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to be emitted. Don't add one to the latency of a completed instruction if the latency of the op is 0. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26718 91177308-0d34-0410-b5e6-96231b3b80d8
1102 lines
38 KiB
C++
1102 lines
38 KiB
C++
//===---- ScheduleDAGList.cpp - Implement a list scheduler for isel DAG ---===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by Evan Cheng and is distributed under the
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// University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This implements bottom-up and top-down list schedulers, using standard
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// algorithms. The basic approach uses a priority queue of available nodes to
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// schedule. One at a time, nodes are taken from the priority queue (thus in
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// priority order), checked for legality to schedule, and emitted if legal.
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//
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// Nodes may not be legal to schedule either due to structural hazards (e.g.
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// pipeline or resource constraints) or because an input to the instruction has
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// not completed execution.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "sched"
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#include "llvm/CodeGen/ScheduleDAG.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/ADT/Statistic.h"
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#include <climits>
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#include <iostream>
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#include <queue>
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#include <set>
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#include <vector>
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#include "llvm/Support/CommandLine.h"
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using namespace llvm;
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namespace {
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Statistic<> NumNoops ("scheduler", "Number of noops inserted");
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Statistic<> NumStalls("scheduler", "Number of pipeline stalls");
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/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
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/// a group of nodes flagged together.
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struct SUnit {
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SDNode *Node; // Representative node.
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std::vector<SDNode*> FlaggedNodes; // All nodes flagged to Node.
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// Preds/Succs - The SUnits before/after us in the graph. The boolean value
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// is true if the edge is a token chain edge, false if it is a value edge.
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std::set<std::pair<SUnit*,bool> > Preds; // All sunit predecessors.
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std::set<std::pair<SUnit*,bool> > Succs; // All sunit successors.
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short NumPredsLeft; // # of preds not scheduled.
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short NumSuccsLeft; // # of succs not scheduled.
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short NumChainPredsLeft; // # of chain preds not scheduled.
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short NumChainSuccsLeft; // # of chain succs not scheduled.
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bool isTwoAddress : 1; // Is a two-address instruction.
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bool isDefNUseOperand : 1; // Is a def&use operand.
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bool isPending : 1; // True once pending.
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bool isAvailable : 1; // True once available.
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bool isScheduled : 1; // True once scheduled.
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unsigned short Latency; // Node latency.
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unsigned CycleBound; // Upper/lower cycle to be scheduled at.
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unsigned Cycle; // Once scheduled, the cycle of the op.
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unsigned NodeNum; // Entry # of node in the node vector.
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SUnit(SDNode *node, unsigned nodenum)
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: Node(node), NumPredsLeft(0), NumSuccsLeft(0),
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NumChainPredsLeft(0), NumChainSuccsLeft(0),
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isTwoAddress(false), isDefNUseOperand(false),
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isPending(false), isAvailable(false), isScheduled(false),
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Latency(0), CycleBound(0), Cycle(0), NodeNum(nodenum) {}
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void dump(const SelectionDAG *G) const;
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void dumpAll(const SelectionDAG *G) const;
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};
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}
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void SUnit::dump(const SelectionDAG *G) const {
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std::cerr << "SU: ";
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Node->dump(G);
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std::cerr << "\n";
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if (FlaggedNodes.size() != 0) {
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for (unsigned i = 0, e = FlaggedNodes.size(); i != e; i++) {
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std::cerr << " ";
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FlaggedNodes[i]->dump(G);
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std::cerr << "\n";
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}
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}
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}
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void SUnit::dumpAll(const SelectionDAG *G) const {
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dump(G);
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std::cerr << " # preds left : " << NumPredsLeft << "\n";
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std::cerr << " # succs left : " << NumSuccsLeft << "\n";
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std::cerr << " # chain preds left : " << NumChainPredsLeft << "\n";
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std::cerr << " # chain succs left : " << NumChainSuccsLeft << "\n";
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std::cerr << " Latency : " << Latency << "\n";
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if (Preds.size() != 0) {
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std::cerr << " Predecessors:\n";
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for (std::set<std::pair<SUnit*,bool> >::const_iterator I = Preds.begin(),
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E = Preds.end(); I != E; ++I) {
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if (I->second)
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std::cerr << " ch ";
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else
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std::cerr << " val ";
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I->first->dump(G);
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}
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}
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if (Succs.size() != 0) {
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std::cerr << " Successors:\n";
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for (std::set<std::pair<SUnit*, bool> >::const_iterator I = Succs.begin(),
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E = Succs.end(); I != E; ++I) {
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if (I->second)
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std::cerr << " ch ";
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else
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std::cerr << " val ";
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I->first->dump(G);
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}
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}
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std::cerr << "\n";
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}
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//===----------------------------------------------------------------------===//
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/// SchedulingPriorityQueue - This interface is used to plug different
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/// priorities computation algorithms into the list scheduler. It implements the
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/// interface of a standard priority queue, where nodes are inserted in
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/// arbitrary order and returned in priority order. The computation of the
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/// priority and the representation of the queue are totally up to the
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/// implementation to decide.
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///
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namespace {
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class SchedulingPriorityQueue {
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public:
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virtual ~SchedulingPriorityQueue() {}
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virtual void initNodes(const std::vector<SUnit> &SUnits) = 0;
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virtual void releaseState() = 0;
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virtual bool empty() const = 0;
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virtual void push(SUnit *U) = 0;
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virtual void push_all(const std::vector<SUnit *> &Nodes) = 0;
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virtual SUnit *pop() = 0;
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/// ScheduledNode - As each node is scheduled, this method is invoked. This
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/// allows the priority function to adjust the priority of node that have
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/// already been emitted.
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virtual void ScheduledNode(SUnit *Node) {}
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};
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}
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namespace {
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//===----------------------------------------------------------------------===//
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/// ScheduleDAGList - The actual list scheduler implementation. This supports
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/// both top-down and bottom-up scheduling.
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///
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class ScheduleDAGList : public ScheduleDAG {
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private:
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// SDNode to SUnit mapping (many to one).
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std::map<SDNode*, SUnit*> SUnitMap;
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// The schedule. Null SUnit*'s represent noop instructions.
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std::vector<SUnit*> Sequence;
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// The scheduling units.
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std::vector<SUnit> SUnits;
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/// isBottomUp - This is true if the scheduling problem is bottom-up, false if
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/// it is top-down.
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bool isBottomUp;
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/// AvailableQueue - The priority queue to use for the available SUnits.
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///
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SchedulingPriorityQueue *AvailableQueue;
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/// PendingQueue - This contains all of the instructions whose operands have
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/// been issued, but their results are not ready yet (due to the latency of
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/// the operation). Once the operands becomes available, the instruction is
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/// added to the AvailableQueue. This keeps track of each SUnit and the
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/// number of cycles left to execute before the operation is available.
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std::vector<std::pair<unsigned, SUnit*> > PendingQueue;
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/// HazardRec - The hazard recognizer to use.
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HazardRecognizer *HazardRec;
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public:
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ScheduleDAGList(SelectionDAG &dag, MachineBasicBlock *bb,
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const TargetMachine &tm, bool isbottomup,
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SchedulingPriorityQueue *availqueue,
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HazardRecognizer *HR)
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: ScheduleDAG(dag, bb, tm), isBottomUp(isbottomup),
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AvailableQueue(availqueue), HazardRec(HR) {
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}
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~ScheduleDAGList() {
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delete HazardRec;
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delete AvailableQueue;
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}
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void Schedule();
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void dumpSchedule() const;
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private:
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SUnit *NewSUnit(SDNode *N);
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void ReleasePred(SUnit *PredSU, bool isChain, unsigned CurCycle);
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void ReleaseSucc(SUnit *SuccSU, bool isChain);
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void ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle);
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void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
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void ListScheduleTopDown();
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void ListScheduleBottomUp();
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void BuildSchedUnits();
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void EmitSchedule();
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};
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} // end anonymous namespace
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HazardRecognizer::~HazardRecognizer() {}
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/// NewSUnit - Creates a new SUnit and return a ptr to it.
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SUnit *ScheduleDAGList::NewSUnit(SDNode *N) {
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SUnits.push_back(SUnit(N, SUnits.size()));
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return &SUnits.back();
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}
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/// BuildSchedUnits - Build SUnits from the selection dag that we are input.
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/// This SUnit graph is similar to the SelectionDAG, but represents flagged
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/// together nodes with a single SUnit.
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void ScheduleDAGList::BuildSchedUnits() {
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// Reserve entries in the vector for each of the SUnits we are creating. This
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// ensure that reallocation of the vector won't happen, so SUnit*'s won't get
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// invalidated.
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SUnits.reserve(std::distance(DAG.allnodes_begin(), DAG.allnodes_end()));
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const InstrItineraryData &InstrItins = TM.getInstrItineraryData();
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for (SelectionDAG::allnodes_iterator NI = DAG.allnodes_begin(),
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E = DAG.allnodes_end(); NI != E; ++NI) {
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if (isPassiveNode(NI)) // Leaf node, e.g. a TargetImmediate.
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continue;
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// If this node has already been processed, stop now.
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if (SUnitMap[NI]) continue;
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SUnit *NodeSUnit = NewSUnit(NI);
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// See if anything is flagged to this node, if so, add them to flagged
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// nodes. Nodes can have at most one flag input and one flag output. Flags
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// are required the be the last operand and result of a node.
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// Scan up, adding flagged preds to FlaggedNodes.
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SDNode *N = NI;
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while (N->getNumOperands() &&
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N->getOperand(N->getNumOperands()-1).getValueType() == MVT::Flag) {
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N = N->getOperand(N->getNumOperands()-1).Val;
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NodeSUnit->FlaggedNodes.push_back(N);
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SUnitMap[N] = NodeSUnit;
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}
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// Scan down, adding this node and any flagged succs to FlaggedNodes if they
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// have a user of the flag operand.
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N = NI;
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while (N->getValueType(N->getNumValues()-1) == MVT::Flag) {
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SDOperand FlagVal(N, N->getNumValues()-1);
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// There are either zero or one users of the Flag result.
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bool HasFlagUse = false;
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for (SDNode::use_iterator UI = N->use_begin(), E = N->use_end();
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UI != E; ++UI)
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if (FlagVal.isOperand(*UI)) {
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HasFlagUse = true;
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NodeSUnit->FlaggedNodes.push_back(N);
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SUnitMap[N] = NodeSUnit;
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N = *UI;
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break;
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}
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if (!HasFlagUse) break;
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}
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// Now all flagged nodes are in FlaggedNodes and N is the bottom-most node.
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// Update the SUnit
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NodeSUnit->Node = N;
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SUnitMap[N] = NodeSUnit;
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// Compute the latency for the node. We use the sum of the latencies for
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// all nodes flagged together into this SUnit.
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if (InstrItins.isEmpty()) {
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// No latency information.
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NodeSUnit->Latency = 1;
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} else {
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NodeSUnit->Latency = 0;
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if (N->isTargetOpcode()) {
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unsigned SchedClass = TII->getSchedClass(N->getTargetOpcode());
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InstrStage *S = InstrItins.begin(SchedClass);
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InstrStage *E = InstrItins.end(SchedClass);
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for (; S != E; ++S)
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NodeSUnit->Latency += S->Cycles;
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}
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for (unsigned i = 0, e = NodeSUnit->FlaggedNodes.size(); i != e; ++i) {
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SDNode *FNode = NodeSUnit->FlaggedNodes[i];
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if (FNode->isTargetOpcode()) {
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unsigned SchedClass = TII->getSchedClass(FNode->getTargetOpcode());
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InstrStage *S = InstrItins.begin(SchedClass);
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InstrStage *E = InstrItins.end(SchedClass);
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for (; S != E; ++S)
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NodeSUnit->Latency += S->Cycles;
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}
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}
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}
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}
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// Pass 2: add the preds, succs, etc.
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for (unsigned su = 0, e = SUnits.size(); su != e; ++su) {
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SUnit *SU = &SUnits[su];
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SDNode *MainNode = SU->Node;
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if (MainNode->isTargetOpcode() &&
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TII->isTwoAddrInstr(MainNode->getTargetOpcode()))
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SU->isTwoAddress = true;
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// Find all predecessors and successors of the group.
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// Temporarily add N to make code simpler.
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SU->FlaggedNodes.push_back(MainNode);
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for (unsigned n = 0, e = SU->FlaggedNodes.size(); n != e; ++n) {
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SDNode *N = SU->FlaggedNodes[n];
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for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
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SDNode *OpN = N->getOperand(i).Val;
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if (isPassiveNode(OpN)) continue; // Not scheduled.
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SUnit *OpSU = SUnitMap[OpN];
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assert(OpSU && "Node has no SUnit!");
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if (OpSU == SU) continue; // In the same group.
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MVT::ValueType OpVT = N->getOperand(i).getValueType();
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assert(OpVT != MVT::Flag && "Flagged nodes should be in same sunit!");
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bool isChain = OpVT == MVT::Other;
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if (SU->Preds.insert(std::make_pair(OpSU, isChain)).second) {
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if (!isChain) {
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SU->NumPredsLeft++;
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} else {
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SU->NumChainPredsLeft++;
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}
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}
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if (OpSU->Succs.insert(std::make_pair(SU, isChain)).second) {
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if (!isChain) {
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OpSU->NumSuccsLeft++;
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} else {
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OpSU->NumChainSuccsLeft++;
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}
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}
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}
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}
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// Remove MainNode from FlaggedNodes again.
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SU->FlaggedNodes.pop_back();
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}
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return;
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DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
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SUnits[su].dumpAll(&DAG));
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}
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/// EmitSchedule - Emit the machine code in scheduled order.
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void ScheduleDAGList::EmitSchedule() {
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std::map<SDNode*, unsigned> VRBaseMap;
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for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
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if (SUnit *SU = Sequence[i]) {
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for (unsigned j = 0, ee = SU->FlaggedNodes.size(); j != ee; j++)
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EmitNode(SU->FlaggedNodes[j], VRBaseMap);
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EmitNode(SU->Node, VRBaseMap);
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} else {
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// Null SUnit* is a noop.
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EmitNoop();
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}
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}
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}
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/// dump - dump the schedule.
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void ScheduleDAGList::dumpSchedule() const {
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for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
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if (SUnit *SU = Sequence[i])
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SU->dump(&DAG);
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else
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std::cerr << "**** NOOP ****\n";
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}
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}
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/// Schedule - Schedule the DAG using list scheduling.
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void ScheduleDAGList::Schedule() {
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DEBUG(std::cerr << "********** List Scheduling **********\n");
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// Build scheduling units.
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BuildSchedUnits();
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AvailableQueue->initNodes(SUnits);
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// Execute the actual scheduling loop Top-Down or Bottom-Up as appropriate.
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if (isBottomUp)
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ListScheduleBottomUp();
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else
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ListScheduleTopDown();
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AvailableQueue->releaseState();
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DEBUG(std::cerr << "*** Final schedule ***\n");
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DEBUG(dumpSchedule());
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DEBUG(std::cerr << "\n");
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// Emit in scheduled order
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EmitSchedule();
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}
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//===----------------------------------------------------------------------===//
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// Bottom-Up Scheduling
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//===----------------------------------------------------------------------===//
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/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. Add it to
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/// the Available queue is the count reaches zero. Also update its cycle bound.
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void ScheduleDAGList::ReleasePred(SUnit *PredSU, bool isChain,
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unsigned CurCycle) {
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// FIXME: the distance between two nodes is not always == the predecessor's
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// latency. For example, the reader can very well read the register written
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// by the predecessor later than the issue cycle. It also depends on the
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// interrupt model (drain vs. freeze).
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PredSU->CycleBound = std::max(PredSU->CycleBound, CurCycle + PredSU->Latency);
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if (!isChain)
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PredSU->NumSuccsLeft--;
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else
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PredSU->NumChainSuccsLeft--;
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#ifndef NDEBUG
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if (PredSU->NumSuccsLeft < 0 || PredSU->NumChainSuccsLeft < 0) {
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std::cerr << "*** List scheduling failed! ***\n";
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PredSU->dump(&DAG);
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std::cerr << " has been released too many times!\n";
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assert(0);
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}
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#endif
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if ((PredSU->NumSuccsLeft + PredSU->NumChainSuccsLeft) == 0) {
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// EntryToken has to go last! Special case it here.
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if (PredSU->Node->getOpcode() != ISD::EntryToken) {
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PredSU->isAvailable = true;
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AvailableQueue->push(PredSU);
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}
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}
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}
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/// ScheduleNodeBottomUp - Add the node to the schedule. Decrement the pending
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/// count of its predecessors. If a predecessor pending count is zero, add it to
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/// the Available queue.
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void ScheduleDAGList::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) {
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DEBUG(std::cerr << "*** Scheduling [" << CurCycle << "]: ");
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DEBUG(SU->dump(&DAG));
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SU->Cycle = CurCycle;
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Sequence.push_back(SU);
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// Bottom up: release predecessors
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for (std::set<std::pair<SUnit*, bool> >::iterator I = SU->Preds.begin(),
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E = SU->Preds.end(); I != E; ++I) {
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ReleasePred(I->first, I->second, CurCycle);
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// FIXME: This is something used by the priority function that it should
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// calculate directly.
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if (!I->second)
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SU->NumPredsLeft--;
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}
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}
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/// isReady - True if node's lower cycle bound is less or equal to the current
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/// scheduling cycle. Always true if all nodes have uniform latency 1.
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static inline bool isReady(SUnit *SU, unsigned CurrCycle) {
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return SU->CycleBound <= CurrCycle;
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}
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|
|
/// ListScheduleBottomUp - The main loop of list scheduling for bottom-up
|
|
/// schedulers.
|
|
void ScheduleDAGList::ListScheduleBottomUp() {
|
|
unsigned CurrCycle = 0;
|
|
// Add root to Available queue.
|
|
AvailableQueue->push(SUnitMap[DAG.getRoot().Val]);
|
|
|
|
// While Available queue is not empty, grab the node with the highest
|
|
// priority. If it is not ready put it back. Schedule the node.
|
|
std::vector<SUnit*> NotReady;
|
|
while (!AvailableQueue->empty()) {
|
|
SUnit *CurrNode = AvailableQueue->pop();
|
|
|
|
while (!isReady(CurrNode, CurrCycle)) {
|
|
NotReady.push_back(CurrNode);
|
|
CurrNode = AvailableQueue->pop();
|
|
}
|
|
|
|
// Add the nodes that aren't ready back onto the available list.
|
|
AvailableQueue->push_all(NotReady);
|
|
NotReady.clear();
|
|
|
|
ScheduleNodeBottomUp(CurrNode, CurrCycle);
|
|
CurrCycle++;
|
|
CurrNode->isScheduled = true;
|
|
AvailableQueue->ScheduledNode(CurrNode);
|
|
}
|
|
|
|
// Add entry node last
|
|
if (DAG.getEntryNode().Val != DAG.getRoot().Val) {
|
|
SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
|
|
Sequence.push_back(Entry);
|
|
}
|
|
|
|
// Reverse the order if it is bottom up.
|
|
std::reverse(Sequence.begin(), Sequence.end());
|
|
|
|
|
|
#ifndef NDEBUG
|
|
// Verify that all SUnits were scheduled.
|
|
bool AnyNotSched = false;
|
|
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
|
|
if (SUnits[i].NumSuccsLeft != 0 || SUnits[i].NumChainSuccsLeft != 0) {
|
|
if (!AnyNotSched)
|
|
std::cerr << "*** List scheduling failed! ***\n";
|
|
SUnits[i].dump(&DAG);
|
|
std::cerr << "has not been scheduled!\n";
|
|
AnyNotSched = true;
|
|
}
|
|
}
|
|
assert(!AnyNotSched);
|
|
#endif
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Top-Down Scheduling
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
|
|
/// the PendingQueue if the count reaches zero.
|
|
void ScheduleDAGList::ReleaseSucc(SUnit *SuccSU, bool isChain) {
|
|
if (!isChain)
|
|
SuccSU->NumPredsLeft--;
|
|
else
|
|
SuccSU->NumChainPredsLeft--;
|
|
|
|
assert(SuccSU->NumPredsLeft >= 0 && SuccSU->NumChainPredsLeft >= 0 &&
|
|
"List scheduling internal error");
|
|
|
|
if ((SuccSU->NumPredsLeft + SuccSU->NumChainPredsLeft) == 0) {
|
|
// Compute how many cycles it will be before this actually becomes
|
|
// available. This is the max of the start time of all predecessors plus
|
|
// their latencies.
|
|
unsigned AvailableCycle = 0;
|
|
for (std::set<std::pair<SUnit*, bool> >::iterator I = SuccSU->Preds.begin(),
|
|
E = SuccSU->Preds.end(); I != E; ++I) {
|
|
// If this is a token edge, we don't need to wait for the latency of the
|
|
// preceeding instruction (e.g. a long-latency load) unless there is also
|
|
// some other data dependence.
|
|
unsigned PredDoneCycle = I->first->Cycle;
|
|
if (!I->second)
|
|
PredDoneCycle += I->first->Latency;
|
|
else if (I->first->Latency)
|
|
PredDoneCycle += 1;
|
|
|
|
AvailableCycle = std::max(AvailableCycle, PredDoneCycle);
|
|
}
|
|
|
|
PendingQueue.push_back(std::make_pair(AvailableCycle, SuccSU));
|
|
SuccSU->isPending = true;
|
|
}
|
|
}
|
|
|
|
/// ScheduleNodeTopDown - Add the node to the schedule. Decrement the pending
|
|
/// count of its successors. If a successor pending count is zero, add it to
|
|
/// the Available queue.
|
|
void ScheduleDAGList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
|
|
DEBUG(std::cerr << "*** Scheduling [" << CurCycle << "]: ");
|
|
DEBUG(SU->dump(&DAG));
|
|
|
|
Sequence.push_back(SU);
|
|
SU->Cycle = CurCycle;
|
|
|
|
// Bottom up: release successors.
|
|
for (std::set<std::pair<SUnit*, bool> >::iterator I = SU->Succs.begin(),
|
|
E = SU->Succs.end(); I != E; ++I)
|
|
ReleaseSucc(I->first, I->second);
|
|
}
|
|
|
|
/// ListScheduleTopDown - The main loop of list scheduling for top-down
|
|
/// schedulers.
|
|
void ScheduleDAGList::ListScheduleTopDown() {
|
|
unsigned CurCycle = 0;
|
|
SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
|
|
|
|
// All leaves to Available queue.
|
|
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
|
|
// It is available if it has no predecessors.
|
|
if (SUnits[i].Preds.size() == 0 && &SUnits[i] != Entry) {
|
|
AvailableQueue->push(&SUnits[i]);
|
|
SUnits[i].isAvailable = SUnits[i].isPending = true;
|
|
}
|
|
}
|
|
|
|
// Emit the entry node first.
|
|
ScheduleNodeTopDown(Entry, CurCycle);
|
|
HazardRec->EmitInstruction(Entry->Node);
|
|
|
|
// While Available queue is not empty, grab the node with the highest
|
|
// priority. If it is not ready put it back. Schedule the node.
|
|
std::vector<SUnit*> NotReady;
|
|
while (!AvailableQueue->empty() || !PendingQueue.empty()) {
|
|
// Check to see if any of the pending instructions are ready to issue. If
|
|
// so, add them to the available queue.
|
|
for (unsigned i = 0, e = PendingQueue.size(); i != e; ++i) {
|
|
if (PendingQueue[i].first == CurCycle) {
|
|
AvailableQueue->push(PendingQueue[i].second);
|
|
PendingQueue[i].second->isAvailable = true;
|
|
PendingQueue[i] = PendingQueue.back();
|
|
PendingQueue.pop_back();
|
|
--i; --e;
|
|
} else {
|
|
assert(PendingQueue[i].first > CurCycle && "Negative latency?");
|
|
}
|
|
}
|
|
|
|
// If there are no instructions available, don't try to issue anything, and
|
|
// don't advance the hazard recognizer.
|
|
if (AvailableQueue->empty()) {
|
|
++CurCycle;
|
|
continue;
|
|
}
|
|
|
|
SUnit *FoundSUnit = 0;
|
|
SDNode *FoundNode = 0;
|
|
|
|
bool HasNoopHazards = false;
|
|
while (!AvailableQueue->empty()) {
|
|
SUnit *CurSUnit = AvailableQueue->pop();
|
|
|
|
// Get the node represented by this SUnit.
|
|
FoundNode = CurSUnit->Node;
|
|
|
|
// If this is a pseudo op, like copyfromreg, look to see if there is a
|
|
// real target node flagged to it. If so, use the target node.
|
|
for (unsigned i = 0, e = CurSUnit->FlaggedNodes.size();
|
|
FoundNode->getOpcode() < ISD::BUILTIN_OP_END && i != e; ++i)
|
|
FoundNode = CurSUnit->FlaggedNodes[i];
|
|
|
|
HazardRecognizer::HazardType HT = HazardRec->getHazardType(FoundNode);
|
|
if (HT == HazardRecognizer::NoHazard) {
|
|
FoundSUnit = CurSUnit;
|
|
break;
|
|
}
|
|
|
|
// Remember if this is a noop hazard.
|
|
HasNoopHazards |= HT == HazardRecognizer::NoopHazard;
|
|
|
|
NotReady.push_back(CurSUnit);
|
|
}
|
|
|
|
// Add the nodes that aren't ready back onto the available list.
|
|
if (!NotReady.empty()) {
|
|
AvailableQueue->push_all(NotReady);
|
|
NotReady.clear();
|
|
}
|
|
|
|
// If we found a node to schedule, do it now.
|
|
if (FoundSUnit) {
|
|
ScheduleNodeTopDown(FoundSUnit, CurCycle);
|
|
HazardRec->EmitInstruction(FoundNode);
|
|
FoundSUnit->isScheduled = true;
|
|
AvailableQueue->ScheduledNode(FoundSUnit);
|
|
|
|
// If this is a pseudo-op node, we don't want to increment the current
|
|
// cycle.
|
|
if (FoundSUnit->Latency) // Don't increment CurCycle for pseudo-ops!
|
|
++CurCycle;
|
|
} else if (!HasNoopHazards) {
|
|
// Otherwise, we have a pipeline stall, but no other problem, just advance
|
|
// the current cycle and try again.
|
|
DEBUG(std::cerr << "*** Advancing cycle, no work to do\n");
|
|
HazardRec->AdvanceCycle();
|
|
++NumStalls;
|
|
++CurCycle;
|
|
} else {
|
|
// Otherwise, we have no instructions to issue and we have instructions
|
|
// that will fault if we don't do this right. This is the case for
|
|
// processors without pipeline interlocks and other cases.
|
|
DEBUG(std::cerr << "*** Emitting noop\n");
|
|
HazardRec->EmitNoop();
|
|
Sequence.push_back(0); // NULL SUnit* -> noop
|
|
++NumNoops;
|
|
++CurCycle;
|
|
}
|
|
}
|
|
|
|
#ifndef NDEBUG
|
|
// Verify that all SUnits were scheduled.
|
|
bool AnyNotSched = false;
|
|
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
|
|
if (SUnits[i].NumPredsLeft != 0 || SUnits[i].NumChainPredsLeft != 0) {
|
|
if (!AnyNotSched)
|
|
std::cerr << "*** List scheduling failed! ***\n";
|
|
SUnits[i].dump(&DAG);
|
|
std::cerr << "has not been scheduled!\n";
|
|
AnyNotSched = true;
|
|
}
|
|
}
|
|
assert(!AnyNotSched);
|
|
#endif
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// RegReductionPriorityQueue Implementation
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This is a SchedulingPriorityQueue that schedules using Sethi Ullman numbers
|
|
// to reduce register pressure.
|
|
//
|
|
namespace {
|
|
class RegReductionPriorityQueue;
|
|
|
|
/// Sorting functions for the Available queue.
|
|
struct ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
|
|
RegReductionPriorityQueue *SPQ;
|
|
ls_rr_sort(RegReductionPriorityQueue *spq) : SPQ(spq) {}
|
|
ls_rr_sort(const ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
|
|
|
|
bool operator()(const SUnit* left, const SUnit* right) const;
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
namespace {
|
|
class RegReductionPriorityQueue : public SchedulingPriorityQueue {
|
|
// SUnits - The SUnits for the current graph.
|
|
const std::vector<SUnit> *SUnits;
|
|
|
|
// SethiUllmanNumbers - The SethiUllman number for each node.
|
|
std::vector<int> SethiUllmanNumbers;
|
|
|
|
std::priority_queue<SUnit*, std::vector<SUnit*>, ls_rr_sort> Queue;
|
|
public:
|
|
RegReductionPriorityQueue() : Queue(ls_rr_sort(this)) {
|
|
}
|
|
|
|
void initNodes(const std::vector<SUnit> &sunits) {
|
|
SUnits = &sunits;
|
|
// Calculate node priorities.
|
|
CalculatePriorities();
|
|
}
|
|
void releaseState() {
|
|
SUnits = 0;
|
|
SethiUllmanNumbers.clear();
|
|
}
|
|
|
|
unsigned getSethiUllmanNumber(unsigned NodeNum) const {
|
|
assert(NodeNum < SethiUllmanNumbers.size());
|
|
return SethiUllmanNumbers[NodeNum];
|
|
}
|
|
|
|
bool empty() const { return Queue.empty(); }
|
|
|
|
void push(SUnit *U) {
|
|
Queue.push(U);
|
|
}
|
|
void push_all(const std::vector<SUnit *> &Nodes) {
|
|
for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
|
|
Queue.push(Nodes[i]);
|
|
}
|
|
|
|
SUnit *pop() {
|
|
SUnit *V = Queue.top();
|
|
Queue.pop();
|
|
return V;
|
|
}
|
|
private:
|
|
void CalculatePriorities();
|
|
int CalcNodePriority(const SUnit *SU);
|
|
};
|
|
}
|
|
|
|
bool ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
|
|
unsigned LeftNum = left->NodeNum;
|
|
unsigned RightNum = right->NodeNum;
|
|
|
|
int LBonus = (int)left ->isDefNUseOperand;
|
|
int RBonus = (int)right->isDefNUseOperand;
|
|
|
|
// Special tie breaker: if two nodes share a operand, the one that
|
|
// use it as a def&use operand is preferred.
|
|
if (left->isTwoAddress && !right->isTwoAddress) {
|
|
SDNode *DUNode = left->Node->getOperand(0).Val;
|
|
if (DUNode->isOperand(right->Node))
|
|
LBonus++;
|
|
}
|
|
if (!left->isTwoAddress && right->isTwoAddress) {
|
|
SDNode *DUNode = right->Node->getOperand(0).Val;
|
|
if (DUNode->isOperand(left->Node))
|
|
RBonus++;
|
|
}
|
|
|
|
// Priority1 is just the number of live range genned.
|
|
int LPriority1 = left ->NumPredsLeft - LBonus;
|
|
int RPriority1 = right->NumPredsLeft - RBonus;
|
|
int LPriority2 = SPQ->getSethiUllmanNumber(LeftNum) + LBonus;
|
|
int RPriority2 = SPQ->getSethiUllmanNumber(RightNum) + RBonus;
|
|
|
|
if (LPriority1 > RPriority1)
|
|
return true;
|
|
else if (LPriority1 == RPriority1)
|
|
if (LPriority2 < RPriority2)
|
|
return true;
|
|
else if (LPriority2 == RPriority2)
|
|
if (left->CycleBound > right->CycleBound)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
/// CalcNodePriority - Priority is the Sethi Ullman number.
|
|
/// Smaller number is the higher priority.
|
|
int RegReductionPriorityQueue::CalcNodePriority(const SUnit *SU) {
|
|
int &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
|
|
if (SethiUllmanNumber != INT_MIN)
|
|
return SethiUllmanNumber;
|
|
|
|
if (SU->Preds.size() == 0) {
|
|
SethiUllmanNumber = 1;
|
|
} else {
|
|
int Extra = 0;
|
|
for (std::set<std::pair<SUnit*, bool> >::const_iterator
|
|
I = SU->Preds.begin(), E = SU->Preds.end(); I != E; ++I) {
|
|
if (I->second) continue; // ignore chain preds.
|
|
SUnit *PredSU = I->first;
|
|
int PredSethiUllman = CalcNodePriority(PredSU);
|
|
if (PredSethiUllman > SethiUllmanNumber) {
|
|
SethiUllmanNumber = PredSethiUllman;
|
|
Extra = 0;
|
|
} else if (PredSethiUllman == SethiUllmanNumber)
|
|
Extra++;
|
|
}
|
|
|
|
if (SU->Node->getOpcode() != ISD::TokenFactor)
|
|
SethiUllmanNumber += Extra;
|
|
else
|
|
SethiUllmanNumber = (Extra == 1) ? 0 : Extra-1;
|
|
}
|
|
|
|
return SethiUllmanNumber;
|
|
}
|
|
|
|
/// CalculatePriorities - Calculate priorities of all scheduling units.
|
|
void RegReductionPriorityQueue::CalculatePriorities() {
|
|
SethiUllmanNumbers.assign(SUnits->size(), INT_MIN);
|
|
|
|
for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
|
|
CalcNodePriority(&(*SUnits)[i]);
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// LatencyPriorityQueue Implementation
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This is a SchedulingPriorityQueue that schedules using latency information to
|
|
// reduce the length of the critical path through the basic block.
|
|
//
|
|
namespace {
|
|
class LatencyPriorityQueue;
|
|
|
|
/// Sorting functions for the Available queue.
|
|
struct latency_sort : public std::binary_function<SUnit*, SUnit*, bool> {
|
|
LatencyPriorityQueue *PQ;
|
|
latency_sort(LatencyPriorityQueue *pq) : PQ(pq) {}
|
|
latency_sort(const latency_sort &RHS) : PQ(RHS.PQ) {}
|
|
|
|
bool operator()(const SUnit* left, const SUnit* right) const;
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
namespace {
|
|
class LatencyPriorityQueue : public SchedulingPriorityQueue {
|
|
// SUnits - The SUnits for the current graph.
|
|
const std::vector<SUnit> *SUnits;
|
|
|
|
// Latencies - The latency (max of latency from this node to the bb exit)
|
|
// for each node.
|
|
std::vector<int> Latencies;
|
|
|
|
/// NumNodesSolelyBlocking - This vector contains, for every node in the
|
|
/// Queue, the number of nodes that the node is the sole unscheduled
|
|
/// predecessor for. This is used as a tie-breaker heuristic for better
|
|
/// mobility.
|
|
std::vector<unsigned> NumNodesSolelyBlocking;
|
|
|
|
std::priority_queue<SUnit*, std::vector<SUnit*>, latency_sort> Queue;
|
|
public:
|
|
LatencyPriorityQueue() : Queue(latency_sort(this)) {
|
|
}
|
|
|
|
void initNodes(const std::vector<SUnit> &sunits) {
|
|
SUnits = &sunits;
|
|
// Calculate node priorities.
|
|
CalculatePriorities();
|
|
}
|
|
void releaseState() {
|
|
SUnits = 0;
|
|
Latencies.clear();
|
|
}
|
|
|
|
unsigned getLatency(unsigned NodeNum) const {
|
|
assert(NodeNum < Latencies.size());
|
|
return Latencies[NodeNum];
|
|
}
|
|
|
|
unsigned getNumSolelyBlockNodes(unsigned NodeNum) const {
|
|
assert(NodeNum < NumNodesSolelyBlocking.size());
|
|
return NumNodesSolelyBlocking[NodeNum];
|
|
}
|
|
|
|
bool empty() const { return Queue.empty(); }
|
|
|
|
virtual void push(SUnit *U) {
|
|
push_impl(U);
|
|
}
|
|
void push_impl(SUnit *U);
|
|
|
|
void push_all(const std::vector<SUnit *> &Nodes) {
|
|
for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
|
|
push_impl(Nodes[i]);
|
|
}
|
|
|
|
SUnit *pop() {
|
|
SUnit *V = Queue.top();
|
|
Queue.pop();
|
|
return V;
|
|
}
|
|
|
|
// ScheduledNode - As nodes are scheduled, we look to see if there are any
|
|
// successor nodes that have a single unscheduled predecessor. If so, that
|
|
// single predecessor has a higher priority, since scheduling it will make
|
|
// the node available.
|
|
void ScheduledNode(SUnit *Node);
|
|
|
|
private:
|
|
void CalculatePriorities();
|
|
int CalcLatency(const SUnit &SU);
|
|
void AdjustPriorityOfUnscheduledPreds(SUnit *SU);
|
|
|
|
/// RemoveFromPriorityQueue - This is a really inefficient way to remove a
|
|
/// node from a priority queue. We should roll our own heap to make this
|
|
/// better or something.
|
|
void RemoveFromPriorityQueue(SUnit *SU) {
|
|
std::vector<SUnit*> Temp;
|
|
|
|
assert(!Queue.empty() && "Not in queue!");
|
|
while (Queue.top() != SU) {
|
|
Temp.push_back(Queue.top());
|
|
Queue.pop();
|
|
assert(!Queue.empty() && "Not in queue!");
|
|
}
|
|
|
|
// Remove the node from the PQ.
|
|
Queue.pop();
|
|
|
|
// Add all the other nodes back.
|
|
for (unsigned i = 0, e = Temp.size(); i != e; ++i)
|
|
Queue.push(Temp[i]);
|
|
}
|
|
};
|
|
}
|
|
|
|
bool latency_sort::operator()(const SUnit *LHS, const SUnit *RHS) const {
|
|
unsigned LHSNum = LHS->NodeNum;
|
|
unsigned RHSNum = RHS->NodeNum;
|
|
|
|
// The most important heuristic is scheduling the critical path.
|
|
unsigned LHSLatency = PQ->getLatency(LHSNum);
|
|
unsigned RHSLatency = PQ->getLatency(RHSNum);
|
|
if (LHSLatency < RHSLatency) return true;
|
|
if (LHSLatency > RHSLatency) return false;
|
|
|
|
// After that, if two nodes have identical latencies, look to see if one will
|
|
// unblock more other nodes than the other.
|
|
unsigned LHSBlocked = PQ->getNumSolelyBlockNodes(LHSNum);
|
|
unsigned RHSBlocked = PQ->getNumSolelyBlockNodes(RHSNum);
|
|
if (LHSBlocked < RHSBlocked) return true;
|
|
if (LHSBlocked > RHSBlocked) return false;
|
|
|
|
// Finally, just to provide a stable ordering, use the node number as a
|
|
// deciding factor.
|
|
return LHSNum < RHSNum;
|
|
}
|
|
|
|
|
|
/// CalcNodePriority - Calculate the maximal path from the node to the exit.
|
|
///
|
|
int LatencyPriorityQueue::CalcLatency(const SUnit &SU) {
|
|
int &Latency = Latencies[SU.NodeNum];
|
|
if (Latency != -1)
|
|
return Latency;
|
|
|
|
int MaxSuccLatency = 0;
|
|
for (std::set<std::pair<SUnit*, bool> >::const_iterator I = SU.Succs.begin(),
|
|
E = SU.Succs.end(); I != E; ++I)
|
|
MaxSuccLatency = std::max(MaxSuccLatency, CalcLatency(*I->first));
|
|
|
|
return Latency = MaxSuccLatency + SU.Latency;
|
|
}
|
|
|
|
/// CalculatePriorities - Calculate priorities of all scheduling units.
|
|
void LatencyPriorityQueue::CalculatePriorities() {
|
|
Latencies.assign(SUnits->size(), -1);
|
|
NumNodesSolelyBlocking.assign(SUnits->size(), 0);
|
|
|
|
for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
|
|
CalcLatency((*SUnits)[i]);
|
|
}
|
|
|
|
/// getSingleUnscheduledPred - If there is exactly one unscheduled predecessor
|
|
/// of SU, return it, otherwise return null.
|
|
static SUnit *getSingleUnscheduledPred(SUnit *SU) {
|
|
SUnit *OnlyAvailablePred = 0;
|
|
for (std::set<std::pair<SUnit*, bool> >::const_iterator I = SU->Preds.begin(),
|
|
E = SU->Preds.end(); I != E; ++I)
|
|
if (!I->first->isScheduled) {
|
|
// We found an available, but not scheduled, predecessor. If it's the
|
|
// only one we have found, keep track of it... otherwise give up.
|
|
if (OnlyAvailablePred && OnlyAvailablePred != I->first)
|
|
return 0;
|
|
OnlyAvailablePred = I->first;
|
|
}
|
|
|
|
return OnlyAvailablePred;
|
|
}
|
|
|
|
void LatencyPriorityQueue::push_impl(SUnit *SU) {
|
|
// Look at all of the successors of this node. Count the number of nodes that
|
|
// this node is the sole unscheduled node for.
|
|
unsigned NumNodesBlocking = 0;
|
|
for (std::set<std::pair<SUnit*, bool> >::const_iterator I = SU->Succs.begin(),
|
|
E = SU->Succs.end(); I != E; ++I)
|
|
if (getSingleUnscheduledPred(I->first) == SU)
|
|
++NumNodesBlocking;
|
|
NumNodesSolelyBlocking[SU->NodeNum] = NumNodesBlocking;
|
|
|
|
Queue.push(SU);
|
|
}
|
|
|
|
|
|
// ScheduledNode - As nodes are scheduled, we look to see if there are any
|
|
// successor nodes that have a single unscheduled predecessor. If so, that
|
|
// single predecessor has a higher priority, since scheduling it will make
|
|
// the node available.
|
|
void LatencyPriorityQueue::ScheduledNode(SUnit *SU) {
|
|
for (std::set<std::pair<SUnit*, bool> >::const_iterator I = SU->Succs.begin(),
|
|
E = SU->Succs.end(); I != E; ++I)
|
|
AdjustPriorityOfUnscheduledPreds(I->first);
|
|
}
|
|
|
|
/// AdjustPriorityOfUnscheduledPreds - One of the predecessors of SU was just
|
|
/// scheduled. If SU is not itself available, then there is at least one
|
|
/// predecessor node that has not been scheduled yet. If SU has exactly ONE
|
|
/// unscheduled predecessor, we want to increase its priority: it getting
|
|
/// scheduled will make this node available, so it is better than some other
|
|
/// node of the same priority that will not make a node available.
|
|
void LatencyPriorityQueue::AdjustPriorityOfUnscheduledPreds(SUnit *SU) {
|
|
if (SU->isPending) return; // All preds scheduled.
|
|
|
|
SUnit *OnlyAvailablePred = getSingleUnscheduledPred(SU);
|
|
if (OnlyAvailablePred == 0 || !OnlyAvailablePred->isAvailable) return;
|
|
|
|
// Okay, we found a single predecessor that is available, but not scheduled.
|
|
// Since it is available, it must be in the priority queue. First remove it.
|
|
RemoveFromPriorityQueue(OnlyAvailablePred);
|
|
|
|
// Reinsert the node into the priority queue, which recomputes its
|
|
// NumNodesSolelyBlocking value.
|
|
push(OnlyAvailablePred);
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Public Constructor Functions
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
llvm::ScheduleDAG* llvm::createBURRListDAGScheduler(SelectionDAG &DAG,
|
|
MachineBasicBlock *BB) {
|
|
return new ScheduleDAGList(DAG, BB, DAG.getTarget(), true,
|
|
new RegReductionPriorityQueue(),
|
|
new HazardRecognizer());
|
|
}
|
|
|
|
/// createTDListDAGScheduler - This creates a top-down list scheduler with the
|
|
/// specified hazard recognizer.
|
|
ScheduleDAG* llvm::createTDListDAGScheduler(SelectionDAG &DAG,
|
|
MachineBasicBlock *BB,
|
|
HazardRecognizer *HR) {
|
|
return new ScheduleDAGList(DAG, BB, DAG.getTarget(), false,
|
|
new LatencyPriorityQueue(),
|
|
HR);
|
|
}
|