
PhiOp2 = VRMap[CurStageNum - StageDiff - np][LoopVal];
|
|
}
|
|
|
|
const TargetRegisterClass *RC = MRI.getRegClass(Def);
|
|
NewReg = MRI.createVirtualRegister(RC);
|
|
|
|
MachineInstrBuilder NewPhi =
|
|
BuildMI(*NewBB, NewBB->getFirstNonPHI(), DebugLoc(),
|
|
TII->get(TargetOpcode::PHI), NewReg);
|
|
NewPhi.addReg(PhiOp1).addMBB(BB1);
|
|
NewPhi.addReg(PhiOp2).addMBB(BB2);
|
|
if (np == 0)
|
|
InstrMap[NewPhi] = &*BBI;
|
|
|
|
// We define the Phis after creating the new pipelined code, so
|
|
// we need to rename the Phi values in scheduled instructions.
|
|
|
|
unsigned PrevReg = 0;
|
|
if (InKernel && VRMap[PrevStage - np].count(LoopVal))
|
|
PrevReg = VRMap[PrevStage - np][LoopVal];
|
|
rewriteScheduledInstr(NewBB, Schedule, InstrMap, CurStageNum, np, &*BBI,
|
|
Def, NewReg, PrevReg);
|
|
// If the Phi has been scheduled, use the new name for rewriting.
|
|
if (VRMap[CurStageNum - np].count(Def)) {
|
|
unsigned R = VRMap[CurStageNum - np][Def];
|
|
rewriteScheduledInstr(NewBB, Schedule, InstrMap, CurStageNum, np, &*BBI,
|
|
R, NewReg);
|
|
}
|
|
|
|
// Check if we need to rename any uses that occurs after the loop. The
|
|
// register to replace depends on whether the Phi is scheduled in the
|
|
// epilog.
|
|
if (IsLast && np == NumPhis - 1)
|
|
replaceRegUsesAfterLoop(Def, NewReg, BB, MRI, LIS);
|
|
|
|
// In the kernel, a dependent Phi uses the value from this Phi.
|
|
if (InKernel)
|
|
PhiOp2 = NewReg;
|
|
|
|
// Update the map with the new Phi name.
|
|
VRMap[CurStageNum - np][Def] = NewReg;
|
|
}
|
|
|
|
while (NumPhis++ < NumStages) {
|
|
rewriteScheduledInstr(NewBB, Schedule, InstrMap, CurStageNum, NumPhis,
|
|
&*BBI, Def, NewReg, 0);
|
|
}
|
|
|
|
// Check if we need to rename a Phi that has been eliminated due to
|
|
// scheduling.
|
|
if (NumStages == 0 && IsLast && VRMap[CurStageNum].count(LoopVal))
|
|
replaceRegUsesAfterLoop(Def, VRMap[CurStageNum][LoopVal], BB, MRI, LIS);
|
|
}
|
|
}
|
|
|
|
/// Generate Phis for the specified block in the generated pipelined code.
|
|
/// These are new Phis needed because the definition is scheduled after the
|
|
/// use in the pipelined sequence.
|
|
void SwingSchedulerDAG::generatePhis(
|
|
MachineBasicBlock *NewBB, MachineBasicBlock *BB1, MachineBasicBlock *BB2,
|
|
MachineBasicBlock *KernelBB, SMSchedule &Schedule, ValueMapTy *VRMap,
|
|
InstrMapTy &InstrMap, unsigned LastStageNum, unsigned CurStageNum,
|
|
bool IsLast) {
|
|
// Compute the stage number that contains the initial Phi value, and
|
|
// the Phi from the previous stage.
|
|
unsigned PrologStage = 0;
|
|
unsigned PrevStage = 0;
|
|
unsigned StageDiff = CurStageNum - LastStageNum;
|
|
bool InKernel = (StageDiff == 0);
|
|
if (InKernel) {
|
|
PrologStage = LastStageNum - 1;
|
|
PrevStage = CurStageNum;
|
|
} else {
|
|
PrologStage = LastStageNum - StageDiff;
|
|
PrevStage = LastStageNum + StageDiff - 1;
|
|
}
|
|
|
|
for (MachineBasicBlock::iterator BBI = BB->getFirstNonPHI(),
|
|
BBE = BB->instr_end();
|
|
BBI != BBE; ++BBI) {
|
|
for (unsigned i = 0, e = BBI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = BBI->getOperand(i);
|
|
if (!MO.isReg() || !MO.isDef() ||
|
|
!TargetRegisterInfo::isVirtualRegister(MO.getReg()))
|
|
continue;
|
|
|
|
int StageScheduled = Schedule.stageScheduled(getSUnit(&*BBI));
|
|
assert(StageScheduled != -1 && "Expecting scheduled instruction.");
|
|
unsigned Def = MO.getReg();
|
|
unsigned NumPhis = Schedule.getStagesForReg(Def, CurStageNum);
|
|
// An instruction scheduled in stage 0 and is used after the loop
|
|
// requires a phi in the epilog for the last definition from either
|
|
// the kernel or prolog.
|
|
if (!InKernel && NumPhis == 0 && StageScheduled == 0 &&
|
|
hasUseAfterLoop(Def, BB, MRI))
|
|
NumPhis = 1;
|
|
if (!InKernel && (unsigned)StageScheduled > PrologStage)
|
|
continue;
|
|
|
|
unsigned PhiOp2 = VRMap[PrevStage][Def];
|
|
if (MachineInstr *InstOp2 = MRI.getVRegDef(PhiOp2))
|
|
if (InstOp2->isPHI() && InstOp2->getParent() == NewBB)
|
|
PhiOp2 = getLoopPhiReg(*InstOp2, BB2);
|
|
// The number of Phis can't exceed the number of prolog stages. The
|
|
// prolog stage number is zero based.
|
|
if (NumPhis > PrologStage + 1 - StageScheduled)
|
|
NumPhis = PrologStage + 1 - StageScheduled;
|
|
for (unsigned np = 0; np < NumPhis; ++np) {
|
|
unsigned PhiOp1 = VRMap[PrologStage][Def];
|
|
if (np <= PrologStage)
|
|
PhiOp1 = VRMap[PrologStage - np][Def];
|
|
if (MachineInstr *InstOp1 = MRI.getVRegDef(PhiOp1)) {
|
|
if (InstOp1->isPHI() && InstOp1->getParent() == KernelBB)
|
|
PhiOp1 = getInitPhiReg(*InstOp1, KernelBB);
|
|
if (InstOp1->isPHI() && InstOp1->getParent() == NewBB)
|
|
PhiOp1 = getInitPhiReg(*InstOp1, NewBB);
|
|
}
|
|
if (!InKernel)
|
|
PhiOp2 = VRMap[PrevStage - np][Def];
|
|
|
|
const TargetRegisterClass *RC = MRI.getRegClass(Def);
|
|
unsigned NewReg = MRI.createVirtualRegister(RC);
|
|
|
|
MachineInstrBuilder NewPhi =
|
|
BuildMI(*NewBB, NewBB->getFirstNonPHI(), DebugLoc(),
|
|
TII->get(TargetOpcode::PHI), NewReg);
|
|
NewPhi.addReg(PhiOp1).addMBB(BB1);
|
|
NewPhi.addReg(PhiOp2).addMBB(BB2);
|
|
if (np == 0)
|
|
InstrMap[NewPhi] = &*BBI;
|
|
|
|
// Rewrite uses and update the map. The actions depend upon whether
|
|
// we generating code for the kernel or epilog blocks.
|
|
if (InKernel) {
|
|
rewriteScheduledInstr(NewBB, Schedule, InstrMap, CurStageNum, np,
|
|
&*BBI, PhiOp1, NewReg);
|
|
rewriteScheduledInstr(NewBB, Schedule, InstrMap, CurStageNum, np,
|
|
&*BBI, PhiOp2, NewReg);
|
|
|
|
PhiOp2 = NewReg;
|
|
VRMap[PrevStage - np - 1][Def] = NewReg;
|
|
} else {
|
|
VRMap[CurStageNum - np][Def] = NewReg;
|
|
if (np == NumPhis - 1)
|
|
rewriteScheduledInstr(NewBB, Schedule, InstrMap, CurStageNum, np,
|
|
&*BBI, Def, NewReg);
|
|
}
|
|
if (IsLast && np == NumPhis - 1)
|
|
replaceRegUsesAfterLoop(Def, NewReg, BB, MRI, LIS);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Remove instructions that generate values with no uses.
|
|
/// Typically, these are induction variable operations that generate values
|
|
/// used in the loop itself. A dead instruction has a definition with
|
|
/// no uses, or uses that occur in the original loop only.
|
|
void SwingSchedulerDAG::removeDeadInstructions(MachineBasicBlock *KernelBB,
|
|
MBBVectorTy &EpilogBBs) {
|
|
// For each epilog block, check that the value defined by each instruction
|
|
// is used. If not, delete it.
|
|
for (MBBVectorTy::reverse_iterator MBB = EpilogBBs.rbegin(),
|
|
MBE = EpilogBBs.rend();
|
|
MBB != MBE; ++MBB)
|
|
for (MachineBasicBlock::reverse_instr_iterator MI = (*MBB)->instr_rbegin(),
|
|
ME = (*MBB)->instr_rend();
|
|
MI != ME;) {
|
|
// From DeadMachineInstructionElem. Don't delete inline assembly.
|
|
if (MI->isInlineAsm()) {
|
|
++MI;
|
|
continue;
|
|
}
|
|
bool SawStore = false;
|
|
// Check if it's safe to remove the instruction due to side effects.
|
|
// We can, and want to, remove Phis here.
|
|
if (!MI->isSafeToMove(nullptr, SawStore) && !MI->isPHI()) {
|
|
++MI;
|
|
continue;
|
|
}
|
|
bool used = true;
|
|
for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
|
|
MOE = MI->operands_end();
|
|
MOI != MOE; ++MOI) {
|
|
if (!MOI->isReg() || !MOI->isDef())
|
|
continue;
|
|
unsigned reg = MOI->getReg();
|
|
// Assume physical registers are used, unless they are marked dead.
|
|
if (TargetRegisterInfo::isPhysicalRegister(reg)) {
|
|
used = !MOI->isDead();
|
|
if (used)
|
|
break;
|
|
continue;
|
|
}
|
|
unsigned realUses = 0;
|
|
for (MachineRegisterInfo::use_iterator UI = MRI.use_begin(reg),
|
|
EI = MRI.use_end();
|
|
UI != EI; ++UI) {
|
|
// Check if there are any uses that occur only in the original
|
|
// loop. If so, that's not a real use.
|
|
if (UI->getParent()->getParent() != BB) {
|
|
realUses++;
|
|
used = true;
|
|
break;
|
|
}
|
|
}
|
|
if (realUses > 0)
|
|
break;
|
|
used = false;
|
|
}
|
|
if (!used) {
|
|
LIS.RemoveMachineInstrFromMaps(*MI);
|
|
MI++->eraseFromParent();
|
|
continue;
|
|
}
|
|
++MI;
|
|
}
|
|
// In the kernel block, check if we can remove a Phi that generates a value
|
|
// used in an instruction removed in the epilog block.
|
|
for (MachineBasicBlock::iterator BBI = KernelBB->instr_begin(),
|
|
BBE = KernelBB->getFirstNonPHI();
|
|
BBI != BBE;) {
|
|
MachineInstr *MI = &*BBI;
|
|
++BBI;
|
|
unsigned reg = MI->getOperand(0).getReg();
|
|
if (MRI.use_begin(reg) == MRI.use_end()) {
|
|
LIS.RemoveMachineInstrFromMaps(*MI);
|
|
MI->eraseFromParent();
|
|
}
|
|
}
|
|
}
|
|
|
|
/// For loop carried definitions, we split the lifetime of a virtual register
|
|
/// that has uses past the definition in the next iteration. A copy with a new
|
|
/// virtual register is inserted before the definition, which helps with
|
|
/// generating a better register assignment.
|
|
///
|
|
/// v1 = phi(a, v2) v1 = phi(a, v2)
|
|
/// v2 = phi(b, v3) v2 = phi(b, v3)
|
|
/// v3 = .. v4 = copy v1
|
|
/// .. = V1 v3 = ..
|
|
/// .. = v4
|
|
void SwingSchedulerDAG::splitLifetimes(MachineBasicBlock *KernelBB,
|
|
MBBVectorTy &EpilogBBs,
|
|
SMSchedule &Schedule) {
|
|
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
|
|
for (auto &PHI : KernelBB->phis()) {
|
|
unsigned Def = PHI.getOperand(0).getReg();
|
|
// Check for any Phi definition that used as an operand of another Phi
|
|
// in the same block.
|
|
for (MachineRegisterInfo::use_instr_iterator I = MRI.use_instr_begin(Def),
|
|
E = MRI.use_instr_end();
|
|
I != E; ++I) {
|
|
if (I->isPHI() && I->getParent() == KernelBB) {
|
|
// Get the loop carried definition.
|
|
unsigned LCDef = getLoopPhiReg(PHI, KernelBB);
|
|
if (!LCDef)
|
|
continue;
|
|
MachineInstr *MI = MRI.getVRegDef(LCDef);
|
|
if (!MI || MI->getParent() != KernelBB || MI->isPHI())
|
|
continue;
|
|
// Search through the rest of the block looking for uses of the Phi
|
|
// definition. If one occurs, then split the lifetime.
|
|
unsigned SplitReg = 0;
|
|
for (auto &BBJ : make_range(MachineBasicBlock::instr_iterator(MI),
|
|
KernelBB->instr_end()))
|
|
if (BBJ.readsRegister(Def)) {
|
|
// We split the lifetime when we find the first use.
|
|
if (SplitReg == 0) {
|
|
SplitReg = MRI.createVirtualRegister(MRI.getRegClass(Def));
|
|
BuildMI(*KernelBB, MI, MI->getDebugLoc(),
|
|
TII->get(TargetOpcode::COPY), SplitReg)
|
|
.addReg(Def);
|
|
}
|
|
BBJ.substituteRegister(Def, SplitReg, 0, *TRI);
|
|
}
|
|
if (!SplitReg)
|
|
continue;
|
|
// Search through each of the epilog blocks for any uses to be renamed.
|
|
for (auto &Epilog : EpilogBBs)
|
|
for (auto &I : *Epilog)
|
|
if (I.readsRegister(Def))
|
|
I.substituteRegister(Def, SplitReg, 0, *TRI);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Remove the incoming block from the Phis in a basic block.
|
|
static void removePhis(MachineBasicBlock *BB, MachineBasicBlock *Incoming) {
|
|
for (MachineInstr &MI : *BB) {
|
|
if (!MI.isPHI())
|
|
break;
|
|
for (unsigned i = 1, e = MI.getNumOperands(); i != e; i += 2)
|
|
if (MI.getOperand(i + 1).getMBB() == Incoming) {
|
|
MI.RemoveOperand(i + 1);
|
|
MI.RemoveOperand(i);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Create branches from each prolog basic block to the appropriate epilog
|
|
/// block. These edges are needed if the loop ends before reaching the
|
|
/// kernel.
|
|
void SwingSchedulerDAG::addBranches(MBBVectorTy &PrologBBs,
|
|
MachineBasicBlock *KernelBB,
|
|
MBBVectorTy &EpilogBBs,
|
|
SMSchedule &Schedule, ValueMapTy *VRMap) {
|
|
assert(PrologBBs.size() == EpilogBBs.size() && "Prolog/Epilog mismatch");
|
|
MachineInstr *IndVar = Pass.LI.LoopInductionVar;
|
|
MachineInstr *Cmp = Pass.LI.LoopCompare;
|
|
MachineBasicBlock *LastPro = KernelBB;
|
|
MachineBasicBlock *LastEpi = KernelBB;
|
|
|
|
// Start from the blocks connected to the kernel and work "out"
|
|
// to the first prolog and the last epilog blocks.
|
|
SmallVector<MachineInstr *, 4> PrevInsts;
|
|
unsigned MaxIter = PrologBBs.size() - 1;
|
|
unsigned LC = UINT_MAX;
|
|
unsigned LCMin = UINT_MAX;
|
|
for (unsigned i = 0, j = MaxIter; i <= MaxIter; ++i, --j) {
|
|
// Add branches to the prolog that go to the corresponding
|
|
// epilog, and the fall-thru prolog/kernel block.
|
|
MachineBasicBlock *Prolog = PrologBBs[j];
|
|
MachineBasicBlock *Epilog = EpilogBBs[i];
|
|
// We've executed one iteration, so decrement the loop count and check for
|
|
// the loop end.
|
|
SmallVector<MachineOperand, 4> Cond;
|
|
// Check if the LOOP0 has already been removed. If so, then there is no need
|
|
// to reduce the trip count.
|
|
if (LC != 0)
|
|
LC = TII->reduceLoopCount(*Prolog, IndVar, *Cmp, Cond, PrevInsts, j,
|
|
MaxIter);
|
|
|
|
// Record the value of the first trip count, which is used to determine if
|
|
// branches and blocks can be removed for constant trip counts.
|
|
if (LCMin == UINT_MAX)
|
|
LCMin = LC;
|
|
|
|
unsigned numAdded = 0;
|
|
if (TargetRegisterInfo::isVirtualRegister(LC)) {
|
|
Prolog->addSuccessor(Epilog);
|
|
numAdded = TII->insertBranch(*Prolog, Epilog, LastPro, Cond, DebugLoc());
|
|
} else if (j >= LCMin) {
|
|
Prolog->addSuccessor(Epilog);
|
|
Prolog->removeSuccessor(LastPro);
|
|
LastEpi->removeSuccessor(Epilog);
|
|
numAdded = TII->insertBranch(*Prolog, Epilog, nullptr, Cond, DebugLoc());
|
|
removePhis(Epilog, LastEpi);
|
|
// Remove the blocks that are no longer referenced.
|
|
if (LastPro != LastEpi) {
|
|
LastEpi->clear();
|
|
LastEpi->eraseFromParent();
|
|
}
|
|
LastPro->clear();
|
|
LastPro->eraseFromParent();
|
|
} else {
|
|
numAdded = TII->insertBranch(*Prolog, LastPro, nullptr, Cond, DebugLoc());
|
|
removePhis(Epilog, Prolog);
|
|
}
|
|
LastPro = Prolog;
|
|
LastEpi = Epilog;
|
|
for (MachineBasicBlock::reverse_instr_iterator I = Prolog->instr_rbegin(),
|
|
E = Prolog->instr_rend();
|
|
I != E && numAdded > 0; ++I, --numAdded)
|
|
updateInstruction(&*I, false, j, 0, Schedule, VRMap);
|
|
}
|
|
}
|
|
|
|
/// Return true if we can compute the amount the instruction changes
|
|
/// during each iteration. Set Delta to the amount of the change.
|
|
bool SwingSchedulerDAG::computeDelta(MachineInstr &MI, unsigned &Delta) {
|
|
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
|
|
unsigned BaseReg;
|
|
int64_t Offset;
|
|
if (!TII->getMemOpBaseRegImmOfs(MI, BaseReg, Offset, TRI))
|
|
return false;
|
|
|
|
MachineRegisterInfo &MRI = MF.getRegInfo();
|
|
// Check if there is a Phi. If so, get the definition in the loop.
|
|
MachineInstr *BaseDef = MRI.getVRegDef(BaseReg);
|
|
if (BaseDef && BaseDef->isPHI()) {
|
|
BaseReg = getLoopPhiReg(*BaseDef, MI.getParent());
|
|
BaseDef = MRI.getVRegDef(BaseReg);
|
|
}
|
|
if (!BaseDef)
|
|
return false;
|
|
|
|
int D = 0;
|
|
if (!TII->getIncrementValue(*BaseDef, D) && D >= 0)
|
|
return false;
|
|
|
|
Delta = D;
|
|
return true;
|
|
}
|
|
|
|
/// Update the memory operand with a new offset when the pipeliner
|
|
/// generates a new copy of the instruction that refers to a
|
|
/// different memory location.
|
|
void SwingSchedulerDAG::updateMemOperands(MachineInstr &NewMI,
|
|
MachineInstr &OldMI, unsigned Num) {
|
|
if (Num == 0)
|
|
return;
|
|
// If the instruction has memory operands, then adjust the offset
|
|
// when the instruction appears in different stages.
|
|
if (NewMI.memoperands_empty())
|
|
return;
|
|
SmallVector<MachineMemOperand *, 2> NewMMOs;
|
|
for (MachineMemOperand *MMO : NewMI.memoperands()) {
|
|
if (MMO->isVolatile() || (MMO->isInvariant() && MMO->isDereferenceable()) ||
|
|
(!MMO->getValue())) {
|
|
NewMMOs.push_back(MMO);
|
|
continue;
|
|
}
|
|
unsigned Delta;
|
|
if (Num != UINT_MAX && computeDelta(OldMI, Delta)) {
|
|
int64_t AdjOffset = Delta * Num;
|
|
NewMMOs.push_back(
|
|
MF.getMachineMemOperand(MMO, AdjOffset, MMO->getSize()));
|
|
} else {
|
|
NewMMOs.push_back(
|
|
MF.getMachineMemOperand(MMO, 0, MemoryLocation::UnknownSize));
|
|
}
|
|
}
|
|
NewMI.setMemRefs(MF, NewMMOs);
|
|
}
|
|
|
|
/// Clone the instruction for the new pipelined loop and update the
|
|
/// memory operands, if needed.
|
|
MachineInstr *SwingSchedulerDAG::cloneInstr(MachineInstr *OldMI,
|
|
unsigned CurStageNum,
|
|
unsigned InstStageNum) {
|
|
MachineInstr *NewMI = MF.CloneMachineInstr(OldMI);
|
|
// Check for tied operands in inline asm instructions. This should be handled
|
|
// elsewhere, but I'm not sure of the best solution.
|
|
if (OldMI->isInlineAsm())
|
|
for (unsigned i = 0, e = OldMI->getNumOperands(); i != e; ++i) {
|
|
const auto &MO = OldMI->getOperand(i);
|
|
if (MO.isReg() && MO.isUse())
|
|
break;
|
|
unsigned UseIdx;
|
|
if (OldMI->isRegTiedToUseOperand(i, &UseIdx))
|
|
NewMI->tieOperands(i, UseIdx);
|
|
}
|
|
updateMemOperands(*NewMI, *OldMI, CurStageNum - InstStageNum);
|
|
return NewMI;
|
|
}
|
|
|
|
/// Clone the instruction for the new pipelined loop. If needed, this
|
|
/// function updates the instruction using the values saved in the
|
|
/// InstrChanges structure.
|
|
MachineInstr *SwingSchedulerDAG::cloneAndChangeInstr(MachineInstr *OldMI,
|
|
unsigned CurStageNum,
|
|
unsigned InstStageNum,
|
|
SMSchedule &Schedule) {
|
|
MachineInstr *NewMI = MF.CloneMachineInstr(OldMI);
|
|
DenseMap<SUnit *, std::pair<unsigned, int64_t>>::iterator It =
|
|
InstrChanges.find(getSUnit(OldMI));
|
|
if (It != InstrChanges.end()) {
|
|
std::pair<unsigned, int64_t> RegAndOffset = It->second;
|
|
unsigned BasePos, OffsetPos;
|
|
if (!TII->getBaseAndOffsetPosition(*OldMI, BasePos, OffsetPos))
|
|
return nullptr;
|
|
int64_t NewOffset = OldMI->getOperand(OffsetPos).getImm();
|
|
MachineInstr *LoopDef = findDefInLoop(RegAndOffset.first);
|
|
if (Schedule.stageScheduled(getSUnit(LoopDef)) > (signed)InstStageNum)
|
|
NewOffset += RegAndOffset.second * (CurStageNum - InstStageNum);
|
|
NewMI->getOperand(OffsetPos).setImm(NewOffset);
|
|
}
|
|
updateMemOperands(*NewMI, *OldMI, CurStageNum - InstStageNum);
|
|
return NewMI;
|
|
}
|
|
|
|
/// Update the machine instruction with new virtual registers. This
|
|
/// function may change the defintions and/or uses.
|
|
void SwingSchedulerDAG::updateInstruction(MachineInstr *NewMI, bool LastDef,
|
|
unsigned CurStageNum,
|
|
unsigned InstrStageNum,
|
|
SMSchedule &Schedule,
|
|
ValueMapTy *VRMap) {
|
|
for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = NewMI->getOperand(i);
|
|
if (!MO.isReg() || !TargetRegisterInfo::isVirtualRegister(MO.getReg()))
|
|
continue;
|
|
unsigned reg = MO.getReg();
|
|
if (MO.isDef()) {
|
|
// Create a new virtual register for the definition.
|
|
const TargetRegisterClass *RC = MRI.getRegClass(reg);
|
|
unsigned NewReg = MRI.createVirtualRegister(RC);
|
|
MO.setReg(NewReg);
|
|
VRMap[CurStageNum][reg] = NewReg;
|
|
if (LastDef)
|
|
replaceRegUsesAfterLoop(reg, NewReg, BB, MRI, LIS);
|
|
} else if (MO.isUse()) {
|
|
MachineInstr *Def = MRI.getVRegDef(reg);
|
|
// Compute the stage that contains the last definition for instruction.
|
|
int DefStageNum = Schedule.stageScheduled(getSUnit(Def));
|
|
unsigned StageNum = CurStageNum;
|
|
if (DefStageNum != -1 && (int)InstrStageNum > DefStageNum) {
|
|
// Compute the difference in stages between the defintion and the use.
|
|
unsigned StageDiff = (InstrStageNum - DefStageNum);
|
|
// Make an adjustment to get the last definition.
|
|
StageNum -= StageDiff;
|
|
}
|
|
if (VRMap[StageNum].count(reg))
|
|
MO.setReg(VRMap[StageNum][reg]);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Return the instruction in the loop that defines the register.
|
|
/// If the definition is a Phi, then follow the Phi operand to
|
|
/// the instruction in the loop.
|
|
MachineInstr *SwingSchedulerDAG::findDefInLoop(unsigned Reg) {
|
|
SmallPtrSet<MachineInstr *, 8> Visited;
|
|
MachineInstr *Def = MRI.getVRegDef(Reg);
|
|
while (Def->isPHI()) {
|
|
if (!Visited.insert(Def).second)
|
|
break;
|
|
for (unsigned i = 1, e = Def->getNumOperands(); i < e; i += 2)
|
|
if (Def->getOperand(i + 1).getMBB() == BB) {
|
|
Def = MRI.getVRegDef(Def->getOperand(i).getReg());
|
|
break;
|
|
}
|
|
}
|
|
return Def;
|
|
}
|
|
|
|
/// Return the new name for the value from the previous stage.
|
|
unsigned SwingSchedulerDAG::getPrevMapVal(unsigned StageNum, unsigned PhiStage,
|
|
unsigned LoopVal, unsigned LoopStage,
|
|
ValueMapTy *VRMap,
|
|
MachineBasicBlock *BB) {
|
|
unsigned PrevVal = 0;
|
|
if (StageNum > PhiStage) {
|
|
MachineInstr *LoopInst = MRI.getVRegDef(LoopVal);
|
|
if (PhiStage == LoopStage && VRMap[StageNum - 1].count(LoopVal))
|
|
// The name is defined in the previous stage.
|
|
PrevVal = VRMap[StageNum - 1][LoopVal];
|
|
else if (VRMap[StageNum].count(LoopVal))
|
|
// The previous name is defined in the current stage when the instruction
|
|
// order is swapped.
|
|
PrevVal = VRMap[StageNum][LoopVal];
|
|
else if (!LoopInst->isPHI() || LoopInst->getParent() != BB)
|
|
// The loop value hasn't yet been scheduled.
|
|
PrevVal = LoopVal;
|
|
else if (StageNum == PhiStage + 1)
|
|
// The loop value is another phi, which has not been scheduled.
|
|
PrevVal = getInitPhiReg(*LoopInst, BB);
|
|
else if (StageNum > PhiStage + 1 && LoopInst->getParent() == BB)
|
|
// The loop value is another phi, which has been scheduled.
|
|
PrevVal =
|
|
getPrevMapVal(StageNum - 1, PhiStage, getLoopPhiReg(*LoopInst, BB),
|
|
LoopStage, VRMap, BB);
|
|
}
|
|
return PrevVal;
|
|
}
|
|
|
|
/// Rewrite the Phi values in the specified block to use the mappings
|
|
/// from the initial operand. Once the Phi is scheduled, we switch
|
|
/// to using the loop value instead of the Phi value, so those names
|
|
/// do not need to be rewritten.
|
|
void SwingSchedulerDAG::rewritePhiValues(MachineBasicBlock *NewBB,
|
|
unsigned StageNum,
|
|
SMSchedule &Schedule,
|
|
ValueMapTy *VRMap,
|
|
InstrMapTy &InstrMap) {
|
|
for (auto &PHI : BB->phis()) {
|
|
unsigned InitVal = 0;
|
|
unsigned LoopVal = 0;
|
|
getPhiRegs(PHI, BB, InitVal, LoopVal);
|
|
unsigned PhiDef = PHI.getOperand(0).getReg();
|
|
|
|
unsigned PhiStage =
|
|
(unsigned)Schedule.stageScheduled(getSUnit(MRI.getVRegDef(PhiDef)));
|
|
unsigned LoopStage =
|
|
(unsigned)Schedule.stageScheduled(getSUnit(MRI.getVRegDef(LoopVal)));
|
|
unsigned NumPhis = Schedule.getStagesForPhi(PhiDef);
|
|
if (NumPhis > StageNum)
|
|
NumPhis = StageNum;
|
|
for (unsigned np = 0; np <= NumPhis; ++np) {
|
|
unsigned NewVal =
|
|
getPrevMapVal(StageNum - np, PhiStage, LoopVal, LoopStage, VRMap, BB);
|
|
if (!NewVal)
|
|
NewVal = InitVal;
|
|
rewriteScheduledInstr(NewBB, Schedule, InstrMap, StageNum - np, np, &PHI,
|
|
PhiDef, NewVal);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Rewrite a previously scheduled instruction to use the register value
|
|
/// from the new instruction. Make sure the instruction occurs in the
|
|
/// basic block, and we don't change the uses in the new instruction.
|
|
void SwingSchedulerDAG::rewriteScheduledInstr(
|
|
MachineBasicBlock *BB, SMSchedule &Schedule, InstrMapTy &InstrMap,
|
|
unsigned CurStageNum, unsigned PhiNum, MachineInstr *Phi, unsigned OldReg,
|
|
unsigned NewReg, unsigned PrevReg) {
|
|
bool InProlog = (CurStageNum < Schedule.getMaxStageCount());
|
|
int StagePhi = Schedule.stageScheduled(getSUnit(Phi)) + PhiNum;
|
|
// Rewrite uses that have been scheduled already to use the new
|
|
// Phi register.
|
|
for (MachineRegisterInfo::use_iterator UI = MRI.use_begin(OldReg),
|
|
EI = MRI.use_end();
|
|
UI != EI;) {
|
|
MachineOperand &UseOp = *UI;
|
|
MachineInstr *UseMI = UseOp.getParent();
|
|
++UI;
|
|
if (UseMI->getParent() != BB)
|
|
continue;
|
|
if (UseMI->isPHI()) {
|
|
if (!Phi->isPHI() && UseMI->getOperand(0).getReg() == NewReg)
|
|
continue;
|
|
if (getLoopPhiReg(*UseMI, BB) != OldReg)
|
|
continue;
|
|
}
|
|
InstrMapTy::iterator OrigInstr = InstrMap.find(UseMI);
|
|
assert(OrigInstr != InstrMap.end() && "Instruction not scheduled.");
|
|
SUnit *OrigMISU = getSUnit(OrigInstr->second);
|
|
int StageSched = Schedule.stageScheduled(OrigMISU);
|
|
int CycleSched = Schedule.cycleScheduled(OrigMISU);
|
|
unsigned ReplaceReg = 0;
|
|
// This is the stage for the scheduled instruction.
|
|
if (StagePhi == StageSched && Phi->isPHI()) {
|
|
int CyclePhi = Schedule.cycleScheduled(getSUnit(Phi));
|
|
if (PrevReg && InProlog)
|
|
ReplaceReg = PrevReg;
|
|
else if (PrevReg && !Schedule.isLoopCarried(this, *Phi) &&
|
|
(CyclePhi <= CycleSched || OrigMISU->getInstr()->isPHI()))
|
|
ReplaceReg = PrevReg;
|
|
else
|
|
ReplaceReg = NewReg;
|
|
}
|
|
// The scheduled instruction occurs before the scheduled Phi, and the
|
|
// Phi is not loop carried.
|
|
if (!InProlog && StagePhi + 1 == StageSched &&
|
|
!Schedule.isLoopCarried(this, *Phi))
|
|
ReplaceReg = NewReg;
|
|
if (StagePhi > StageSched && Phi->isPHI())
|
|
ReplaceReg = NewReg;
|
|
if (!InProlog && !Phi->isPHI() && StagePhi < StageSched)
|
|
ReplaceReg = NewReg;
|
|
if (ReplaceReg) {
|
|
MRI.constrainRegClass(ReplaceReg, MRI.getRegClass(OldReg));
|
|
UseOp.setReg(ReplaceReg);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Check if we can change the instruction to use an offset value from the
|
|
/// previous iteration. If so, return true and set the base and offset values
|
|
/// so that we can rewrite the load, if necessary.
|
|
/// v1 = Phi(v0, v3)
|
|
/// v2 = load v1, 0
|
|
/// v3 = post_store v1, 4, x
|
|
/// This function enables the load to be rewritten as v2 = load v3, 4.
|
|
bool SwingSchedulerDAG::canUseLastOffsetValue(MachineInstr *MI,
|
|
unsigned &BasePos,
|
|
unsigned &OffsetPos,
|
|
unsigned &NewBase,
|
|
int64_t &Offset) {
|
|
// Get the load instruction.
|
|
if (TII->isPostIncrement(*MI))
|
|
return false;
|
|
unsigned BasePosLd, OffsetPosLd;
|
|
if (!TII->getBaseAndOffsetPosition(*MI, BasePosLd, OffsetPosLd))
|
|
return false;
|
|
unsigned BaseReg = MI->getOperand(BasePosLd).getReg();
|
|
|
|
// Look for the Phi instruction.
|
|
MachineRegisterInfo &MRI = MI->getMF()->getRegInfo();
|
|
MachineInstr *Phi = MRI.getVRegDef(BaseReg);
|
|
if (!Phi || !Phi->isPHI())
|
|
return false;
|
|
// Get the register defined in the loop block.
|
|
unsigned PrevReg = getLoopPhiReg(*Phi, MI->getParent());
|
|
if (!PrevReg)
|
|
return false;
|
|
|
|
// Check for the post-increment load/store instruction.
|
|
MachineInstr *PrevDef = MRI.getVRegDef(PrevReg);
|
|
if (!PrevDef || PrevDef == MI)
|
|
return false;
|
|
|
|
if (!TII->isPostIncrement(*PrevDef))
|
|
return false;
|
|
|
|
unsigned BasePos1 = 0, OffsetPos1 = 0;
|
|
if (!TII->getBaseAndOffsetPosition(*PrevDef, BasePos1, OffsetPos1))
|
|
return false;
|
|
|
|
// Make sure that the instructions do not access the same memory location in
|
|
// the next iteration.
|
|
int64_t LoadOffset = MI->getOperand(OffsetPosLd).getImm();
|
|
int64_t StoreOffset = PrevDef->getOperand(OffsetPos1).getImm();
|
|
MachineInstr *NewMI = MF.CloneMachineInstr(MI);
|
|
NewMI->getOperand(OffsetPosLd).setImm(LoadOffset + StoreOffset);
|
|
bool Disjoint = TII->areMemAccessesTriviallyDisjoint(*NewMI, *PrevDef);
|
|
MF.DeleteMachineInstr(NewMI);
|
|
if (!Disjoint)
|
|
return false;
|
|
|
|
// Set the return value once we determine that we return true.
|
|
BasePos = BasePosLd;
|
|
OffsetPos = OffsetPosLd;
|
|
NewBase = PrevReg;
|
|
Offset = StoreOffset;
|
|
return true;
|
|
}
|
|
|
|
/// Apply changes to the instruction if needed. The changes are need
|
|
/// to improve the scheduling and depend up on the final schedule.
|
|
void SwingSchedulerDAG::applyInstrChange(MachineInstr *MI,
|
|
SMSchedule &Schedule) {
|
|
SUnit *SU = getSUnit(MI);
|
|
DenseMap<SUnit *, std::pair<unsigned, int64_t>>::iterator It =
|
|
InstrChanges.find(SU);
|
|
if (It != InstrChanges.end()) {
|
|
std::pair<unsigned, int64_t> RegAndOffset = It->second;
|
|
unsigned BasePos, OffsetPos;
|
|
if (!TII->getBaseAndOffsetPosition(*MI, BasePos, OffsetPos))
|
|
return;
|
|
unsigned BaseReg = MI->getOperand(BasePos).getReg();
|
|
MachineInstr *LoopDef = findDefInLoop(BaseReg);
|
|
int DefStageNum = Schedule.stageScheduled(getSUnit(LoopDef));
|
|
int DefCycleNum = Schedule.cycleScheduled(getSUnit(LoopDef));
|
|
int BaseStageNum = Schedule.stageScheduled(SU);
|
|
int BaseCycleNum = Schedule.cycleScheduled(SU);
|
|
if (BaseStageNum < DefStageNum) {
|
|
MachineInstr *NewMI = MF.CloneMachineInstr(MI);
|
|
int OffsetDiff = DefStageNum - BaseStageNum;
|
|
if (DefCycleNum < BaseCycleNum) {
|
|
NewMI->getOperand(BasePos).setReg(RegAndOffset.first);
|
|
if (OffsetDiff > 0)
|
|
--OffsetDiff;
|
|
}
|
|
int64_t NewOffset =
|
|
MI->getOperand(OffsetPos).getImm() + RegAndOffset.second * OffsetDiff;
|
|
NewMI->getOperand(OffsetPos).setImm(NewOffset);
|
|
SU->setInstr(NewMI);
|
|
MISUnitMap[NewMI] = SU;
|
|
NewMIs.insert(NewMI);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Return true for an order or output dependence that is loop carried
|
|
/// potentially. A dependence is loop carried if the destination defines a valu
|
|
/// that may be used or defined by the source in a subsequent iteration.
|
|
bool SwingSchedulerDAG::isLoopCarriedDep(SUnit *Source, const SDep &Dep,
|
|
bool isSucc) {
|
|
if ((Dep.getKind() != SDep::Order && Dep.getKind() != SDep::Output) ||
|
|
Dep.isArtificial())
|
|
return false;
|
|
|
|
if (!SwpPruneLoopCarried)
|
|
return true;
|
|
|
|
if (Dep.getKind() == SDep::Output)
|
|
return true;
|
|
|
|
MachineInstr *SI = Source->getInstr();
|
|
MachineInstr *DI = Dep.getSUnit()->getInstr();
|
|
if (!isSucc)
|
|
std::swap(SI, DI);
|
|
assert(SI != nullptr && DI != nullptr && "Expecting SUnit with an MI.");
|
|
|
|
// Assume ordered loads and stores may have a loop carried dependence.
|
|
if (SI->hasUnmodeledSideEffects() || DI->hasUnmodeledSideEffects() ||
|
|
SI->hasOrderedMemoryRef() || DI->hasOrderedMemoryRef())
|
|
return true;
|
|
|
|
// Only chain dependences between a load and store can be loop carried.
|
|
if (!DI->mayStore() || !SI->mayLoad())
|
|
return false;
|
|
|
|
unsigned DeltaS, DeltaD;
|
|
if (!computeDelta(*SI, DeltaS) || !computeDelta(*DI, DeltaD))
|
|
return true;
|
|
|
|
unsigned BaseRegS, BaseRegD;
|
|
int64_t OffsetS, OffsetD;
|
|
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
|
|
if (!TII->getMemOpBaseRegImmOfs(*SI, BaseRegS, OffsetS, TRI) ||
|
|
!TII->getMemOpBaseRegImmOfs(*DI, BaseRegD, OffsetD, TRI))
|
|
return true;
|
|
|
|
if (BaseRegS != BaseRegD)
|
|
return true;
|
|
|
|
// Check that the base register is incremented by a constant value for each
|
|
// iteration.
|
|
MachineInstr *Def = MRI.getVRegDef(BaseRegS);
|
|
if (!Def || !Def->isPHI())
|
|
return true;
|
|
unsigned InitVal = 0;
|
|
unsigned LoopVal = 0;
|
|
getPhiRegs(*Def, BB, InitVal, LoopVal);
|
|
MachineInstr *LoopDef = MRI.getVRegDef(LoopVal);
|
|
int D = 0;
|
|
if (!LoopDef || !TII->getIncrementValue(*LoopDef, D))
|
|
return true;
|
|
|
|
uint64_t AccessSizeS = (*SI->memoperands_begin())->getSize();
|
|
uint64_t AccessSizeD = (*DI->memoperands_begin())->getSize();
|
|
|
|
// This is the main test, which checks the offset values and the loop
|
|
// increment value to determine if the accesses may be loop carried.
|
|
if (OffsetS >= OffsetD)
|
|
return OffsetS + AccessSizeS > DeltaS;
|
|
else
|
|
return OffsetD + AccessSizeD > DeltaD;
|
|
|
|
return true;
|
|
}
|
|
|
|
void SwingSchedulerDAG::postprocessDAG() {
|
|
for (auto &M : Mutations)
|
|
M->apply(this);
|
|
}
|
|
|
|
/// Try to schedule the node at the specified StartCycle and continue
|
|
/// until the node is schedule or the EndCycle is reached. This function
|
|
/// returns true if the node is scheduled. This routine may search either
|
|
/// forward or backward for a place to insert the instruction based upon
|
|
/// the relative values of StartCycle and EndCycle.
|
|
bool SMSchedule::insert(SUnit *SU, int StartCycle, int EndCycle, int II) {
|
|
bool forward = true;
|
|
if (StartCycle > EndCycle)
|
|
forward = false;
|
|
|
|
// The terminating condition depends on the direction.
|
|
int termCycle = forward ? EndCycle + 1 : EndCycle - 1;
|
|
for (int curCycle = StartCycle; curCycle != termCycle;
|
|
forward ? ++curCycle : --curCycle) {
|
|
|
|
// Add the already scheduled instructions at the specified cycle to the DFA.
|
|
Resources->clearResources();
|
|
for (int checkCycle = FirstCycle + ((curCycle - FirstCycle) % II);
|
|
checkCycle <= LastCycle; checkCycle += II) {
|
|
std::deque<SUnit *> &cycleInstrs = ScheduledInstrs[checkCycle];
|
|
|
|
for (std::deque<SUnit *>::iterator I = cycleInstrs.begin(),
|
|
E = cycleInstrs.end();
|
|
I != E; ++I) {
|
|
if (ST.getInstrInfo()->isZeroCost((*I)->getInstr()->getOpcode()))
|
|
continue;
|
|
assert(Resources->canReserveResources(*(*I)->getInstr()) &&
|
|
"These instructions have already been scheduled.");
|
|
Resources->reserveResources(*(*I)->getInstr());
|
|
}
|
|
}
|
|
if (ST.getInstrInfo()->isZeroCost(SU->getInstr()->getOpcode()) ||
|
|
Resources->canReserveResources(*SU->getInstr())) {
|
|
LLVM_DEBUG({
|
|
dbgs() << "\tinsert at cycle " << curCycle << " ";
|
|
SU->getInstr()->dump();
|
|
});
|
|
|
|
ScheduledInstrs[curCycle].push_back(SU);
|
|
InstrToCycle.insert(std::make_pair(SU, curCycle));
|
|
if (curCycle > LastCycle)
|
|
LastCycle = curCycle;
|
|
if (curCycle < FirstCycle)
|
|
FirstCycle = curCycle;
|
|
return true;
|
|
}
|
|
LLVM_DEBUG({
|
|
dbgs() << "\tfailed to insert at cycle " << curCycle << " ";
|
|
SU->getInstr()->dump();
|
|
});
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Return the cycle of the earliest scheduled instruction in the chain.
|
|
int SMSchedule::earliestCycleInChain(const SDep &Dep) {
|
|
SmallPtrSet<SUnit *, 8> Visited;
|
|
SmallVector<SDep, 8> Worklist;
|
|
Worklist.push_back(Dep);
|
|
int EarlyCycle = INT_MAX;
|
|
while (!Worklist.empty()) {
|
|
const SDep &Cur = Worklist.pop_back_val();
|
|
SUnit *PrevSU = Cur.getSUnit();
|
|
if (Visited.count(PrevSU))
|
|
continue;
|
|
std::map<SUnit *, int>::const_iterator it = InstrToCycle.find(PrevSU);
|
|
if (it == InstrToCycle.end())
|
|
continue;
|
|
EarlyCycle = std::min(EarlyCycle, it->second);
|
|
for (const auto &PI : PrevSU->Preds)
|
|
if (PI.getKind() == SDep::Order || Dep.getKind() == SDep::Output)
|
|
Worklist.push_back(PI);
|
|
Visited.insert(PrevSU);
|
|
}
|
|
return EarlyCycle;
|
|
}
|
|
|
|
// Return the cycle of the latest scheduled instruction in the chain.
|
|
int SMSchedule::latestCycleInChain(const SDep &Dep) {
|
|
SmallPtrSet<SUnit *, 8> Visited;
|
|
SmallVector<SDep, 8> Worklist;
|
|
Worklist.push_back(Dep);
|
|
int LateCycle = INT_MIN;
|
|
while (!Worklist.empty()) {
|
|
const SDep &Cur = Worklist.pop_back_val();
|
|
SUnit *SuccSU = Cur.getSUnit();
|
|
if (Visited.count(SuccSU))
|
|
continue;
|
|
std::map<SUnit *, int>::const_iterator it = InstrToCycle.find(SuccSU);
|
|
if (it == InstrToCycle.end())
|
|
continue;
|
|
LateCycle = std::max(LateCycle, it->second);
|
|
for (const auto &SI : SuccSU->Succs)
|
|
if (SI.getKind() == SDep::Order || Dep.getKind() == SDep::Output)
|
|
Worklist.push_back(SI);
|
|
Visited.insert(SuccSU);
|
|
}
|
|
return LateCycle;
|
|
}
|
|
|
|
/// If an instruction has a use that spans multiple iterations, then
|
|
/// return true. These instructions are characterized by having a back-ege
|
|
/// to a Phi, which contains a reference to another Phi.
|
|
static SUnit *multipleIterations(SUnit *SU, SwingSchedulerDAG *DAG) {
|
|
for (auto &P : SU->Preds)
|
|
if (DAG->isBackedge(SU, P) && P.getSUnit()->getInstr()->isPHI())
|
|
for (auto &S : P.getSUnit()->Succs)
|
|
if (S.getKind() == SDep::Data && S.getSUnit()->getInstr()->isPHI())
|
|
return P.getSUnit();
|
|
return nullptr;
|
|
}
|
|
|
|
/// Compute the scheduling start slot for the instruction. The start slot
|
|
/// depends on any predecessor or successor nodes scheduled already.
|
|
void SMSchedule::computeStart(SUnit *SU, int *MaxEarlyStart, int *MinLateStart,
|
|
int *MinEnd, int *MaxStart, int II,
|
|
SwingSchedulerDAG *DAG) {
|
|
// Iterate over each instruction that has been scheduled already. The start
|
|
// slot computation depends on whether the previously scheduled instruction
|
|
// is a predecessor or successor of the specified instruction.
|
|
for (int cycle = getFirstCycle(); cycle <= LastCycle; ++cycle) {
|
|
|
|
// Iterate over each instruction in the current cycle.
|
|
for (SUnit *I : getInstructions(cycle)) {
|
|
// Because we're processing a DAG for the dependences, we recognize
|
|
// the back-edge in recurrences by anti dependences.
|
|
for (unsigned i = 0, e = (unsigned)SU->Preds.size(); i != e; ++i) {
|
|
const SDep &Dep = SU->Preds[i];
|
|
if (Dep.getSUnit() == I) {
|
|
if (!DAG->isBackedge(SU, Dep)) {
|
|
int EarlyStart = cycle + Dep.getLatency() -
|
|
DAG->getDistance(Dep.getSUnit(), SU, Dep) * II;
|
|
*MaxEarlyStart = std::max(*MaxEarlyStart, EarlyStart);
|
|
if (DAG->isLoopCarriedDep(SU, Dep, false)) {
|
|
int End = earliestCycleInChain(Dep) + (II - 1);
|
|
*MinEnd = std::min(*MinEnd, End);
|
|
}
|
|
} else {
|
|
int LateStart = cycle - Dep.getLatency() +
|
|
DAG->getDistance(SU, Dep.getSUnit(), Dep) * II;
|
|
*MinLateStart = std::min(*MinLateStart, LateStart);
|
|
}
|
|
}
|
|
// For instruction that requires multiple iterations, make sure that
|
|
// the dependent instruction is not scheduled past the definition.
|
|
SUnit *BE = multipleIterations(I, DAG);
|
|
if (BE && Dep.getSUnit() == BE && !SU->getInstr()->isPHI() &&
|
|
!SU->isPred(I))
|
|
*MinLateStart = std::min(*MinLateStart, cycle);
|
|
}
|
|
for (unsigned i = 0, e = (unsigned)SU->Succs.size(); i != e; ++i) {
|
|
if (SU->Succs[i].getSUnit() == I) {
|
|
const SDep &Dep = SU->Succs[i];
|
|
if (!DAG->isBackedge(SU, Dep)) {
|
|
int LateStart = cycle - Dep.getLatency() +
|
|
DAG->getDistance(SU, Dep.getSUnit(), Dep) * II;
|
|
*MinLateStart = std::min(*MinLateStart, LateStart);
|
|
if (DAG->isLoopCarriedDep(SU, Dep)) {
|
|
int Start = latestCycleInChain(Dep) + 1 - II;
|
|
*MaxStart = std::max(*MaxStart, Start);
|
|
}
|
|
} else {
|
|
int EarlyStart = cycle + Dep.getLatency() -
|
|
DAG->getDistance(Dep.getSUnit(), SU, Dep) * II;
|
|
*MaxEarlyStart = std::max(*MaxEarlyStart, EarlyStart);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Order the instructions within a cycle so that the definitions occur
|
|
/// before the uses. Returns true if the instruction is added to the start
|
|
/// of the list, or false if added to the end.
|
|
void SMSchedule::orderDependence(SwingSchedulerDAG *SSD, SUnit *SU,
|
|
std::deque<SUnit *> &Insts) {
|
|
MachineInstr *MI = SU->getInstr();
|
|
bool OrderBeforeUse = false;
|
|
bool OrderAfterDef = false;
|
|
bool OrderBeforeDef = false;
|
|
unsigned MoveDef = 0;
|
|
unsigned MoveUse = 0;
|
|
int StageInst1 = stageScheduled(SU);
|
|
|
|
unsigned Pos = 0;
|
|
for (std::deque<SUnit *>::iterator I = Insts.begin(), E = Insts.end(); I != E;
|
|
++I, ++Pos) {
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i < e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg() || !TargetRegisterInfo::isVirtualRegister(MO.getReg()))
|
|
continue;
|
|
|
|
unsigned Reg = MO.getReg();
|
|
unsigned BasePos, OffsetPos;
|
|
if (ST.getInstrInfo()->getBaseAndOffsetPosition(*MI, BasePos, OffsetPos))
|
|
if (MI->getOperand(BasePos).getReg() == Reg)
|
|
if (unsigned NewReg = SSD->getInstrBaseReg(SU))
|
|
Reg = NewReg;
|
|
bool Reads, Writes;
|
|
std::tie(Reads, Writes) =
|
|
(*I)->getInstr()->readsWritesVirtualRegister(Reg);
|
|
if (MO.isDef() && Reads && stageScheduled(*I) <= StageInst1) {
|
|
OrderBeforeUse = true;
|
|
if (MoveUse == 0)
|
|
MoveUse = Pos;
|
|
} else if (MO.isDef() && Reads && stageScheduled(*I) > StageInst1) {
|
|
// Add the instruction after the scheduled instruction.
|
|
OrderAfterDef = true;
|
|
MoveDef = Pos;
|
|
} else if (MO.isUse() && Writes && stageScheduled(*I) == StageInst1) {
|
|
if (cycleScheduled(*I) == cycleScheduled(SU) && !(*I)->isSucc(SU)) {
|
|
OrderBeforeUse = true;
|
|
if (MoveUse == 0)
|
|
MoveUse = Pos;
|
|
} else {
|
|
OrderAfterDef = true;
|
|
MoveDef = Pos;
|
|
}
|
|
} else if (MO.isUse() && Writes && stageScheduled(*I) > StageInst1) {
|
|
OrderBeforeUse = true;
|
|
if (MoveUse == 0)
|
|
MoveUse = Pos;
|
|
if (MoveUse != 0) {
|
|
OrderAfterDef = true;
|
|
MoveDef = Pos - 1;
|
|
}
|
|
} else if (MO.isUse() && Writes && stageScheduled(*I) < StageInst1) {
|
|
// Add the instruction before the scheduled instruction.
|
|
OrderBeforeUse = true;
|
|
if (MoveUse == 0)
|
|
MoveUse = Pos;
|
|
} else if (MO.isUse() && stageScheduled(*I) == StageInst1 &&
|
|
isLoopCarriedDefOfUse(SSD, (*I)->getInstr(), MO)) {
|
|
if (MoveUse == 0) {
|
|
OrderBeforeDef = true;
|
|
MoveUse = Pos;
|
|
}
|
|
}
|
|
}
|
|
// Check for order dependences between instructions. Make sure the source
|
|
// is ordered before the destination.
|
|
for (auto &S : SU->Succs) {
|
|
if (S.getSUnit() != *I)
|
|
continue;
|
|
if (S.getKind() == SDep::Order && stageScheduled(*I) == StageInst1) {
|
|
OrderBeforeUse = true;
|
|
if (Pos < MoveUse)
|
|
MoveUse = Pos;
|
|
}
|
|
}
|
|
for (auto &P : SU->Preds) {
|
|
if (P.getSUnit() != *I)
|
|
continue;
|
|
if (P.getKind() == SDep::Order && stageScheduled(*I) == StageInst1) {
|
|
OrderAfterDef = true;
|
|
MoveDef = Pos;
|
|
}
|
|
}
|
|
}
|
|
|
|
// A circular dependence.
|
|
if (OrderAfterDef && OrderBeforeUse && MoveUse == MoveDef)
|
|
OrderBeforeUse = false;
|
|
|
|
// OrderAfterDef takes precedences over OrderBeforeDef. The latter is due
|
|
// to a loop-carried dependence.
|
|
if (OrderBeforeDef)
|
|
OrderBeforeUse = !OrderAfterDef || (MoveUse > MoveDef);
|
|
|
|
// The uncommon case when the instruction order needs to be updated because
|
|
// there is both a use and def.
|
|
if (OrderBeforeUse && OrderAfterDef) {
|
|
SUnit *UseSU = Insts.at(MoveUse);
|
|
SUnit *DefSU = Insts.at(MoveDef);
|
|
if (MoveUse > MoveDef) {
|
|
Insts.erase(Insts.begin() + MoveUse);
|
|
Insts.erase(Insts.begin() + MoveDef);
|
|
} else {
|
|
Insts.erase(Insts.begin() + MoveDef);
|
|
Insts.erase(Insts.begin() + MoveUse);
|
|
}
|
|
orderDependence(SSD, UseSU, Insts);
|
|
orderDependence(SSD, SU, Insts);
|
|
orderDependence(SSD, DefSU, Insts);
|
|
return;
|
|
}
|
|
// Put the new instruction first if there is a use in the list. Otherwise,
|
|
// put it at the end of the list.
|
|
if (OrderBeforeUse)
|
|
Insts.push_front(SU);
|
|
else
|
|
Insts.push_back(SU);
|
|
}
|
|
|
|
/// Return true if the scheduled Phi has a loop carried operand.
|
|
bool SMSchedule::isLoopCarried(SwingSchedulerDAG *SSD, MachineInstr &Phi) {
|
|
if (!Phi.isPHI())
|
|
return false;
|
|
assert(Phi.isPHI() && "Expecting a Phi.");
|
|
SUnit *DefSU = SSD->getSUnit(&Phi);
|
|
unsigned DefCycle = cycleScheduled(DefSU);
|
|
int DefStage = stageScheduled(DefSU);
|
|
|
|
unsigned InitVal = 0;
|
|
unsigned LoopVal = 0;
|
|
getPhiRegs(Phi, Phi.getParent(), InitVal, LoopVal);
|
|
SUnit *UseSU = SSD->getSUnit(MRI.getVRegDef(LoopVal));
|
|
if (!UseSU)
|
|
return true;
|
|
if (UseSU->getInstr()->isPHI())
|
|
return true;
|
|
unsigned LoopCycle = cycleScheduled(UseSU);
|
|
int LoopStage = stageScheduled(UseSU);
|
|
return (LoopCycle > DefCycle) || (LoopStage <= DefStage);
|
|
}
|
|
|
|
/// Return true if the instruction is a definition that is loop carried
|
|
/// and defines the use on the next iteration.
|
|
/// v1 = phi(v2, v3)
|
|
/// (Def) v3 = op v1
|
|
/// (MO) = v1
|
|
/// If MO appears before Def, then then v1 and v3 may get assigned to the same
|
|
/// register.
|
|
bool SMSchedule::isLoopCarriedDefOfUse(SwingSchedulerDAG *SSD,
|
|
MachineInstr *Def, MachineOperand &MO) {
|
|
if (!MO.isReg())
|
|
return false;
|
|
if (Def->isPHI())
|
|
return false;
|
|
MachineInstr *Phi = MRI.getVRegDef(MO.getReg());
|
|
if (!Phi || !Phi->isPHI() || Phi->getParent() != Def->getParent())
|
|
return false;
|
|
if (!isLoopCarried(SSD, *Phi))
|
|
return false;
|
|
unsigned LoopReg = getLoopPhiReg(*Phi, Phi->getParent());
|
|
for (unsigned i = 0, e = Def->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &DMO = Def->getOperand(i);
|
|
if (!DMO.isReg() || !DMO.isDef())
|
|
continue;
|
|
if (DMO.getReg() == LoopReg)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Check if the generated schedule is valid. This function checks if
|
|
// an instruction that uses a physical register is scheduled in a
|
|
// different stage than the definition. The pipeliner does not handle
|
|
// physical register values that may cross a basic block boundary.
|
|
bool SMSchedule::isValidSchedule(SwingSchedulerDAG *SSD) {
|
|
for (int i = 0, e = SSD->SUnits.size(); i < e; ++i) {
|
|
SUnit &SU = SSD->SUnits[i];
|
|
if (!SU.hasPhysRegDefs)
|
|
continue;
|
|
int StageDef = stageScheduled(&SU);
|
|
assert(StageDef != -1 && "Instruction should have been scheduled.");
|
|
for (auto &SI : SU.Succs)
|
|
if (SI.isAssignedRegDep())
|
|
if (ST.getRegisterInfo()->isPhysicalRegister(SI.getReg()))
|
|
if (stageScheduled(SI.getSUnit()) != StageDef)
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// A property of the node order in swing-modulo-scheduling is
|
|
/// that for nodes outside circuits the following holds:
|
|
/// none of them is scheduled after both a successor and a
|
|
/// predecessor.
|
|
/// The method below checks whether the property is met.
|
|
/// If not, debug information is printed and statistics information updated.
|
|
/// Note that we do not use an assert statement.
|
|
/// The reason is that although an invalid node oder may prevent
|
|
/// the pipeliner from finding a pipelined schedule for arbitrary II,
|
|
/// it does not lead to the generation of incorrect code.
|
|
void SwingSchedulerDAG::checkValidNodeOrder(const NodeSetType &Circuits) const {
|
|
|
|
// a sorted vector that maps each SUnit to its index in the NodeOrder
|
|
typedef std::pair<SUnit *, unsigned> UnitIndex;
|
|
std::vector<UnitIndex> Indices(NodeOrder.size(), std::make_pair(nullptr, 0));
|
|
|
|
for (unsigned i = 0, s = NodeOrder.size(); i < s; ++i)
|
|
Indices.push_back(std::make_pair(NodeOrder[i], i));
|
|
|
|
auto CompareKey = [](UnitIndex i1, UnitIndex i2) {
|
|
return std::get<0>(i1) < std::get<0>(i2);
|
|
};
|
|
|
|
// sort, so that we can perform a binary search
|
|
llvm::sort(Indices, CompareKey);
|
|
|
|
bool Valid = true;
|
|
(void)Valid;
|
|
// for each SUnit in the NodeOrder, check whether
|
|
// it appears after both a successor and a predecessor
|
|
// of the SUnit. If this is the case, and the SUnit
|
|
// is not part of circuit, then the NodeOrder is not
|
|
// valid.
|
|
for (unsigned i = 0, s = NodeOrder.size(); i < s; ++i) {
|
|
SUnit *SU = NodeOrder[i];
|
|
unsigned Index = i;
|
|
|
|
bool PredBefore = false;
|
|
bool SuccBefore = false;
|
|
|
|
SUnit *Succ;
|
|
SUnit *Pred;
|
|
(void)Succ;
|
|
(void)Pred;
|
|
|
|
for (SDep &PredEdge : SU->Preds) {
|
|
SUnit *PredSU = PredEdge.getSUnit();
|
|
unsigned PredIndex =
|
|
std::get<1>(*std::lower_bound(Indices.begin(), Indices.end(),
|
|
std::make_pair(PredSU, 0), CompareKey));
|
|
if (!PredSU->getInstr()->isPHI() && PredIndex < Index) {
|
|
PredBefore = true;
|
|
Pred = PredSU;
|
|
break;
|
|
}
|
|
}
|
|
|
|
for (SDep &SuccEdge : SU->Succs) {
|
|
SUnit *SuccSU = SuccEdge.getSUnit();
|
|
unsigned SuccIndex =
|
|
std::get<1>(*std::lower_bound(Indices.begin(), Indices.end(),
|
|
std::make_pair(SuccSU, 0), CompareKey));
|
|
if (!SuccSU->getInstr()->isPHI() && SuccIndex < Index) {
|
|
SuccBefore = true;
|
|
Succ = SuccSU;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (PredBefore && SuccBefore && !SU->getInstr()->isPHI()) {
|
|
// instructions in circuits are allowed to be scheduled
|
|
// after both a successor and predecessor.
|
|
bool InCircuit = std::any_of(
|
|
Circuits.begin(), Circuits.end(),
|
|
[SU](const NodeSet &Circuit) { return Circuit.count(SU); });
|
|
if (InCircuit)
|
|
LLVM_DEBUG(dbgs() << "In a circuit, predecessor ";);
|
|
else {
|
|
Valid = false;
|
|
NumNodeOrderIssues++;
|
|
LLVM_DEBUG(dbgs() << "Predecessor ";);
|
|
}
|
|
LLVM_DEBUG(dbgs() << Pred->NodeNum << " and successor " << Succ->NodeNum
|
|
<< " are scheduled before node " << SU->NodeNum
|
|
<< "\n";);
|
|
}
|
|
}
|
|
|
|
LLVM_DEBUG({
|
|
if (!Valid)
|
|
dbgs() << "Invalid node order found!\n";
|
|
});
|
|
}
|
|
|
|
/// Attempt to fix the degenerate cases when the instruction serialization
|
|
/// causes the register lifetimes to overlap. For example,
|
|
/// p' = store_pi(p, b)
|
|
/// = load p, offset
|
|
/// In this case p and p' overlap, which means that two registers are needed.
|
|
/// Instead, this function changes the load to use p' and updates the offset.
|
|
void SwingSchedulerDAG::fixupRegisterOverlaps(std::deque<SUnit *> &Instrs) {
|
|
unsigned OverlapReg = 0;
|
|
unsigned NewBaseReg = 0;
|
|
for (SUnit *SU : Instrs) {
|
|
MachineInstr *MI = SU->getInstr();
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i < e; ++i) {
|
|
const MachineOperand &MO = MI->getOperand(i);
|
|
// Look for an instruction that uses p. The instruction occurs in the
|
|
// same cycle but occurs later in the serialized order.
|
|
if (MO.isReg() && MO.isUse() && MO.getReg() == OverlapReg) {
|
|
// Check that the instruction appears in the InstrChanges structure,
|
|
// which contains instructions that can have the offset updated.
|
|
DenseMap<SUnit *, std::pair<unsigned, int64_t>>::iterator It =
|
|
InstrChanges.find(SU);
|
|
if (It != InstrChanges.end()) {
|
|
unsigned BasePos, OffsetPos;
|
|
// Update the base register and adjust the offset.
|
|
if (TII->getBaseAndOffsetPosition(*MI, BasePos, OffsetPos)) {
|
|
MachineInstr *NewMI = MF.CloneMachineInstr(MI);
|
|
NewMI->getOperand(BasePos).setReg(NewBaseReg);
|
|
int64_t NewOffset =
|
|
MI->getOperand(OffsetPos).getImm() - It->second.second;
|
|
NewMI->getOperand(OffsetPos).setImm(NewOffset);
|
|
SU->setInstr(NewMI);
|
|
MISUnitMap[NewMI] = SU;
|
|
NewMIs.insert(NewMI);
|
|
}
|
|
}
|
|
OverlapReg = 0;
|
|
NewBaseReg = 0;
|
|
break;
|
|
}
|
|
// Look for an instruction of the form p' = op(p), which uses and defines
|
|
// two virtual registers that get allocated to the same physical register.
|
|
unsigned TiedUseIdx = 0;
|
|
if (MI->isRegTiedToUseOperand(i, &TiedUseIdx)) {
|
|
// OverlapReg is p in the example above.
|
|
OverlapReg = MI->getOperand(TiedUseIdx).getReg();
|
|
// NewBaseReg is p' in the example above.
|
|
NewBaseReg = MI->getOperand(i).getReg();
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// After the schedule has been formed, call this function to combine
|
|
/// the instructions from the different stages/cycles. That is, this
|
|
/// function creates a schedule that represents a single iteration.
|
|
void SMSchedule::finalizeSchedule(SwingSchedulerDAG *SSD) {
|
|
// Move all instructions to the first stage from later stages.
|
|
for (int cycle = getFirstCycle(); cycle <= getFinalCycle(); ++cycle) {
|
|
for (int stage = 1, lastStage = getMaxStageCount(); stage <= lastStage;
|
|
++stage) {
|
|
std::deque<SUnit *> &cycleInstrs =
|
|
ScheduledInstrs[cycle + (stage * InitiationInterval)];
|
|
for (std::deque<SUnit *>::reverse_iterator I = cycleInstrs.rbegin(),
|
|
E = cycleInstrs.rend();
|
|
I != E; ++I)
|
|
ScheduledInstrs[cycle].push_front(*I);
|
|
}
|
|
}
|
|
// Iterate over the definitions in each instruction, and compute the
|
|
// stage difference for each use. Keep the maximum value.
|
|
for (auto &I : InstrToCycle) {
|
|
int DefStage = stageScheduled(I.first);
|
|
MachineInstr *MI = I.first->getInstr();
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i < e; ++i) {
|
|
MachineOperand &Op = MI->getOperand(i);
|
|
if (!Op.isReg() || !Op.isDef())
|
|
continue;
|
|
|
|
unsigned Reg = Op.getReg();
|
|
unsigned MaxDiff = 0;
|
|
bool PhiIsSwapped = false;
|
|
for (MachineRegisterInfo::use_iterator UI = MRI.use_begin(Reg),
|
|
EI = MRI.use_end();
|
|
UI != EI; ++UI) {
|
|
MachineOperand &UseOp = *UI;
|
|
MachineInstr *UseMI = UseOp.getParent();
|
|
SUnit *SUnitUse = SSD->getSUnit(UseMI);
|
|
int UseStage = stageScheduled(SUnitUse);
|
|
unsigned Diff = 0;
|
|
if (UseStage != -1 && UseStage >= DefStage)
|
|
Diff = UseStage - DefStage;
|
|
if (MI->isPHI()) {
|
|
if (isLoopCarried(SSD, *MI))
|
|
++Diff;
|
|
else
|
|
PhiIsSwapped = true;
|
|
}
|
|
MaxDiff = std::max(Diff, MaxDiff);
|
|
}
|
|
RegToStageDiff[Reg] = std::make_pair(MaxDiff, PhiIsSwapped);
|
|
}
|
|
}
|
|
|
|
// Erase all the elements in the later stages. Only one iteration should
|
|
// remain in the scheduled list, and it contains all the instructions.
|
|
for (int cycle = getFinalCycle() + 1; cycle <= LastCycle; ++cycle)
|
|
ScheduledInstrs.erase(cycle);
|
|
|
|
// Change the registers in instruction as specified in the InstrChanges
|
|
// map. We need to use the new registers to create the correct order.
|
|
for (int i = 0, e = SSD->SUnits.size(); i != e; ++i) {
|
|
SUnit *SU = &SSD->SUnits[i];
|
|
SSD->applyInstrChange(SU->getInstr(), *this);
|
|
}
|
|
|
|
// Reorder the instructions in each cycle to fix and improve the
|
|
// generated code.
|
|
for (int Cycle = getFirstCycle(), E = getFinalCycle(); Cycle <= E; ++Cycle) {
|
|
std::deque<SUnit *> &cycleInstrs = ScheduledInstrs[Cycle];
|
|
std::deque<SUnit *> newOrderPhi;
|
|
for (unsigned i = 0, e = cycleInstrs.size(); i < e; ++i) {
|
|
SUnit *SU = cycleInstrs[i];
|
|
if (SU->getInstr()->isPHI())
|
|
newOrderPhi.push_back(SU);
|
|
}
|
|
std::deque<SUnit *> newOrderI;
|
|
for (unsigned i = 0, e = cycleInstrs.size(); i < e; ++i) {
|
|
SUnit *SU = cycleInstrs[i];
|
|
if (!SU->getInstr()->isPHI())
|
|
orderDependence(SSD, SU, newOrderI);
|
|
}
|
|
// Replace the old order with the new order.
|
|
cycleInstrs.swap(newOrderPhi);
|
|
cycleInstrs.insert(cycleInstrs.end(), newOrderI.begin(), newOrderI.end());
|
|
SSD->fixupRegisterOverlaps(cycleInstrs);
|
|
}
|
|
|
|
LLVM_DEBUG(dump(););
|
|
}
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
/// Print the schedule information to the given output.
|
|
void SMSchedule::print(raw_ostream &os) const {
|
|
// Iterate over each cycle.
|
|
for (int cycle = getFirstCycle(); cycle <= getFinalCycle(); ++cycle) {
|
|
// Iterate over each instruction in the cycle.
|
|
const_sched_iterator cycleInstrs = ScheduledInstrs.find(cycle);
|
|
for (SUnit *CI : cycleInstrs->second) {
|
|
os << "cycle " << cycle << " (" << stageScheduled(CI) << ") ";
|
|
os << "(" << CI->NodeNum << ") ";
|
|
CI->getInstr()->print(os);
|
|
os << "\n";
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Utility function used for debugging to print the schedule.
|
|
LLVM_DUMP_METHOD void SMSchedule::dump() const { print(dbgs()); }
|
|
#endif
|