mirror of
https://github.com/RPCS3/llvm-mirror.git
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d66ff79b2c
llvm-svn: 162347
792 lines
27 KiB
C++
792 lines
27 KiB
C++
//===----- SchedulePostRAList.cpp - list scheduler ------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This implements a top-down list scheduler, using standard algorithms.
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// The basic approach uses a priority queue of available nodes to schedule.
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// One at a time, nodes are taken from the priority queue (thus in priority
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// 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 "post-RA-sched"
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#include "AntiDepBreaker.h"
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#include "AggressiveAntiDepBreaker.h"
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#include "CriticalAntiDepBreaker.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/LatencyPriorityQueue.h"
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#include "llvm/CodeGen/SchedulerRegistry.h"
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#include "llvm/CodeGen/MachineDominators.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineLoopInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/RegisterClassInfo.h"
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#include "llvm/CodeGen/ScheduleDAGInstrs.h"
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#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Target/TargetLowering.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/Target/TargetRegisterInfo.h"
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#include "llvm/Target/TargetSubtargetInfo.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/ADT/BitVector.h"
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#include "llvm/ADT/Statistic.h"
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using namespace llvm;
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STATISTIC(NumNoops, "Number of noops inserted");
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STATISTIC(NumStalls, "Number of pipeline stalls");
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STATISTIC(NumFixedAnti, "Number of fixed anti-dependencies");
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// Post-RA scheduling is enabled with
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// TargetSubtargetInfo.enablePostRAScheduler(). This flag can be used to
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// override the target.
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static cl::opt<bool>
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EnablePostRAScheduler("post-RA-scheduler",
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cl::desc("Enable scheduling after register allocation"),
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cl::init(false), cl::Hidden);
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static cl::opt<std::string>
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EnableAntiDepBreaking("break-anti-dependencies",
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cl::desc("Break post-RA scheduling anti-dependencies: "
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"\"critical\", \"all\", or \"none\""),
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cl::init("none"), cl::Hidden);
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// If DebugDiv > 0 then only schedule MBB with (ID % DebugDiv) == DebugMod
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static cl::opt<int>
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DebugDiv("postra-sched-debugdiv",
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cl::desc("Debug control MBBs that are scheduled"),
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cl::init(0), cl::Hidden);
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static cl::opt<int>
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DebugMod("postra-sched-debugmod",
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cl::desc("Debug control MBBs that are scheduled"),
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cl::init(0), cl::Hidden);
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AntiDepBreaker::~AntiDepBreaker() { }
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namespace {
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class PostRAScheduler : public MachineFunctionPass {
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const TargetInstrInfo *TII;
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RegisterClassInfo RegClassInfo;
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public:
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static char ID;
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PostRAScheduler() : MachineFunctionPass(ID) {}
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void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesCFG();
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AU.addRequired<AliasAnalysis>();
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AU.addRequired<TargetPassConfig>();
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AU.addRequired<MachineDominatorTree>();
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AU.addPreserved<MachineDominatorTree>();
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AU.addRequired<MachineLoopInfo>();
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AU.addPreserved<MachineLoopInfo>();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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bool runOnMachineFunction(MachineFunction &Fn);
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};
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char PostRAScheduler::ID = 0;
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class SchedulePostRATDList : public ScheduleDAGInstrs {
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/// AvailableQueue - The priority queue to use for the available SUnits.
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///
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LatencyPriorityQueue 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.
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std::vector<SUnit*> PendingQueue;
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/// Topo - A topological ordering for SUnits.
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ScheduleDAGTopologicalSort Topo;
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/// HazardRec - The hazard recognizer to use.
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ScheduleHazardRecognizer *HazardRec;
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/// AntiDepBreak - Anti-dependence breaking object, or NULL if none
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AntiDepBreaker *AntiDepBreak;
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/// AA - AliasAnalysis for making memory reference queries.
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AliasAnalysis *AA;
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/// LiveRegs - true if the register is live.
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BitVector LiveRegs;
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/// The schedule. Null SUnit*'s represent noop instructions.
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std::vector<SUnit*> Sequence;
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public:
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SchedulePostRATDList(
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MachineFunction &MF, MachineLoopInfo &MLI, MachineDominatorTree &MDT,
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AliasAnalysis *AA, const RegisterClassInfo&,
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TargetSubtargetInfo::AntiDepBreakMode AntiDepMode,
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SmallVectorImpl<const TargetRegisterClass*> &CriticalPathRCs);
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~SchedulePostRATDList();
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/// startBlock - Initialize register live-range state for scheduling in
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/// this block.
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///
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void startBlock(MachineBasicBlock *BB);
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/// Initialize the scheduler state for the next scheduling region.
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virtual void enterRegion(MachineBasicBlock *bb,
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MachineBasicBlock::iterator begin,
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MachineBasicBlock::iterator end,
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unsigned endcount);
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/// Notify that the scheduler has finished scheduling the current region.
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virtual void exitRegion();
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/// Schedule - Schedule the instruction range using list scheduling.
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///
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void schedule();
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void EmitSchedule();
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/// Observe - Update liveness information to account for the current
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/// instruction, which will not be scheduled.
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///
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void Observe(MachineInstr *MI, unsigned Count);
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/// finishBlock - Clean up register live-range state.
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///
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void finishBlock();
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/// FixupKills - Fix register kill flags that have been made
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/// invalid due to scheduling
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///
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void FixupKills(MachineBasicBlock *MBB);
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private:
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void ReleaseSucc(SUnit *SU, SDep *SuccEdge);
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void ReleaseSuccessors(SUnit *SU);
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void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
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void ListScheduleTopDown();
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void StartBlockForKills(MachineBasicBlock *BB);
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// ToggleKillFlag - Toggle a register operand kill flag. Other
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// adjustments may be made to the instruction if necessary. Return
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// true if the operand has been deleted, false if not.
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bool ToggleKillFlag(MachineInstr *MI, MachineOperand &MO);
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void dumpSchedule() const;
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};
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}
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char &llvm::PostRASchedulerID = PostRAScheduler::ID;
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INITIALIZE_PASS(PostRAScheduler, "post-RA-sched",
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"Post RA top-down list latency scheduler", false, false)
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SchedulePostRATDList::SchedulePostRATDList(
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MachineFunction &MF, MachineLoopInfo &MLI, MachineDominatorTree &MDT,
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AliasAnalysis *AA, const RegisterClassInfo &RCI,
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TargetSubtargetInfo::AntiDepBreakMode AntiDepMode,
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SmallVectorImpl<const TargetRegisterClass*> &CriticalPathRCs)
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: ScheduleDAGInstrs(MF, MLI, MDT, /*IsPostRA=*/true), Topo(SUnits), AA(AA),
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LiveRegs(TRI->getNumRegs())
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{
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const TargetMachine &TM = MF.getTarget();
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const InstrItineraryData *InstrItins = TM.getInstrItineraryData();
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HazardRec =
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TM.getInstrInfo()->CreateTargetPostRAHazardRecognizer(InstrItins, this);
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assert((AntiDepMode == TargetSubtargetInfo::ANTIDEP_NONE ||
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MRI.tracksLiveness()) &&
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"Live-ins must be accurate for anti-dependency breaking");
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AntiDepBreak =
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((AntiDepMode == TargetSubtargetInfo::ANTIDEP_ALL) ?
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(AntiDepBreaker *)new AggressiveAntiDepBreaker(MF, RCI, CriticalPathRCs) :
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((AntiDepMode == TargetSubtargetInfo::ANTIDEP_CRITICAL) ?
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(AntiDepBreaker *)new CriticalAntiDepBreaker(MF, RCI) : NULL));
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}
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SchedulePostRATDList::~SchedulePostRATDList() {
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delete HazardRec;
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delete AntiDepBreak;
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}
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/// Initialize state associated with the next scheduling region.
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void SchedulePostRATDList::enterRegion(MachineBasicBlock *bb,
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MachineBasicBlock::iterator begin,
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MachineBasicBlock::iterator end,
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unsigned endcount) {
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ScheduleDAGInstrs::enterRegion(bb, begin, end, endcount);
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Sequence.clear();
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}
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/// Print the schedule before exiting the region.
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void SchedulePostRATDList::exitRegion() {
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DEBUG({
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dbgs() << "*** Final schedule ***\n";
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dumpSchedule();
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dbgs() << '\n';
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});
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ScheduleDAGInstrs::exitRegion();
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}
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/// dumpSchedule - dump the scheduled Sequence.
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void SchedulePostRATDList::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(this);
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else
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dbgs() << "**** NOOP ****\n";
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}
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}
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bool PostRAScheduler::runOnMachineFunction(MachineFunction &Fn) {
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TII = Fn.getTarget().getInstrInfo();
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MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
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MachineDominatorTree &MDT = getAnalysis<MachineDominatorTree>();
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AliasAnalysis *AA = &getAnalysis<AliasAnalysis>();
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TargetPassConfig *PassConfig = &getAnalysis<TargetPassConfig>();
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RegClassInfo.runOnMachineFunction(Fn);
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// Check for explicit enable/disable of post-ra scheduling.
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TargetSubtargetInfo::AntiDepBreakMode AntiDepMode =
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TargetSubtargetInfo::ANTIDEP_NONE;
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SmallVector<const TargetRegisterClass*, 4> CriticalPathRCs;
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if (EnablePostRAScheduler.getPosition() > 0) {
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if (!EnablePostRAScheduler)
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return false;
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} else {
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// Check that post-RA scheduling is enabled for this target.
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// This may upgrade the AntiDepMode.
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const TargetSubtargetInfo &ST = Fn.getTarget().getSubtarget<TargetSubtargetInfo>();
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if (!ST.enablePostRAScheduler(PassConfig->getOptLevel(), AntiDepMode,
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CriticalPathRCs))
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return false;
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}
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// Check for antidep breaking override...
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if (EnableAntiDepBreaking.getPosition() > 0) {
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AntiDepMode = (EnableAntiDepBreaking == "all")
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? TargetSubtargetInfo::ANTIDEP_ALL
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: ((EnableAntiDepBreaking == "critical")
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? TargetSubtargetInfo::ANTIDEP_CRITICAL
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: TargetSubtargetInfo::ANTIDEP_NONE);
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}
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DEBUG(dbgs() << "PostRAScheduler\n");
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SchedulePostRATDList Scheduler(Fn, MLI, MDT, AA, RegClassInfo, AntiDepMode,
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CriticalPathRCs);
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// Loop over all of the basic blocks
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for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
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MBB != MBBe; ++MBB) {
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#ifndef NDEBUG
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// If DebugDiv > 0 then only schedule MBB with (ID % DebugDiv) == DebugMod
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if (DebugDiv > 0) {
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static int bbcnt = 0;
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if (bbcnt++ % DebugDiv != DebugMod)
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continue;
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dbgs() << "*** DEBUG scheduling " << Fn.getName()
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<< ":BB#" << MBB->getNumber() << " ***\n";
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}
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#endif
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// Initialize register live-range state for scheduling in this block.
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Scheduler.startBlock(MBB);
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// Schedule each sequence of instructions not interrupted by a label
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// or anything else that effectively needs to shut down scheduling.
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MachineBasicBlock::iterator Current = MBB->end();
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unsigned Count = MBB->size(), CurrentCount = Count;
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for (MachineBasicBlock::iterator I = Current; I != MBB->begin(); ) {
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MachineInstr *MI = llvm::prior(I);
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// Calls are not scheduling boundaries before register allocation, but
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// post-ra we don't gain anything by scheduling across calls since we
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// don't need to worry about register pressure.
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if (MI->isCall() || TII->isSchedulingBoundary(MI, MBB, Fn)) {
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Scheduler.enterRegion(MBB, I, Current, CurrentCount);
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Scheduler.schedule();
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Scheduler.exitRegion();
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Scheduler.EmitSchedule();
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Current = MI;
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CurrentCount = Count - 1;
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Scheduler.Observe(MI, CurrentCount);
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}
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I = MI;
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--Count;
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if (MI->isBundle())
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Count -= MI->getBundleSize();
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}
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assert(Count == 0 && "Instruction count mismatch!");
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assert((MBB->begin() == Current || CurrentCount != 0) &&
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"Instruction count mismatch!");
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Scheduler.enterRegion(MBB, MBB->begin(), Current, CurrentCount);
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Scheduler.schedule();
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Scheduler.exitRegion();
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Scheduler.EmitSchedule();
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// Clean up register live-range state.
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Scheduler.finishBlock();
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// Update register kills
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Scheduler.FixupKills(MBB);
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}
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return true;
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}
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/// StartBlock - Initialize register live-range state for scheduling in
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/// this block.
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///
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void SchedulePostRATDList::startBlock(MachineBasicBlock *BB) {
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// Call the superclass.
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ScheduleDAGInstrs::startBlock(BB);
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// Reset the hazard recognizer and anti-dep breaker.
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HazardRec->Reset();
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if (AntiDepBreak != NULL)
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AntiDepBreak->StartBlock(BB);
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}
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/// Schedule - Schedule the instruction range using list scheduling.
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///
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void SchedulePostRATDList::schedule() {
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// Build the scheduling graph.
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buildSchedGraph(AA);
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if (AntiDepBreak != NULL) {
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unsigned Broken =
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AntiDepBreak->BreakAntiDependencies(SUnits, RegionBegin, RegionEnd,
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EndIndex, DbgValues);
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if (Broken != 0) {
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// We made changes. Update the dependency graph.
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// Theoretically we could update the graph in place:
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// When a live range is changed to use a different register, remove
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// the def's anti-dependence *and* output-dependence edges due to
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// that register, and add new anti-dependence and output-dependence
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// edges based on the next live range of the register.
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ScheduleDAG::clearDAG();
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buildSchedGraph(AA);
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NumFixedAnti += Broken;
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}
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}
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DEBUG(dbgs() << "********** List Scheduling **********\n");
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DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
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SUnits[su].dumpAll(this));
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AvailableQueue.initNodes(SUnits);
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ListScheduleTopDown();
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AvailableQueue.releaseState();
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}
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/// Observe - Update liveness information to account for the current
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/// instruction, which will not be scheduled.
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///
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void SchedulePostRATDList::Observe(MachineInstr *MI, unsigned Count) {
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if (AntiDepBreak != NULL)
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AntiDepBreak->Observe(MI, Count, EndIndex);
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}
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/// FinishBlock - Clean up register live-range state.
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///
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void SchedulePostRATDList::finishBlock() {
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if (AntiDepBreak != NULL)
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AntiDepBreak->FinishBlock();
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// Call the superclass.
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ScheduleDAGInstrs::finishBlock();
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}
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/// StartBlockForKills - Initialize register live-range state for updating kills
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///
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void SchedulePostRATDList::StartBlockForKills(MachineBasicBlock *BB) {
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// Start with no live registers.
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LiveRegs.reset();
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// Determine the live-out physregs for this block.
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if (!BB->empty() && BB->back().isReturn()) {
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// In a return block, examine the function live-out regs.
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for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(),
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E = MRI.liveout_end(); I != E; ++I) {
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unsigned Reg = *I;
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LiveRegs.set(Reg);
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// Repeat, for all subregs.
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for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
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LiveRegs.set(*SubRegs);
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}
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}
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else {
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// In a non-return block, examine the live-in regs of all successors.
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for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
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SE = BB->succ_end(); SI != SE; ++SI) {
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for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(),
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E = (*SI)->livein_end(); I != E; ++I) {
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unsigned Reg = *I;
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LiveRegs.set(Reg);
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// Repeat, for all subregs.
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for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
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LiveRegs.set(*SubRegs);
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}
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}
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}
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}
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bool SchedulePostRATDList::ToggleKillFlag(MachineInstr *MI,
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MachineOperand &MO) {
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// Setting kill flag...
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if (!MO.isKill()) {
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MO.setIsKill(true);
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return false;
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}
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// If MO itself is live, clear the kill flag...
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if (LiveRegs.test(MO.getReg())) {
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MO.setIsKill(false);
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return false;
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}
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// If any subreg of MO is live, then create an imp-def for that
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// subreg and keep MO marked as killed.
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MO.setIsKill(false);
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bool AllDead = true;
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const unsigned SuperReg = MO.getReg();
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for (MCSubRegIterator SubRegs(SuperReg, TRI); SubRegs.isValid(); ++SubRegs) {
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if (LiveRegs.test(*SubRegs)) {
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MI->addOperand(MachineOperand::CreateReg(*SubRegs,
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true /*IsDef*/,
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true /*IsImp*/,
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false /*IsKill*/,
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false /*IsDead*/));
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AllDead = false;
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}
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}
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if(AllDead)
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MO.setIsKill(true);
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return false;
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}
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/// FixupKills - Fix the register kill flags, they may have been made
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/// incorrect by instruction reordering.
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///
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void SchedulePostRATDList::FixupKills(MachineBasicBlock *MBB) {
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DEBUG(dbgs() << "Fixup kills for BB#" << MBB->getNumber() << '\n');
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BitVector killedRegs(TRI->getNumRegs());
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BitVector ReservedRegs = TRI->getReservedRegs(MF);
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StartBlockForKills(MBB);
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// Examine block from end to start...
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unsigned Count = MBB->size();
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for (MachineBasicBlock::iterator I = MBB->end(), E = MBB->begin();
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I != E; --Count) {
|
|
MachineInstr *MI = --I;
|
|
if (MI->isDebugValue())
|
|
continue;
|
|
|
|
// Update liveness. Registers that are defed but not used in this
|
|
// instruction are now dead. Mark register and all subregs as they
|
|
// are completely defined.
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (MO.isRegMask())
|
|
LiveRegs.clearBitsNotInMask(MO.getRegMask());
|
|
if (!MO.isReg()) continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (Reg == 0) continue;
|
|
if (!MO.isDef()) continue;
|
|
// Ignore two-addr defs.
|
|
if (MI->isRegTiedToUseOperand(i)) continue;
|
|
|
|
LiveRegs.reset(Reg);
|
|
|
|
// Repeat for all subregs.
|
|
for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
|
|
LiveRegs.reset(*SubRegs);
|
|
}
|
|
|
|
// Examine all used registers and set/clear kill flag. When a
|
|
// register is used multiple times we only set the kill flag on
|
|
// the first use.
|
|
killedRegs.reset();
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg() || !MO.isUse()) continue;
|
|
unsigned Reg = MO.getReg();
|
|
if ((Reg == 0) || ReservedRegs.test(Reg)) continue;
|
|
|
|
bool kill = false;
|
|
if (!killedRegs.test(Reg)) {
|
|
kill = true;
|
|
// A register is not killed if any subregs are live...
|
|
for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
|
|
if (LiveRegs.test(*SubRegs)) {
|
|
kill = false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If subreg is not live, then register is killed if it became
|
|
// live in this instruction
|
|
if (kill)
|
|
kill = !LiveRegs.test(Reg);
|
|
}
|
|
|
|
if (MO.isKill() != kill) {
|
|
DEBUG(dbgs() << "Fixing " << MO << " in ");
|
|
// Warning: ToggleKillFlag may invalidate MO.
|
|
ToggleKillFlag(MI, MO);
|
|
DEBUG(MI->dump());
|
|
}
|
|
|
|
killedRegs.set(Reg);
|
|
}
|
|
|
|
// Mark any used register (that is not using undef) and subregs as
|
|
// now live...
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (!MO.isReg() || !MO.isUse() || MO.isUndef()) continue;
|
|
unsigned Reg = MO.getReg();
|
|
if ((Reg == 0) || ReservedRegs.test(Reg)) continue;
|
|
|
|
LiveRegs.set(Reg);
|
|
|
|
for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
|
|
LiveRegs.set(*SubRegs);
|
|
}
|
|
}
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Top-Down Scheduling
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
|
|
/// the PendingQueue if the count reaches zero. Also update its cycle bound.
|
|
void SchedulePostRATDList::ReleaseSucc(SUnit *SU, SDep *SuccEdge) {
|
|
SUnit *SuccSU = SuccEdge->getSUnit();
|
|
|
|
#ifndef NDEBUG
|
|
if (SuccSU->NumPredsLeft == 0) {
|
|
dbgs() << "*** Scheduling failed! ***\n";
|
|
SuccSU->dump(this);
|
|
dbgs() << " has been released too many times!\n";
|
|
llvm_unreachable(0);
|
|
}
|
|
#endif
|
|
--SuccSU->NumPredsLeft;
|
|
|
|
// Standard scheduler algorithms will recompute the depth of the successor
|
|
// here as such:
|
|
// SuccSU->setDepthToAtLeast(SU->getDepth() + SuccEdge->getLatency());
|
|
//
|
|
// However, we lazily compute node depth instead. Note that
|
|
// ScheduleNodeTopDown has already updated the depth of this node which causes
|
|
// all descendents to be marked dirty. Setting the successor depth explicitly
|
|
// here would cause depth to be recomputed for all its ancestors. If the
|
|
// successor is not yet ready (because of a transitively redundant edge) then
|
|
// this causes depth computation to be quadratic in the size of the DAG.
|
|
|
|
// If all the node's predecessors are scheduled, this node is ready
|
|
// to be scheduled. Ignore the special ExitSU node.
|
|
if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU)
|
|
PendingQueue.push_back(SuccSU);
|
|
}
|
|
|
|
/// ReleaseSuccessors - Call ReleaseSucc on each of SU's successors.
|
|
void SchedulePostRATDList::ReleaseSuccessors(SUnit *SU) {
|
|
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
|
|
I != E; ++I) {
|
|
ReleaseSucc(SU, &*I);
|
|
}
|
|
}
|
|
|
|
/// 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 SchedulePostRATDList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
|
|
DEBUG(dbgs() << "*** Scheduling [" << CurCycle << "]: ");
|
|
DEBUG(SU->dump(this));
|
|
|
|
Sequence.push_back(SU);
|
|
assert(CurCycle >= SU->getDepth() &&
|
|
"Node scheduled above its depth!");
|
|
SU->setDepthToAtLeast(CurCycle);
|
|
|
|
ReleaseSuccessors(SU);
|
|
SU->isScheduled = true;
|
|
AvailableQueue.scheduledNode(SU);
|
|
}
|
|
|
|
/// ListScheduleTopDown - The main loop of list scheduling for top-down
|
|
/// schedulers.
|
|
void SchedulePostRATDList::ListScheduleTopDown() {
|
|
unsigned CurCycle = 0;
|
|
|
|
// We're scheduling top-down but we're visiting the regions in
|
|
// bottom-up order, so we don't know the hazards at the start of a
|
|
// region. So assume no hazards (this should usually be ok as most
|
|
// blocks are a single region).
|
|
HazardRec->Reset();
|
|
|
|
// Release any successors of the special Entry node.
|
|
ReleaseSuccessors(&EntrySU);
|
|
|
|
// Add all leaves to Available queue.
|
|
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
|
|
// It is available if it has no predecessors.
|
|
bool available = SUnits[i].Preds.empty();
|
|
if (available) {
|
|
AvailableQueue.push(&SUnits[i]);
|
|
SUnits[i].isAvailable = true;
|
|
}
|
|
}
|
|
|
|
// In any cycle where we can't schedule any instructions, we must
|
|
// stall or emit a noop, depending on the target.
|
|
bool CycleHasInsts = false;
|
|
|
|
// 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;
|
|
Sequence.reserve(SUnits.size());
|
|
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.
|
|
unsigned MinDepth = ~0u;
|
|
for (unsigned i = 0, e = PendingQueue.size(); i != e; ++i) {
|
|
if (PendingQueue[i]->getDepth() <= CurCycle) {
|
|
AvailableQueue.push(PendingQueue[i]);
|
|
PendingQueue[i]->isAvailable = true;
|
|
PendingQueue[i] = PendingQueue.back();
|
|
PendingQueue.pop_back();
|
|
--i; --e;
|
|
} else if (PendingQueue[i]->getDepth() < MinDepth)
|
|
MinDepth = PendingQueue[i]->getDepth();
|
|
}
|
|
|
|
DEBUG(dbgs() << "\n*** Examining Available\n"; AvailableQueue.dump(this));
|
|
|
|
SUnit *FoundSUnit = 0;
|
|
bool HasNoopHazards = false;
|
|
while (!AvailableQueue.empty()) {
|
|
SUnit *CurSUnit = AvailableQueue.pop();
|
|
|
|
ScheduleHazardRecognizer::HazardType HT =
|
|
HazardRec->getHazardType(CurSUnit, 0/*no stalls*/);
|
|
if (HT == ScheduleHazardRecognizer::NoHazard) {
|
|
FoundSUnit = CurSUnit;
|
|
break;
|
|
}
|
|
|
|
// Remember if this is a noop hazard.
|
|
HasNoopHazards |= HT == ScheduleHazardRecognizer::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...
|
|
if (FoundSUnit) {
|
|
// ... schedule the node...
|
|
ScheduleNodeTopDown(FoundSUnit, CurCycle);
|
|
HazardRec->EmitInstruction(FoundSUnit);
|
|
CycleHasInsts = true;
|
|
if (HazardRec->atIssueLimit()) {
|
|
DEBUG(dbgs() << "*** Max instructions per cycle " << CurCycle << '\n');
|
|
HazardRec->AdvanceCycle();
|
|
++CurCycle;
|
|
CycleHasInsts = false;
|
|
}
|
|
} else {
|
|
if (CycleHasInsts) {
|
|
DEBUG(dbgs() << "*** Finished cycle " << CurCycle << '\n');
|
|
HazardRec->AdvanceCycle();
|
|
} else if (!HasNoopHazards) {
|
|
// Otherwise, we have a pipeline stall, but no other problem,
|
|
// just advance the current cycle and try again.
|
|
DEBUG(dbgs() << "*** Stall in cycle " << CurCycle << '\n');
|
|
HazardRec->AdvanceCycle();
|
|
++NumStalls;
|
|
} 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(dbgs() << "*** Emitting noop in cycle " << CurCycle << '\n');
|
|
HazardRec->EmitNoop();
|
|
Sequence.push_back(0); // NULL here means noop
|
|
++NumNoops;
|
|
}
|
|
|
|
++CurCycle;
|
|
CycleHasInsts = false;
|
|
}
|
|
}
|
|
|
|
#ifndef NDEBUG
|
|
unsigned ScheduledNodes = VerifyScheduledDAG(/*isBottomUp=*/false);
|
|
unsigned Noops = 0;
|
|
for (unsigned i = 0, e = Sequence.size(); i != e; ++i)
|
|
if (!Sequence[i])
|
|
++Noops;
|
|
assert(Sequence.size() - Noops == ScheduledNodes &&
|
|
"The number of nodes scheduled doesn't match the expected number!");
|
|
#endif // NDEBUG
|
|
}
|
|
|
|
// EmitSchedule - Emit the machine code in scheduled order.
|
|
void SchedulePostRATDList::EmitSchedule() {
|
|
RegionBegin = RegionEnd;
|
|
|
|
// If first instruction was a DBG_VALUE then put it back.
|
|
if (FirstDbgValue)
|
|
BB->splice(RegionEnd, BB, FirstDbgValue);
|
|
|
|
// Then re-insert them according to the given schedule.
|
|
for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
|
|
if (SUnit *SU = Sequence[i])
|
|
BB->splice(RegionEnd, BB, SU->getInstr());
|
|
else
|
|
// Null SUnit* is a noop.
|
|
TII->insertNoop(*BB, RegionEnd);
|
|
|
|
// Update the Begin iterator, as the first instruction in the block
|
|
// may have been scheduled later.
|
|
if (i == 0)
|
|
RegionBegin = prior(RegionEnd);
|
|
}
|
|
|
|
// Reinsert any remaining debug_values.
|
|
for (std::vector<std::pair<MachineInstr *, MachineInstr *> >::iterator
|
|
DI = DbgValues.end(), DE = DbgValues.begin(); DI != DE; --DI) {
|
|
std::pair<MachineInstr *, MachineInstr *> P = *prior(DI);
|
|
MachineInstr *DbgValue = P.first;
|
|
MachineBasicBlock::iterator OrigPrivMI = P.second;
|
|
BB->splice(++OrigPrivMI, BB, DbgValue);
|
|
}
|
|
DbgValues.clear();
|
|
FirstDbgValue = NULL;
|
|
}
|