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Diffstat (limited to 'llvm/lib/CodeGen/LiveDebugValues.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/LiveDebugValues.cpp | 1976 |
1 files changed, 0 insertions, 1976 deletions
diff --git a/llvm/lib/CodeGen/LiveDebugValues.cpp b/llvm/lib/CodeGen/LiveDebugValues.cpp deleted file mode 100644 index 07a275b..0000000 --- a/llvm/lib/CodeGen/LiveDebugValues.cpp +++ /dev/null @@ -1,1976 +0,0 @@ -//===- LiveDebugValues.cpp - Tracking Debug Value MIs ---------------------===// -// -// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. -// See https://llvm.org/LICENSE.txt for license information. -// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception -// -//===----------------------------------------------------------------------===// -/// -/// \file LiveDebugValues.cpp -/// -/// LiveDebugValues is an optimistic "available expressions" dataflow -/// algorithm. The set of expressions is the set of machine locations -/// (registers, spill slots, constants) that a variable fragment might be -/// located, qualified by a DIExpression and indirect-ness flag, while each -/// variable is identified by a DebugVariable object. The availability of an -/// expression begins when a DBG_VALUE instruction specifies the location of a -/// DebugVariable, and continues until that location is clobbered or -/// re-specified by a different DBG_VALUE for the same DebugVariable. -/// -/// The cannonical "available expressions" problem doesn't have expression -/// clobbering, instead when a variable is re-assigned, any expressions using -/// that variable get invalidated. LiveDebugValues can map onto "available -/// expressions" by having every register represented by a variable, which is -/// used in an expression that becomes available at a DBG_VALUE instruction. -/// When the register is clobbered, its variable is effectively reassigned, and -/// expressions computed from it become unavailable. A similar construct is -/// needed when a DebugVariable has its location re-specified, to invalidate -/// all other locations for that DebugVariable. -/// -/// Using the dataflow analysis to compute the available expressions, we create -/// a DBG_VALUE at the beginning of each block where the expression is -/// live-in. This propagates variable locations into every basic block where -/// the location can be determined, rather than only having DBG_VALUEs in blocks -/// where locations are specified due to an assignment or some optimization. -/// Movements of values between registers and spill slots are annotated with -/// DBG_VALUEs too to track variable values bewteen locations. All this allows -/// DbgEntityHistoryCalculator to focus on only the locations within individual -/// blocks, facilitating testing and improving modularity. -/// -/// We follow an optimisic dataflow approach, with this lattice: -/// -/// \verbatim -/// ┬ "Unknown" -/// | -/// v -/// True -/// | -/// v -/// ⊥ False -/// \endverbatim With "True" signifying that the expression is available (and -/// thus a DebugVariable's location is the corresponding register), while -/// "False" signifies that the expression is unavailable. "Unknown"s never -/// survive to the end of the analysis (see below). -/// -/// Formally, all DebugVariable locations that are live-out of a block are -/// initialized to \top. A blocks live-in values take the meet of the lattice -/// value for every predecessors live-outs, except for the entry block, where -/// all live-ins are \bot. The usual dataflow propagation occurs: the transfer -/// function for a block assigns an expression for a DebugVariable to be "True" -/// if a DBG_VALUE in the block specifies it; "False" if the location is -/// clobbered; or the live-in value if it is unaffected by the block. We -/// visit each block in reverse post order until a fixedpoint is reached. The -/// solution produced is maximal. -/// -/// Intuitively, we start by assuming that every expression / variable location -/// is at least "True", and then propagate "False" from the entry block and any -/// clobbers until there are no more changes to make. This gives us an accurate -/// solution because all incorrect locations will have a "False" propagated into -/// them. It also gives us a solution that copes well with loops by assuming -/// that variable locations are live-through every loop, and then removing those -/// that are not through dataflow. -/// -/// Within LiveDebugValues: each variable location is represented by a -/// VarLoc object that identifies the source variable, its current -/// machine-location, and the DBG_VALUE inst that specifies the location. Each -/// VarLoc is indexed in the (function-scope) \p VarLocMap, giving each VarLoc a -/// unique index. Rather than operate directly on machine locations, the -/// dataflow analysis in this pass identifies locations by their index in the -/// VarLocMap, meaning all the variable locations in a block can be described -/// by a sparse vector of VarLocMap indicies. -/// -/// All the storage for the dataflow analysis is local to the ExtendRanges -/// method and passed down to helper methods. "OutLocs" and "InLocs" record the -/// in and out lattice values for each block. "OpenRanges" maintains a list of -/// variable locations and, with the "process" method, evaluates the transfer -/// function of each block. "flushPendingLocs" installs DBG_VALUEs for each -/// live-in location at the start of blocks, while "Transfers" records -/// transfers of values between machine-locations. -/// -/// We avoid explicitly representing the "Unknown" (\top) lattice value in the -/// implementation. Instead, unvisited blocks implicitly have all lattice -/// values set as "Unknown". After being visited, there will be path back to -/// the entry block where the lattice value is "False", and as the transfer -/// function cannot make new "Unknown" locations, there are no scenarios where -/// a block can have an "Unknown" location after being visited. Similarly, we -/// don't enumerate all possible variable locations before exploring the -/// function: when a new location is discovered, all blocks previously explored -/// were implicitly "False" but unrecorded, and become explicitly "False" when -/// a new VarLoc is created with its bit not set in predecessor InLocs or -/// OutLocs. -/// -//===----------------------------------------------------------------------===// - -#include "llvm/ADT/CoalescingBitVector.h" -#include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/PostOrderIterator.h" -#include "llvm/ADT/SmallPtrSet.h" -#include "llvm/ADT/SmallSet.h" -#include "llvm/ADT/SmallVector.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/RegisterScavenging.h" -#include "llvm/CodeGen/TargetFrameLowering.h" -#include "llvm/CodeGen/TargetInstrInfo.h" -#include "llvm/CodeGen/TargetLowering.h" -#include "llvm/CodeGen/TargetPassConfig.h" -#include "llvm/CodeGen/TargetRegisterInfo.h" -#include "llvm/CodeGen/TargetSubtargetInfo.h" -#include "llvm/Config/llvm-config.h" -#include "llvm/IR/DIBuilder.h" -#include "llvm/IR/DebugInfoMetadata.h" -#include "llvm/IR/DebugLoc.h" -#include "llvm/IR/Function.h" -#include "llvm/IR/Module.h" -#include "llvm/InitializePasses.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 "llvm/Target/TargetMachine.h" -#include <algorithm> -#include <cassert> -#include <cstdint> -#include <functional> -#include <queue> -#include <tuple> -#include <utility> -#include <vector> - -using namespace llvm; - -#define DEBUG_TYPE "livedebugvalues" - -STATISTIC(NumInserted, "Number of DBG_VALUE instructions inserted"); - -// Options to prevent pathological compile-time behavior. If InputBBLimit and -// InputDbgValueLimit are both exceeded, range extension is disabled. -static cl::opt<unsigned> InputBBLimit( - "livedebugvalues-input-bb-limit", - cl::desc("Maximum input basic blocks before DBG_VALUE limit applies"), - cl::init(10000), cl::Hidden); -static cl::opt<unsigned> InputDbgValueLimit( - "livedebugvalues-input-dbg-value-limit", - cl::desc( - "Maximum input DBG_VALUE insts supported by debug range extension"), - cl::init(50000), cl::Hidden); - -// 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 Register 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.getDebugOperand(0).isReg() ? MI.getDebugOperand(0).getReg() - : Register(); -} - -/// If \p Op is a stack or frame register return true, otherwise return false. -/// This is used to avoid basing the debug entry values on the registers, since -/// we do not support it at the moment. -static bool isRegOtherThanSPAndFP(const MachineOperand &Op, - const MachineInstr &MI, - const TargetRegisterInfo *TRI) { - if (!Op.isReg()) - return false; - - const MachineFunction *MF = MI.getParent()->getParent(); - const TargetLowering *TLI = MF->getSubtarget().getTargetLowering(); - Register SP = TLI->getStackPointerRegisterToSaveRestore(); - Register FP = TRI->getFrameRegister(*MF); - Register Reg = Op.getReg(); - - return Reg && Reg != SP && Reg != FP; -} - -namespace { - -// Max out the number of statically allocated elements in DefinedRegsSet, as -// this prevents fallback to std::set::count() operations. -using DefinedRegsSet = SmallSet<Register, 32>; - -using VarLocSet = CoalescingBitVector<uint64_t>; - -/// A type-checked pair of {Register Location (or 0), Index}, used to index -/// into a \ref VarLocMap. This can be efficiently converted to a 64-bit int -/// for insertion into a \ref VarLocSet, and efficiently converted back. The -/// type-checker helps ensure that the conversions aren't lossy. -/// -/// Why encode a location /into/ the VarLocMap index? This makes it possible -/// to find the open VarLocs killed by a register def very quickly. This is a -/// performance-critical operation for LiveDebugValues. -struct LocIndex { - using u32_location_t = uint32_t; - using u32_index_t = uint32_t; - - u32_location_t Location; // Physical registers live in the range [1;2^30) (see - // \ref MCRegister), so we have plenty of range left - // here to encode non-register locations. - u32_index_t Index; - - /// The first location greater than 0 that is not reserved for VarLocs of - /// kind RegisterKind. - static constexpr u32_location_t kFirstInvalidRegLocation = 1 << 30; - - /// A special location reserved for VarLocs of kind SpillLocKind. - static constexpr u32_location_t kSpillLocation = kFirstInvalidRegLocation; - - /// A special location reserved for VarLocs of kind EntryValueBackupKind and - /// EntryValueCopyBackupKind. - static constexpr u32_location_t kEntryValueBackupLocation = - kFirstInvalidRegLocation + 1; - - LocIndex(u32_location_t Location, u32_index_t Index) - : Location(Location), Index(Index) {} - - uint64_t getAsRawInteger() const { - return (static_cast<uint64_t>(Location) << 32) | Index; - } - - template<typename IntT> static LocIndex fromRawInteger(IntT ID) { - static_assert(std::is_unsigned<IntT>::value && - sizeof(ID) == sizeof(uint64_t), - "Cannot convert raw integer to LocIndex"); - return {static_cast<u32_location_t>(ID >> 32), - static_cast<u32_index_t>(ID)}; - } - - /// Get the start of the interval reserved for VarLocs of kind RegisterKind - /// which reside in \p Reg. The end is at rawIndexForReg(Reg+1)-1. - static uint64_t rawIndexForReg(uint32_t Reg) { - return LocIndex(Reg, 0).getAsRawInteger(); - } - - /// Return a range covering all set indices in the interval reserved for - /// \p Location in \p Set. - static auto indexRangeForLocation(const VarLocSet &Set, - u32_location_t Location) { - uint64_t Start = LocIndex(Location, 0).getAsRawInteger(); - uint64_t End = LocIndex(Location + 1, 0).getAsRawInteger(); - return Set.half_open_range(Start, End); - } -}; - -class LiveDebugValues : public MachineFunctionPass { -private: - const TargetRegisterInfo *TRI; - const TargetInstrInfo *TII; - const TargetFrameLowering *TFI; - BitVector CalleeSavedRegs; - LexicalScopes LS; - VarLocSet::Allocator Alloc; - - enum struct TransferKind { TransferCopy, TransferSpill, TransferRestore }; - - using FragmentInfo = DIExpression::FragmentInfo; - using OptFragmentInfo = Optional<DIExpression::FragmentInfo>; - - /// A pair of debug variable and value location. - struct VarLoc { - // The location at which a spilled variable resides. It consists of a - // register and an offset. - struct SpillLoc { - unsigned SpillBase; - int SpillOffset; - bool operator==(const SpillLoc &Other) const { - return SpillBase == Other.SpillBase && SpillOffset == Other.SpillOffset; - } - bool operator!=(const SpillLoc &Other) const { - return !(*this == Other); - } - }; - - /// Identity of the variable at this location. - const DebugVariable Var; - - /// The expression applied to this location. - const DIExpression *Expr; - - /// DBG_VALUE to clone var/expr information from if this location - /// is moved. - const MachineInstr &MI; - - enum VarLocKind { - InvalidKind = 0, - RegisterKind, - SpillLocKind, - ImmediateKind, - EntryValueKind, - EntryValueBackupKind, - EntryValueCopyBackupKind - } Kind = InvalidKind; - - /// The value location. Stored separately to avoid repeatedly - /// extracting it from MI. - union { - uint64_t RegNo; - SpillLoc SpillLocation; - uint64_t Hash; - int64_t Immediate; - const ConstantFP *FPImm; - const ConstantInt *CImm; - } Loc; - - VarLoc(const MachineInstr &MI, LexicalScopes &LS) - : Var(MI.getDebugVariable(), MI.getDebugExpression(), - MI.getDebugLoc()->getInlinedAt()), - Expr(MI.getDebugExpression()), MI(MI) { - 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; - } else if (MI.getDebugOperand(0).isImm()) { - Kind = ImmediateKind; - Loc.Immediate = MI.getDebugOperand(0).getImm(); - } else if (MI.getDebugOperand(0).isFPImm()) { - Kind = ImmediateKind; - Loc.FPImm = MI.getDebugOperand(0).getFPImm(); - } else if (MI.getDebugOperand(0).isCImm()) { - Kind = ImmediateKind; - Loc.CImm = MI.getDebugOperand(0).getCImm(); - } - - // We create the debug entry values from the factory functions rather than - // from this ctor. - assert(Kind != EntryValueKind && !isEntryBackupLoc()); - } - - /// Take the variable and machine-location in DBG_VALUE MI, and build an - /// entry location using the given expression. - static VarLoc CreateEntryLoc(const MachineInstr &MI, LexicalScopes &LS, - const DIExpression *EntryExpr, Register Reg) { - VarLoc VL(MI, LS); - assert(VL.Kind == RegisterKind); - VL.Kind = EntryValueKind; - VL.Expr = EntryExpr; - VL.Loc.RegNo = Reg; - return VL; - } - - /// Take the variable and machine-location from the DBG_VALUE (from the - /// function entry), and build an entry value backup location. The backup - /// location will turn into the normal location if the backup is valid at - /// the time of the primary location clobbering. - static VarLoc CreateEntryBackupLoc(const MachineInstr &MI, - LexicalScopes &LS, - const DIExpression *EntryExpr) { - VarLoc VL(MI, LS); - assert(VL.Kind == RegisterKind); - VL.Kind = EntryValueBackupKind; - VL.Expr = EntryExpr; - return VL; - } - - /// Take the variable and machine-location from the DBG_VALUE (from the - /// function entry), and build a copy of an entry value backup location by - /// setting the register location to NewReg. - static VarLoc CreateEntryCopyBackupLoc(const MachineInstr &MI, - LexicalScopes &LS, - const DIExpression *EntryExpr, - Register NewReg) { - VarLoc VL(MI, LS); - assert(VL.Kind == RegisterKind); - VL.Kind = EntryValueCopyBackupKind; - VL.Expr = EntryExpr; - VL.Loc.RegNo = NewReg; - return VL; - } - - /// Copy the register location in DBG_VALUE MI, updating the register to - /// be NewReg. - static VarLoc CreateCopyLoc(const MachineInstr &MI, LexicalScopes &LS, - Register NewReg) { - VarLoc VL(MI, LS); - assert(VL.Kind == RegisterKind); - VL.Loc.RegNo = NewReg; - return VL; - } - - /// Take the variable described by DBG_VALUE MI, and create a VarLoc - /// locating it in the specified spill location. - static VarLoc CreateSpillLoc(const MachineInstr &MI, unsigned SpillBase, - int SpillOffset, LexicalScopes &LS) { - VarLoc VL(MI, LS); - assert(VL.Kind == RegisterKind); - VL.Kind = SpillLocKind; - VL.Loc.SpillLocation = {SpillBase, SpillOffset}; - return VL; - } - - /// Create a DBG_VALUE representing this VarLoc in the given function. - /// Copies variable-specific information such as DILocalVariable and - /// inlining information from the original DBG_VALUE instruction, which may - /// have been several transfers ago. - MachineInstr *BuildDbgValue(MachineFunction &MF) const { - const DebugLoc &DbgLoc = MI.getDebugLoc(); - bool Indirect = MI.isIndirectDebugValue(); - const auto &IID = MI.getDesc(); - const DILocalVariable *Var = MI.getDebugVariable(); - const DIExpression *DIExpr = MI.getDebugExpression(); - NumInserted++; - - switch (Kind) { - case EntryValueKind: - // An entry value is a register location -- but with an updated - // expression. The register location of such DBG_VALUE is always the one - // from the entry DBG_VALUE, it does not matter if the entry value was - // copied in to another register due to some optimizations. - return BuildMI(MF, DbgLoc, IID, Indirect, - MI.getDebugOperand(0).getReg(), Var, Expr); - case RegisterKind: - // Register locations are like the source DBG_VALUE, but with the - // register number from this VarLoc. - return BuildMI(MF, DbgLoc, IID, Indirect, Loc.RegNo, Var, DIExpr); - case SpillLocKind: { - // Spills are indirect DBG_VALUEs, with a base register and offset. - // Use the original DBG_VALUEs expression to build the spilt location - // on top of. FIXME: spill locations created before this pass runs - // are not recognized, and not handled here. - auto *SpillExpr = DIExpression::prepend( - DIExpr, DIExpression::ApplyOffset, Loc.SpillLocation.SpillOffset); - unsigned Base = Loc.SpillLocation.SpillBase; - return BuildMI(MF, DbgLoc, IID, true, Base, Var, SpillExpr); - } - case ImmediateKind: { - MachineOperand MO = MI.getDebugOperand(0); - return BuildMI(MF, DbgLoc, IID, Indirect, MO, Var, DIExpr); - } - case EntryValueBackupKind: - case EntryValueCopyBackupKind: - case InvalidKind: - llvm_unreachable( - "Tried to produce DBG_VALUE for invalid or backup VarLoc"); - } - llvm_unreachable("Unrecognized LiveDebugValues.VarLoc.Kind enum"); - } - - /// Is the Loc field a constant or constant object? - bool isConstant() const { return Kind == ImmediateKind; } - - /// Check if the Loc field is an entry backup location. - bool isEntryBackupLoc() const { - return Kind == EntryValueBackupKind || Kind == EntryValueCopyBackupKind; - } - - /// If this variable is described by a register holding the entry value, - /// return it, otherwise return 0. - unsigned getEntryValueBackupReg() const { - if (Kind == EntryValueBackupKind) - return Loc.RegNo; - return 0; - } - - /// If this variable is described by a register holding the copy of the - /// entry value, return it, otherwise return 0. - unsigned getEntryValueCopyBackupReg() const { - if (Kind == EntryValueCopyBackupKind) - return Loc.RegNo; - return 0; - } - - /// 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(LexicalScopes &LS, MachineBasicBlock &MBB) const { - return LS.dominates(MI.getDebugLoc().get(), &MBB); - } - -#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) - // TRI can be null. - void dump(const TargetRegisterInfo *TRI, raw_ostream &Out = dbgs()) const { - Out << "VarLoc("; - switch (Kind) { - case RegisterKind: - case EntryValueKind: - case EntryValueBackupKind: - case EntryValueCopyBackupKind: - Out << printReg(Loc.RegNo, TRI); - break; - case SpillLocKind: - Out << printReg(Loc.SpillLocation.SpillBase, TRI); - Out << "[" << Loc.SpillLocation.SpillOffset << "]"; - break; - case ImmediateKind: - Out << Loc.Immediate; - break; - case InvalidKind: - llvm_unreachable("Invalid VarLoc in dump method"); - } - - Out << ", \"" << Var.getVariable()->getName() << "\", " << *Expr << ", "; - if (Var.getInlinedAt()) - Out << "!" << Var.getInlinedAt()->getMetadataID() << ")\n"; - else - Out << "(null))"; - - if (isEntryBackupLoc()) - Out << " (backup loc)\n"; - else - Out << "\n"; - } -#endif - - bool operator==(const VarLoc &Other) const { - return Kind == Other.Kind && Var == Other.Var && - Loc.Hash == Other.Loc.Hash && Expr == Other.Expr; - } - - /// This operator guarantees that VarLocs are sorted by Variable first. - bool operator<(const VarLoc &Other) const { - return std::tie(Var, Kind, Loc.Hash, Expr) < - std::tie(Other.Var, Other.Kind, Other.Loc.Hash, Other.Expr); - } - }; - - /// VarLocMap is used for two things: - /// 1) Assigning a unique LocIndex to a VarLoc. This LocIndex can be used to - /// virtually insert a VarLoc into a VarLocSet. - /// 2) Given a LocIndex, look up the unique associated VarLoc. - class VarLocMap { - /// Map a VarLoc to an index within the vector reserved for its location - /// within Loc2Vars. - std::map<VarLoc, LocIndex::u32_index_t> Var2Index; - - /// Map a location to a vector which holds VarLocs which live in that - /// location. - SmallDenseMap<LocIndex::u32_location_t, std::vector<VarLoc>> Loc2Vars; - - /// Determine the 32-bit location reserved for \p VL, based on its kind. - static LocIndex::u32_location_t getLocationForVar(const VarLoc &VL) { - switch (VL.Kind) { - case VarLoc::RegisterKind: - assert((VL.Loc.RegNo < LocIndex::kFirstInvalidRegLocation) && - "Physreg out of range?"); - return VL.Loc.RegNo; - case VarLoc::SpillLocKind: - return LocIndex::kSpillLocation; - case VarLoc::EntryValueBackupKind: - case VarLoc::EntryValueCopyBackupKind: - return LocIndex::kEntryValueBackupLocation; - default: - return 0; - } - } - - public: - /// Retrieve a unique LocIndex for \p VL. - LocIndex insert(const VarLoc &VL) { - LocIndex::u32_location_t Location = getLocationForVar(VL); - LocIndex::u32_index_t &Index = Var2Index[VL]; - if (!Index) { - auto &Vars = Loc2Vars[Location]; - Vars.push_back(VL); - Index = Vars.size(); - } - return {Location, Index - 1}; - } - - /// Retrieve the unique VarLoc associated with \p ID. - const VarLoc &operator[](LocIndex ID) const { - auto LocIt = Loc2Vars.find(ID.Location); - assert(LocIt != Loc2Vars.end() && "Location not tracked"); - return LocIt->second[ID.Index]; - } - }; - - using VarLocInMBB = - SmallDenseMap<const MachineBasicBlock *, std::unique_ptr<VarLocSet>>; - struct TransferDebugPair { - MachineInstr *TransferInst; ///< Instruction where this transfer occurs. - LocIndex LocationID; ///< Location number for the transfer dest. - }; - using TransferMap = SmallVector<TransferDebugPair, 4>; - - // Types for recording sets of variable fragments that overlap. For a given - // local variable, we record all other fragments of that variable that could - // overlap it, to reduce search time. - using FragmentOfVar = - std::pair<const DILocalVariable *, DIExpression::FragmentInfo>; - using OverlapMap = - DenseMap<FragmentOfVar, SmallVector<DIExpression::FragmentInfo, 1>>; - - // Helper while building OverlapMap, a map of all fragments seen for a given - // DILocalVariable. - using VarToFragments = - DenseMap<const DILocalVariable *, SmallSet<FragmentInfo, 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. In addition, we keep - /// two different maps (Vars/EntryValuesBackupVars), so erase/insert - /// methods act differently depending on whether a VarLoc is primary - /// location or backup one. In the case the VarLoc is backup location - /// we will erase/insert from the EntryValuesBackupVars map, otherwise - /// we perform the operation on the Vars. - class OpenRangesSet { - VarLocSet VarLocs; - // Map the DebugVariable to recent primary location ID. - SmallDenseMap<DebugVariable, LocIndex, 8> Vars; - // Map the DebugVariable to recent backup location ID. - SmallDenseMap<DebugVariable, LocIndex, 8> EntryValuesBackupVars; - OverlapMap &OverlappingFragments; - - public: - OpenRangesSet(VarLocSet::Allocator &Alloc, OverlapMap &_OLapMap) - : VarLocs(Alloc), OverlappingFragments(_OLapMap) {} - - const VarLocSet &getVarLocs() const { return VarLocs; } - - /// Terminate all open ranges for VL.Var by removing it from the set. - void erase(const VarLoc &VL); - - /// Terminate all open ranges listed in \c KillSet by removing - /// them from the set. - void erase(const VarLocSet &KillSet, const VarLocMap &VarLocIDs); - - /// Insert a new range into the set. - void insert(LocIndex VarLocID, const VarLoc &VL); - - /// Insert a set of ranges. - void insertFromLocSet(const VarLocSet &ToLoad, const VarLocMap &Map) { - for (uint64_t ID : ToLoad) { - LocIndex Idx = LocIndex::fromRawInteger(ID); - const VarLoc &VarL = Map[Idx]; - insert(Idx, VarL); - } - } - - llvm::Optional<LocIndex> getEntryValueBackup(DebugVariable Var); - - /// Empty the set. - void clear() { - VarLocs.clear(); - Vars.clear(); - EntryValuesBackupVars.clear(); - } - - /// Return whether the set is empty or not. - bool empty() const { - assert(Vars.empty() == EntryValuesBackupVars.empty() && - Vars.empty() == VarLocs.empty() && - "open ranges are inconsistent"); - return VarLocs.empty(); - } - - /// Get an empty range of VarLoc IDs. - auto getEmptyVarLocRange() const { - return iterator_range<VarLocSet::const_iterator>(getVarLocs().end(), - getVarLocs().end()); - } - - /// Get all set IDs for VarLocs of kind RegisterKind in \p Reg. - auto getRegisterVarLocs(Register Reg) const { - return LocIndex::indexRangeForLocation(getVarLocs(), Reg); - } - - /// Get all set IDs for VarLocs of kind SpillLocKind. - auto getSpillVarLocs() const { - return LocIndex::indexRangeForLocation(getVarLocs(), - LocIndex::kSpillLocation); - } - - /// Get all set IDs for VarLocs of kind EntryValueBackupKind or - /// EntryValueCopyBackupKind. - auto getEntryValueBackupVarLocs() const { - return LocIndex::indexRangeForLocation( - getVarLocs(), LocIndex::kEntryValueBackupLocation); - } - }; - - /// Collect all VarLoc IDs from \p CollectFrom for VarLocs of kind - /// RegisterKind which are located in any reg in \p Regs. Insert collected IDs - /// into \p Collected. - void collectIDsForRegs(VarLocSet &Collected, const DefinedRegsSet &Regs, - const VarLocSet &CollectFrom) const; - - /// Get the registers which are used by VarLocs of kind RegisterKind tracked - /// by \p CollectFrom. - void getUsedRegs(const VarLocSet &CollectFrom, - SmallVectorImpl<uint32_t> &UsedRegs) const; - - VarLocSet &getVarLocsInMBB(const MachineBasicBlock *MBB, VarLocInMBB &Locs) { - std::unique_ptr<VarLocSet> &VLS = Locs[MBB]; - if (!VLS) - VLS = std::make_unique<VarLocSet>(Alloc); - return *VLS.get(); - } - - const VarLocSet &getVarLocsInMBB(const MachineBasicBlock *MBB, - const VarLocInMBB &Locs) const { - auto It = Locs.find(MBB); - assert(It != Locs.end() && "MBB not in map"); - return *It->second.get(); - } - - /// Tests whether this instruction is a spill to a stack location. - bool isSpillInstruction(const MachineInstr &MI, MachineFunction *MF); - - /// 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 isLocationSpill(const MachineInstr &MI, MachineFunction *MF, - Register &Reg); - - /// Returns true if the given machine instruction is a debug value which we - /// can emit entry values for. - /// - /// Currently, we generate debug entry values only for parameters that are - /// unmodified throughout the function and located in a register. - bool isEntryValueCandidate(const MachineInstr &MI, - const DefinedRegsSet &Regs) const; - - /// If a given instruction is identified as a spill, return the spill location - /// and set \p Reg to the spilled register. - Optional<VarLoc::SpillLoc> isRestoreInstruction(const MachineInstr &MI, - MachineFunction *MF, - Register &Reg); - /// Given a spill instruction, extract the register and offset used to - /// address the spill location in a target independent way. - VarLoc::SpillLoc extractSpillBaseRegAndOffset(const MachineInstr &MI); - void insertTransferDebugPair(MachineInstr &MI, OpenRangesSet &OpenRanges, - TransferMap &Transfers, VarLocMap &VarLocIDs, - LocIndex OldVarID, TransferKind Kind, - Register NewReg = Register()); - - void transferDebugValue(const MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs); - void transferSpillOrRestoreInst(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, TransferMap &Transfers); - bool removeEntryValue(const MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, const VarLoc &EntryVL); - void emitEntryValues(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, TransferMap &Transfers, - VarLocSet &KillSet); - void recordEntryValue(const MachineInstr &MI, - const DefinedRegsSet &DefinedRegs, - OpenRangesSet &OpenRanges, VarLocMap &VarLocIDs); - void transferRegisterCopy(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, TransferMap &Transfers); - void transferRegisterDef(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, TransferMap &Transfers); - bool transferTerminator(MachineBasicBlock *MBB, OpenRangesSet &OpenRanges, - VarLocInMBB &OutLocs, const VarLocMap &VarLocIDs); - - void process(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, TransferMap &Transfers); - - void accumulateFragmentMap(MachineInstr &MI, VarToFragments &SeenFragments, - OverlapMap &OLapMap); - - bool join(MachineBasicBlock &MBB, VarLocInMBB &OutLocs, VarLocInMBB &InLocs, - const VarLocMap &VarLocIDs, - SmallPtrSet<const MachineBasicBlock *, 16> &Visited, - SmallPtrSetImpl<const MachineBasicBlock *> &ArtificialBlocks); - - /// Create DBG_VALUE insts for inlocs that have been propagated but - /// had their instruction creation deferred. - void flushPendingLocs(VarLocInMBB &PendingInLocs, VarLocMap &VarLocIDs); - - 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); -} - -/// Erase a variable from the set of open ranges, and additionally erase any -/// fragments that may overlap it. If the VarLoc is a buckup location, erase -/// the variable from the EntryValuesBackupVars set, indicating we should stop -/// tracking its backup entry location. Otherwise, if the VarLoc is primary -/// location, erase the variable from the Vars set. -void LiveDebugValues::OpenRangesSet::erase(const VarLoc &VL) { - // Erasure helper. - auto DoErase = [VL, this](DebugVariable VarToErase) { - auto *EraseFrom = VL.isEntryBackupLoc() ? &EntryValuesBackupVars : &Vars; - auto It = EraseFrom->find(VarToErase); - if (It != EraseFrom->end()) { - LocIndex ID = It->second; - VarLocs.reset(ID.getAsRawInteger()); - EraseFrom->erase(It); - } - }; - - DebugVariable Var = VL.Var; - - // Erase the variable/fragment that ends here. - DoErase(Var); - - // Extract the fragment. Interpret an empty fragment as one that covers all - // possible bits. - FragmentInfo ThisFragment = Var.getFragmentOrDefault(); - - // There may be fragments that overlap the designated fragment. Look them up - // in the pre-computed overlap map, and erase them too. - auto MapIt = OverlappingFragments.find({Var.getVariable(), ThisFragment}); - if (MapIt != OverlappingFragments.end()) { - for (auto Fragment : MapIt->second) { - LiveDebugValues::OptFragmentInfo FragmentHolder; - if (!DebugVariable::isDefaultFragment(Fragment)) - FragmentHolder = LiveDebugValues::OptFragmentInfo(Fragment); - DoErase({Var.getVariable(), FragmentHolder, Var.getInlinedAt()}); - } - } -} - -void LiveDebugValues::OpenRangesSet::erase(const VarLocSet &KillSet, - const VarLocMap &VarLocIDs) { - VarLocs.intersectWithComplement(KillSet); - for (uint64_t ID : KillSet) { - const VarLoc *VL = &VarLocIDs[LocIndex::fromRawInteger(ID)]; - auto *EraseFrom = VL->isEntryBackupLoc() ? &EntryValuesBackupVars : &Vars; - EraseFrom->erase(VL->Var); - } -} - -void LiveDebugValues::OpenRangesSet::insert(LocIndex VarLocID, - const VarLoc &VL) { - auto *InsertInto = VL.isEntryBackupLoc() ? &EntryValuesBackupVars : &Vars; - VarLocs.set(VarLocID.getAsRawInteger()); - InsertInto->insert({VL.Var, VarLocID}); -} - -/// Return the Loc ID of an entry value backup location, if it exists for the -/// variable. -llvm::Optional<LocIndex> -LiveDebugValues::OpenRangesSet::getEntryValueBackup(DebugVariable Var) { - auto It = EntryValuesBackupVars.find(Var); - if (It != EntryValuesBackupVars.end()) - return It->second; - - return llvm::None; -} - -void LiveDebugValues::collectIDsForRegs(VarLocSet &Collected, - const DefinedRegsSet &Regs, - const VarLocSet &CollectFrom) const { - assert(!Regs.empty() && "Nothing to collect"); - SmallVector<uint32_t, 32> SortedRegs; - for (Register Reg : Regs) - SortedRegs.push_back(Reg); - array_pod_sort(SortedRegs.begin(), SortedRegs.end()); - auto It = CollectFrom.find(LocIndex::rawIndexForReg(SortedRegs.front())); - auto End = CollectFrom.end(); - for (uint32_t Reg : SortedRegs) { - // The half-open interval [FirstIndexForReg, FirstInvalidIndex) contains all - // possible VarLoc IDs for VarLocs of kind RegisterKind which live in Reg. - uint64_t FirstIndexForReg = LocIndex::rawIndexForReg(Reg); - uint64_t FirstInvalidIndex = LocIndex::rawIndexForReg(Reg + 1); - It.advanceToLowerBound(FirstIndexForReg); - - // Iterate through that half-open interval and collect all the set IDs. - for (; It != End && *It < FirstInvalidIndex; ++It) - Collected.set(*It); - - if (It == End) - return; - } -} - -void LiveDebugValues::getUsedRegs(const VarLocSet &CollectFrom, - SmallVectorImpl<uint32_t> &UsedRegs) const { - // All register-based VarLocs are assigned indices greater than or equal to - // FirstRegIndex. - uint64_t FirstRegIndex = LocIndex::rawIndexForReg(1); - uint64_t FirstInvalidIndex = - LocIndex::rawIndexForReg(LocIndex::kFirstInvalidRegLocation); - for (auto It = CollectFrom.find(FirstRegIndex), - End = CollectFrom.find(FirstInvalidIndex); - It != End;) { - // We found a VarLoc ID for a VarLoc that lives in a register. Figure out - // which register and add it to UsedRegs. - uint32_t FoundReg = LocIndex::fromRawInteger(*It).Location; - assert((UsedRegs.empty() || FoundReg != UsedRegs.back()) && - "Duplicate used reg"); - UsedRegs.push_back(FoundReg); - - // Skip to the next /set/ register. Note that this finds a lower bound, so - // even if there aren't any VarLocs living in `FoundReg+1`, we're still - // guaranteed to move on to the next register (or to end()). - uint64_t NextRegIndex = LocIndex::rawIndexForReg(FoundReg + 1); - It.advanceToLowerBound(NextRegIndex); - } -} - -//===----------------------------------------------------------------------===// -// 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) { - if (!V.count(&BB)) - continue; - const VarLocSet &L = getVarLocsInMBB(&BB, V); - if (L.empty()) - continue; - Out << "MBB: " << BB.getNumber() << ":\n"; - for (uint64_t VLL : L) { - const VarLoc &VL = VarLocIDs[LocIndex::fromRawInteger(VLL)]; - Out << " Var: " << VL.Var.getVariable()->getName(); - Out << " MI: "; - VL.dump(TRI, Out); - } - } - Out << "\n"; -} -#endif - -LiveDebugValues::VarLoc::SpillLoc -LiveDebugValues::extractSpillBaseRegAndOffset(const MachineInstr &MI) { - 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(); - Register Reg; - int Offset = TFI->getFrameIndexReference(*MBB->getParent(), FI, Reg); - return {Reg, Offset}; -} - -/// Try to salvage the debug entry value if we encounter a new debug value -/// describing the same parameter, otherwise stop tracking the value. Return -/// true if we should stop tracking the entry value, otherwise return false. -bool LiveDebugValues::removeEntryValue(const MachineInstr &MI, - OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, - const VarLoc &EntryVL) { - // Skip the DBG_VALUE which is the debug entry value itself. - if (MI.isIdenticalTo(EntryVL.MI)) - return false; - - // If the parameter's location is not register location, we can not track - // the entry value any more. In addition, if the debug expression from the - // DBG_VALUE is not empty, we can assume the parameter's value has changed - // indicating that we should stop tracking its entry value as well. - if (!MI.getDebugOperand(0).isReg() || - MI.getDebugExpression()->getNumElements() != 0) - return true; - - // If the DBG_VALUE comes from a copy instruction that copies the entry value, - // it means the parameter's value has not changed and we should be able to use - // its entry value. - bool TrySalvageEntryValue = false; - Register Reg = MI.getDebugOperand(0).getReg(); - auto I = std::next(MI.getReverseIterator()); - const MachineOperand *SrcRegOp, *DestRegOp; - if (I != MI.getParent()->rend()) { - // TODO: Try to keep tracking of an entry value if we encounter a propagated - // DBG_VALUE describing the copy of the entry value. (Propagated entry value - // does not indicate the parameter modification.) - auto DestSrc = TII->isCopyInstr(*I); - if (!DestSrc) - return true; - - SrcRegOp = DestSrc->Source; - DestRegOp = DestSrc->Destination; - if (Reg != DestRegOp->getReg()) - return true; - TrySalvageEntryValue = true; - } - - if (TrySalvageEntryValue) { - for (uint64_t ID : OpenRanges.getEntryValueBackupVarLocs()) { - const VarLoc &VL = VarLocIDs[LocIndex::fromRawInteger(ID)]; - if (VL.getEntryValueCopyBackupReg() == Reg && - VL.MI.getDebugOperand(0).getReg() == SrcRegOp->getReg()) - return false; - } - } - - return true; -} - -/// 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 DIExpression *Expr = MI.getDebugExpression(); - const DILocation *DebugLoc = MI.getDebugLoc(); - const DILocation *InlinedAt = DebugLoc->getInlinedAt(); - assert(Var->isValidLocationForIntrinsic(DebugLoc) && - "Expected inlined-at fields to agree"); - - DebugVariable V(Var, Expr, InlinedAt); - - // Check if this DBG_VALUE indicates a parameter's value changing. - // If that is the case, we should stop tracking its entry value. - auto EntryValBackupID = OpenRanges.getEntryValueBackup(V); - if (Var->isParameter() && EntryValBackupID) { - const VarLoc &EntryVL = VarLocIDs[*EntryValBackupID]; - if (removeEntryValue(MI, OpenRanges, VarLocIDs, EntryVL)) { - LLVM_DEBUG(dbgs() << "Deleting a DBG entry value because of: "; - MI.print(dbgs(), /*IsStandalone*/ false, - /*SkipOpers*/ false, /*SkipDebugLoc*/ false, - /*AddNewLine*/ true, TII)); - OpenRanges.erase(EntryVL); - } - } - - if (isDbgValueDescribedByReg(MI) || MI.getDebugOperand(0).isImm() || - MI.getDebugOperand(0).isFPImm() || MI.getDebugOperand(0).isCImm()) { - // Use normal VarLoc constructor for registers and immediates. - VarLoc VL(MI, LS); - // End all previous ranges of VL.Var. - OpenRanges.erase(VL); - - LocIndex ID = VarLocIDs.insert(VL); - // Add the VarLoc to OpenRanges from this DBG_VALUE. - OpenRanges.insert(ID, VL); - } else if (MI.hasOneMemOperand()) { - llvm_unreachable("DBG_VALUE with mem operand encountered after regalloc?"); - } else { - // This must be an undefined location. If it has an open range, erase it. - assert(MI.getDebugOperand(0).isReg() && - MI.getDebugOperand(0).getReg() == 0 && - "Unexpected non-undef DBG_VALUE encountered"); - VarLoc VL(MI, LS); - OpenRanges.erase(VL); - } -} - -/// Turn the entry value backup locations into primary locations. -void LiveDebugValues::emitEntryValues(MachineInstr &MI, - OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, - TransferMap &Transfers, - VarLocSet &KillSet) { - // Do not insert entry value locations after a terminator. - if (MI.isTerminator()) - return; - - for (uint64_t ID : KillSet) { - LocIndex Idx = LocIndex::fromRawInteger(ID); - const VarLoc &VL = VarLocIDs[Idx]; - if (!VL.Var.getVariable()->isParameter()) - continue; - - auto DebugVar = VL.Var; - Optional<LocIndex> EntryValBackupID = - OpenRanges.getEntryValueBackup(DebugVar); - - // If the parameter has the entry value backup, it means we should - // be able to use its entry value. - if (!EntryValBackupID) - continue; - - const VarLoc &EntryVL = VarLocIDs[*EntryValBackupID]; - VarLoc EntryLoc = - VarLoc::CreateEntryLoc(EntryVL.MI, LS, EntryVL.Expr, EntryVL.Loc.RegNo); - LocIndex EntryValueID = VarLocIDs.insert(EntryLoc); - Transfers.push_back({&MI, EntryValueID}); - OpenRanges.insert(EntryValueID, EntryLoc); - } -} - -/// 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, LocIndex OldVarID, TransferKind Kind, - Register NewReg) { - const MachineInstr *DebugInstr = &VarLocIDs[OldVarID].MI; - - auto ProcessVarLoc = [&MI, &OpenRanges, &Transfers, &VarLocIDs](VarLoc &VL) { - LocIndex LocId = VarLocIDs.insert(VL); - - // Close this variable's previous location range. - OpenRanges.erase(VL); - - // Record the new location as an open range, and a postponed transfer - // inserting a DBG_VALUE for this location. - OpenRanges.insert(LocId, VL); - assert(!MI.isTerminator() && "Cannot insert DBG_VALUE after terminator"); - TransferDebugPair MIP = {&MI, LocId}; - Transfers.push_back(MIP); - }; - - // End all previous ranges of VL.Var. - OpenRanges.erase(VarLocIDs[OldVarID]); - switch (Kind) { - case TransferKind::TransferCopy: { - assert(NewReg && - "No register supplied when handling a copy of a debug value"); - // Create a DBG_VALUE instruction to describe the Var in its new - // register location. - VarLoc VL = VarLoc::CreateCopyLoc(*DebugInstr, LS, NewReg); - ProcessVarLoc(VL); - LLVM_DEBUG({ - dbgs() << "Creating VarLoc for register copy:"; - VL.dump(TRI); - }); - return; - } - case TransferKind::TransferSpill: { - // Create a DBG_VALUE instruction to describe the Var in its spilled - // location. - VarLoc::SpillLoc SpillLocation = extractSpillBaseRegAndOffset(MI); - VarLoc VL = VarLoc::CreateSpillLoc(*DebugInstr, SpillLocation.SpillBase, - SpillLocation.SpillOffset, LS); - ProcessVarLoc(VL); - LLVM_DEBUG({ - dbgs() << "Creating VarLoc for spill:"; - VL.dump(TRI); - }); - return; - } - case TransferKind::TransferRestore: { - assert(NewReg && - "No register supplied when handling a restore of a debug value"); - // DebugInstr refers to the pre-spill location, therefore we can reuse - // its expression. - VarLoc VL = VarLoc::CreateCopyLoc(*DebugInstr, LS, NewReg); - ProcessVarLoc(VL); - LLVM_DEBUG({ - dbgs() << "Creating VarLoc for restore:"; - VL.dump(TRI); - }); - return; - } - } - llvm_unreachable("Invalid transfer kind"); -} - -/// A definition of a register may mark the end of a range. -void LiveDebugValues::transferRegisterDef( - MachineInstr &MI, OpenRangesSet &OpenRanges, VarLocMap &VarLocIDs, - TransferMap &Transfers) { - - // Meta Instructions do not affect the debug liveness of any register they - // define. - if (MI.isMetaInstruction()) - return; - - MachineFunction *MF = MI.getMF(); - const TargetLowering *TLI = MF->getSubtarget().getTargetLowering(); - Register SP = TLI->getStackPointerRegisterToSaveRestore(); - - // Find the regs killed by MI, and find regmasks of preserved regs. - DefinedRegsSet DeadRegs; - SmallVector<const uint32_t *, 4> RegMasks; - for (const MachineOperand &MO : MI.operands()) { - // Determine whether the operand is a register def. - if (MO.isReg() && MO.isDef() && MO.getReg() && - Register::isPhysicalRegister(MO.getReg()) && - !(MI.isCall() && MO.getReg() == SP)) { - // Remove ranges of all aliased registers. - for (MCRegAliasIterator RAI(MO.getReg(), TRI, true); RAI.isValid(); ++RAI) - // FIXME: Can we break out of this loop early if no insertion occurs? - DeadRegs.insert(*RAI); - } else if (MO.isRegMask()) { - RegMasks.push_back(MO.getRegMask()); - } - } - - // Erase VarLocs which reside in one of the dead registers. For performance - // reasons, it's critical to not iterate over the full set of open VarLocs. - // Iterate over the set of dying/used regs instead. - if (!RegMasks.empty()) { - SmallVector<uint32_t, 32> UsedRegs; - getUsedRegs(OpenRanges.getVarLocs(), UsedRegs); - for (uint32_t Reg : UsedRegs) { - // Remove ranges of all clobbered registers. Register masks don't usually - // list SP as preserved. Assume that call instructions never clobber SP, - // because some backends (e.g., AArch64) never list SP in the regmask. - // 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. - if (Reg == SP) - continue; - bool AnyRegMaskKillsReg = - any_of(RegMasks, [Reg](const uint32_t *RegMask) { - return MachineOperand::clobbersPhysReg(RegMask, Reg); - }); - if (AnyRegMaskKillsReg) - DeadRegs.insert(Reg); - } - } - - if (DeadRegs.empty()) - return; - - VarLocSet KillSet(Alloc); - collectIDsForRegs(KillSet, DeadRegs, OpenRanges.getVarLocs()); - OpenRanges.erase(KillSet, VarLocIDs); - - if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) { - auto &TM = TPC->getTM<TargetMachine>(); - if (TM.Options.ShouldEmitDebugEntryValues()) - emitEntryValues(MI, OpenRanges, VarLocIDs, Transfers, KillSet); - } -} - -bool LiveDebugValues::isSpillInstruction(const MachineInstr &MI, - MachineFunction *MF) { - // TODO: Handle multiple stores folded into one. - if (!MI.hasOneMemOperand()) - return false; - - if (!MI.getSpillSize(TII) && !MI.getFoldedSpillSize(TII)) - return false; // This is not a spill instruction, since no valid size was - // returned from either function. - - return true; -} - -bool LiveDebugValues::isLocationSpill(const MachineInstr &MI, - MachineFunction *MF, Register &Reg) { - if (!isSpillInstruction(MI, MF)) - return false; - - auto isKilledReg = [&](const MachineOperand MO, Register &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; - Register 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; -} - -Optional<LiveDebugValues::VarLoc::SpillLoc> -LiveDebugValues::isRestoreInstruction(const MachineInstr &MI, - MachineFunction *MF, Register &Reg) { - if (!MI.hasOneMemOperand()) - return None; - - // FIXME: Handle folded restore instructions with more than one memory - // operand. - if (MI.getRestoreSize(TII)) { - Reg = MI.getOperand(0).getReg(); - return extractSpillBaseRegAndOffset(MI); - } - return None; -} - -/// 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. -/// A restored register may indicate the reverse situation. -/// 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::transferSpillOrRestoreInst(MachineInstr &MI, - OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, - TransferMap &Transfers) { - MachineFunction *MF = MI.getMF(); - TransferKind TKind; - Register Reg; - Optional<VarLoc::SpillLoc> Loc; - - LLVM_DEBUG(dbgs() << "Examining instruction: "; MI.dump();); - - // First, if there are any DBG_VALUEs pointing at a spill slot that is - // written to, then close the variable location. The value in memory - // will have changed. - VarLocSet KillSet(Alloc); - if (isSpillInstruction(MI, MF)) { - Loc = extractSpillBaseRegAndOffset(MI); - for (uint64_t ID : OpenRanges.getSpillVarLocs()) { - LocIndex Idx = LocIndex::fromRawInteger(ID); - const VarLoc &VL = VarLocIDs[Idx]; - assert(VL.Kind == VarLoc::SpillLocKind && "Broken VarLocSet?"); - if (VL.Loc.SpillLocation == *Loc) { - // This location is overwritten by the current instruction -- terminate - // the open range, and insert an explicit DBG_VALUE $noreg. - // - // Doing this at a later stage would require re-interpreting all - // DBG_VALUes and DIExpressions to identify whether they point at - // memory, and then analysing all memory writes to see if they - // overwrite that memory, which is expensive. - // - // At this stage, we already know which DBG_VALUEs are for spills and - // where they are located; it's best to fix handle overwrites now. - KillSet.set(ID); - VarLoc UndefVL = VarLoc::CreateCopyLoc(VL.MI, LS, 0); - LocIndex UndefLocID = VarLocIDs.insert(UndefVL); - Transfers.push_back({&MI, UndefLocID}); - } - } - OpenRanges.erase(KillSet, VarLocIDs); - } - - // Try to recognise spill and restore instructions that may create a new - // variable location. - if (isLocationSpill(MI, MF, Reg)) { - TKind = TransferKind::TransferSpill; - LLVM_DEBUG(dbgs() << "Recognized as spill: "; MI.dump();); - LLVM_DEBUG(dbgs() << "Register: " << Reg << " " << printReg(Reg, TRI) - << "\n"); - } else { - if (!(Loc = isRestoreInstruction(MI, MF, Reg))) - return; - TKind = TransferKind::TransferRestore; - LLVM_DEBUG(dbgs() << "Recognized as restore: "; MI.dump();); - LLVM_DEBUG(dbgs() << "Register: " << Reg << " " << printReg(Reg, TRI) - << "\n"); - } - // Check if the register or spill location is the location of a debug value. - auto TransferCandidates = OpenRanges.getEmptyVarLocRange(); - if (TKind == TransferKind::TransferSpill) - TransferCandidates = OpenRanges.getRegisterVarLocs(Reg); - else if (TKind == TransferKind::TransferRestore) - TransferCandidates = OpenRanges.getSpillVarLocs(); - for (uint64_t ID : TransferCandidates) { - LocIndex Idx = LocIndex::fromRawInteger(ID); - const VarLoc &VL = VarLocIDs[Idx]; - if (TKind == TransferKind::TransferSpill) { - assert(VL.isDescribedByReg() == Reg && "Broken VarLocSet?"); - LLVM_DEBUG(dbgs() << "Spilling Register " << printReg(Reg, TRI) << '(' - << VL.Var.getVariable()->getName() << ")\n"); - } else { - assert(TKind == TransferKind::TransferRestore && - VL.Kind == VarLoc::SpillLocKind && "Broken VarLocSet?"); - if (VL.Loc.SpillLocation != *Loc) - // The spill location is not the location of a debug value. - continue; - LLVM_DEBUG(dbgs() << "Restoring Register " << printReg(Reg, TRI) << '(' - << VL.Var.getVariable()->getName() << ")\n"); - } - insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, Idx, TKind, - Reg); - // FIXME: A comment should explain why it's correct to return early here, - // if that is in fact correct. - 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) { - auto DestSrc = TII->isCopyInstr(MI); - if (!DestSrc) - return; - - const MachineOperand *DestRegOp = DestSrc->Destination; - const MachineOperand *SrcRegOp = DestSrc->Source; - - if (!DestRegOp->isDef()) - return; - - auto isCalleeSavedReg = [&](Register Reg) { - for (MCRegAliasIterator RAI(Reg, TRI, true); RAI.isValid(); ++RAI) - if (CalleeSavedRegs.test(*RAI)) - return true; - return false; - }; - - Register SrcReg = SrcRegOp->getReg(); - Register 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 (!isCalleeSavedReg(DestReg)) - return; - - // Remember an entry value movement. If we encounter a new debug value of - // a parameter describing only a moving of the value around, rather then - // modifying it, we are still able to use the entry value if needed. - if (isRegOtherThanSPAndFP(*DestRegOp, MI, TRI)) { - for (uint64_t ID : OpenRanges.getEntryValueBackupVarLocs()) { - LocIndex Idx = LocIndex::fromRawInteger(ID); - const VarLoc &VL = VarLocIDs[Idx]; - if (VL.getEntryValueBackupReg() == SrcReg) { - LLVM_DEBUG(dbgs() << "Copy of the entry value: "; MI.dump();); - VarLoc EntryValLocCopyBackup = - VarLoc::CreateEntryCopyBackupLoc(VL.MI, LS, VL.Expr, DestReg); - - // Stop tracking the original entry value. - OpenRanges.erase(VL); - - // Start tracking the entry value copy. - LocIndex EntryValCopyLocID = VarLocIDs.insert(EntryValLocCopyBackup); - OpenRanges.insert(EntryValCopyLocID, EntryValLocCopyBackup); - break; - } - } - } - - if (!SrcRegOp->isKill()) - return; - - for (uint64_t ID : OpenRanges.getRegisterVarLocs(SrcReg)) { - LocIndex Idx = LocIndex::fromRawInteger(ID); - assert(VarLocIDs[Idx].isDescribedByReg() == SrcReg && "Broken VarLocSet?"); - insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, Idx, - TransferKind::TransferCopy, DestReg); - // FIXME: A comment should explain why it's correct to return early here, - // if that is in fact correct. - return; - } -} - -/// Terminate all open ranges at the end of the current basic block. -bool LiveDebugValues::transferTerminator(MachineBasicBlock *CurMBB, - OpenRangesSet &OpenRanges, - VarLocInMBB &OutLocs, - const VarLocMap &VarLocIDs) { - bool Changed = false; - - LLVM_DEBUG(for (uint64_t ID - : OpenRanges.getVarLocs()) { - // Copy OpenRanges to OutLocs, if not already present. - dbgs() << "Add to OutLocs in MBB #" << CurMBB->getNumber() << ": "; - VarLocIDs[LocIndex::fromRawInteger(ID)].dump(TRI); - }); - VarLocSet &VLS = getVarLocsInMBB(CurMBB, OutLocs); - Changed = VLS != OpenRanges.getVarLocs(); - // New OutLocs set may be different due to spill, restore or register - // copy instruction processing. - if (Changed) - VLS = OpenRanges.getVarLocs(); - OpenRanges.clear(); - return Changed; -} - -/// Accumulate a mapping between each DILocalVariable fragment and other -/// fragments of that DILocalVariable which overlap. This reduces work during -/// the data-flow stage from "Find any overlapping fragments" to "Check if the -/// known-to-overlap fragments are present". -/// \param MI A previously unprocessed DEBUG_VALUE instruction to analyze for -/// fragment usage. -/// \param SeenFragments Map from DILocalVariable to all fragments of that -/// Variable which are known to exist. -/// \param OverlappingFragments The overlap map being constructed, from one -/// Var/Fragment pair to a vector of fragments known to overlap. -void LiveDebugValues::accumulateFragmentMap(MachineInstr &MI, - VarToFragments &SeenFragments, - OverlapMap &OverlappingFragments) { - DebugVariable MIVar(MI.getDebugVariable(), MI.getDebugExpression(), - MI.getDebugLoc()->getInlinedAt()); - FragmentInfo ThisFragment = MIVar.getFragmentOrDefault(); - - // If this is the first sighting of this variable, then we are guaranteed - // there are currently no overlapping fragments either. Initialize the set - // of seen fragments, record no overlaps for the current one, and return. - auto SeenIt = SeenFragments.find(MIVar.getVariable()); - if (SeenIt == SeenFragments.end()) { - SmallSet<FragmentInfo, 4> OneFragment; - OneFragment.insert(ThisFragment); - SeenFragments.insert({MIVar.getVariable(), OneFragment}); - - OverlappingFragments.insert({{MIVar.getVariable(), ThisFragment}, {}}); - return; - } - - // If this particular Variable/Fragment pair already exists in the overlap - // map, it has already been accounted for. - auto IsInOLapMap = - OverlappingFragments.insert({{MIVar.getVariable(), ThisFragment}, {}}); - if (!IsInOLapMap.second) - return; - - auto &ThisFragmentsOverlaps = IsInOLapMap.first->second; - auto &AllSeenFragments = SeenIt->second; - - // Otherwise, examine all other seen fragments for this variable, with "this" - // fragment being a previously unseen fragment. Record any pair of - // overlapping fragments. - for (auto &ASeenFragment : AllSeenFragments) { - // Does this previously seen fragment overlap? - if (DIExpression::fragmentsOverlap(ThisFragment, ASeenFragment)) { - // Yes: Mark the current fragment as being overlapped. - ThisFragmentsOverlaps.push_back(ASeenFragment); - // Mark the previously seen fragment as being overlapped by the current - // one. - auto ASeenFragmentsOverlaps = - OverlappingFragments.find({MIVar.getVariable(), ASeenFragment}); - assert(ASeenFragmentsOverlaps != OverlappingFragments.end() && - "Previously seen var fragment has no vector of overlaps"); - ASeenFragmentsOverlaps->second.push_back(ThisFragment); - } - } - - AllSeenFragments.insert(ThisFragment); -} - -/// This routine creates OpenRanges. -void LiveDebugValues::process(MachineInstr &MI, OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs, TransferMap &Transfers) { - transferDebugValue(MI, OpenRanges, VarLocIDs); - transferRegisterDef(MI, OpenRanges, VarLocIDs, Transfers); - transferRegisterCopy(MI, OpenRanges, VarLocIDs, Transfers); - transferSpillOrRestoreInst(MI, OpenRanges, VarLocIDs, Transfers); -} - -/// 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"); - - VarLocSet InLocsT(Alloc); // 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 backedges if we have not visited the predecessor yet. As the - // predecessor hasn't yet had locations propagated into it, most locations - // will not yet be valid, so treat them as all being uninitialized and - // potentially valid. If a location guessed to be correct here is - // invalidated later, we will remove it when we revisit this block. - 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. - VarLocSet &OutLocVLS = *OL->second.get(); - if (!NumVisited) - InLocsT = OutLocVLS; - else - InLocsT &= OutLocVLS; - - LLVM_DEBUG({ - if (!InLocsT.empty()) { - for (uint64_t ID : InLocsT) - dbgs() << " gathered candidate incoming var: " - << VarLocIDs[LocIndex::fromRawInteger(ID)] - .Var.getVariable() - ->getName() - << "\n"; - } - }); - - NumVisited++; - } - - // Filter out DBG_VALUES that are out of scope. - VarLocSet KillSet(Alloc); - bool IsArtificial = ArtificialBlocks.count(&MBB); - if (!IsArtificial) { - for (uint64_t ID : InLocsT) { - LocIndex Idx = LocIndex::fromRawInteger(ID); - if (!VarLocIDs[Idx].dominates(LS, MBB)) { - KillSet.set(ID); - LLVM_DEBUG({ - auto Name = VarLocIDs[Idx].Var.getVariable()->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"); - - VarLocSet &ILS = getVarLocsInMBB(&MBB, InLocs); - bool Changed = false; - if (ILS != InLocsT) { - ILS = InLocsT; - Changed = true; - } - - return Changed; -} - -void LiveDebugValues::flushPendingLocs(VarLocInMBB &PendingInLocs, - VarLocMap &VarLocIDs) { - // PendingInLocs records all locations propagated into blocks, which have - // not had DBG_VALUE insts created. Go through and create those insts now. - for (auto &Iter : PendingInLocs) { - // Map is keyed on a constant pointer, unwrap it so we can insert insts. - auto &MBB = const_cast<MachineBasicBlock &>(*Iter.first); - VarLocSet &Pending = *Iter.second.get(); - - for (uint64_t ID : Pending) { - // The ID location is live-in to MBB -- work out what kind of machine - // location it is and create a DBG_VALUE. - const VarLoc &DiffIt = VarLocIDs[LocIndex::fromRawInteger(ID)]; - if (DiffIt.isEntryBackupLoc()) - continue; - MachineInstr *MI = DiffIt.BuildDbgValue(*MBB.getParent()); - MBB.insert(MBB.instr_begin(), MI); - - (void)MI; - LLVM_DEBUG(dbgs() << "Inserted: "; MI->dump();); - } - } -} - -bool LiveDebugValues::isEntryValueCandidate( - const MachineInstr &MI, const DefinedRegsSet &DefinedRegs) const { - assert(MI.isDebugValue() && "This must be DBG_VALUE."); - - // TODO: Add support for local variables that are expressed in terms of - // parameters entry values. - // TODO: Add support for modified arguments that can be expressed - // by using its entry value. - auto *DIVar = MI.getDebugVariable(); - if (!DIVar->isParameter()) - return false; - - // Do not consider parameters that belong to an inlined function. - if (MI.getDebugLoc()->getInlinedAt()) - return false; - - // Only consider parameters that are described using registers. Parameters - // that are passed on the stack are not yet supported, so ignore debug - // values that are described by the frame or stack pointer. - if (!isRegOtherThanSPAndFP(MI.getDebugOperand(0), MI, TRI)) - return false; - - // If a parameter's value has been propagated from the caller, then the - // parameter's DBG_VALUE may be described using a register defined by some - // instruction in the entry block, in which case we shouldn't create an - // entry value. - if (DefinedRegs.count(MI.getDebugOperand(0).getReg())) - return false; - - // TODO: Add support for parameters that have a pre-existing debug expressions - // (e.g. fragments). - if (MI.getDebugExpression()->getNumElements() > 0) - return false; - - return true; -} - -/// Collect all register defines (including aliases) for the given instruction. -static void collectRegDefs(const MachineInstr &MI, DefinedRegsSet &Regs, - const TargetRegisterInfo *TRI) { - for (const MachineOperand &MO : MI.operands()) - if (MO.isReg() && MO.isDef() && MO.getReg()) - for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid(); ++AI) - Regs.insert(*AI); -} - -/// This routine records the entry values of function parameters. The values -/// could be used as backup values. If we loose the track of some unmodified -/// parameters, the backup values will be used as a primary locations. -void LiveDebugValues::recordEntryValue(const MachineInstr &MI, - const DefinedRegsSet &DefinedRegs, - OpenRangesSet &OpenRanges, - VarLocMap &VarLocIDs) { - if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) { - auto &TM = TPC->getTM<TargetMachine>(); - if (!TM.Options.ShouldEmitDebugEntryValues()) - return; - } - - DebugVariable V(MI.getDebugVariable(), MI.getDebugExpression(), - MI.getDebugLoc()->getInlinedAt()); - - if (!isEntryValueCandidate(MI, DefinedRegs) || - OpenRanges.getEntryValueBackup(V)) - return; - - LLVM_DEBUG(dbgs() << "Creating the backup entry location: "; MI.dump();); - - // Create the entry value and use it as a backup location until it is - // valid. It is valid until a parameter is not changed. - DIExpression *NewExpr = - DIExpression::prepend(MI.getDebugExpression(), DIExpression::EntryValue); - VarLoc EntryValLocAsBackup = VarLoc::CreateEntryBackupLoc(MI, LS, NewExpr); - LocIndex EntryValLocID = VarLocIDs.insert(EntryValLocAsBackup); - OpenRanges.insert(EntryValLocID, EntryValLocAsBackup); -} - -/// 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. - OverlapMap OverlapFragments; // Map of overlapping variable fragments. - OpenRangesSet OpenRanges(Alloc, OverlapFragments); - // 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 transfers (such as - // spills, copies and restores). - - VarToFragments SeenFragments; - - // 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; - - // Set of register defines that are seen when traversing the entry block - // looking for debug entry value candidates. - DefinedRegsSet DefinedRegs; - - // Only in the case of entry MBB collect DBG_VALUEs representing - // function parameters in order to generate debug entry values for them. - MachineBasicBlock &First_MBB = *(MF.begin()); - for (auto &MI : First_MBB) { - collectRegDefs(MI, DefinedRegs, TRI); - if (MI.isDebugValue()) - recordEntryValue(MI, DefinedRegs, OpenRanges, VarLocIDs); - } - - // Initialize per-block structures and scan for fragment overlaps. - for (auto &MBB : MF) - for (auto &MI : MBB) - if (MI.isDebugValue()) - accumulateFragmentMap(MI, SeenFragments, OverlapFragments); - - 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; - } - - if (RPONumber > InputBBLimit) { - unsigned NumInputDbgValues = 0; - for (auto &MBB : MF) - for (auto &MI : MBB) - if (MI.isDebugValue()) - ++NumInputDbgValues; - if (NumInputDbgValues > InputDbgValueLimit) { - LLVM_DEBUG(dbgs() << "Disabling LiveDebugValues: " << MF.getName() - << " has " << RPONumber << " basic blocks and " - << NumInputDbgValues - << " input DBG_VALUEs, exceeding limits.\n"); - return false; - } - } - - // 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); - MBBJoined |= Visited.insert(MBB).second; - if (MBBJoined) { - MBBJoined = false; - Changed = true; - // Now that we have started to extend ranges across BBs we need to - // examine spill, copy and restore instructions to see whether they - // operate with registers that correspond to user variables. - // First load any pending inlocs. - OpenRanges.insertFromLocSet(getVarLocsInMBB(MBB, InLocs), VarLocIDs); - for (auto &MI : *MBB) - process(MI, OpenRanges, VarLocIDs, Transfers); - OLChanged |= transferTerminator(MBB, OpenRanges, OutLocs, VarLocIDs); - - 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"); - } - - // Add any DBG_VALUE instructions created by location transfers. - for (auto &TR : Transfers) { - assert(!TR.TransferInst->isTerminator() && - "Cannot insert DBG_VALUE after terminator"); - MachineBasicBlock *MBB = TR.TransferInst->getParent(); - const VarLoc &VL = VarLocIDs[TR.LocationID]; - MachineInstr *MI = VL.BuildDbgValue(MF); - MBB->insertAfterBundle(TR.TransferInst->getIterator(), MI); - } - Transfers.clear(); - - // Deferred inlocs will not have had any DBG_VALUE insts created; do - // that now. - flushPendingLocs(InLocs, VarLocIDs); - - 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->getCalleeSaves(MF, CalleeSavedRegs); - LS.initialize(MF); - - bool Changed = ExtendRanges(MF); - return Changed; -} |