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https://github.com/c64scene-ar/llvm-6502.git
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Fix for PR1075: bottom-up register-reduction scheduling actually increases register pressure.
- Fixed bugs in sethi-ullman number computation and priority queue comparison functions. - Separate code that handles priority computation special cases from SU number computation. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33025 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
parent
ddae4bd683
commit
c62d4bb695
@ -414,6 +414,12 @@ namespace {
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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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@ -428,7 +434,7 @@ namespace {
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std::vector<SUnit> &sunits) {}
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virtual void releaseState() {}
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virtual int getSethiUllmanNumber(unsigned NodeNum) const {
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virtual unsigned getSethiUllmanNumber(const SUnit *SU) const {
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return 0;
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}
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@ -464,7 +470,7 @@ namespace {
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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<int> SethiUllmanNumbers;
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std::vector<unsigned> SethiUllmanNumbers;
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const TargetInstrInfo *TII;
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public:
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@ -486,9 +492,30 @@ namespace {
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SethiUllmanNumbers.clear();
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}
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int getSethiUllmanNumber(unsigned NodeNum) const {
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assert(NodeNum < SethiUllmanNumbers.size());
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return SethiUllmanNumbers[NodeNum];
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unsigned getSethiUllmanNumber(const SUnit *SU) const {
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assert(SU->NodeNum < SethiUllmanNumbers.size());
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unsigned Opc = SU->Node->getOpcode();
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if (Opc == ISD::CopyFromReg && !isCopyFromLiveIn(SU))
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// CopyFromReg should be close to its def because it restricts
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// allocation choices. But if it is a livein then perhaps we want it
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// closer to its uses so it can be coalesced.
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return 0xffff;
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else if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
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// CopyToReg should be close to its uses to facilitate coalescing and
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// avoid spilling.
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return 0;
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else if (SU->NumSuccs == 0)
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// If SU does not have a use, i.e. it doesn't produce a value that would
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// be consumed (e.g. store), then it terminates a chain of computation.
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// Give it a large SethiUllman number so it will be scheduled right
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// before its predecessors that it doesn't lengthen their live ranges.
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return 0xffff;
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else if (SU->NumPreds == 0)
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// If SU does not have a def, schedule it close to its uses because it
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// does not lengthen any live ranges.
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return 0;
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else
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return SethiUllmanNumbers[SU->NodeNum];
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}
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bool isDUOperand(const SUnit *SU1, const SUnit *SU2) {
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@ -507,7 +534,7 @@ namespace {
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bool canClobber(SUnit *SU, SUnit *Op);
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void AddPseudoTwoAddrDeps();
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void CalculatePriorities();
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int CalcNodePriority(const SUnit *SU);
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unsigned CalcNodePriority(const SUnit *SU);
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};
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@ -520,7 +547,7 @@ namespace {
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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<int> SethiUllmanNumbers;
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std::vector<unsigned> SethiUllmanNumbers;
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public:
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TDRegReductionPriorityQueue() {}
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@ -538,86 +565,38 @@ namespace {
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SethiUllmanNumbers.clear();
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}
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int getSethiUllmanNumber(unsigned NodeNum) const {
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assert(NodeNum < SethiUllmanNumbers.size());
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return SethiUllmanNumbers[NodeNum];
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unsigned getSethiUllmanNumber(const SUnit *SU) const {
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assert(SU->NodeNum < SethiUllmanNumbers.size());
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return SethiUllmanNumbers[SU->NodeNum];
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}
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private:
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void CalculatePriorities();
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int CalcNodePriority(const SUnit *SU);
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unsigned CalcNodePriority(const SUnit *SU);
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};
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}
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static bool isFloater(const SUnit *SU) {
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if (SU->Node->isTargetOpcode()) {
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if (SU->NumPreds == 0)
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return true;
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if (SU->NumPreds == 1) {
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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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if (I->second) continue;
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SUnit *PredSU = I->first;
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unsigned Opc = PredSU->Node->getOpcode();
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if (Opc != ISD::EntryToken && Opc != ISD::TokenFactor &&
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Opc != ISD::CopyToReg)
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return false;
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}
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return true;
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}
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}
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return false;
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}
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static bool isSimpleFloaterUse(const SUnit *SU) {
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unsigned NumOps = 0;
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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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if (I->second) continue;
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if (++NumOps > 1)
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return false;
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if (!isFloater(I->first))
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return false;
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}
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return true;
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}
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// Bottom up
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bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
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unsigned LeftNum = left->NodeNum;
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unsigned RightNum = right->NodeNum;
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bool LIsTarget = left->Node->isTargetOpcode();
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bool RIsTarget = right->Node->isTargetOpcode();
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int LPriority = SPQ->getSethiUllmanNumber(LeftNum);
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int RPriority = SPQ->getSethiUllmanNumber(RightNum);
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int LBonus = 0;
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int RBonus = 0;
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// Schedule floaters (e.g. load from some constant address) and those nodes
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// with a single predecessor each first. They maintain / reduce register
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// pressure.
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if (isFloater(left) || isSimpleFloaterUse(left))
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LBonus += 2;
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if (isFloater(right) || isSimpleFloaterUse(right))
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RBonus += 2;
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unsigned LPriority = SPQ->getSethiUllmanNumber(left);
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unsigned RPriority = SPQ->getSethiUllmanNumber(right);
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// Special tie breaker: if two nodes share a operand, the one that use it
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// as a def&use operand is preferred.
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if (LIsTarget && RIsTarget) {
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if (left->isTwoAddress && !right->isTwoAddress) {
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if (left->isTwoAddress && !right->isTwoAddress)
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if (SPQ->isDUOperand(left, right))
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LBonus += 2;
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}
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if (!left->isTwoAddress && right->isTwoAddress) {
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return false;
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if (!left->isTwoAddress && right->isTwoAddress)
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if (SPQ->isDUOperand(right, left))
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RBonus += 2;
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}
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return true;
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}
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if (LPriority+LBonus < RPriority+RBonus)
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if (LPriority > RPriority)
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return true;
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else if (LPriority+LBonus == RPriority+RBonus)
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else if (LPriority == RPriority)
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if (left->Height > right->Height)
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return true;
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else if (left->Height == right->Height)
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@ -629,12 +608,6 @@ bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
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return false;
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}
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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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// FIXME: This is probably too slow!
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static void isReachable(SUnit *SU, SUnit *TargetSU,
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std::set<SUnit *> &Visited, bool &Reached) {
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@ -723,47 +696,28 @@ void BURegReductionPriorityQueue<SF>::AddPseudoTwoAddrDeps() {
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/// CalcNodePriority - Priority is the Sethi Ullman number.
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/// Smaller number is the higher priority.
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template<class SF>
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int BURegReductionPriorityQueue<SF>::CalcNodePriority(const SUnit *SU) {
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int &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
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unsigned BURegReductionPriorityQueue<SF>::CalcNodePriority(const SUnit *SU) {
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unsigned &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
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if (SethiUllmanNumber != 0)
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return SethiUllmanNumber;
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unsigned Opc = SU->Node->getOpcode();
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if (Opc == ISD::CopyFromReg && !isCopyFromLiveIn(SU))
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// CopyFromReg should be close to its def because it restricts allocation
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// choices. But if it is a livein then perhaps we want it closer to the
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// uses so it can be coalesced.
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SethiUllmanNumber = INT_MIN + 10;
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else if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
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// CopyToReg should be close to its uses to facilitate coalescing and avoid
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// spilling.
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SethiUllmanNumber = INT_MAX - 10;
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else if (SU->NumSuccsLeft == 0)
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// If SU does not have a use, i.e. it doesn't produce a value that would
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// be consumed (e.g. store), then it terminates a chain of computation.
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// Give it a small SethiUllman number so it will be scheduled right before its
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// predecessors that it doesn't lengthen their live ranges.
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SethiUllmanNumber = INT_MIN + 10;
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else if (SU->NumPredsLeft == 0)
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// If SU does not have a def, schedule it close to its uses because it does
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// not lengthen any live ranges.
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SethiUllmanNumber = INT_MAX - 10;
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else {
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int Extra = 0;
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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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if (I->second) continue; // ignore chain preds
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SUnit *PredSU = I->first;
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int PredSethiUllman = CalcNodePriority(PredSU);
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if (PredSethiUllman > SethiUllmanNumber) {
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SethiUllmanNumber = PredSethiUllman;
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Extra = 0;
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} else if (PredSethiUllman == SethiUllmanNumber && !I->second)
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Extra++;
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}
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SethiUllmanNumber += Extra;
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unsigned Extra = 0;
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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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if (I->second) continue; // ignore chain preds
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SUnit *PredSU = I->first;
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unsigned PredSethiUllman = CalcNodePriority(PredSU);
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if (PredSethiUllman > SethiUllmanNumber) {
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SethiUllmanNumber = PredSethiUllman;
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Extra = 0;
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} else if (PredSethiUllman == SethiUllmanNumber && !I->second)
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Extra++;
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}
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SethiUllmanNumber += Extra;
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if (SethiUllmanNumber == 0)
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SethiUllmanNumber = 1;
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return SethiUllmanNumber;
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}
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@ -796,10 +750,8 @@ static unsigned SumOfUnscheduledPredsOfSuccs(const SUnit *SU) {
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// Top down
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bool td_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
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unsigned LeftNum = left->NodeNum;
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unsigned RightNum = right->NodeNum;
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int LPriority = SPQ->getSethiUllmanNumber(LeftNum);
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int RPriority = SPQ->getSethiUllmanNumber(RightNum);
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unsigned LPriority = SPQ->getSethiUllmanNumber(left);
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unsigned RPriority = SPQ->getSethiUllmanNumber(right);
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bool LIsTarget = left->Node->isTargetOpcode();
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bool RIsTarget = right->Node->isTargetOpcode();
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bool LIsFloater = LIsTarget && left->NumPreds == 0;
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@ -852,30 +804,30 @@ bool td_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
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/// CalcNodePriority - Priority is the Sethi Ullman number.
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/// Smaller number is the higher priority.
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template<class SF>
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int TDRegReductionPriorityQueue<SF>::CalcNodePriority(const SUnit *SU) {
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int &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
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unsigned TDRegReductionPriorityQueue<SF>::CalcNodePriority(const SUnit *SU) {
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unsigned &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
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if (SethiUllmanNumber != 0)
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return SethiUllmanNumber;
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unsigned Opc = SU->Node->getOpcode();
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if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
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SethiUllmanNumber = INT_MAX - 10;
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SethiUllmanNumber = 0xffff;
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else if (SU->NumSuccsLeft == 0)
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// If SU does not have a use, i.e. it doesn't produce a value that would
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// be consumed (e.g. store), then it terminates a chain of computation.
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// Give it a small SethiUllman number so it will be scheduled right before its
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// predecessors that it doesn't lengthen their live ranges.
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SethiUllmanNumber = INT_MIN + 10;
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SethiUllmanNumber = 0;
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else if (SU->NumPredsLeft == 0 &&
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(Opc != ISD::CopyFromReg || isCopyFromLiveIn(SU)))
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SethiUllmanNumber = 1;
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SethiUllmanNumber = 0xffff;
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else {
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int Extra = 0;
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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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if (I->second) continue; // ignore chain preds
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SUnit *PredSU = I->first;
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int PredSethiUllman = CalcNodePriority(PredSU);
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unsigned PredSethiUllman = CalcNodePriority(PredSU);
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if (PredSethiUllman > SethiUllmanNumber) {
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SethiUllmanNumber = PredSethiUllman;
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Extra = 0;
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