void apply(PBQPRAGraph &G) override {
LiveIntervals &LIS = G.getMetadata().LIS;
+ // A minimum spill costs, so that register constraints can can be set
+ // without normalization in the [0.0:MinSpillCost( interval.
+ const PBQP::PBQPNum MinSpillCost = 10.0;
+
for (auto NId : G.nodeIds()) {
PBQP::PBQPNum SpillCost =
LIS.getInterval(G.getNodeMetadata(NId).getVReg()).weight;
if (SpillCost == 0.0)
SpillCost = std::numeric_limits<PBQP::PBQPNum>::min();
+ else
+ SpillCost += MinSpillCost;
PBQPRAGraph::RawVector NodeCosts(G.getNodeCosts(NId));
NodeCosts[PBQP::RegAlloc::getSpillOptionIdx()] = SpillCost;
G.setNodeCosts(NId, std::move(NodeCosts));
class Interference : public PBQPRAConstraint {
private:
+private:
+
+ typedef const PBQP::RegAlloc::AllowedRegVector* AllowedRegVecPtr;
+ typedef std::pair<AllowedRegVecPtr, AllowedRegVecPtr> IMatrixKey;
+ typedef DenseMap<IMatrixKey, PBQPRAGraph::MatrixPtr> IMatrixCache;
+
// Holds (Interval, CurrentSegmentID, and NodeId). The first two are required
// for the fast interference graph construction algorithm. The last is there
// to save us from looking up node ids via the VRegToNode map in the graph
// number of registers, but rather the size of the largest clique in the
// graph. Still, we expect this to be better than N^2.
LiveIntervals &LIS = G.getMetadata().LIS;
- const TargetRegisterInfo &TRI =
- *G.getMetadata().MF.getTarget().getSubtargetImpl()->getRegisterInfo();
+
+ // Interferenc matrices are incredibly regular - they're only a function of
+ // the allowed sets, so we cache them to avoid the overhead of constructing
+ // and uniquing them.
+ IMatrixCache C;
typedef std::set<IntervalInfo, decltype(&lowestEndPoint)> IntervalSet;
typedef std::priority_queue<IntervalInfo, std::vector<IntervalInfo>,
// Check that we haven't already added this edge
// FIXME: findEdge is expensive in the worst case (O(max_clique(G))).
// It might be better to replace this with a local bit-matrix.
- if (G.findEdge(NId, MId) != PBQP::GraphBase::invalidEdgeId())
+ if (G.findEdge(NId, MId) != PBQPRAGraph::invalidEdgeId())
continue;
// This is a new edge - add it to the graph.
- const auto &NOpts = G.getNodeMetadata(NId).getOptionRegs();
- const auto &MOpts = G.getNodeMetadata(MId).getOptionRegs();
- G.addEdge(NId, MId, createInterferenceMatrix(TRI, NOpts, MOpts));
+ createInterferenceEdge(G, NId, MId, C);
}
// Finally, add Cur to the Active set.
private:
- PBQPRAGraph::RawMatrix createInterferenceMatrix(
- const TargetRegisterInfo &TRI,
- const PBQPRAGraph::NodeMetadata::OptionToRegMap &NOpts,
- const PBQPRAGraph::NodeMetadata::OptionToRegMap &MOpts) {
- PBQPRAGraph::RawMatrix M(NOpts.size() + 1, MOpts.size() + 1, 0);
- for (unsigned I = 0; I != NOpts.size(); ++I) {
- unsigned PRegN = NOpts[I];
- for (unsigned J = 0; J != MOpts.size(); ++J) {
- unsigned PRegM = MOpts[J];
+ void createInterferenceEdge(PBQPRAGraph &G, PBQPRAGraph::NodeId NId,
+ PBQPRAGraph::NodeId MId, IMatrixCache &C) {
+
+ const TargetRegisterInfo &TRI =
+ *G.getMetadata().MF.getTarget().getSubtargetImpl()->getRegisterInfo();
+
+ const auto &NRegs = G.getNodeMetadata(NId).getAllowedRegs();
+ const auto &MRegs = G.getNodeMetadata(MId).getAllowedRegs();
+
+ // Try looking the edge costs up in the IMatrixCache first.
+ IMatrixKey K(&NRegs, &MRegs);
+ IMatrixCache::iterator I = C.find(K);
+ if (I != C.end()) {
+ G.addEdgeBypassingCostAllocator(NId, MId, I->second);
+ return;
+ }
+
+ PBQPRAGraph::RawMatrix M(NRegs.size() + 1, MRegs.size() + 1, 0);
+ for (unsigned I = 0; I != NRegs.size(); ++I) {
+ unsigned PRegN = NRegs[I];
+ for (unsigned J = 0; J != MRegs.size(); ++J) {
+ unsigned PRegM = MRegs[J];
if (TRI.regsOverlap(PRegN, PRegM))
M[I + 1][J + 1] = std::numeric_limits<PBQP::PBQPNum>::infinity();
}
}
- return M;
+ PBQPRAGraph::EdgeId EId = G.addEdge(NId, MId, std::move(M));
+ C[K] = G.getEdgeCostsPtr(EId);
}
};
unsigned DstReg = CP.getDstReg();
unsigned SrcReg = CP.getSrcReg();
- const float CopyFactor = 0.5; // Cost of copy relative to load. Current
- // value plucked randomly out of the air.
-
- PBQP::PBQPNum CBenefit =
- CopyFactor * LiveIntervals::getSpillWeight(false, true, &MBFI, &MI);
+ const float Scale = 1.0f / MBFI.getEntryFreq();
+ PBQP::PBQPNum CBenefit = MBFI.getBlockFreq(&MBB).getFrequency() * Scale;
if (CP.isPhys()) {
if (!MF.getRegInfo().isAllocatable(DstReg))
PBQPRAGraph::NodeId NId = G.getMetadata().getNodeIdForVReg(SrcReg);
- const PBQPRAGraph::NodeMetadata::OptionToRegMap &Allowed =
- G.getNodeMetadata(NId).getOptionRegs();
+ const PBQPRAGraph::NodeMetadata::AllowedRegVector &Allowed =
+ G.getNodeMetadata(NId).getAllowedRegs();
unsigned PRegOpt = 0;
while (PRegOpt < Allowed.size() && Allowed[PRegOpt] != DstReg)
} else {
PBQPRAGraph::NodeId N1Id = G.getMetadata().getNodeIdForVReg(DstReg);
PBQPRAGraph::NodeId N2Id = G.getMetadata().getNodeIdForVReg(SrcReg);
- const PBQPRAGraph::NodeMetadata::OptionToRegMap *Allowed1 =
- &G.getNodeMetadata(N1Id).getOptionRegs();
- const PBQPRAGraph::NodeMetadata::OptionToRegMap *Allowed2 =
- &G.getNodeMetadata(N2Id).getOptionRegs();
+ const PBQPRAGraph::NodeMetadata::AllowedRegVector *Allowed1 =
+ &G.getNodeMetadata(N1Id).getAllowedRegs();
+ const PBQPRAGraph::NodeMetadata::AllowedRegVector *Allowed2 =
+ &G.getNodeMetadata(N2Id).getAllowedRegs();
PBQPRAGraph::EdgeId EId = G.findEdge(N1Id, N2Id);
if (EId == G.invalidEdgeId()) {
private:
void addVirtRegCoalesce(
- PBQPRAGraph::RawMatrix &CostMat,
- const PBQPRAGraph::NodeMetadata::OptionToRegMap &Allowed1,
- const PBQPRAGraph::NodeMetadata::OptionToRegMap &Allowed2,
- PBQP::PBQPNum Benefit) {
+ PBQPRAGraph::RawMatrix &CostMat,
+ const PBQPRAGraph::NodeMetadata::AllowedRegVector &Allowed1,
+ const PBQPRAGraph::NodeMetadata::AllowedRegVector &Allowed2,
+ PBQP::PBQPNum Benefit) {
assert(CostMat.getRows() == Allowed1.size() + 1 && "Size mismatch.");
assert(CostMat.getCols() == Allowed2.size() + 1 && "Size mismatch.");
for (unsigned I = 0; I != Allowed1.size(); ++I) {
}
}
+static bool isACalleeSavedRegister(unsigned reg, const TargetRegisterInfo &TRI,
+ const MachineFunction &MF) {
+ const MCPhysReg *CSR = TRI.getCalleeSavedRegs(&MF);
+ for (unsigned i = 0; CSR[i] != 0; ++i)
+ if (TRI.regsOverlap(reg, CSR[i]))
+ return true;
+ return false;
+}
+
void RegAllocPBQP::initializeGraph(PBQPRAGraph &G) {
MachineFunction &MF = G.getMetadata().MF;
}
PBQPRAGraph::RawVector NodeCosts(VRegAllowed.size() + 1, 0);
+
+ // Tweak cost of callee saved registers, as using then force spilling and
+ // restoring them. This would only happen in the prologue / epilogue though.
+ for (unsigned i = 0; i != VRegAllowed.size(); ++i)
+ if (isACalleeSavedRegister(VRegAllowed[i], TRI, MF))
+ NodeCosts[1 + i] += 1.0;
+
PBQPRAGraph::NodeId NId = G.addNode(std::move(NodeCosts));
G.getNodeMetadata(NId).setVReg(VReg);
- G.getNodeMetadata(NId).setOptionRegs(std::move(VRegAllowed));
+ G.getNodeMetadata(NId).setAllowedRegs(
+ G.getMetadata().getAllowedRegs(std::move(VRegAllowed)));
G.getMetadata().setNodeIdForVReg(VReg, NId);
}
}
unsigned AllocOption = Solution.getSelection(NId);
if (AllocOption != PBQP::RegAlloc::getSpillOptionIdx()) {
- unsigned PReg = G.getNodeMetadata(NId).getOptionRegs()[AllocOption - 1];
+ unsigned PReg = G.getNodeMetadata(NId).getAllowedRegs()[AllocOption - 1];
DEBUG(dbgs() << "VREG " << PrintReg(VReg, &TRI) << " -> "
<< TRI.getName(PReg) << "\n");
assert(PReg != 0 && "Invalid preg selected.");
return !AnotherRoundNeeded;
}
-
void RegAllocPBQP::finalizeAlloc(MachineFunction &MF,
LiveIntervals &LIS,
VirtRegMap &VRM) const {
}
}
+static inline float normalizePBQPSpillWeight(float UseDefFreq, unsigned Size,
+ unsigned NumInstr) {
+ // All intervals have a spill weight that is mostly proportional to the number
+ // of uses, with uses in loops having a bigger weight.
+ return NumInstr * normalizeSpillWeight(UseDefFreq, Size, 1);
+}
+
bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
LiveIntervals &LIS = getAnalysis<LiveIntervals>();
MachineBlockFrequencyInfo &MBFI =
getAnalysis<MachineBlockFrequencyInfo>();
- calculateSpillWeightsAndHints(LIS, MF, getAnalysis<MachineLoopInfo>(), MBFI);
+ calculateSpillWeightsAndHints(LIS, MF, getAnalysis<MachineLoopInfo>(), MBFI,
+ normalizePBQPSpillWeight);
VirtRegMap &VRM = getAnalysis<VirtRegMap>();
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