| //===------ LiveDebugValues.cpp - Tracking Debug Value MIs ----------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| /// |
| /// This pass implements a data flow analysis that propagates debug location |
| /// information by inserting additional DBG_VALUE instructions into the machine |
| /// instruction stream. The pass internally builds debug location liveness |
| /// ranges to determine the points where additional DBG_VALUEs need to be |
| /// inserted. |
| /// |
| /// This is a separate pass from DbgValueHistoryCalculator to facilitate |
| /// testing and improve modularity. |
| /// |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/ADT/PostOrderIterator.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| #include "llvm/ADT/SparseBitVector.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/ADT/UniqueVector.h" |
| #include "llvm/CodeGen/LexicalScopes.h" |
| #include "llvm/CodeGen/MachineFrameInfo.h" |
| #include "llvm/CodeGen/MachineFunction.h" |
| #include "llvm/CodeGen/MachineFunctionPass.h" |
| #include "llvm/CodeGen/MachineInstrBuilder.h" |
| #include "llvm/CodeGen/MachineMemOperand.h" |
| #include "llvm/CodeGen/Passes.h" |
| #include "llvm/IR/DebugInfo.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Target/TargetFrameLowering.h" |
| #include "llvm/Target/TargetInstrInfo.h" |
| #include "llvm/Target/TargetLowering.h" |
| #include "llvm/Target/TargetRegisterInfo.h" |
| #include "llvm/Target/TargetSubtargetInfo.h" |
| #include <list> |
| #include <queue> |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "livedebugvalues" |
| |
| STATISTIC(NumInserted, "Number of DBG_VALUE instructions inserted"); |
| |
| namespace { |
| |
| // \brief If @MI is a DBG_VALUE with debug value described by a defined |
| // register, returns the number of this register. In the other case, returns 0. |
| static unsigned isDbgValueDescribedByReg(const MachineInstr &MI) { |
| assert(MI.isDebugValue() && "expected a DBG_VALUE"); |
| assert(MI.getNumOperands() == 4 && "malformed DBG_VALUE"); |
| // If location of variable is described using a register (directly |
| // or indirectly), this register is always a first operand. |
| return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0; |
| } |
| |
| class LiveDebugValues : public MachineFunctionPass { |
| |
| private: |
| const TargetRegisterInfo *TRI; |
| const TargetInstrInfo *TII; |
| const TargetFrameLowering *TFI; |
| LexicalScopes LS; |
| |
| /// Keeps track of lexical scopes associated with a user value's source |
| /// location. |
| class UserValueScopes { |
| DebugLoc DL; |
| LexicalScopes &LS; |
| SmallPtrSet<const MachineBasicBlock *, 4> LBlocks; |
| |
| public: |
| UserValueScopes(DebugLoc D, LexicalScopes &L) : DL(std::move(D)), LS(L) {} |
| |
| /// Return true if current scope dominates at least one machine |
| /// instruction in a given machine basic block. |
| bool dominates(MachineBasicBlock *MBB) { |
| if (LBlocks.empty()) |
| LS.getMachineBasicBlocks(DL, LBlocks); |
| return LBlocks.count(MBB) != 0 || LS.dominates(DL, MBB); |
| } |
| }; |
| |
| /// Based on std::pair so it can be used as an index into a DenseMap. |
| typedef std::pair<const DILocalVariable *, const DILocation *> |
| DebugVariableBase; |
| /// A potentially inlined instance of a variable. |
| struct DebugVariable : public DebugVariableBase { |
| DebugVariable(const DILocalVariable *Var, const DILocation *InlinedAt) |
| : DebugVariableBase(Var, InlinedAt) {} |
| |
| const DILocalVariable *getVar() const { return this->first; }; |
| const DILocation *getInlinedAt() const { return this->second; }; |
| |
| bool operator<(const DebugVariable &DV) const { |
| if (getVar() == DV.getVar()) |
| return getInlinedAt() < DV.getInlinedAt(); |
| return getVar() < DV.getVar(); |
| } |
| }; |
| |
| /// A pair of debug variable and value location. |
| struct VarLoc { |
| const DebugVariable Var; |
| const MachineInstr &MI; ///< Only used for cloning a new DBG_VALUE. |
| mutable UserValueScopes UVS; |
| enum { InvalidKind = 0, RegisterKind } Kind; |
| |
| /// The value location. Stored separately to avoid repeatedly |
| /// extracting it from MI. |
| union { |
| struct { |
| uint32_t RegNo; |
| uint32_t Offset; |
| } RegisterLoc; |
| uint64_t Hash; |
| } Loc; |
| |
| VarLoc(const MachineInstr &MI, LexicalScopes &LS) |
| : Var(MI.getDebugVariable(), MI.getDebugLoc()->getInlinedAt()), MI(MI), |
| UVS(MI.getDebugLoc(), LS), Kind(InvalidKind) { |
| static_assert((sizeof(Loc) == sizeof(uint64_t)), |
| "hash does not cover all members of Loc"); |
| assert(MI.isDebugValue() && "not a DBG_VALUE"); |
| assert(MI.getNumOperands() == 4 && "malformed DBG_VALUE"); |
| if (int RegNo = isDbgValueDescribedByReg(MI)) { |
| Kind = RegisterKind; |
| Loc.RegisterLoc.RegNo = RegNo; |
| int64_t Offset = |
| MI.isIndirectDebugValue() ? MI.getOperand(1).getImm() : 0; |
| // We don't support offsets larger than 4GiB here. They are |
| // slated to be replaced with DIExpressions anyway. |
| // With indirect debug values used for spill locations, Offset |
| // can be negative. |
| if (Offset == INT64_MIN || std::abs(Offset) >= (1LL << 32)) |
| Kind = InvalidKind; |
| else |
| Loc.RegisterLoc.Offset = Offset; |
| } |
| } |
| |
| /// If this variable is described by a register, return it, |
| /// otherwise return 0. |
| unsigned isDescribedByReg() const { |
| if (Kind == RegisterKind) |
| return Loc.RegisterLoc.RegNo; |
| return 0; |
| } |
| |
| /// Determine whether the lexical scope of this value's debug location |
| /// dominates MBB. |
| bool dominates(MachineBasicBlock &MBB) const { return UVS.dominates(&MBB); } |
| |
| #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
| LLVM_DUMP_METHOD void dump() const { MI.dump(); } |
| #endif |
| |
| bool operator==(const VarLoc &Other) const { |
| return Var == Other.Var && Loc.Hash == Other.Loc.Hash; |
| } |
| |
| /// This operator guarantees that VarLocs are sorted by Variable first. |
| bool operator<(const VarLoc &Other) const { |
| if (Var == Other.Var) |
| return Loc.Hash < Other.Loc.Hash; |
| return Var < Other.Var; |
| } |
| }; |
| |
| typedef UniqueVector<VarLoc> VarLocMap; |
| typedef SparseBitVector<> VarLocSet; |
| typedef SmallDenseMap<const MachineBasicBlock *, VarLocSet> VarLocInMBB; |
| struct SpillDebugPair { |
| MachineInstr *SpillInst; |
| MachineInstr *DebugInst; |
| }; |
| typedef SmallVector<SpillDebugPair, 4> SpillMap; |
| |
| /// This holds the working set of currently open ranges. For fast |
| /// access, this is done both as a set of VarLocIDs, and a map of |
| /// DebugVariable to recent VarLocID. Note that a DBG_VALUE ends all |
| /// previous open ranges for the same variable. |
| class OpenRangesSet { |
| VarLocSet VarLocs; |
| SmallDenseMap<DebugVariableBase, unsigned, 8> Vars; |
| |
| public: |
| const VarLocSet &getVarLocs() const { return VarLocs; } |
| |
| /// Terminate all open ranges for Var by removing it from the set. |
| void erase(DebugVariable Var) { |
| auto It = Vars.find(Var); |
| if (It != Vars.end()) { |
| unsigned ID = It->second; |
| VarLocs.reset(ID); |
| Vars.erase(It); |
| } |
| } |
| |
| /// Terminate all open ranges listed in \c KillSet by removing |
| /// them from the set. |
| void erase(const VarLocSet &KillSet, const VarLocMap &VarLocIDs) { |
| VarLocs.intersectWithComplement(KillSet); |
| for (unsigned ID : KillSet) |
| Vars.erase(VarLocIDs[ID].Var); |
| } |
| |
| /// Insert a new range into the set. |
| void insert(unsigned VarLocID, DebugVariableBase Var) { |
| VarLocs.set(VarLocID); |
| Vars.insert({Var, VarLocID}); |
| } |
| |
| /// Empty the set. |
| void clear() { |
| VarLocs.clear(); |
| Vars.clear(); |
| } |
| |
| /// Return whether the set is empty or not. |
| bool empty() const { |
| assert(Vars.empty() == VarLocs.empty() && "open ranges are inconsistent"); |
| return VarLocs.empty(); |
| } |
| }; |
| |
| bool isSpillInstruction(const MachineInstr &MI, MachineFunction *MF, |
| unsigned &Reg); |
| int extractSpillBaseRegAndOffset(const MachineInstr &MI, unsigned &Reg); |
| |
| void transferDebugValue(const MachineInstr &MI, OpenRangesSet &OpenRanges, |
| VarLocMap &VarLocIDs); |
| void transferSpillInst(MachineInstr &MI, OpenRangesSet &OpenRanges, |
| VarLocMap &VarLocIDs, SpillMap &Spills); |
| void transferRegisterDef(MachineInstr &MI, OpenRangesSet &OpenRanges, |
| const VarLocMap &VarLocIDs); |
| bool transferTerminatorInst(MachineInstr &MI, OpenRangesSet &OpenRanges, |
| VarLocInMBB &OutLocs, const VarLocMap &VarLocIDs); |
| bool transfer(MachineInstr &MI, OpenRangesSet &OpenRanges, |
| VarLocInMBB &OutLocs, VarLocMap &VarLocIDs, SpillMap &Spills, |
| bool transferSpills); |
| |
| bool join(MachineBasicBlock &MBB, VarLocInMBB &OutLocs, VarLocInMBB &InLocs, |
| const VarLocMap &VarLocIDs, |
| SmallPtrSet<const MachineBasicBlock *, 16> &Visited); |
| |
| bool ExtendRanges(MachineFunction &MF); |
| |
| public: |
| static char ID; |
| |
| /// Default construct and initialize the pass. |
| LiveDebugValues(); |
| |
| /// Tell the pass manager which passes we depend on and what |
| /// information we preserve. |
| void getAnalysisUsage(AnalysisUsage &AU) const override; |
| |
| MachineFunctionProperties getRequiredProperties() const override { |
| return MachineFunctionProperties().set( |
| MachineFunctionProperties::Property::NoVRegs); |
| } |
| |
| /// Print to ostream with a message. |
| void printVarLocInMBB(const MachineFunction &MF, const VarLocInMBB &V, |
| const VarLocMap &VarLocIDs, const char *msg, |
| raw_ostream &Out) const; |
| |
| /// Calculate the liveness information for the given machine function. |
| bool runOnMachineFunction(MachineFunction &MF) override; |
| }; |
| |
| } // namespace |
| |
| //===----------------------------------------------------------------------===// |
| // Implementation |
| //===----------------------------------------------------------------------===// |
| |
| char LiveDebugValues::ID = 0; |
| char &llvm::LiveDebugValuesID = LiveDebugValues::ID; |
| INITIALIZE_PASS(LiveDebugValues, DEBUG_TYPE, "Live DEBUG_VALUE analysis", |
| false, false) |
| |
| /// Default construct and initialize the pass. |
| LiveDebugValues::LiveDebugValues() : MachineFunctionPass(ID) { |
| initializeLiveDebugValuesPass(*PassRegistry::getPassRegistry()); |
| } |
| |
| /// Tell the pass manager which passes we depend on and what information we |
| /// preserve. |
| void LiveDebugValues::getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.setPreservesCFG(); |
| MachineFunctionPass::getAnalysisUsage(AU); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Debug Range Extension Implementation |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef NDEBUG |
| void LiveDebugValues::printVarLocInMBB(const MachineFunction &MF, |
| const VarLocInMBB &V, |
| const VarLocMap &VarLocIDs, |
| const char *msg, |
| raw_ostream &Out) const { |
| Out << '\n' << msg << '\n'; |
| for (const MachineBasicBlock &BB : MF) { |
| const auto &L = V.lookup(&BB); |
| Out << "MBB: " << BB.getName() << ":\n"; |
| for (unsigned VLL : L) { |
| const VarLoc &VL = VarLocIDs[VLL]; |
| Out << " Var: " << VL.Var.getVar()->getName(); |
| Out << " MI: "; |
| VL.dump(); |
| } |
| } |
| Out << "\n"; |
| } |
| #endif |
| |
| /// Given a spill instruction, extract the register and offset used to |
| /// address the spill location in a target independent way. |
| int LiveDebugValues::extractSpillBaseRegAndOffset(const MachineInstr &MI, |
| unsigned &Reg) { |
| assert(MI.hasOneMemOperand() && |
| "Spill instruction does not have exactly one memory operand?"); |
| auto MMOI = MI.memoperands_begin(); |
| const PseudoSourceValue *PVal = (*MMOI)->getPseudoValue(); |
| assert(PVal->kind() == PseudoSourceValue::FixedStack && |
| "Inconsistent memory operand in spill instruction"); |
| int FI = cast<FixedStackPseudoSourceValue>(PVal)->getFrameIndex(); |
| const MachineBasicBlock *MBB = MI.getParent(); |
| return TFI->getFrameIndexReference(*MBB->getParent(), FI, Reg); |
| } |
| |
| /// End all previous ranges related to @MI and start a new range from @MI |
| /// if it is a DBG_VALUE instr. |
| void LiveDebugValues::transferDebugValue(const MachineInstr &MI, |
| OpenRangesSet &OpenRanges, |
| VarLocMap &VarLocIDs) { |
| if (!MI.isDebugValue()) |
| return; |
| const DILocalVariable *Var = MI.getDebugVariable(); |
| const DILocation *DebugLoc = MI.getDebugLoc(); |
| const DILocation *InlinedAt = DebugLoc->getInlinedAt(); |
| assert(Var->isValidLocationForIntrinsic(DebugLoc) && |
| "Expected inlined-at fields to agree"); |
| |
| // End all previous ranges of Var. |
| DebugVariable V(Var, InlinedAt); |
| OpenRanges.erase(V); |
| |
| // Add the VarLoc to OpenRanges from this DBG_VALUE. |
| // TODO: Currently handles DBG_VALUE which has only reg as location. |
| if (isDbgValueDescribedByReg(MI)) { |
| VarLoc VL(MI, LS); |
| unsigned ID = VarLocIDs.insert(VL); |
| OpenRanges.insert(ID, VL.Var); |
| } |
| } |
| |
| /// A definition of a register may mark the end of a range. |
| void LiveDebugValues::transferRegisterDef(MachineInstr &MI, |
| OpenRangesSet &OpenRanges, |
| const VarLocMap &VarLocIDs) { |
| MachineFunction *MF = MI.getParent()->getParent(); |
| const TargetLowering *TLI = MF->getSubtarget().getTargetLowering(); |
| unsigned SP = TLI->getStackPointerRegisterToSaveRestore(); |
| SparseBitVector<> KillSet; |
| for (const MachineOperand &MO : MI.operands()) { |
| // Determine whether the operand is a register def. Assume that call |
| // instructions never clobber SP, because some backends (e.g., AArch64) |
| // never list SP in the regmask. |
| if (MO.isReg() && MO.isDef() && MO.getReg() && |
| TRI->isPhysicalRegister(MO.getReg()) && |
| !(MI.isCall() && MO.getReg() == SP)) { |
| // Remove ranges of all aliased registers. |
| for (MCRegAliasIterator RAI(MO.getReg(), TRI, true); RAI.isValid(); ++RAI) |
| for (unsigned ID : OpenRanges.getVarLocs()) |
| if (VarLocIDs[ID].isDescribedByReg() == *RAI) |
| KillSet.set(ID); |
| } else if (MO.isRegMask()) { |
| // Remove ranges of all clobbered registers. Register masks don't usually |
| // list SP as preserved. While the debug info may be off for an |
| // instruction or two around callee-cleanup calls, transferring the |
| // DEBUG_VALUE across the call is still a better user experience. |
| for (unsigned ID : OpenRanges.getVarLocs()) { |
| unsigned Reg = VarLocIDs[ID].isDescribedByReg(); |
| if (Reg && Reg != SP && MO.clobbersPhysReg(Reg)) |
| KillSet.set(ID); |
| } |
| } |
| } |
| OpenRanges.erase(KillSet, VarLocIDs); |
| } |
| |
| /// Decide if @MI is a spill instruction and return true if it is. We use 2 |
| /// criteria to make this decision: |
| /// - Is this instruction a store to a spill slot? |
| /// - Is there a register operand that is both used and killed? |
| /// TODO: Store optimization can fold spills into other stores (including |
| /// other spills). We do not handle this yet (more than one memory operand). |
| bool LiveDebugValues::isSpillInstruction(const MachineInstr &MI, |
| MachineFunction *MF, unsigned &Reg) { |
| const MachineFrameInfo &FrameInfo = MF->getFrameInfo(); |
| int FI; |
| const MachineMemOperand *MMO; |
| |
| // TODO: Handle multiple stores folded into one. |
| if (!MI.hasOneMemOperand()) |
| return false; |
| |
| // To identify a spill instruction, use the same criteria as in AsmPrinter. |
| if (!((TII->isStoreToStackSlotPostFE(MI, FI) || |
| TII->hasStoreToStackSlot(MI, MMO, FI)) && |
| FrameInfo.isSpillSlotObjectIndex(FI))) |
| return false; |
| |
| // In a spill instruction generated by the InlineSpiller the spilled register |
| // has its kill flag set. Return false if we don't find such a register. |
| Reg = 0; |
| for (const MachineOperand &MO : MI.operands()) { |
| if (MO.isReg() && MO.isUse() && MO.isKill()) { |
| Reg = MO.getReg(); |
| break; |
| } |
| } |
| return Reg != 0; |
| } |
| |
| /// A spilled register may indicate that we have to end the current range of |
| /// a variable and create a new one for the spill location. |
| /// We don't want to insert any instructions in transfer(), so we just create |
| /// the DBG_VALUE witout inserting it and keep track of it in @Spills. |
| /// It will be inserted into the BB when we're done iterating over the |
| /// instructions. |
| void LiveDebugValues::transferSpillInst(MachineInstr &MI, |
| OpenRangesSet &OpenRanges, |
| VarLocMap &VarLocIDs, |
| SpillMap &Spills) { |
| unsigned Reg; |
| MachineFunction *MF = MI.getParent()->getParent(); |
| if (!isSpillInstruction(MI, MF, Reg)) |
| return; |
| |
| // Check if the register is the location of a debug value. |
| for (unsigned ID : OpenRanges.getVarLocs()) { |
| if (VarLocIDs[ID].isDescribedByReg() == Reg) { |
| DEBUG(dbgs() << "Spilling Register " << PrintReg(Reg, TRI) << '(' |
| << VarLocIDs[ID].Var.getVar()->getName() << ")\n"); |
| |
| // Create a DBG_VALUE instruction to describe the Var in its spilled |
| // location, but don't insert it yet to avoid invalidating the |
| // iterator in our caller. |
| unsigned SpillBase; |
| int SpillOffset = extractSpillBaseRegAndOffset(MI, SpillBase); |
| const MachineInstr *DMI = &VarLocIDs[ID].MI; |
| MachineInstr *SpDMI = |
| BuildMI(*MF, DMI->getDebugLoc(), DMI->getDesc(), true, SpillBase, 0, |
| DMI->getDebugVariable(), DMI->getDebugExpression()); |
| SpDMI->getOperand(1).setImm(SpillOffset); |
| DEBUG(dbgs() << "Creating DBG_VALUE inst for spill: "; |
| SpDMI->print(dbgs(), false, TII)); |
| |
| // The newly created DBG_VALUE instruction SpDMI must be inserted after |
| // MI. Keep track of the pairing. |
| SpillDebugPair MIP = {&MI, SpDMI}; |
| Spills.push_back(MIP); |
| |
| // End all previous ranges of Var. |
| OpenRanges.erase(VarLocIDs[ID].Var); |
| |
| // Add the VarLoc to OpenRanges. |
| VarLoc VL(*SpDMI, LS); |
| unsigned SpillLocID = VarLocIDs.insert(VL); |
| OpenRanges.insert(SpillLocID, VL.Var); |
| return; |
| } |
| } |
| } |
| |
| /// Terminate all open ranges at the end of the current basic block. |
| bool LiveDebugValues::transferTerminatorInst(MachineInstr &MI, |
| OpenRangesSet &OpenRanges, |
| VarLocInMBB &OutLocs, |
| const VarLocMap &VarLocIDs) { |
| bool Changed = false; |
| const MachineBasicBlock *CurMBB = MI.getParent(); |
| if (!(MI.isTerminator() || (&MI == &CurMBB->instr_back()))) |
| return false; |
| |
| if (OpenRanges.empty()) |
| return false; |
| |
| DEBUG(for (unsigned ID : OpenRanges.getVarLocs()) { |
| // Copy OpenRanges to OutLocs, if not already present. |
| dbgs() << "Add to OutLocs: "; VarLocIDs[ID].dump(); |
| }); |
| VarLocSet &VLS = OutLocs[CurMBB]; |
| Changed = VLS |= OpenRanges.getVarLocs(); |
| OpenRanges.clear(); |
| return Changed; |
| } |
| |
| /// This routine creates OpenRanges and OutLocs. |
| bool LiveDebugValues::transfer(MachineInstr &MI, OpenRangesSet &OpenRanges, |
| VarLocInMBB &OutLocs, VarLocMap &VarLocIDs, |
| SpillMap &Spills, bool transferSpills) { |
| bool Changed = false; |
| transferDebugValue(MI, OpenRanges, VarLocIDs); |
| transferRegisterDef(MI, OpenRanges, VarLocIDs); |
| if (transferSpills) |
| transferSpillInst(MI, OpenRanges, VarLocIDs, Spills); |
| Changed = transferTerminatorInst(MI, OpenRanges, OutLocs, VarLocIDs); |
| return Changed; |
| } |
| |
| /// This routine joins the analysis results of all incoming edges in @MBB by |
| /// inserting a new DBG_VALUE instruction at the start of the @MBB - if the same |
| /// source variable in all the predecessors of @MBB reside in the same location. |
| bool LiveDebugValues::join(MachineBasicBlock &MBB, VarLocInMBB &OutLocs, |
| VarLocInMBB &InLocs, const VarLocMap &VarLocIDs, |
| SmallPtrSet<const MachineBasicBlock *, 16> &Visited) { |
| DEBUG(dbgs() << "join MBB: " << MBB.getName() << "\n"); |
| bool Changed = false; |
| |
| VarLocSet InLocsT; // Temporary incoming locations. |
| |
| // For all predecessors of this MBB, find the set of VarLocs that |
| // can be joined. |
| int NumVisited = 0; |
| for (auto p : MBB.predecessors()) { |
| // Ignore unvisited predecessor blocks. As we are processing |
| // the blocks in reverse post-order any unvisited block can |
| // be considered to not remove any incoming values. |
| if (!Visited.count(p)) |
| continue; |
| auto OL = OutLocs.find(p); |
| // Join is null in case of empty OutLocs from any of the pred. |
| if (OL == OutLocs.end()) |
| return false; |
| |
| // Just copy over the Out locs to incoming locs for the first visited |
| // predecessor, and for all other predecessors join the Out locs. |
| if (!NumVisited) |
| InLocsT = OL->second; |
| else |
| InLocsT &= OL->second; |
| NumVisited++; |
| } |
| |
| // Filter out DBG_VALUES that are out of scope. |
| VarLocSet KillSet; |
| for (auto ID : InLocsT) |
| if (!VarLocIDs[ID].dominates(MBB)) |
| KillSet.set(ID); |
| InLocsT.intersectWithComplement(KillSet); |
| |
| // As we are processing blocks in reverse post-order we |
| // should have processed at least one predecessor, unless it |
| // is the entry block which has no predecessor. |
| assert((NumVisited || MBB.pred_empty()) && |
| "Should have processed at least one predecessor"); |
| if (InLocsT.empty()) |
| return false; |
| |
| VarLocSet &ILS = InLocs[&MBB]; |
| |
| // Insert DBG_VALUE instructions, if not already inserted. |
| VarLocSet Diff = InLocsT; |
| Diff.intersectWithComplement(ILS); |
| for (auto ID : Diff) { |
| // This VarLoc is not found in InLocs i.e. it is not yet inserted. So, a |
| // new range is started for the var from the mbb's beginning by inserting |
| // a new DBG_VALUE. transfer() will end this range however appropriate. |
| const VarLoc &DiffIt = VarLocIDs[ID]; |
| const MachineInstr *DMI = &DiffIt.MI; |
| MachineInstr *MI = |
| BuildMI(MBB, MBB.instr_begin(), DMI->getDebugLoc(), DMI->getDesc(), |
| DMI->isIndirectDebugValue(), DMI->getOperand(0).getReg(), 0, |
| DMI->getDebugVariable(), DMI->getDebugExpression()); |
| if (DMI->isIndirectDebugValue()) |
| MI->getOperand(1).setImm(DMI->getOperand(1).getImm()); |
| DEBUG(dbgs() << "Inserted: "; MI->dump();); |
| ILS.set(ID); |
| ++NumInserted; |
| Changed = true; |
| } |
| return Changed; |
| } |
| |
| /// Calculate the liveness information for the given machine function and |
| /// extend ranges across basic blocks. |
| bool LiveDebugValues::ExtendRanges(MachineFunction &MF) { |
| |
| DEBUG(dbgs() << "\nDebug Range Extension\n"); |
| |
| bool Changed = false; |
| bool OLChanged = false; |
| bool MBBJoined = false; |
| |
| VarLocMap VarLocIDs; // Map VarLoc<>unique ID for use in bitvectors. |
| OpenRangesSet OpenRanges; // Ranges that are open until end of bb. |
| VarLocInMBB OutLocs; // Ranges that exist beyond bb. |
| VarLocInMBB InLocs; // Ranges that are incoming after joining. |
| SpillMap Spills; // DBG_VALUEs associated with spills. |
| |
| DenseMap<unsigned int, MachineBasicBlock *> OrderToBB; |
| DenseMap<MachineBasicBlock *, unsigned int> BBToOrder; |
| std::priority_queue<unsigned int, std::vector<unsigned int>, |
| std::greater<unsigned int>> |
| Worklist; |
| std::priority_queue<unsigned int, std::vector<unsigned int>, |
| std::greater<unsigned int>> |
| Pending; |
| |
| // Initialize every mbb with OutLocs. |
| // We are not looking at any spill instructions during the initial pass |
| // over the BBs. The LiveDebugVariables pass has already created DBG_VALUE |
| // instructions for spills of registers that are known to be user variables |
| // within the BB in which the spill occurs. |
| for (auto &MBB : MF) |
| for (auto &MI : MBB) |
| transfer(MI, OpenRanges, OutLocs, VarLocIDs, Spills, |
| /*transferSpills=*/false); |
| |
| DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs, "OutLocs after initialization", |
| dbgs())); |
| |
| ReversePostOrderTraversal<MachineFunction *> RPOT(&MF); |
| unsigned int RPONumber = 0; |
| for (auto RI = RPOT.begin(), RE = RPOT.end(); RI != RE; ++RI) { |
| OrderToBB[RPONumber] = *RI; |
| BBToOrder[*RI] = RPONumber; |
| Worklist.push(RPONumber); |
| ++RPONumber; |
| } |
| // This is a standard "union of predecessor outs" dataflow problem. |
| // To solve it, we perform join() and transfer() using the two worklist method |
| // until the ranges converge. |
| // Ranges have converged when both worklists are empty. |
| SmallPtrSet<const MachineBasicBlock *, 16> Visited; |
| while (!Worklist.empty() || !Pending.empty()) { |
| // We track what is on the pending worklist to avoid inserting the same |
| // thing twice. We could avoid this with a custom priority queue, but this |
| // is probably not worth it. |
| SmallPtrSet<MachineBasicBlock *, 16> OnPending; |
| DEBUG(dbgs() << "Processing Worklist\n"); |
| while (!Worklist.empty()) { |
| MachineBasicBlock *MBB = OrderToBB[Worklist.top()]; |
| Worklist.pop(); |
| MBBJoined = join(*MBB, OutLocs, InLocs, VarLocIDs, Visited); |
| Visited.insert(MBB); |
| if (MBBJoined) { |
| MBBJoined = false; |
| Changed = true; |
| // Now that we have started to extend ranges across BBs we need to |
| // examine spill instructions to see whether they spill registers that |
| // correspond to user variables. |
| for (auto &MI : *MBB) |
| OLChanged |= transfer(MI, OpenRanges, OutLocs, VarLocIDs, Spills, |
| /*transferSpills=*/true); |
| |
| // Add any DBG_VALUE instructions necessitated by spills. |
| for (auto &SP : Spills) |
| MBB->insertAfter(MachineBasicBlock::iterator(*SP.SpillInst), |
| SP.DebugInst); |
| Spills.clear(); |
| |
| DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs, |
| "OutLocs after propagating", dbgs())); |
| DEBUG(printVarLocInMBB(MF, InLocs, VarLocIDs, |
| "InLocs after propagating", dbgs())); |
| |
| if (OLChanged) { |
| OLChanged = false; |
| for (auto s : MBB->successors()) |
| if (OnPending.insert(s).second) { |
| Pending.push(BBToOrder[s]); |
| } |
| } |
| } |
| } |
| Worklist.swap(Pending); |
| // At this point, pending must be empty, since it was just the empty |
| // worklist |
| assert(Pending.empty() && "Pending should be empty"); |
| } |
| |
| DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs, "Final OutLocs", dbgs())); |
| DEBUG(printVarLocInMBB(MF, InLocs, VarLocIDs, "Final InLocs", dbgs())); |
| return Changed; |
| } |
| |
| bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) { |
| if (!MF.getFunction()->getSubprogram()) |
| // LiveDebugValues will already have removed all DBG_VALUEs. |
| return false; |
| |
| TRI = MF.getSubtarget().getRegisterInfo(); |
| TII = MF.getSubtarget().getInstrInfo(); |
| TFI = MF.getSubtarget().getFrameLowering(); |
| LS.initialize(MF); |
| |
| bool Changed = ExtendRanges(MF); |
| return Changed; |
| } |