From: Evan Cheng Date: Wed, 3 May 2006 02:10:45 +0000 (+0000) Subject: Bottom up register pressure reduction work: clean up some hacks and enhanced X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c9a83a45ba53abeab329548e7ac9f3968b440e64;p=oota-llvm.git Bottom up register pressure reduction work: clean up some hacks and enhanced the heuristic to further reduce spills for several test cases. (Note, it may not necessarily translate to runtime win!) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28076 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp index f964490b1c2..3b418ba82b1 100644 --- a/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp +++ b/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp @@ -32,13 +32,6 @@ #include "llvm/Support/CommandLine.h" using namespace llvm; -namespace { - // TEMPORARY option to test a fix. - cl::opt - SchedIgnorStore("sched-ignore-store", cl::Hidden); - -} - namespace { Statistic<> NumNoops ("scheduler", "Number of noops inserted"); Statistic<> NumStalls("scheduler", "Number of pipeline stalls"); @@ -58,7 +51,6 @@ namespace { short NumSuccsLeft; // # of succs not scheduled. short NumChainPredsLeft; // # of chain preds not scheduled. short NumChainSuccsLeft; // # of chain succs not scheduled. - bool isStore : 1; // Is a store. bool isTwoAddress : 1; // Is a two-address instruction. bool isDefNUseOperand : 1; // Is a def&use operand. bool isPending : 1; // True once pending. @@ -71,9 +63,9 @@ namespace { SUnit(SDNode *node, unsigned nodenum) : Node(node), NumPredsLeft(0), NumSuccsLeft(0), - NumChainPredsLeft(0), NumChainSuccsLeft(0), isStore(false), - isTwoAddress(false), isDefNUseOperand(false), - isPending(false), isAvailable(false), isScheduled(false), + NumChainPredsLeft(0), NumChainSuccsLeft(0), + isTwoAddress(false), isDefNUseOperand(false), isPending(false), + isAvailable(false), isScheduled(false), Latency(0), CycleBound(0), Cycle(0), NodeNum(nodenum) {} void dump(const SelectionDAG *G) const; @@ -82,7 +74,7 @@ namespace { } void SUnit::dump(const SelectionDAG *G) const { - std::cerr << "SU: "; + std::cerr << "SU(" << NodeNum << "): "; Node->dump(G); std::cerr << "\n"; if (FlaggedNodes.size() != 0) { @@ -325,11 +317,13 @@ void ScheduleDAGList::BuildSchedUnits() { if (MainNode->isTargetOpcode()) { unsigned Opc = MainNode->getTargetOpcode(); - if (TII->isTwoAddrInstr(Opc)) + if (TII->isTwoAddrInstr(Opc)) { SU->isTwoAddress = true; - if (TII->isStore(Opc)) - if (!SchedIgnorStore) - SU->isStore = true; + SDNode *OpN = MainNode->getOperand(0).Val; + SUnit *OpSU = SUnitMap[OpN]; + if (OpSU) + OpSU->isDefNUseOperand = true; + } } // Find all predecessors and successors of the group. @@ -345,7 +339,7 @@ void ScheduleDAGList::BuildSchedUnits() { SUnit *OpSU = SUnitMap[OpN]; assert(OpSU && "Node has no SUnit!"); if (OpSU == SU) continue; // In the same group. - + MVT::ValueType OpVT = N->getOperand(i).getValueType(); assert(OpVT != MVT::Flag && "Flagged nodes should be in same sunit!"); bool isChain = OpVT == MVT::Other; @@ -470,6 +464,7 @@ void ScheduleDAGList::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) { DEBUG(SU->dump(&DAG)); SU->Cycle = CurCycle; + AvailableQueue->ScheduledNode(SU); Sequence.push_back(SU); // Bottom up: release predecessors @@ -480,6 +475,8 @@ void ScheduleDAGList::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) { // calculate directly. if (!I->second) SU->NumPredsLeft--; + else + SU->NumChainPredsLeft--; } } @@ -499,9 +496,9 @@ void ScheduleDAGList::ListScheduleBottomUp() { // While Available queue is not empty, grab the node with the highest // priority. If it is not ready put it back. Schedule the node. std::vector NotReady; + SUnit *CurrNode = NULL; while (!AvailableQueue->empty()) { SUnit *CurrNode = AvailableQueue->pop(); - while (!isReady(CurrNode, CurrCycle)) { NotReady.push_back(CurrNode); CurrNode = AvailableQueue->pop(); @@ -514,7 +511,6 @@ void ScheduleDAGList::ListScheduleBottomUp() { ScheduleNodeBottomUp(CurrNode, CurrCycle); CurrCycle++; CurrNode->isScheduled = true; - AvailableQueue->ScheduledNode(CurrNode); } // Add entry node last @@ -748,12 +744,12 @@ namespace { const std::vector *SUnits; // SethiUllmanNumbers - The SethiUllman number for each node. - std::vector SethiUllmanNumbers; + std::vector SethiUllmanNumbers; std::priority_queue, ls_rr_sort> Queue; public: - RegReductionPriorityQueue() : Queue(ls_rr_sort(this)) { - } + RegReductionPriorityQueue() : + Queue(ls_rr_sort(this)) {} void initNodes(const std::vector &sunits) { SUnits = &sunits; @@ -765,7 +761,7 @@ namespace { SethiUllmanNumbers.clear(); } - unsigned getSethiUllmanNumber(unsigned NodeNum) const { + int getSethiUllmanNumber(unsigned NodeNum) const { assert(NodeNum < SethiUllmanNumbers.size()); return SethiUllmanNumbers[NodeNum]; } @@ -785,88 +781,89 @@ namespace { Queue.pop(); return V; } + private: void CalculatePriorities(); - unsigned CalcNodePriority(const SUnit *SU); + int CalcNodePriority(const SUnit *SU); }; } bool ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const { unsigned LeftNum = left->NodeNum; unsigned RightNum = right->NodeNum; - - int LBonus = (int)left ->isDefNUseOperand; - int RBonus = (int)right->isDefNUseOperand; - - // Special tie breaker: if two nodes share a operand, the one that - // use it as a def&use operand is preferred. - if (left->isTwoAddress && !right->isTwoAddress) { - SDNode *DUNode = left->Node->getOperand(0).Val; - if (DUNode->isOperand(right->Node)) - LBonus++; - } - if (!left->isTwoAddress && right->isTwoAddress) { - SDNode *DUNode = right->Node->getOperand(0).Val; - if (DUNode->isOperand(left->Node)) - RBonus++; + bool LIsTarget = left->Node->isTargetOpcode(); + bool RIsTarget = right->Node->isTargetOpcode(); + int LPriority = SPQ->getSethiUllmanNumber(LeftNum); + int RPriority = SPQ->getSethiUllmanNumber(RightNum); + bool LIsFloater = LIsTarget && (LPriority == 1 || LPriority == 0); + bool RIsFloater = RIsTarget && (RPriority == 1 || RPriority == 0); + + // Schedule floaters (e.g. load from some constant address) and immediate use + // of floaters (with no other operands) just before the use. + if (LIsFloater && !RIsFloater) + LPriority += 2; + else if (!LIsFloater && RIsFloater) + RPriority += 2; + + // 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)) + LPriority += 2; + } + if (!left->isTwoAddress && right->isTwoAddress) { + SDNode *DUNode = right->Node->getOperand(0).Val; + if (DUNode->isOperand(left->Node)) + RPriority += 2; + } } - - // Push stores up as much as possible. This really help code like this: - // load - // compute - // store - // load - // compute - // store - // This would make sure the scheduled code completed all computations and - // the stores before the next series of computation starts. - if (!left->isStore && right->isStore) - LBonus += 4; - if (left->isStore && !right->isStore) - RBonus += 4; - - // Priority1 is just the number of live range genned. - int LPriority1 = left ->NumPredsLeft - LBonus; - int RPriority1 = right->NumPredsLeft - RBonus; - int LPriority2 = SPQ->getSethiUllmanNumber(LeftNum) + LBonus; - int RPriority2 = SPQ->getSethiUllmanNumber(RightNum) + RBonus; - - if (LPriority1 > RPriority1) + + if (LPriority < RPriority) return true; - else if (LPriority1 == RPriority1) - if (LPriority2 < RPriority2) + else if (LPriority == RPriority) + if (left->NumPredsLeft > right->NumPredsLeft) return true; - else if (LPriority2 == RPriority2) + else if (left->NumPredsLeft == right->NumPredsLeft) if (left->CycleBound > right->CycleBound) return true; - return false; } /// CalcNodePriority - Priority is the Sethi Ullman number. /// Smaller number is the higher priority. -unsigned RegReductionPriorityQueue::CalcNodePriority(const SUnit *SU) { - unsigned &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum]; +int RegReductionPriorityQueue::CalcNodePriority(const SUnit *SU) { + int &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum]; if (SethiUllmanNumber != 0) return SethiUllmanNumber; - - if (SU->Preds.size() == 0) { + + unsigned Opc = SU->Node->getOpcode(); + if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg) + SethiUllmanNumber = INT_MAX - 10; + 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 = INT_MIN + 10; + else if (SU->NumPredsLeft == 0 && Opc != ISD::CopyFromReg) SethiUllmanNumber = 1; - } else { + else { int Extra = 0; for (std::set >::const_iterator I = SU->Preds.begin(), E = SU->Preds.end(); I != E; ++I) { - if (I->second) continue; // ignore chain preds. + if (I->second) continue; // ignore chain preds SUnit *PredSU = I->first; - unsigned PredSethiUllman = CalcNodePriority(PredSU); + int PredSethiUllman = CalcNodePriority(PredSU); if (PredSethiUllman > SethiUllmanNumber) { SethiUllmanNumber = PredSethiUllman; Extra = 0; - } else if (PredSethiUllman == SethiUllmanNumber) + } else if (PredSethiUllman == SethiUllmanNumber && !I->second) Extra++; } - + SethiUllmanNumber += Extra; } @@ -964,7 +961,7 @@ public: // single predecessor has a higher priority, since scheduling it will make // the node available. void ScheduledNode(SUnit *Node); - + private: void CalculatePriorities(); int CalcLatency(const SUnit &SU);