| //===------ 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/Statistic.h" |
| #include "llvm/ADT/PostOrderIterator.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/CodeGen/MachineFunction.h" |
| #include "llvm/CodeGen/MachineFunctionPass.h" |
| #include "llvm/CodeGen/MachineInstrBuilder.h" |
| #include "llvm/CodeGen/Passes.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Target/TargetInstrInfo.h" |
| #include "llvm/Target/TargetRegisterInfo.h" |
| #include "llvm/Target/TargetSubtargetInfo.h" |
| #include <queue> |
| #include <list> |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "live-debug-values" |
| |
| STATISTIC(NumInserted, "Number of DBG_VALUE instructions inserted"); |
| |
| namespace { |
| |
| class LiveDebugValues : public MachineFunctionPass { |
| |
| private: |
| const TargetRegisterInfo *TRI; |
| const TargetInstrInfo *TII; |
| |
| typedef std::pair<const DILocalVariable *, const DILocation *> |
| InlinedVariable; |
| |
| /// A potentially inlined instance of a variable. |
| struct DebugVariable { |
| const DILocalVariable *Var; |
| const DILocation *InlinedAt; |
| |
| DebugVariable(const DILocalVariable *_var, const DILocation *_inlinedAt) |
| : Var(_var), InlinedAt(_inlinedAt) {} |
| |
| bool operator==(const DebugVariable &DV) const { |
| return (Var == DV.Var) && (InlinedAt == DV.InlinedAt); |
| } |
| }; |
| |
| /// Member variables and functions for Range Extension across basic blocks. |
| struct VarLoc { |
| DebugVariable Var; |
| const MachineInstr *MI; // MachineInstr should be a DBG_VALUE instr. |
| |
| VarLoc(DebugVariable _var, const MachineInstr *_mi) : Var(_var), MI(_mi) {} |
| |
| bool operator==(const VarLoc &V) const; |
| }; |
| |
| typedef std::list<VarLoc> VarLocList; |
| typedef SmallDenseMap<const MachineBasicBlock *, VarLocList> VarLocInMBB; |
| |
| void transferDebugValue(MachineInstr &MI, VarLocList &OpenRanges); |
| void transferRegisterDef(MachineInstr &MI, VarLocList &OpenRanges); |
| bool transferTerminatorInst(MachineInstr &MI, VarLocList &OpenRanges, |
| VarLocInMBB &OutLocs); |
| bool transfer(MachineInstr &MI, VarLocList &OpenRanges, VarLocInMBB &OutLocs); |
| |
| bool join(MachineBasicBlock &MBB, VarLocInMBB &OutLocs, VarLocInMBB &InLocs); |
| |
| 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; |
| |
| /// Print to ostream with a message. |
| void printVarLocInMBB(const VarLocInMBB &V, 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, "livedebugvalues", "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 { |
| MachineFunctionPass::getAnalysisUsage(AU); |
| } |
| |
| // \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 isDescribedByReg(const MachineInstr &MI) { |
| assert(MI.isDebugValue()); |
| assert(MI.getNumOperands() == 4); |
| // If location of variable is described using a register (directly or |
| // indirecltly), this register is always a first operand. |
| return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0; |
| } |
| |
| // \brief This function takes two DBG_VALUE instructions and returns true |
| // if their offsets are equal; otherwise returns false. |
| static bool areOffsetsEqual(const MachineInstr &MI1, const MachineInstr &MI2) { |
| assert(MI1.isDebugValue()); |
| assert(MI1.getNumOperands() == 4); |
| |
| assert(MI2.isDebugValue()); |
| assert(MI2.getNumOperands() == 4); |
| |
| if (!MI1.isIndirectDebugValue() && !MI2.isIndirectDebugValue()) |
| return true; |
| |
| // Check if both MIs are indirect and they are equal. |
| if (MI1.isIndirectDebugValue() && MI2.isIndirectDebugValue()) |
| return MI1.getOperand(1).getImm() == MI2.getOperand(1).getImm(); |
| |
| return false; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Debug Range Extension Implementation |
| //===----------------------------------------------------------------------===// |
| |
| void LiveDebugValues::printVarLocInMBB(const VarLocInMBB &V, const char *msg, |
| raw_ostream &Out) const { |
| Out << "Printing " << msg << ":\n"; |
| for (const auto &L : V) { |
| Out << "MBB: " << L.first->getName() << ":\n"; |
| for (const auto &VLL : L.second) { |
| Out << " Var: " << VLL.Var.Var->getName(); |
| Out << " MI: "; |
| (*VLL.MI).dump(); |
| Out << "\n"; |
| } |
| } |
| Out << "\n"; |
| } |
| |
| bool LiveDebugValues::VarLoc::operator==(const VarLoc &V) const { |
| return (Var == V.Var) && (isDescribedByReg(*MI) == isDescribedByReg(*V.MI)) && |
| (areOffsetsEqual(*MI, *V.MI)); |
| } |
| |
| /// End all previous ranges related to @MI and start a new range from @MI |
| /// if it is a DBG_VALUE instr. |
| void LiveDebugValues::transferDebugValue(MachineInstr &MI, |
| VarLocList &OpenRanges) { |
| if (!MI.isDebugValue()) |
| return; |
| const DILocalVariable *RawVar = MI.getDebugVariable(); |
| assert(RawVar->isValidLocationForIntrinsic(MI.getDebugLoc()) && |
| "Expected inlined-at fields to agree"); |
| DebugVariable Var(RawVar, MI.getDebugLoc()->getInlinedAt()); |
| |
| // End all previous ranges of Var. |
| OpenRanges.erase( |
| std::remove_if(OpenRanges.begin(), OpenRanges.end(), |
| [&](const VarLoc &V) { return (Var == V.Var); }), |
| OpenRanges.end()); |
| |
| // Add Var to OpenRanges from this DBG_VALUE. |
| // TODO: Currently handles DBG_VALUE which has only reg as location. |
| if (isDescribedByReg(MI)) { |
| VarLoc V(Var, &MI); |
| OpenRanges.push_back(std::move(V)); |
| } |
| } |
| |
| /// A definition of a register may mark the end of a range. |
| void LiveDebugValues::transferRegisterDef(MachineInstr &MI, |
| VarLocList &OpenRanges) { |
| for (const MachineOperand &MO : MI.operands()) { |
| if (!(MO.isReg() && MO.isDef() && MO.getReg() && |
| TRI->isPhysicalRegister(MO.getReg()))) |
| continue; |
| // Remove ranges of all aliased registers. |
| for (MCRegAliasIterator RAI(MO.getReg(), TRI, true); RAI.isValid(); ++RAI) |
| OpenRanges.erase(std::remove_if(OpenRanges.begin(), OpenRanges.end(), |
| [&](const VarLoc &V) { |
| return (*RAI == |
| isDescribedByReg(*V.MI)); |
| }), |
| OpenRanges.end()); |
| } |
| } |
| |
| /// Terminate all open ranges at the end of the current basic block. |
| bool LiveDebugValues::transferTerminatorInst(MachineInstr &MI, |
| VarLocList &OpenRanges, |
| VarLocInMBB &OutLocs) { |
| bool Changed = false; |
| const MachineBasicBlock *CurMBB = MI.getParent(); |
| if (!(MI.isTerminator() || (&MI == &CurMBB->instr_back()))) |
| return false; |
| |
| if (OpenRanges.empty()) |
| return false; |
| |
| VarLocList &VLL = OutLocs[CurMBB]; |
| |
| for (auto OR : OpenRanges) { |
| // Copy OpenRanges to OutLocs, if not already present. |
| assert(OR.MI->isDebugValue()); |
| DEBUG(dbgs() << "Add to OutLocs: "; OR.MI->dump();); |
| if (std::find_if(VLL.begin(), VLL.end(), |
| [&](const VarLoc &V) { return (OR == V); }) == VLL.end()) { |
| VLL.push_back(std::move(OR)); |
| Changed = true; |
| } |
| } |
| OpenRanges.clear(); |
| return Changed; |
| } |
| |
| /// This routine creates OpenRanges and OutLocs. |
| bool LiveDebugValues::transfer(MachineInstr &MI, VarLocList &OpenRanges, |
| VarLocInMBB &OutLocs) { |
| bool Changed = false; |
| transferDebugValue(MI, OpenRanges); |
| transferRegisterDef(MI, OpenRanges); |
| Changed = transferTerminatorInst(MI, OpenRanges, OutLocs); |
| 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) { |
| DEBUG(dbgs() << "join MBB: " << MBB.getName() << "\n"); |
| bool Changed = false; |
| |
| VarLocList InLocsT; // Temporary incoming locations. |
| |
| // For all predecessors of this MBB, find the set of VarLocs that can be |
| // joined. |
| for (auto p : MBB.predecessors()) { |
| 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 predecessor. |
| if (p == *MBB.pred_begin()) { |
| InLocsT = OL->second; |
| continue; |
| } |
| |
| // Join with this predecessor. |
| VarLocList &VLL = OL->second; |
| InLocsT.erase( |
| std::remove_if(InLocsT.begin(), InLocsT.end(), [&](VarLoc &ILT) { |
| return (std::find_if(VLL.begin(), VLL.end(), [&](const VarLoc &V) { |
| return (ILT == V); |
| }) == VLL.end()); |
| }), InLocsT.end()); |
| } |
| |
| if (InLocsT.empty()) |
| return false; |
| |
| VarLocList &ILL = InLocs[&MBB]; |
| |
| // Insert DBG_VALUE instructions, if not already inserted. |
| for (auto ILT : InLocsT) { |
| if (std::find_if(ILL.begin(), ILL.end(), [&](const VarLoc &I) { |
| return (ILT == I); |
| }) == ILL.end()) { |
| // 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 MachineInstr *DMI = ILT.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();); |
| ++NumInserted; |
| Changed = true; |
| |
| VarLoc V(ILT.Var, MI); |
| ILL.push_back(std::move(V)); |
| } |
| } |
| 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; |
| |
| VarLocList OpenRanges; // Ranges that are open until end of bb. |
| VarLocInMBB OutLocs; // Ranges that exist beyond bb. |
| VarLocInMBB InLocs; // Ranges that are incoming after joining. |
| |
| 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. |
| for (auto &MBB : MF) |
| for (auto &MI : MBB) |
| transfer(MI, OpenRanges, OutLocs); |
| DEBUG(printVarLocInMBB(OutLocs, "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. |
| 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; |
| while (!Worklist.empty()) { |
| MachineBasicBlock *MBB = OrderToBB[Worklist.top()]; |
| Worklist.pop(); |
| MBBJoined = join(*MBB, OutLocs, InLocs); |
| |
| if (MBBJoined) { |
| MBBJoined = false; |
| Changed = true; |
| for (auto &MI : *MBB) |
| OLChanged |= transfer(MI, OpenRanges, OutLocs); |
| DEBUG(printVarLocInMBB(OutLocs, "OutLocs after propagating", dbgs())); |
| DEBUG(printVarLocInMBB(InLocs, "InLocs after propagating", dbgs())); |
| |
| if (OLChanged) { |
| OLChanged = false; |
| for (auto s : MBB->successors()) |
| if (!OnPending.count(s)) { |
| OnPending.insert(s); |
| 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(OutLocs, "Final OutLocs", dbgs())); |
| DEBUG(printVarLocInMBB(InLocs, "Final InLocs", dbgs())); |
| return Changed; |
| } |
| |
| bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) { |
| TRI = MF.getSubtarget().getRegisterInfo(); |
| TII = MF.getSubtarget().getInstrInfo(); |
| |
| bool Changed = false; |
| |
| Changed |= ExtendRanges(MF); |
| |
| return Changed; |
| } |