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Diffstat (limited to 'gnu/llvm/lib/CodeGen/LiveDebugValues.cpp')
| -rw-r--r-- | gnu/llvm/lib/CodeGen/LiveDebugValues.cpp | 868 |
1 files changed, 0 insertions, 868 deletions
diff --git a/gnu/llvm/lib/CodeGen/LiveDebugValues.cpp b/gnu/llvm/lib/CodeGen/LiveDebugValues.cpp deleted file mode 100644 index fc0ebea2d36..00000000000 --- a/gnu/llvm/lib/CodeGen/LiveDebugValues.cpp +++ /dev/null @@ -1,868 +0,0 @@ -//===- 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/DenseMap.h" -#include "llvm/ADT/PostOrderIterator.h" -#include "llvm/ADT/SmallPtrSet.h" -#include "llvm/ADT/SmallVector.h" -#include "llvm/ADT/SparseBitVector.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/ADT/UniqueVector.h" -#include "llvm/CodeGen/LexicalScopes.h" -#include "llvm/CodeGen/MachineBasicBlock.h" -#include "llvm/CodeGen/MachineFrameInfo.h" -#include "llvm/CodeGen/MachineFunction.h" -#include "llvm/CodeGen/MachineFunctionPass.h" -#include "llvm/CodeGen/MachineInstr.h" -#include "llvm/CodeGen/MachineInstrBuilder.h" -#include "llvm/CodeGen/MachineMemOperand.h" -#include "llvm/CodeGen/MachineOperand.h" -#include "llvm/CodeGen/PseudoSourceValue.h" -#include "llvm/CodeGen/TargetFrameLowering.h" -#include "llvm/CodeGen/TargetInstrInfo.h" -#include "llvm/CodeGen/TargetLowering.h" -#include "llvm/CodeGen/TargetRegisterInfo.h" -#include "llvm/CodeGen/TargetSubtargetInfo.h" -#include "llvm/CodeGen/RegisterScavenging.h" -#include "llvm/Config/llvm-config.h" -#include "llvm/IR/DebugInfoMetadata.h" -#include "llvm/IR/DebugLoc.h" -#include "llvm/IR/Function.h" -#include "llvm/IR/Module.h" -#include "llvm/MC/MCRegisterInfo.h" -#include "llvm/Pass.h" -#include "llvm/Support/Casting.h" -#include "llvm/Support/Compiler.h" -#include "llvm/Support/Debug.h" -#include "llvm/Support/raw_ostream.h" -#include <algorithm> -#include <cassert> -#include <cstdint> -#include <functional> -#include <queue> -#include <utility> -#include <vector> - -using namespace llvm; - -#define DEBUG_TYPE "livedebugvalues" - -STATISTIC(NumInserted, "Number of DBG_VALUE instructions inserted"); - -// 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; -} - -namespace { - -class LiveDebugValues : public MachineFunctionPass { -private: - const TargetRegisterInfo *TRI; - const TargetInstrInfo *TII; - const TargetFrameLowering *TFI; - BitVector CalleeSavedRegs; - 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. - using DebugVariableBase = - std::pair<const DILocalVariable *, const DILocation *>; - /// 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 = InvalidKind; - - /// The value location. Stored separately to avoid repeatedly - /// extracting it from MI. - union { - uint64_t RegNo; - uint64_t Hash; - } Loc; - - VarLoc(const MachineInstr &MI, LexicalScopes &LS) - : Var(MI.getDebugVariable(), MI.getDebugLoc()->getInlinedAt()), MI(MI), - UVS(MI.getDebugLoc(), LS) { - 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.RegNo = RegNo; - } - } - - /// If this variable is described by a register, return it, - /// otherwise return 0. - unsigned isDescribedByReg() const { - if (Kind == RegisterKind) - return Loc.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; - } - }; - - using VarLocMap = UniqueVector<VarLoc>; - using VarLocSet = SparseBitVector<>; - using VarLocInMBB = SmallDenseMap<const MachineBasicBlock *, VarLocSet>; - struct TransferDebugPair { - MachineInstr *TransferInst; - MachineInstr *DebugInst; - }; - using TransferMap = SmallVector<TransferDebugPair, 4>; - - /// 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 insertTransferDebugPair(MachineInstr &MI, OpenRangesSet &OpenRanges, - TransferMap &Transfers, VarLocMap &VarLocIDs, - unsigned OldVarID, unsigned NewReg = 0); - - void transferDebugValue(const MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs); - void transferSpillInst(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, TransferMap &Transfers); - void transferRegisterCopy(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, TransferMap &Transfers); - void transferRegisterDef(MachineInstr &MI, OpenRangesSet &OpenRanges, - const VarLocMap &VarLocIDs); - bool transferTerminatorInst(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocInMBB &OutLocs, const VarLocMap &VarLocIDs); - bool process(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocInMBB &OutLocs, VarLocMap &VarLocIDs, - TransferMap &Transfers, bool transferChanges); - - bool join(MachineBasicBlock &MBB, VarLocInMBB &OutLocs, VarLocInMBB &InLocs, - const VarLocMap &VarLocIDs, - SmallPtrSet<const MachineBasicBlock *, 16> &Visited, - SmallPtrSetImpl<const MachineBasicBlock *> &ArtificialBlocks); - - 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; -}; - -} // end anonymous 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 VarLocSet &L = V.lookup(&BB); - if (L.empty()) - continue; - Out << "MBB: " << BB.getNumber() << ":\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); - } -} - -/// Create new TransferDebugPair and insert it in \p Transfers. The VarLoc -/// with \p OldVarID should be deleted form \p OpenRanges and replaced with -/// new VarLoc. If \p NewReg is different than default zero value then the -/// new location will be register location created by the copy like instruction, -/// otherwise it is variable's location on the stack. -void LiveDebugValues::insertTransferDebugPair( - MachineInstr &MI, OpenRangesSet &OpenRanges, TransferMap &Transfers, - VarLocMap &VarLocIDs, unsigned OldVarID, unsigned NewReg) { - const MachineInstr *DMI = &VarLocIDs[OldVarID].MI; - MachineFunction *MF = MI.getParent()->getParent(); - MachineInstr *NewDMI; - if (NewReg) { - // Create a DBG_VALUE instruction to describe the Var in its new - // register location. - NewDMI = BuildMI(*MF, DMI->getDebugLoc(), DMI->getDesc(), - DMI->isIndirectDebugValue(), NewReg, - DMI->getDebugVariable(), DMI->getDebugExpression()); - if (DMI->isIndirectDebugValue()) - NewDMI->getOperand(1).setImm(DMI->getOperand(1).getImm()); - LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for register copy: "; - NewDMI->print(dbgs(), false, false, false, TII)); - } else { - // Create a DBG_VALUE instruction to describe the Var in its spilled - // location. - unsigned SpillBase; - int SpillOffset = extractSpillBaseRegAndOffset(MI, SpillBase); - auto *SpillExpr = DIExpression::prepend(DMI->getDebugExpression(), - DIExpression::NoDeref, SpillOffset); - NewDMI = BuildMI(*MF, DMI->getDebugLoc(), DMI->getDesc(), true, SpillBase, - DMI->getDebugVariable(), SpillExpr); - LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for spill: "; - NewDMI->print(dbgs(), false, false, false, TII)); - } - - // The newly created DBG_VALUE instruction NewDMI must be inserted after - // MI. Keep track of the pairing. - TransferDebugPair MIP = {&MI, NewDMI}; - Transfers.push_back(MIP); - - // End all previous ranges of Var. - OpenRanges.erase(VarLocIDs[OldVarID].Var); - - // Add the VarLoc to OpenRanges. - VarLoc VL(*NewDMI, LS); - unsigned LocID = VarLocIDs.insert(VL); - OpenRanges.insert(LocID, 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.getMF(); - 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; - SmallVector<const MachineMemOperand*, 1> Accesses; - - // 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) && - FrameInfo.isSpillSlotObjectIndex(FI)) || - (TII->hasStoreToStackSlot(MI, Accesses) && - llvm::any_of(Accesses, [&FrameInfo](const MachineMemOperand *MMO) { - return FrameInfo.isSpillSlotObjectIndex( - cast<FixedStackPseudoSourceValue>(MMO->getPseudoValue()) - ->getFrameIndex()); - })))) - return false; - - auto isKilledReg = [&](const MachineOperand MO, unsigned &Reg) { - if (!MO.isReg() || !MO.isUse()) { - Reg = 0; - return false; - } - Reg = MO.getReg(); - return MO.isKill(); - }; - - for (const MachineOperand &MO : MI.operands()) { - // In a spill instruction generated by the InlineSpiller the spilled - // register has its kill flag set. - if (isKilledReg(MO, Reg)) - return true; - if (Reg != 0) { - // Check whether next instruction kills the spilled register. - // FIXME: Current solution does not cover search for killed register in - // bundles and instructions further down the chain. - auto NextI = std::next(MI.getIterator()); - // Skip next instruction that points to basic block end iterator. - if (MI.getParent()->end() == NextI) - continue; - unsigned RegNext; - for (const MachineOperand &MONext : NextI->operands()) { - // Return true if we came across the register from the - // previous spill instruction that is killed in NextI. - if (isKilledReg(MONext, RegNext) && RegNext == Reg) - return true; - } - } - } - // Return false if we didn't find spilled register. - return false; -} - -/// 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 process(), so we just create -/// the DBG_VALUE without inserting it and keep track of it in \p Transfers. -/// It will be inserted into the BB when we're done iterating over the -/// instructions. -void LiveDebugValues::transferSpillInst(MachineInstr &MI, - OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, - TransferMap &Transfers) { - unsigned Reg; - MachineFunction *MF = MI.getMF(); - 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) { - LLVM_DEBUG(dbgs() << "Spilling Register " << printReg(Reg, TRI) << '(' - << VarLocIDs[ID].Var.getVar()->getName() << ")\n"); - insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, ID); - return; - } - } -} - -/// If \p MI is a register copy instruction, that copies a previously tracked -/// value from one register to another register that is callee saved, we -/// create new DBG_VALUE instruction described with copy destination register. -void LiveDebugValues::transferRegisterCopy(MachineInstr &MI, - OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, - TransferMap &Transfers) { - const MachineOperand *SrcRegOp, *DestRegOp; - - if (!TII->isCopyInstr(MI, SrcRegOp, DestRegOp) || !SrcRegOp->isKill() || - !DestRegOp->isDef()) - return; - - auto isCalleSavedReg = [&](unsigned Reg) { - for (MCRegAliasIterator RAI(Reg, TRI, true); RAI.isValid(); ++RAI) - if (CalleeSavedRegs.test(*RAI)) - return true; - return false; - }; - - unsigned SrcReg = SrcRegOp->getReg(); - unsigned DestReg = DestRegOp->getReg(); - - // We want to recognize instructions where destination register is callee - // saved register. If register that could be clobbered by the call is - // included, there would be a great chance that it is going to be clobbered - // soon. It is more likely that previous register location, which is callee - // saved, is going to stay unclobbered longer, even if it is killed. - if (!isCalleSavedReg(DestReg)) - return; - - for (unsigned ID : OpenRanges.getVarLocs()) { - if (VarLocIDs[ID].isDescribedByReg() == SrcReg) { - insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, ID, - DestReg); - 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->back()))) - return false; - - if (OpenRanges.empty()) - return false; - - LLVM_DEBUG(for (unsigned ID - : OpenRanges.getVarLocs()) { - // Copy OpenRanges to OutLocs, if not already present. - dbgs() << "Add to OutLocs in MBB #" << CurMBB->getNumber() << ": "; - VarLocIDs[ID].dump(); - }); - VarLocSet &VLS = OutLocs[CurMBB]; - Changed = VLS |= OpenRanges.getVarLocs(); - OpenRanges.clear(); - return Changed; -} - -/// This routine creates OpenRanges and OutLocs. -bool LiveDebugValues::process(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocInMBB &OutLocs, VarLocMap &VarLocIDs, - TransferMap &Transfers, bool transferChanges) { - bool Changed = false; - transferDebugValue(MI, OpenRanges, VarLocIDs); - transferRegisterDef(MI, OpenRanges, VarLocIDs); - if (transferChanges) { - transferRegisterCopy(MI, OpenRanges, VarLocIDs, Transfers); - transferSpillInst(MI, OpenRanges, VarLocIDs, Transfers); - } - 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, - SmallPtrSetImpl<const MachineBasicBlock *> &ArtificialBlocks) { - LLVM_DEBUG(dbgs() << "join MBB: " << MBB.getNumber() << "\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)) { - LLVM_DEBUG(dbgs() << " ignoring unvisited pred MBB: " << p->getNumber() - << "\n"); - 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; - - LLVM_DEBUG({ - if (!InLocsT.empty()) { - for (auto ID : InLocsT) - dbgs() << " gathered candidate incoming var: " - << VarLocIDs[ID].Var.getVar()->getName() << "\n"; - } - }); - - NumVisited++; - } - - // Filter out DBG_VALUES that are out of scope. - VarLocSet KillSet; - bool IsArtificial = ArtificialBlocks.count(&MBB); - if (!IsArtificial) { - for (auto ID : InLocsT) { - if (!VarLocIDs[ID].dominates(MBB)) { - KillSet.set(ID); - LLVM_DEBUG({ - auto Name = VarLocIDs[ID].Var.getVar()->getName(); - dbgs() << " killing " << Name << ", it doesn't dominate MBB\n"; - }); - } - } - } - 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. process() 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(), - DMI->getDebugVariable(), DMI->getDebugExpression()); - if (DMI->isIndirectDebugValue()) - MI->getOperand(1).setImm(DMI->getOperand(1).getImm()); - LLVM_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) { - LLVM_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. - TransferMap Transfers; // DBG_VALUEs associated with spills. - - // Blocks which are artificial, i.e. blocks which exclusively contain - // instructions without locations, or with line 0 locations. - SmallPtrSet<const MachineBasicBlock *, 16> ArtificialBlocks; - - 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; - - enum : bool { dontTransferChanges = false, transferChanges = true }; - - // 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) - process(MI, OpenRanges, OutLocs, VarLocIDs, Transfers, - dontTransferChanges); - - auto hasNonArtificialLocation = [](const MachineInstr &MI) -> bool { - if (const DebugLoc &DL = MI.getDebugLoc()) - return DL.getLine() != 0; - return false; - }; - for (auto &MBB : MF) - if (none_of(MBB.instrs(), hasNonArtificialLocation)) - ArtificialBlocks.insert(&MBB); - - LLVM_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 process() 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; - LLVM_DEBUG(dbgs() << "Processing Worklist\n"); - while (!Worklist.empty()) { - MachineBasicBlock *MBB = OrderToBB[Worklist.top()]; - Worklist.pop(); - MBBJoined = - join(*MBB, OutLocs, InLocs, VarLocIDs, Visited, ArtificialBlocks); - 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 |= process(MI, OpenRanges, OutLocs, VarLocIDs, Transfers, - transferChanges); - - // Add any DBG_VALUE instructions necessitated by spills. - for (auto &TR : Transfers) - MBB->insertAfter(MachineBasicBlock::iterator(*TR.TransferInst), - TR.DebugInst); - Transfers.clear(); - - LLVM_DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs, - "OutLocs after propagating", dbgs())); - LLVM_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"); - } - - LLVM_DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs, "Final OutLocs", dbgs())); - LLVM_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; - - // Skip functions from NoDebug compilation units. - if (MF.getFunction().getSubprogram()->getUnit()->getEmissionKind() == - DICompileUnit::NoDebug) - return false; - - TRI = MF.getSubtarget().getRegisterInfo(); - TII = MF.getSubtarget().getInstrInfo(); - TFI = MF.getSubtarget().getFrameLowering(); - TFI->determineCalleeSaves(MF, CalleeSavedRegs, - make_unique<RegScavenger>().get()); - LS.initialize(MF); - - bool Changed = ExtendRanges(MF); - return Changed; -} |