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8d1bfad00b
scheduler implementations. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41191 91177308-0d34-0410-b5e6-96231b3b80d8
947 lines
32 KiB
C++
947 lines
32 KiB
C++
//===----- ScheduleDAGList.cpp - Reg pressure reduction list scheduler ----===//
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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 register pressure reduction list
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// schedulers, using standard algorithms. The basic approach uses a priority
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// queue of available nodes to schedule. One at a time, nodes are taken from
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// the priority queue (thus in priority order), checked for legality to
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// schedule, and emitted if legal.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "pre-RA-sched"
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#include "llvm/CodeGen/ScheduleDAG.h"
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#include "llvm/CodeGen/SchedulerRegistry.h"
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#include "llvm/CodeGen/SSARegMap.h"
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#include "llvm/Target/MRegisterInfo.h"
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#include "llvm/Target/TargetData.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/Support/Compiler.h"
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#include "llvm/ADT/Statistic.h"
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#include <climits>
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#include <queue>
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#include "llvm/Support/CommandLine.h"
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using namespace llvm;
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static RegisterScheduler
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burrListDAGScheduler("list-burr",
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" Bottom-up register reduction list scheduling",
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createBURRListDAGScheduler);
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static RegisterScheduler
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tdrListrDAGScheduler("list-tdrr",
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" Top-down register reduction list scheduling",
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createTDRRListDAGScheduler);
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namespace {
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//===----------------------------------------------------------------------===//
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/// ScheduleDAGRRList - The actual register reduction list scheduler
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/// implementation. This supports both top-down and bottom-up scheduling.
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///
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class VISIBILITY_HIDDEN ScheduleDAGRRList : public ScheduleDAG {
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private:
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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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public:
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ScheduleDAGRRList(SelectionDAG &dag, MachineBasicBlock *bb,
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const TargetMachine &tm, bool isbottomup,
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SchedulingPriorityQueue *availqueue)
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: ScheduleDAG(dag, bb, tm), isBottomUp(isbottomup),
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AvailableQueue(availqueue) {
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}
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~ScheduleDAGRRList() {
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delete AvailableQueue;
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}
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void Schedule();
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private:
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void ReleasePred(SUnit *PredSU, bool isChain, unsigned CurCycle);
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void ReleaseSucc(SUnit *SuccSU, bool isChain, unsigned CurCycle);
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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 CommuteNodesToReducePressure();
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};
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} // end anonymous namespace
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/// Schedule - Schedule the DAG using list scheduling.
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void ScheduleDAGRRList::Schedule() {
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DOUT << "********** List Scheduling **********\n";
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// Build scheduling units.
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BuildSchedUnits();
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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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CalculateDepths();
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CalculateHeights();
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AvailableQueue->initNodes(SUnitMap, 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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CommuteNodesToReducePressure();
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DOUT << "*** Final schedule ***\n";
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DEBUG(dumpSchedule());
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DOUT << "\n";
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// Emit in scheduled order
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EmitSchedule();
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}
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/// CommuteNodesToReducePressure - If a node is two-address and commutable, and
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/// it is not the last use of its first operand, add it to the CommuteSet if
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/// possible. It will be commuted when it is translated to a MI.
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void ScheduleDAGRRList::CommuteNodesToReducePressure() {
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SmallPtrSet<SUnit*, 4> OperandSeen;
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for (unsigned i = Sequence.size()-1; i != 0; --i) { // Ignore first node.
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SUnit *SU = Sequence[i];
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if (!SU) continue;
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if (SU->isCommutable) {
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unsigned Opc = SU->Node->getTargetOpcode();
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unsigned NumRes = CountResults(SU->Node);
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unsigned NumOps = CountOperands(SU->Node);
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for (unsigned j = 0; j != NumOps; ++j) {
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if (TII->getOperandConstraint(Opc, j+NumRes, TOI::TIED_TO) == -1)
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continue;
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SDNode *OpN = SU->Node->getOperand(j).Val;
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SUnit *OpSU = SUnitMap[OpN];
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if (OpSU && OperandSeen.count(OpSU) == 1) {
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// Ok, so SU is not the last use of OpSU, but SU is two-address so
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// it will clobber OpSU. Try to commute SU if no other source operands
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// are live below.
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bool DoCommute = true;
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for (unsigned k = 0; k < NumOps; ++k) {
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if (k != j) {
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OpN = SU->Node->getOperand(k).Val;
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OpSU = SUnitMap[OpN];
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if (OpSU && OperandSeen.count(OpSU) == 1) {
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DoCommute = false;
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break;
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}
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}
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}
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if (DoCommute)
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CommuteSet.insert(SU->Node);
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}
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// Only look at the first use&def node for now.
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break;
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}
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}
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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->second)
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OperandSeen.insert(I->first);
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}
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}
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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 AvailableQueue if the count reaches zero. Also update its cycle bound.
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void ScheduleDAGRRList::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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cerr << "*** List scheduling failed! ***\n";
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PredSU->dump(&DAG);
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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 ScheduleDAGRRList::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) {
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DOUT << "*** Scheduling [" << CurCycle << "]: ";
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DEBUG(SU->dump(&DAG));
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SU->Cycle = CurCycle;
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AvailableQueue->ScheduledNode(SU);
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Sequence.push_back(SU);
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// Bottom up: release predecessors
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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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ReleasePred(I->first, I->second, CurCycle);
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SU->isScheduled = true;
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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 CurCycle) {
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return SU->CycleBound <= CurCycle;
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}
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/// ListScheduleBottomUp - The main loop of list scheduling for bottom-up
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/// schedulers.
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void ScheduleDAGRRList::ListScheduleBottomUp() {
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unsigned CurCycle = 0;
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// Add root to Available queue.
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AvailableQueue->push(SUnitMap[DAG.getRoot().Val]);
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// While Available queue is not empty, grab the node with the highest
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// priority. If it is not ready put it back. Schedule the node.
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std::vector<SUnit*> NotReady;
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while (!AvailableQueue->empty()) {
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SUnit *CurNode = AvailableQueue->pop();
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while (CurNode && !isReady(CurNode, CurCycle)) {
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NotReady.push_back(CurNode);
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CurNode = AvailableQueue->pop();
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}
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// Add the nodes that aren't ready back onto the available list.
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AvailableQueue->push_all(NotReady);
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NotReady.clear();
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if (CurNode != NULL)
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ScheduleNodeBottomUp(CurNode, CurCycle);
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CurCycle++;
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}
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// Add entry node last
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if (DAG.getEntryNode().Val != DAG.getRoot().Val) {
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SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
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Sequence.push_back(Entry);
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}
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// Reverse the order if it is bottom up.
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std::reverse(Sequence.begin(), Sequence.end());
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#ifndef NDEBUG
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// Verify that all SUnits were scheduled.
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bool AnyNotSched = false;
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for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
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if (SUnits[i].NumSuccsLeft != 0 || SUnits[i].NumChainSuccsLeft != 0) {
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if (!AnyNotSched)
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cerr << "*** List scheduling failed! ***\n";
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SUnits[i].dump(&DAG);
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cerr << "has not been scheduled!\n";
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AnyNotSched = true;
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}
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}
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assert(!AnyNotSched);
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#endif
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}
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//===----------------------------------------------------------------------===//
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// Top-Down Scheduling
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//===----------------------------------------------------------------------===//
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/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
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/// the AvailableQueue if the count reaches zero. Also update its cycle bound.
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void ScheduleDAGRRList::ReleaseSucc(SUnit *SuccSU, 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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SuccSU->CycleBound = std::max(SuccSU->CycleBound, CurCycle + SuccSU->Latency);
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if (!isChain)
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SuccSU->NumPredsLeft--;
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else
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SuccSU->NumChainPredsLeft--;
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#ifndef NDEBUG
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if (SuccSU->NumPredsLeft < 0 || SuccSU->NumChainPredsLeft < 0) {
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cerr << "*** List scheduling failed! ***\n";
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SuccSU->dump(&DAG);
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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 ((SuccSU->NumPredsLeft + SuccSU->NumChainPredsLeft) == 0) {
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SuccSU->isAvailable = true;
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AvailableQueue->push(SuccSU);
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}
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}
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/// ScheduleNodeTopDown - Add the node to the schedule. Decrement the pending
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/// count of its successors. If a successor pending count is zero, add it to
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/// the Available queue.
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void ScheduleDAGRRList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
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DOUT << "*** Scheduling [" << CurCycle << "]: ";
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DEBUG(SU->dump(&DAG));
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SU->Cycle = CurCycle;
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AvailableQueue->ScheduledNode(SU);
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Sequence.push_back(SU);
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// Top down: release successors
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for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
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I != E; ++I)
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ReleaseSucc(I->first, I->second, CurCycle);
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SU->isScheduled = true;
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}
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/// ListScheduleTopDown - The main loop of list scheduling for top-down
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/// schedulers.
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void ScheduleDAGRRList::ListScheduleTopDown() {
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unsigned CurCycle = 0;
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SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
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// All leaves to Available queue.
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for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
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// It is available if it has no predecessors.
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if (SUnits[i].Preds.size() == 0 && &SUnits[i] != Entry) {
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AvailableQueue->push(&SUnits[i]);
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SUnits[i].isAvailable = true;
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}
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}
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// Emit the entry node first.
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ScheduleNodeTopDown(Entry, CurCycle);
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CurCycle++;
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// While Available queue is not empty, grab the node with the highest
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// priority. If it is not ready put it back. Schedule the node.
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std::vector<SUnit*> NotReady;
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while (!AvailableQueue->empty()) {
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SUnit *CurNode = AvailableQueue->pop();
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while (CurNode && !isReady(CurNode, CurCycle)) {
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NotReady.push_back(CurNode);
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CurNode = AvailableQueue->pop();
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}
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// Add the nodes that aren't ready back onto the available list.
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AvailableQueue->push_all(NotReady);
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NotReady.clear();
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if (CurNode != NULL)
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ScheduleNodeTopDown(CurNode, CurCycle);
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CurCycle++;
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}
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#ifndef NDEBUG
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// Verify that all SUnits were scheduled.
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bool AnyNotSched = false;
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for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
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if (!SUnits[i].isScheduled) {
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if (!AnyNotSched)
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cerr << "*** List scheduling failed! ***\n";
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SUnits[i].dump(&DAG);
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cerr << "has not been scheduled!\n";
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AnyNotSched = true;
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}
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}
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assert(!AnyNotSched);
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#endif
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}
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//===----------------------------------------------------------------------===//
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// RegReductionPriorityQueue Implementation
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//===----------------------------------------------------------------------===//
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//
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// This is a SchedulingPriorityQueue that schedules using Sethi Ullman numbers
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// to reduce register pressure.
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//
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namespace {
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template<class SF>
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class RegReductionPriorityQueue;
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/// Sorting functions for the Available queue.
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struct bu_ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
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RegReductionPriorityQueue<bu_ls_rr_sort> *SPQ;
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bu_ls_rr_sort(RegReductionPriorityQueue<bu_ls_rr_sort> *spq) : SPQ(spq) {}
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bu_ls_rr_sort(const bu_ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
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bool operator()(const SUnit* left, const SUnit* right) const;
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};
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struct td_ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
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RegReductionPriorityQueue<td_ls_rr_sort> *SPQ;
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td_ls_rr_sort(RegReductionPriorityQueue<td_ls_rr_sort> *spq) : SPQ(spq) {}
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td_ls_rr_sort(const td_ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
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bool operator()(const SUnit* left, const SUnit* right) const;
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};
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} // end anonymous namespace
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static inline bool isCopyFromLiveIn(const SUnit *SU) {
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SDNode *N = SU->Node;
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return N->getOpcode() == ISD::CopyFromReg &&
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N->getOperand(N->getNumOperands()-1).getValueType() != MVT::Flag;
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}
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namespace {
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template<class SF>
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class VISIBILITY_HIDDEN RegReductionPriorityQueue
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: public SchedulingPriorityQueue {
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std::priority_queue<SUnit*, std::vector<SUnit*>, SF> Queue;
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public:
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RegReductionPriorityQueue() :
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Queue(SF(this)) {}
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virtual void initNodes(DenseMap<SDNode*, SUnit*> &sumap,
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std::vector<SUnit> &sunits) {}
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virtual void releaseState() {}
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virtual unsigned getNodePriority(const SUnit *SU) const {
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return 0;
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}
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bool empty() const { return Queue.empty(); }
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void push(SUnit *U) {
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Queue.push(U);
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}
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void push_all(const std::vector<SUnit *> &Nodes) {
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for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
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Queue.push(Nodes[i]);
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}
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SUnit *pop() {
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if (empty()) return NULL;
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SUnit *V = Queue.top();
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Queue.pop();
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return V;
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}
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virtual bool isDUOperand(const SUnit *SU1, const SUnit *SU2) {
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return false;
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}
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};
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template<class SF>
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class VISIBILITY_HIDDEN BURegReductionPriorityQueue
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: public RegReductionPriorityQueue<SF> {
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// SUnitMap SDNode to SUnit mapping (n -> 1).
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DenseMap<SDNode*, SUnit*> *SUnitMap;
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// SUnits - The SUnits for the current graph.
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const std::vector<SUnit> *SUnits;
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// SethiUllmanNumbers - The SethiUllman number for each node.
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std::vector<unsigned> SethiUllmanNumbers;
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const TargetInstrInfo *TII;
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public:
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explicit BURegReductionPriorityQueue(const TargetInstrInfo *tii)
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: TII(tii) {}
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void initNodes(DenseMap<SDNode*, SUnit*> &sumap,
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std::vector<SUnit> &sunits) {
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SUnitMap = &sumap;
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SUnits = &sunits;
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// Add pseudo dependency edges for two-address nodes.
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AddPseudoTwoAddrDeps();
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// Calculate node priorities.
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CalculateSethiUllmanNumbers();
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}
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void releaseState() {
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SUnits = 0;
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SethiUllmanNumbers.clear();
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}
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unsigned getNodePriority(const SUnit *SU) const {
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assert(SU->NodeNum < SethiUllmanNumbers.size());
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unsigned Opc = SU->Node->getOpcode();
|
|
if (Opc == ISD::CopyFromReg && !isCopyFromLiveIn(SU))
|
|
// CopyFromReg should be close to its def because it restricts
|
|
// allocation choices. But if it is a livein then perhaps we want it
|
|
// closer to its uses so it can be coalesced.
|
|
return 0xffff;
|
|
else if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
|
|
// CopyToReg should be close to its uses to facilitate coalescing and
|
|
// avoid spilling.
|
|
return 0;
|
|
else if (SU->NumSuccs == 0)
|
|
// If SU does not have a use, i.e. it doesn't produce a value that would
|
|
// be consumed (e.g. store), then it terminates a chain of computation.
|
|
// Give it a large SethiUllman number so it will be scheduled right
|
|
// before its predecessors that it doesn't lengthen their live ranges.
|
|
return 0xffff;
|
|
else if (SU->NumPreds == 0)
|
|
// If SU does not have a def, schedule it close to its uses because it
|
|
// does not lengthen any live ranges.
|
|
return 0;
|
|
else
|
|
return SethiUllmanNumbers[SU->NodeNum];
|
|
}
|
|
|
|
bool isDUOperand(const SUnit *SU1, const SUnit *SU2) {
|
|
unsigned Opc = SU1->Node->getTargetOpcode();
|
|
unsigned NumRes = ScheduleDAG::CountResults(SU1->Node);
|
|
unsigned NumOps = ScheduleDAG::CountOperands(SU1->Node);
|
|
for (unsigned i = 0; i != NumOps; ++i) {
|
|
if (TII->getOperandConstraint(Opc, i+NumRes, TOI::TIED_TO) == -1)
|
|
continue;
|
|
if (SU1->Node->getOperand(i).isOperand(SU2->Node))
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
private:
|
|
bool canClobber(SUnit *SU, SUnit *Op);
|
|
void AddPseudoTwoAddrDeps();
|
|
void CalculateSethiUllmanNumbers();
|
|
unsigned CalcNodeSethiUllmanNumber(const SUnit *SU);
|
|
};
|
|
|
|
|
|
template<class SF>
|
|
class VISIBILITY_HIDDEN TDRegReductionPriorityQueue
|
|
: public RegReductionPriorityQueue<SF> {
|
|
// SUnitMap SDNode to SUnit mapping (n -> 1).
|
|
DenseMap<SDNode*, SUnit*> *SUnitMap;
|
|
|
|
// SUnits - The SUnits for the current graph.
|
|
const std::vector<SUnit> *SUnits;
|
|
|
|
// SethiUllmanNumbers - The SethiUllman number for each node.
|
|
std::vector<unsigned> SethiUllmanNumbers;
|
|
|
|
public:
|
|
TDRegReductionPriorityQueue() {}
|
|
|
|
void initNodes(DenseMap<SDNode*, SUnit*> &sumap,
|
|
std::vector<SUnit> &sunits) {
|
|
SUnitMap = &sumap;
|
|
SUnits = &sunits;
|
|
// Calculate node priorities.
|
|
CalculateSethiUllmanNumbers();
|
|
}
|
|
|
|
void releaseState() {
|
|
SUnits = 0;
|
|
SethiUllmanNumbers.clear();
|
|
}
|
|
|
|
unsigned getNodePriority(const SUnit *SU) const {
|
|
assert(SU->NodeNum < SethiUllmanNumbers.size());
|
|
return SethiUllmanNumbers[SU->NodeNum];
|
|
}
|
|
|
|
private:
|
|
void CalculateSethiUllmanNumbers();
|
|
unsigned CalcNodeSethiUllmanNumber(const SUnit *SU);
|
|
};
|
|
}
|
|
|
|
/// closestSucc - Returns the scheduled cycle of the successor which is
|
|
/// closet to the current cycle.
|
|
static unsigned closestSucc(const SUnit *SU) {
|
|
unsigned MaxCycle = 0;
|
|
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
|
|
I != E; ++I) {
|
|
unsigned Cycle = I->first->Cycle;
|
|
// If there are bunch of CopyToRegs stacked up, they should be considered
|
|
// to be at the same position.
|
|
if (I->first->Node->getOpcode() == ISD::CopyToReg)
|
|
Cycle = closestSucc(I->first)+1;
|
|
if (Cycle > MaxCycle)
|
|
MaxCycle = Cycle;
|
|
}
|
|
return MaxCycle;
|
|
}
|
|
|
|
/// calcMaxScratches - Returns an cost estimate of the worse case requirement
|
|
/// for scratch registers. Live-in operands and live-out results don't count
|
|
/// since they are "fixed".
|
|
static unsigned calcMaxScratches(const SUnit *SU) {
|
|
unsigned Scratches = 0;
|
|
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
|
|
I != E; ++I) {
|
|
if (I->second) continue; // ignore chain preds
|
|
if (I->first->Node->getOpcode() != ISD::CopyFromReg)
|
|
Scratches++;
|
|
}
|
|
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
|
|
I != E; ++I) {
|
|
if (I->second) continue; // ignore chain succs
|
|
if (I->first->Node->getOpcode() != ISD::CopyToReg)
|
|
Scratches += 10;
|
|
}
|
|
return Scratches;
|
|
}
|
|
|
|
// Bottom up
|
|
bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
|
|
// There used to be a special tie breaker here that looked for
|
|
// two-address instructions and preferred the instruction with a
|
|
// def&use operand. The special case triggered diagnostics when
|
|
// _GLIBCXX_DEBUG was enabled because it broke the strict weak
|
|
// ordering that priority_queue requires. It didn't help much anyway
|
|
// because AddPseudoTwoAddrDeps already covers many of the cases
|
|
// where it would have applied. In addition, it's counter-intuitive
|
|
// that a tie breaker would be the first thing attempted. There's a
|
|
// "real" tie breaker below that is the operation of last resort.
|
|
// The fact that the "special tie breaker" would trigger when there
|
|
// wasn't otherwise a tie is what broke the strict weak ordering
|
|
// constraint.
|
|
|
|
unsigned LPriority = SPQ->getNodePriority(left);
|
|
unsigned RPriority = SPQ->getNodePriority(right);
|
|
if (LPriority > RPriority)
|
|
return true;
|
|
else if (LPriority == RPriority) {
|
|
// Try schedule def + use closer when Sethi-Ullman numbers are the same.
|
|
// e.g.
|
|
// t1 = op t2, c1
|
|
// t3 = op t4, c2
|
|
//
|
|
// and the following instructions are both ready.
|
|
// t2 = op c3
|
|
// t4 = op c4
|
|
//
|
|
// Then schedule t2 = op first.
|
|
// i.e.
|
|
// t4 = op c4
|
|
// t2 = op c3
|
|
// t1 = op t2, c1
|
|
// t3 = op t4, c2
|
|
//
|
|
// This creates more short live intervals.
|
|
unsigned LDist = closestSucc(left);
|
|
unsigned RDist = closestSucc(right);
|
|
if (LDist < RDist)
|
|
return true;
|
|
else if (LDist == RDist) {
|
|
// Intuitively, it's good to push down instructions whose results are
|
|
// liveout so their long live ranges won't conflict with other values
|
|
// which are needed inside the BB. Further prioritize liveout instructions
|
|
// by the number of operands which are calculated within the BB.
|
|
unsigned LScratch = calcMaxScratches(left);
|
|
unsigned RScratch = calcMaxScratches(right);
|
|
if (LScratch > RScratch)
|
|
return true;
|
|
else if (LScratch == RScratch)
|
|
if (left->Height > right->Height)
|
|
return true;
|
|
else if (left->Height == right->Height)
|
|
if (left->Depth < right->Depth)
|
|
return true;
|
|
else if (left->Depth == right->Depth)
|
|
if (left->CycleBound > right->CycleBound)
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// FIXME: This is probably too slow!
|
|
static void isReachable(SUnit *SU, SUnit *TargetSU,
|
|
SmallPtrSet<SUnit*, 32> &Visited, bool &Reached) {
|
|
if (Reached) return;
|
|
if (SU == TargetSU) {
|
|
Reached = true;
|
|
return;
|
|
}
|
|
if (!Visited.insert(SU)) return;
|
|
|
|
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); I != E;
|
|
++I)
|
|
isReachable(I->first, TargetSU, Visited, Reached);
|
|
}
|
|
|
|
static bool isReachable(SUnit *SU, SUnit *TargetSU) {
|
|
SmallPtrSet<SUnit*, 32> Visited;
|
|
bool Reached = false;
|
|
isReachable(SU, TargetSU, Visited, Reached);
|
|
return Reached;
|
|
}
|
|
|
|
template<class SF>
|
|
bool BURegReductionPriorityQueue<SF>::canClobber(SUnit *SU, SUnit *Op) {
|
|
if (SU->isTwoAddress) {
|
|
unsigned Opc = SU->Node->getTargetOpcode();
|
|
unsigned NumRes = ScheduleDAG::CountResults(SU->Node);
|
|
unsigned NumOps = ScheduleDAG::CountOperands(SU->Node);
|
|
for (unsigned i = 0; i != NumOps; ++i) {
|
|
if (TII->getOperandConstraint(Opc, i+NumRes, TOI::TIED_TO) != -1) {
|
|
SDNode *DU = SU->Node->getOperand(i).Val;
|
|
if (Op == (*SUnitMap)[DU])
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
|
|
/// AddPseudoTwoAddrDeps - If two nodes share an operand and one of them uses
|
|
/// it as a def&use operand. Add a pseudo control edge from it to the other
|
|
/// node (if it won't create a cycle) so the two-address one will be scheduled
|
|
/// first (lower in the schedule).
|
|
template<class SF>
|
|
void BURegReductionPriorityQueue<SF>::AddPseudoTwoAddrDeps() {
|
|
for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
|
|
SUnit *SU = (SUnit *)&((*SUnits)[i]);
|
|
if (!SU->isTwoAddress)
|
|
continue;
|
|
|
|
SDNode *Node = SU->Node;
|
|
if (!Node->isTargetOpcode())
|
|
continue;
|
|
|
|
unsigned Opc = Node->getTargetOpcode();
|
|
unsigned NumRes = ScheduleDAG::CountResults(Node);
|
|
unsigned NumOps = ScheduleDAG::CountOperands(Node);
|
|
for (unsigned j = 0; j != NumOps; ++j) {
|
|
if (TII->getOperandConstraint(Opc, j+NumRes, TOI::TIED_TO) != -1) {
|
|
SDNode *DU = SU->Node->getOperand(j).Val;
|
|
SUnit *DUSU = (*SUnitMap)[DU];
|
|
if (!DUSU) continue;
|
|
for (SUnit::succ_iterator I = DUSU->Succs.begin(),E = DUSU->Succs.end();
|
|
I != E; ++I) {
|
|
if (I->second) continue;
|
|
SUnit *SuccSU = I->first;
|
|
if (SuccSU != SU &&
|
|
(!canClobber(SuccSU, DUSU) ||
|
|
(!SU->isCommutable && SuccSU->isCommutable))){
|
|
if (SuccSU->Depth == SU->Depth && !isReachable(SuccSU, SU)) {
|
|
DOUT << "Adding an edge from SU # " << SU->NodeNum
|
|
<< " to SU #" << SuccSU->NodeNum << "\n";
|
|
if (SU->addPred(SuccSU, true))
|
|
SU->NumChainPredsLeft++;
|
|
if (SuccSU->addSucc(SU, true))
|
|
SuccSU->NumChainSuccsLeft++;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// CalcNodeSethiUllmanNumber - Priority is the Sethi Ullman number.
|
|
/// Smaller number is the higher priority.
|
|
template<class SF>
|
|
unsigned BURegReductionPriorityQueue<SF>::
|
|
CalcNodeSethiUllmanNumber(const SUnit *SU) {
|
|
unsigned &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
|
|
if (SethiUllmanNumber != 0)
|
|
return SethiUllmanNumber;
|
|
|
|
unsigned Extra = 0;
|
|
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
|
|
I != E; ++I) {
|
|
if (I->second) continue; // ignore chain preds
|
|
SUnit *PredSU = I->first;
|
|
unsigned PredSethiUllman = CalcNodeSethiUllmanNumber(PredSU);
|
|
if (PredSethiUllman > SethiUllmanNumber) {
|
|
SethiUllmanNumber = PredSethiUllman;
|
|
Extra = 0;
|
|
} else if (PredSethiUllman == SethiUllmanNumber && !I->second)
|
|
Extra++;
|
|
}
|
|
|
|
SethiUllmanNumber += Extra;
|
|
|
|
if (SethiUllmanNumber == 0)
|
|
SethiUllmanNumber = 1;
|
|
|
|
return SethiUllmanNumber;
|
|
}
|
|
|
|
/// CalculateSethiUllmanNumbers - Calculate Sethi-Ullman numbers of all
|
|
/// scheduling units.
|
|
template<class SF>
|
|
void BURegReductionPriorityQueue<SF>::CalculateSethiUllmanNumbers() {
|
|
SethiUllmanNumbers.assign(SUnits->size(), 0);
|
|
|
|
for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
|
|
CalcNodeSethiUllmanNumber(&(*SUnits)[i]);
|
|
}
|
|
|
|
static unsigned SumOfUnscheduledPredsOfSuccs(const SUnit *SU) {
|
|
unsigned Sum = 0;
|
|
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
|
|
I != E; ++I) {
|
|
SUnit *SuccSU = I->first;
|
|
for (SUnit::const_pred_iterator II = SuccSU->Preds.begin(),
|
|
EE = SuccSU->Preds.end(); II != EE; ++II) {
|
|
SUnit *PredSU = II->first;
|
|
if (!PredSU->isScheduled)
|
|
Sum++;
|
|
}
|
|
}
|
|
|
|
return Sum;
|
|
}
|
|
|
|
|
|
// Top down
|
|
bool td_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
|
|
unsigned LPriority = SPQ->getNodePriority(left);
|
|
unsigned RPriority = SPQ->getNodePriority(right);
|
|
bool LIsTarget = left->Node->isTargetOpcode();
|
|
bool RIsTarget = right->Node->isTargetOpcode();
|
|
bool LIsFloater = LIsTarget && left->NumPreds == 0;
|
|
bool RIsFloater = RIsTarget && right->NumPreds == 0;
|
|
unsigned LBonus = (SumOfUnscheduledPredsOfSuccs(left) == 1) ? 2 : 0;
|
|
unsigned RBonus = (SumOfUnscheduledPredsOfSuccs(right) == 1) ? 2 : 0;
|
|
|
|
if (left->NumSuccs == 0 && right->NumSuccs != 0)
|
|
return false;
|
|
else if (left->NumSuccs != 0 && right->NumSuccs == 0)
|
|
return true;
|
|
|
|
// Special tie breaker: if two nodes share a operand, the one that use it
|
|
// as a def&use operand is preferred.
|
|
if (LIsTarget && RIsTarget) {
|
|
if (left->isTwoAddress && !right->isTwoAddress) {
|
|
SDNode *DUNode = left->Node->getOperand(0).Val;
|
|
if (DUNode->isOperand(right->Node))
|
|
RBonus += 2;
|
|
}
|
|
if (!left->isTwoAddress && right->isTwoAddress) {
|
|
SDNode *DUNode = right->Node->getOperand(0).Val;
|
|
if (DUNode->isOperand(left->Node))
|
|
LBonus += 2;
|
|
}
|
|
}
|
|
if (LIsFloater)
|
|
LBonus -= 2;
|
|
if (RIsFloater)
|
|
RBonus -= 2;
|
|
if (left->NumSuccs == 1)
|
|
LBonus += 2;
|
|
if (right->NumSuccs == 1)
|
|
RBonus += 2;
|
|
|
|
if (LPriority+LBonus < RPriority+RBonus)
|
|
return true;
|
|
else if (LPriority == RPriority)
|
|
if (left->Depth < right->Depth)
|
|
return true;
|
|
else if (left->Depth == right->Depth)
|
|
if (left->NumSuccsLeft > right->NumSuccsLeft)
|
|
return true;
|
|
else if (left->NumSuccsLeft == right->NumSuccsLeft)
|
|
if (left->CycleBound > right->CycleBound)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
/// CalcNodeSethiUllmanNumber - Priority is the Sethi Ullman number.
|
|
/// Smaller number is the higher priority.
|
|
template<class SF>
|
|
unsigned TDRegReductionPriorityQueue<SF>::
|
|
CalcNodeSethiUllmanNumber(const SUnit *SU) {
|
|
unsigned &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
|
|
if (SethiUllmanNumber != 0)
|
|
return SethiUllmanNumber;
|
|
|
|
unsigned Opc = SU->Node->getOpcode();
|
|
if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
|
|
SethiUllmanNumber = 0xffff;
|
|
else if (SU->NumSuccsLeft == 0)
|
|
// If SU does not have a use, i.e. it doesn't produce a value that would
|
|
// be consumed (e.g. store), then it terminates a chain of computation.
|
|
// Give it a small SethiUllman number so it will be scheduled right before
|
|
// its predecessors that it doesn't lengthen their live ranges.
|
|
SethiUllmanNumber = 0;
|
|
else if (SU->NumPredsLeft == 0 &&
|
|
(Opc != ISD::CopyFromReg || isCopyFromLiveIn(SU)))
|
|
SethiUllmanNumber = 0xffff;
|
|
else {
|
|
int Extra = 0;
|
|
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
|
|
I != E; ++I) {
|
|
if (I->second) continue; // ignore chain preds
|
|
SUnit *PredSU = I->first;
|
|
unsigned PredSethiUllman = CalcNodeSethiUllmanNumber(PredSU);
|
|
if (PredSethiUllman > SethiUllmanNumber) {
|
|
SethiUllmanNumber = PredSethiUllman;
|
|
Extra = 0;
|
|
} else if (PredSethiUllman == SethiUllmanNumber && !I->second)
|
|
Extra++;
|
|
}
|
|
|
|
SethiUllmanNumber += Extra;
|
|
}
|
|
|
|
return SethiUllmanNumber;
|
|
}
|
|
|
|
/// CalculateSethiUllmanNumbers - Calculate Sethi-Ullman numbers of all
|
|
/// scheduling units.
|
|
template<class SF>
|
|
void TDRegReductionPriorityQueue<SF>::CalculateSethiUllmanNumbers() {
|
|
SethiUllmanNumbers.assign(SUnits->size(), 0);
|
|
|
|
for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
|
|
CalcNodeSethiUllmanNumber(&(*SUnits)[i]);
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Public Constructor Functions
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
llvm::ScheduleDAG* llvm::createBURRListDAGScheduler(SelectionDAGISel *IS,
|
|
SelectionDAG *DAG,
|
|
MachineBasicBlock *BB) {
|
|
const TargetInstrInfo *TII = DAG->getTarget().getInstrInfo();
|
|
return new ScheduleDAGRRList(*DAG, BB, DAG->getTarget(), true,
|
|
new BURegReductionPriorityQueue<bu_ls_rr_sort>(TII));
|
|
}
|
|
|
|
llvm::ScheduleDAG* llvm::createTDRRListDAGScheduler(SelectionDAGISel *IS,
|
|
SelectionDAG *DAG,
|
|
MachineBasicBlock *BB) {
|
|
return new ScheduleDAGRRList(*DAG, BB, DAG->getTarget(), false,
|
|
new TDRegReductionPriorityQueue<td_ls_rr_sort>());
|
|
}
|
|
|