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define below all header includes in the lib/CodeGen/... tree. While the current modules implementation doesn't check for this kind of ODR violation yet, it is likely to grow support for it in the future. It also removes one layer of macro pollution across all the included headers. Other sub-trees will follow. llvm-svn: 206837
656 lines
20 KiB
C++
656 lines
20 KiB
C++
//===- ResourcePriorityQueue.cpp - A DFA-oriented priority queue -*- C++ -*-==//
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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 file implements the ResourcePriorityQueue class, which is a
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// SchedulingPriorityQueue that prioritizes instructions using DFA state to
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// reduce the length of the critical path through the basic block
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// on VLIW platforms.
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// The scheduler is basically a top-down adaptable list scheduler with DFA
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// resource tracking added to the cost function.
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// DFA is queried as a state machine to model "packets/bundles" during
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// schedule. Currently packets/bundles are discarded at the end of
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// scheduling, affecting only order of instructions.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/ResourcePriorityQueue.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/SelectionDAGNodes.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/raw_ostream.h"
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#include "llvm/Target/TargetLowering.h"
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#include "llvm/Target/TargetMachine.h"
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using namespace llvm;
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#define DEBUG_TYPE "scheduler"
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static cl::opt<bool> DisableDFASched("disable-dfa-sched", cl::Hidden,
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cl::ZeroOrMore, cl::init(false),
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cl::desc("Disable use of DFA during scheduling"));
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static cl::opt<signed> RegPressureThreshold(
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"dfa-sched-reg-pressure-threshold", cl::Hidden, cl::ZeroOrMore, cl::init(5),
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cl::desc("Track reg pressure and switch priority to in-depth"));
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ResourcePriorityQueue::ResourcePriorityQueue(SelectionDAGISel *IS) :
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Picker(this),
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InstrItins(IS->getTargetLowering()->getTargetMachine().getInstrItineraryData())
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{
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TII = IS->getTargetLowering()->getTargetMachine().getInstrInfo();
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TRI = IS->getTargetLowering()->getTargetMachine().getRegisterInfo();
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TLI = IS->getTargetLowering();
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const TargetMachine &tm = (*IS->MF).getTarget();
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ResourcesModel = tm.getInstrInfo()->CreateTargetScheduleState(&tm,nullptr);
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// This hard requirement could be relaxed, but for now
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// do not let it procede.
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assert (ResourcesModel && "Unimplemented CreateTargetScheduleState.");
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unsigned NumRC = TRI->getNumRegClasses();
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RegLimit.resize(NumRC);
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RegPressure.resize(NumRC);
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std::fill(RegLimit.begin(), RegLimit.end(), 0);
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std::fill(RegPressure.begin(), RegPressure.end(), 0);
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for (TargetRegisterInfo::regclass_iterator I = TRI->regclass_begin(),
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E = TRI->regclass_end(); I != E; ++I)
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RegLimit[(*I)->getID()] = TRI->getRegPressureLimit(*I, *IS->MF);
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ParallelLiveRanges = 0;
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HorizontalVerticalBalance = 0;
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}
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unsigned
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ResourcePriorityQueue::numberRCValPredInSU(SUnit *SU, unsigned RCId) {
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unsigned NumberDeps = 0;
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for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
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I != E; ++I) {
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if (I->isCtrl())
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continue;
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SUnit *PredSU = I->getSUnit();
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const SDNode *ScegN = PredSU->getNode();
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if (!ScegN)
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continue;
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// If value is passed to CopyToReg, it is probably
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// live outside BB.
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switch (ScegN->getOpcode()) {
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default: break;
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case ISD::TokenFactor: break;
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case ISD::CopyFromReg: NumberDeps++; break;
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case ISD::CopyToReg: break;
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case ISD::INLINEASM: break;
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}
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if (!ScegN->isMachineOpcode())
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continue;
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for (unsigned i = 0, e = ScegN->getNumValues(); i != e; ++i) {
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MVT VT = ScegN->getSimpleValueType(i);
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if (TLI->isTypeLegal(VT)
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&& (TLI->getRegClassFor(VT)->getID() == RCId)) {
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NumberDeps++;
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break;
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}
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}
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}
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return NumberDeps;
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}
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unsigned ResourcePriorityQueue::numberRCValSuccInSU(SUnit *SU,
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unsigned RCId) {
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unsigned NumberDeps = 0;
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for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
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I != E; ++I) {
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if (I->isCtrl())
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continue;
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SUnit *SuccSU = I->getSUnit();
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const SDNode *ScegN = SuccSU->getNode();
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if (!ScegN)
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continue;
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// If value is passed to CopyToReg, it is probably
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// live outside BB.
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switch (ScegN->getOpcode()) {
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default: break;
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case ISD::TokenFactor: break;
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case ISD::CopyFromReg: break;
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case ISD::CopyToReg: NumberDeps++; break;
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case ISD::INLINEASM: break;
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}
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if (!ScegN->isMachineOpcode())
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continue;
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for (unsigned i = 0, e = ScegN->getNumOperands(); i != e; ++i) {
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const SDValue &Op = ScegN->getOperand(i);
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MVT VT = Op.getNode()->getSimpleValueType(Op.getResNo());
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if (TLI->isTypeLegal(VT)
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&& (TLI->getRegClassFor(VT)->getID() == RCId)) {
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NumberDeps++;
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break;
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}
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}
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}
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return NumberDeps;
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}
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static unsigned numberCtrlDepsInSU(SUnit *SU) {
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unsigned NumberDeps = 0;
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for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
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I != E; ++I)
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if (I->isCtrl())
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NumberDeps++;
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return NumberDeps;
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}
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static unsigned numberCtrlPredInSU(SUnit *SU) {
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unsigned NumberDeps = 0;
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for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
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I != E; ++I)
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if (I->isCtrl())
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NumberDeps++;
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return NumberDeps;
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}
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///
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/// Initialize nodes.
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///
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void ResourcePriorityQueue::initNodes(std::vector<SUnit> &sunits) {
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SUnits = &sunits;
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NumNodesSolelyBlocking.resize(SUnits->size(), 0);
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for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
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SUnit *SU = &(*SUnits)[i];
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initNumRegDefsLeft(SU);
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SU->NodeQueueId = 0;
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}
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}
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/// This heuristic is used if DFA scheduling is not desired
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/// for some VLIW platform.
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bool resource_sort::operator()(const SUnit *LHS, const SUnit *RHS) const {
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// The isScheduleHigh flag allows nodes with wraparound dependencies that
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// cannot easily be modeled as edges with latencies to be scheduled as
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// soon as possible in a top-down schedule.
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if (LHS->isScheduleHigh && !RHS->isScheduleHigh)
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return false;
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if (!LHS->isScheduleHigh && RHS->isScheduleHigh)
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return true;
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unsigned LHSNum = LHS->NodeNum;
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unsigned RHSNum = RHS->NodeNum;
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// The most important heuristic is scheduling the critical path.
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unsigned LHSLatency = PQ->getLatency(LHSNum);
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unsigned RHSLatency = PQ->getLatency(RHSNum);
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if (LHSLatency < RHSLatency) return true;
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if (LHSLatency > RHSLatency) return false;
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// After that, if two nodes have identical latencies, look to see if one will
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// unblock more other nodes than the other.
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unsigned LHSBlocked = PQ->getNumSolelyBlockNodes(LHSNum);
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unsigned RHSBlocked = PQ->getNumSolelyBlockNodes(RHSNum);
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if (LHSBlocked < RHSBlocked) return true;
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if (LHSBlocked > RHSBlocked) return false;
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// Finally, just to provide a stable ordering, use the node number as a
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// deciding factor.
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return LHSNum < RHSNum;
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}
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/// getSingleUnscheduledPred - If there is exactly one unscheduled predecessor
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/// of SU, return it, otherwise return null.
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SUnit *ResourcePriorityQueue::getSingleUnscheduledPred(SUnit *SU) {
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SUnit *OnlyAvailablePred = nullptr;
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for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
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I != E; ++I) {
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SUnit &Pred = *I->getSUnit();
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if (!Pred.isScheduled) {
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// We found an available, but not scheduled, predecessor. If it's the
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// only one we have found, keep track of it... otherwise give up.
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if (OnlyAvailablePred && OnlyAvailablePred != &Pred)
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return nullptr;
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OnlyAvailablePred = &Pred;
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}
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}
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return OnlyAvailablePred;
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}
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void ResourcePriorityQueue::push(SUnit *SU) {
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// Look at all of the successors of this node. Count the number of nodes that
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// this node is the sole unscheduled node for.
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unsigned NumNodesBlocking = 0;
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for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
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I != E; ++I)
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if (getSingleUnscheduledPred(I->getSUnit()) == SU)
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++NumNodesBlocking;
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NumNodesSolelyBlocking[SU->NodeNum] = NumNodesBlocking;
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Queue.push_back(SU);
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}
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/// Check if scheduling of this SU is possible
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/// in the current packet.
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bool ResourcePriorityQueue::isResourceAvailable(SUnit *SU) {
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if (!SU || !SU->getNode())
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return false;
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// If this is a compound instruction,
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// it is likely to be a call. Do not delay it.
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if (SU->getNode()->getGluedNode())
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return true;
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// First see if the pipeline could receive this instruction
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// in the current cycle.
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if (SU->getNode()->isMachineOpcode())
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switch (SU->getNode()->getMachineOpcode()) {
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default:
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if (!ResourcesModel->canReserveResources(&TII->get(
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SU->getNode()->getMachineOpcode())))
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return false;
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case TargetOpcode::EXTRACT_SUBREG:
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case TargetOpcode::INSERT_SUBREG:
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case TargetOpcode::SUBREG_TO_REG:
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case TargetOpcode::REG_SEQUENCE:
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case TargetOpcode::IMPLICIT_DEF:
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break;
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}
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// Now see if there are no other dependencies
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// to instructions alredy in the packet.
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for (unsigned i = 0, e = Packet.size(); i != e; ++i)
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for (SUnit::const_succ_iterator I = Packet[i]->Succs.begin(),
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E = Packet[i]->Succs.end(); I != E; ++I) {
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// Since we do not add pseudos to packets, might as well
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// ignor order deps.
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if (I->isCtrl())
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continue;
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if (I->getSUnit() == SU)
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return false;
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}
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return true;
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}
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/// Keep track of available resources.
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void ResourcePriorityQueue::reserveResources(SUnit *SU) {
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// If this SU does not fit in the packet
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// start a new one.
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if (!isResourceAvailable(SU) || SU->getNode()->getGluedNode()) {
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ResourcesModel->clearResources();
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Packet.clear();
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}
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if (SU->getNode() && SU->getNode()->isMachineOpcode()) {
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switch (SU->getNode()->getMachineOpcode()) {
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default:
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ResourcesModel->reserveResources(&TII->get(
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SU->getNode()->getMachineOpcode()));
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break;
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case TargetOpcode::EXTRACT_SUBREG:
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case TargetOpcode::INSERT_SUBREG:
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case TargetOpcode::SUBREG_TO_REG:
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case TargetOpcode::REG_SEQUENCE:
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case TargetOpcode::IMPLICIT_DEF:
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break;
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}
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Packet.push_back(SU);
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}
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// Forcefully end packet for PseudoOps.
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else {
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ResourcesModel->clearResources();
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Packet.clear();
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}
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// If packet is now full, reset the state so in the next cycle
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// we start fresh.
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if (Packet.size() >= InstrItins->SchedModel->IssueWidth) {
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ResourcesModel->clearResources();
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Packet.clear();
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}
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}
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signed ResourcePriorityQueue::rawRegPressureDelta(SUnit *SU, unsigned RCId) {
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signed RegBalance = 0;
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if (!SU || !SU->getNode() || !SU->getNode()->isMachineOpcode())
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return RegBalance;
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// Gen estimate.
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for (unsigned i = 0, e = SU->getNode()->getNumValues(); i != e; ++i) {
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MVT VT = SU->getNode()->getSimpleValueType(i);
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if (TLI->isTypeLegal(VT)
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&& TLI->getRegClassFor(VT)
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&& TLI->getRegClassFor(VT)->getID() == RCId)
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RegBalance += numberRCValSuccInSU(SU, RCId);
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}
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// Kill estimate.
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for (unsigned i = 0, e = SU->getNode()->getNumOperands(); i != e; ++i) {
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const SDValue &Op = SU->getNode()->getOperand(i);
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MVT VT = Op.getNode()->getSimpleValueType(Op.getResNo());
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if (isa<ConstantSDNode>(Op.getNode()))
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continue;
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if (TLI->isTypeLegal(VT) && TLI->getRegClassFor(VT)
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&& TLI->getRegClassFor(VT)->getID() == RCId)
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RegBalance -= numberRCValPredInSU(SU, RCId);
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}
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return RegBalance;
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}
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/// Estimates change in reg pressure from this SU.
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/// It is achieved by trivial tracking of defined
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/// and used vregs in dependent instructions.
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/// The RawPressure flag makes this function to ignore
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/// existing reg file sizes, and report raw def/use
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/// balance.
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signed ResourcePriorityQueue::regPressureDelta(SUnit *SU, bool RawPressure) {
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signed RegBalance = 0;
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if (!SU || !SU->getNode() || !SU->getNode()->isMachineOpcode())
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return RegBalance;
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if (RawPressure) {
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for (TargetRegisterInfo::regclass_iterator I = TRI->regclass_begin(),
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E = TRI->regclass_end(); I != E; ++I) {
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const TargetRegisterClass *RC = *I;
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RegBalance += rawRegPressureDelta(SU, RC->getID());
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}
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}
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else {
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for (TargetRegisterInfo::regclass_iterator I = TRI->regclass_begin(),
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E = TRI->regclass_end(); I != E; ++I) {
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const TargetRegisterClass *RC = *I;
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if ((RegPressure[RC->getID()] +
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rawRegPressureDelta(SU, RC->getID()) > 0) &&
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(RegPressure[RC->getID()] +
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rawRegPressureDelta(SU, RC->getID()) >= RegLimit[RC->getID()]))
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RegBalance += rawRegPressureDelta(SU, RC->getID());
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}
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}
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return RegBalance;
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}
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// Constants used to denote relative importance of
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// heuristic components for cost computation.
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static const unsigned PriorityOne = 200;
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static const unsigned PriorityTwo = 50;
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static const unsigned PriorityThree = 15;
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static const unsigned PriorityFour = 5;
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static const unsigned ScaleOne = 20;
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static const unsigned ScaleTwo = 10;
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static const unsigned ScaleThree = 5;
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static const unsigned FactorOne = 2;
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/// Returns single number reflecting benefit of scheduling SU
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/// in the current cycle.
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signed ResourcePriorityQueue::SUSchedulingCost(SUnit *SU) {
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// Initial trivial priority.
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signed ResCount = 1;
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// Do not waste time on a node that is already scheduled.
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if (SU->isScheduled)
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return ResCount;
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// Forced priority is high.
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if (SU->isScheduleHigh)
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ResCount += PriorityOne;
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// Adaptable scheduling
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// A small, but very parallel
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// region, where reg pressure is an issue.
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if (HorizontalVerticalBalance > RegPressureThreshold) {
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// Critical path first
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ResCount += (SU->getHeight() * ScaleTwo);
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// If resources are available for it, multiply the
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// chance of scheduling.
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if (isResourceAvailable(SU))
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ResCount <<= FactorOne;
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// Consider change to reg pressure from scheduling
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// this SU.
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ResCount -= (regPressureDelta(SU,true) * ScaleOne);
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}
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// Default heuristic, greeady and
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// critical path driven.
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else {
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// Critical path first.
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ResCount += (SU->getHeight() * ScaleTwo);
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// Now see how many instructions is blocked by this SU.
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ResCount += (NumNodesSolelyBlocking[SU->NodeNum] * ScaleTwo);
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// If resources are available for it, multiply the
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// chance of scheduling.
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if (isResourceAvailable(SU))
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ResCount <<= FactorOne;
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ResCount -= (regPressureDelta(SU) * ScaleTwo);
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}
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// These are platform specific things.
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// Will need to go into the back end
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// and accessed from here via a hook.
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for (SDNode *N = SU->getNode(); N; N = N->getGluedNode()) {
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if (N->isMachineOpcode()) {
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const MCInstrDesc &TID = TII->get(N->getMachineOpcode());
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if (TID.isCall())
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ResCount += (PriorityTwo + (ScaleThree*N->getNumValues()));
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}
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else
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switch (N->getOpcode()) {
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default: break;
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case ISD::TokenFactor:
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case ISD::CopyFromReg:
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case ISD::CopyToReg:
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ResCount += PriorityFour;
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break;
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case ISD::INLINEASM:
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ResCount += PriorityThree;
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break;
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}
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}
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return ResCount;
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}
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/// Main resource tracking point.
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void ResourcePriorityQueue::scheduledNode(SUnit *SU) {
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// Use NULL entry as an event marker to reset
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// the DFA state.
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if (!SU) {
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ResourcesModel->clearResources();
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Packet.clear();
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return;
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}
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const SDNode *ScegN = SU->getNode();
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// Update reg pressure tracking.
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// First update current node.
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if (ScegN->isMachineOpcode()) {
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// Estimate generated regs.
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for (unsigned i = 0, e = ScegN->getNumValues(); i != e; ++i) {
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MVT VT = ScegN->getSimpleValueType(i);
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if (TLI->isTypeLegal(VT)) {
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const TargetRegisterClass *RC = TLI->getRegClassFor(VT);
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if (RC)
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RegPressure[RC->getID()] += numberRCValSuccInSU(SU, RC->getID());
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}
|
|
}
|
|
// Estimate killed regs.
|
|
for (unsigned i = 0, e = ScegN->getNumOperands(); i != e; ++i) {
|
|
const SDValue &Op = ScegN->getOperand(i);
|
|
MVT VT = Op.getNode()->getSimpleValueType(Op.getResNo());
|
|
|
|
if (TLI->isTypeLegal(VT)) {
|
|
const TargetRegisterClass *RC = TLI->getRegClassFor(VT);
|
|
if (RC) {
|
|
if (RegPressure[RC->getID()] >
|
|
(numberRCValPredInSU(SU, RC->getID())))
|
|
RegPressure[RC->getID()] -= numberRCValPredInSU(SU, RC->getID());
|
|
else RegPressure[RC->getID()] = 0;
|
|
}
|
|
}
|
|
}
|
|
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
|
|
I != E; ++I) {
|
|
if (I->isCtrl() || (I->getSUnit()->NumRegDefsLeft == 0))
|
|
continue;
|
|
--I->getSUnit()->NumRegDefsLeft;
|
|
}
|
|
}
|
|
|
|
// Reserve resources for this SU.
|
|
reserveResources(SU);
|
|
|
|
// Adjust number of parallel live ranges.
|
|
// Heuristic is simple - node with no data successors reduces
|
|
// number of live ranges. All others, increase it.
|
|
unsigned NumberNonControlDeps = 0;
|
|
|
|
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
|
|
I != E; ++I) {
|
|
adjustPriorityOfUnscheduledPreds(I->getSUnit());
|
|
if (!I->isCtrl())
|
|
NumberNonControlDeps++;
|
|
}
|
|
|
|
if (!NumberNonControlDeps) {
|
|
if (ParallelLiveRanges >= SU->NumPreds)
|
|
ParallelLiveRanges -= SU->NumPreds;
|
|
else
|
|
ParallelLiveRanges = 0;
|
|
|
|
}
|
|
else
|
|
ParallelLiveRanges += SU->NumRegDefsLeft;
|
|
|
|
// Track parallel live chains.
|
|
HorizontalVerticalBalance += (SU->Succs.size() - numberCtrlDepsInSU(SU));
|
|
HorizontalVerticalBalance -= (SU->Preds.size() - numberCtrlPredInSU(SU));
|
|
}
|
|
|
|
void ResourcePriorityQueue::initNumRegDefsLeft(SUnit *SU) {
|
|
unsigned NodeNumDefs = 0;
|
|
for (SDNode *N = SU->getNode(); N; N = N->getGluedNode())
|
|
if (N->isMachineOpcode()) {
|
|
const MCInstrDesc &TID = TII->get(N->getMachineOpcode());
|
|
// No register need be allocated for this.
|
|
if (N->getMachineOpcode() == TargetOpcode::IMPLICIT_DEF) {
|
|
NodeNumDefs = 0;
|
|
break;
|
|
}
|
|
NodeNumDefs = std::min(N->getNumValues(), TID.getNumDefs());
|
|
}
|
|
else
|
|
switch(N->getOpcode()) {
|
|
default: break;
|
|
case ISD::CopyFromReg:
|
|
NodeNumDefs++;
|
|
break;
|
|
case ISD::INLINEASM:
|
|
NodeNumDefs++;
|
|
break;
|
|
}
|
|
|
|
SU->NumRegDefsLeft = NodeNumDefs;
|
|
}
|
|
|
|
/// 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 ResourcePriorityQueue::adjustPriorityOfUnscheduledPreds(SUnit *SU) {
|
|
if (SU->isAvailable) return; // All preds scheduled.
|
|
|
|
SUnit *OnlyAvailablePred = getSingleUnscheduledPred(SU);
|
|
if (!OnlyAvailablePred || !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.
|
|
remove(OnlyAvailablePred);
|
|
|
|
// Reinsert the node into the priority queue, which recomputes its
|
|
// NumNodesSolelyBlocking value.
|
|
push(OnlyAvailablePred);
|
|
}
|
|
|
|
|
|
/// Main access point - returns next instructions
|
|
/// to be placed in scheduling sequence.
|
|
SUnit *ResourcePriorityQueue::pop() {
|
|
if (empty())
|
|
return nullptr;
|
|
|
|
std::vector<SUnit *>::iterator Best = Queue.begin();
|
|
if (!DisableDFASched) {
|
|
signed BestCost = SUSchedulingCost(*Best);
|
|
for (std::vector<SUnit *>::iterator I = std::next(Queue.begin()),
|
|
E = Queue.end(); I != E; ++I) {
|
|
|
|
if (SUSchedulingCost(*I) > BestCost) {
|
|
BestCost = SUSchedulingCost(*I);
|
|
Best = I;
|
|
}
|
|
}
|
|
}
|
|
// Use default TD scheduling mechanism.
|
|
else {
|
|
for (std::vector<SUnit *>::iterator I = std::next(Queue.begin()),
|
|
E = Queue.end(); I != E; ++I)
|
|
if (Picker(*Best, *I))
|
|
Best = I;
|
|
}
|
|
|
|
SUnit *V = *Best;
|
|
if (Best != std::prev(Queue.end()))
|
|
std::swap(*Best, Queue.back());
|
|
|
|
Queue.pop_back();
|
|
|
|
return V;
|
|
}
|
|
|
|
|
|
void ResourcePriorityQueue::remove(SUnit *SU) {
|
|
assert(!Queue.empty() && "Queue is empty!");
|
|
std::vector<SUnit *>::iterator I = std::find(Queue.begin(), Queue.end(), SU);
|
|
if (I != std::prev(Queue.end()))
|
|
std::swap(*I, Queue.back());
|
|
|
|
Queue.pop_back();
|
|
}
|
|
|
|
|
|
#ifdef NDEBUG
|
|
void ResourcePriorityQueue::dump(ScheduleDAG *DAG) const {}
|
|
#else
|
|
void ResourcePriorityQueue::dump(ScheduleDAG *DAG) const {
|
|
ResourcePriorityQueue q = *this;
|
|
while (!q.empty()) {
|
|
SUnit *su = q.pop();
|
|
dbgs() << "Height " << su->getHeight() << ": ";
|
|
su->dump(DAG);
|
|
}
|
|
}
|
|
#endif
|