bool RenameIndependentSubregs::findComponents(IntEqClasses &Classes, SmallVectorImpl<RenameIndependentSubregs::SubRangeInfo> &SubRangeInfos, LiveInterval &LI) const { // First step: Create connected components for the VNInfos inside the // subranges and count the global number of such components. unsigned NumComponents = 0; for (LiveInterval::SubRange &SR : LI.subranges()) { SubRangeInfos.push_back(SubRangeInfo(*LIS, SR, NumComponents)); ConnectedVNInfoEqClasses &ConEQ = SubRangeInfos.back().ConEQ; unsigned NumSubComponents = ConEQ.Classify(SR); NumComponents += NumSubComponents; } // Shortcut: With only 1 subrange, the normal separate component tests are // enough and we do not need to perform the union-find on the subregister // segments. if (SubRangeInfos.size() < 2) return false; // Next step: Build union-find structure over all subranges and merge classes // across subranges when they are affected by the same MachineOperand. const TargetRegisterInfo &TRI = *MRI->getTargetRegisterInfo(); Classes.grow(NumComponents); unsigned Reg = LI.reg; for (const MachineOperand &MO : MRI->reg_nodbg_operands(Reg)) { if (!MO.isDef() && !MO.readsReg()) continue; unsigned SubRegIdx = MO.getSubReg(); LaneBitmask LaneMask = TRI.getSubRegIndexLaneMask(SubRegIdx); unsigned MergedID = ~0u; for (RenameIndependentSubregs::SubRangeInfo &SRInfo : SubRangeInfos) { const LiveInterval::SubRange &SR = *SRInfo.SR; if ((SR.LaneMask & LaneMask) == 0) continue; SlotIndex Pos = LIS->getInstructionIndex(*MO.getParent()); Pos = MO.isDef() ? Pos.getRegSlot(MO.isEarlyClobber()) : Pos.getBaseIndex(); const VNInfo *VNI = SR.getVNInfoAt(Pos); if (VNI == nullptr) continue; // Map to local representant ID. unsigned LocalID = SRInfo.ConEQ.getEqClass(VNI); // Global ID unsigned ID = LocalID + SRInfo.Index; // Merge other sets MergedID = MergedID == ~0u ? ID : Classes.join(MergedID, ID); } } // Early exit if we ended up with a single equivalence class. Classes.compress(); unsigned NumClasses = Classes.getNumClasses(); return NumClasses > 1; }
/// Set each node's subtree ID to the representative ID and record connections /// between trees. void finalize() { SubtreeClasses.compress(); R.SubtreeConnections.resize(SubtreeClasses.getNumClasses()); R.SubtreeConnectLevels.resize(SubtreeClasses.getNumClasses()); DEBUG(dbgs() << R.getNumSubtrees() << " subtrees:\n"); for (unsigned Idx = 0, End = R.DFSData.size(); Idx != End; ++Idx) { R.DFSData[Idx].SubtreeID = SubtreeClasses[Idx]; DEBUG(dbgs() << " SU(" << Idx << ") in tree " << R.DFSData[Idx].SubtreeID << '\n'); } for (std::vector<std::pair<const SUnit*, const SUnit*> >::const_iterator I = ConnectionPairs.begin(), E = ConnectionPairs.end(); I != E; ++I) { unsigned PredTree = SubtreeClasses[I->first->NodeNum]; unsigned SuccTree = SubtreeClasses[I->second->NodeNum]; if (PredTree == SuccTree) continue; unsigned Depth = I->first->getDepth(); addConnection(PredTree, SuccTree, Depth); addConnection(SuccTree, PredTree, Depth); } }