MachineModuleInfo.cpp

//===-- llvm/CodeGen/MachineModuleInfo.cpp ----------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/Analysis/LibCallSemantics.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
using namespace llvm::dwarf;

// Handle the Pass registration stuff necessary to use DataLayout's.
INITIALIZE_PASS(MachineModuleInfo, "machinemoduleinfo",
                "Machine Module Information", false, false)
char MachineModuleInfo::ID = 0;

// Out of line virtual method.
MachineModuleInfoImpl::~MachineModuleInfoImpl() {}

namespace llvm {
class MMIAddrLabelMapCallbackPtr : CallbackVH {
  MMIAddrLabelMap *Map;
public:
  MMIAddrLabelMapCallbackPtr() : Map(nullptr) {}
  MMIAddrLabelMapCallbackPtr(Value *V) : CallbackVH(V), Map(nullptr) {}

  void setPtr(BasicBlock *BB) {
    ValueHandleBase::operator=(BB);
  }

  void setMap(MMIAddrLabelMap *map) { Map = map; }

  void deleted() override;
  void allUsesReplacedWith(Value *V2) override;
};

class MMIAddrLabelMap {
  MCContext &Context;
  struct AddrLabelSymEntry {
    /// Symbols - The symbols for the label.  This is a pointer union that is
    /// either one symbol (the common case) or a list of symbols.
    PointerUnion<MCSymbol *, std::vector<MCSymbol*>*> Symbols;

    Function *Fn;   // The containing function of the BasicBlock.
    unsigned Index; // The index in BBCallbacks for the BasicBlock.
  };

  DenseMap<AssertingVH<BasicBlock>, AddrLabelSymEntry> AddrLabelSymbols;

  /// BBCallbacks - Callbacks for the BasicBlock's that we have entries for.  We
  /// use this so we get notified if a block is deleted or RAUWd.
  std::vector<MMIAddrLabelMapCallbackPtr> BBCallbacks;

  /// DeletedAddrLabelsNeedingEmission - This is a per-function list of symbols
  /// whose corresponding BasicBlock got deleted.  These symbols need to be
  /// emitted at some point in the file, so AsmPrinter emits them after the
  /// function body.
  DenseMap<AssertingVH<Function>, std::vector<MCSymbol*> >
    DeletedAddrLabelsNeedingEmission;
public:

  MMIAddrLabelMap(MCContext &context) : Context(context) {}
  ~MMIAddrLabelMap() {
    assert(DeletedAddrLabelsNeedingEmission.empty() &&
           "Some labels for deleted blocks never got emitted");

    // Deallocate any of the 'list of symbols' case.
    for (DenseMap<AssertingVH<BasicBlock>, AddrLabelSymEntry>::iterator
         I = AddrLabelSymbols.begin(), E = AddrLabelSymbols.end(); I != E; ++I)
      if (I->second.Symbols.is<std::vector<MCSymbol*>*>())
        delete I->second.Symbols.get<std::vector<MCSymbol*>*>();
  }

  MCSymbol *getAddrLabelSymbol(BasicBlock *BB);
  std::vector<MCSymbol*> getAddrLabelSymbolToEmit(BasicBlock *BB);

  void takeDeletedSymbolsForFunction(Function *F,
                                     std::vector<MCSymbol*> &Result);

  void UpdateForDeletedBlock(BasicBlock *BB);
  void UpdateForRAUWBlock(BasicBlock *Old, BasicBlock *New);
};
}

MCSymbol *MMIAddrLabelMap::getAddrLabelSymbol(BasicBlock *BB) {
  assert(BB->hasAddressTaken() &&
         "Shouldn't get label for block without address taken");
  AddrLabelSymEntry &Entry = AddrLabelSymbols[BB];

  // If we already had an entry for this block, just return it.
  if (!Entry.Symbols.isNull()) {
    assert(BB->getParent() == Entry.Fn && "Parent changed");
    if (Entry.Symbols.is<MCSymbol*>())
      return Entry.Symbols.get<MCSymbol*>();
    return (*Entry.Symbols.get<std::vector<MCSymbol*>*>())[0];
  }

  // Otherwise, this is a new entry, create a new symbol for it and add an
  // entry to BBCallbacks so we can be notified if the BB is deleted or RAUWd.
  BBCallbacks.push_back(BB);
  BBCallbacks.back().setMap(this);
  Entry.Index = BBCallbacks.size()-1;
  Entry.Fn = BB->getParent();
  MCSymbol *Result = Context.CreateTempSymbol();
  Entry.Symbols = Result;
  return Result;
}

std::vector<MCSymbol*>
MMIAddrLabelMap::getAddrLabelSymbolToEmit(BasicBlock *BB) {
  assert(BB->hasAddressTaken() &&
         "Shouldn't get label for block without address taken");
  AddrLabelSymEntry &Entry = AddrLabelSymbols[BB];

  std::vector<MCSymbol*> Result;

  // If we already had an entry for this block, just return it.
  if (Entry.Symbols.isNull())
    Result.push_back(getAddrLabelSymbol(BB));
  else if (MCSymbol *Sym = Entry.Symbols.dyn_cast<MCSymbol*>())
    Result.push_back(Sym);
  else
    Result = *Entry.Symbols.get<std::vector<MCSymbol*>*>();
  return Result;
}


/// takeDeletedSymbolsForFunction - If we have any deleted symbols for F, return
/// them.
void MMIAddrLabelMap::
takeDeletedSymbolsForFunction(Function *F, std::vector<MCSymbol*> &Result) {
  DenseMap<AssertingVH<Function>, std::vector<MCSymbol*> >::iterator I =
    DeletedAddrLabelsNeedingEmission.find(F);

  // If there are no entries for the function, just return.
  if (I == DeletedAddrLabelsNeedingEmission.end()) return;

  // Otherwise, take the list.
  std::swap(Result, I->second);
  DeletedAddrLabelsNeedingEmission.erase(I);
}


void MMIAddrLabelMap::UpdateForDeletedBlock(BasicBlock *BB) {
  // If the block got deleted, there is no need for the symbol.  If the symbol
  // was already emitted, we can just forget about it, otherwise we need to
  // queue it up for later emission when the function is output.
  AddrLabelSymEntry Entry = AddrLabelSymbols[BB];
  AddrLabelSymbols.erase(BB);
  assert(!Entry.Symbols.isNull() && "Didn't have a symbol, why a callback?");
  BBCallbacks[Entry.Index] = nullptr;  // Clear the callback.

  assert((BB->getParent() == nullptr || BB->getParent() == Entry.Fn) &&
         "Block/parent mismatch");

  // Handle both the single and the multiple symbols cases.
  if (MCSymbol *Sym = Entry.Symbols.dyn_cast<MCSymbol*>()) {
    if (Sym->isDefined())
      return;

    // If the block is not yet defined, we need to emit it at the end of the
    // function.  Add the symbol to the DeletedAddrLabelsNeedingEmission list
    // for the containing Function.  Since the block is being deleted, its
    // parent may already be removed, we have to get the function from 'Entry'.
    DeletedAddrLabelsNeedingEmission[Entry.Fn].push_back(Sym);
  } else {
    std::vector<MCSymbol*> *Syms = Entry.Symbols.get<std::vector<MCSymbol*>*>();

    for (unsigned i = 0, e = Syms->size(); i != e; ++i) {
      MCSymbol *Sym = (*Syms)[i];
      if (Sym->isDefined()) continue;  // Ignore already emitted labels.

      // If the block is not yet defined, we need to emit it at the end of the
      // function.  Add the symbol to the DeletedAddrLabelsNeedingEmission list
      // for the containing Function.  Since the block is being deleted, its
      // parent may already be removed, we have to get the function from
      // 'Entry'.
      DeletedAddrLabelsNeedingEmission[Entry.Fn].push_back(Sym);
    }

    // The entry is deleted, free the memory associated with the symbol list.
    delete Syms;
  }
}

void MMIAddrLabelMap::UpdateForRAUWBlock(BasicBlock *Old, BasicBlock *New) {
  // Get the entry for the RAUW'd block and remove it from our map.
  AddrLabelSymEntry OldEntry = AddrLabelSymbols[Old];
  AddrLabelSymbols.erase(Old);
  assert(!OldEntry.Symbols.isNull() && "Didn't have a symbol, why a callback?");

  AddrLabelSymEntry &NewEntry = AddrLabelSymbols[New];

  // If New is not address taken, just move our symbol over to it.
  if (NewEntry.Symbols.isNull()) {
    BBCallbacks[OldEntry.Index].setPtr(New);    // Update the callback.
    NewEntry = OldEntry;     // Set New's entry.
    return;
  }

  BBCallbacks[OldEntry.Index] = nullptr;    // Update the callback.

  // Otherwise, we need to add the old symbol to the new block's set.  If it is
  // just a single entry, upgrade it to a symbol list.
  if (MCSymbol *PrevSym = NewEntry.Symbols.dyn_cast<MCSymbol*>()) {
    std::vector<MCSymbol*> *SymList = new std::vector<MCSymbol*>();
    SymList->push_back(PrevSym);
    NewEntry.Symbols = SymList;
  }

  std::vector<MCSymbol*> *SymList =
    NewEntry.Symbols.get<std::vector<MCSymbol*>*>();

  // If the old entry was a single symbol, add it.
  if (MCSymbol *Sym = OldEntry.Symbols.dyn_cast<MCSymbol*>()) {
    SymList->push_back(Sym);
    return;
  }

  // Otherwise, concatenate the list.
  std::vector<MCSymbol*> *Syms =OldEntry.Symbols.get<std::vector<MCSymbol*>*>();
  SymList->insert(SymList->end(), Syms->begin(), Syms->end());
  delete Syms;
}


void MMIAddrLabelMapCallbackPtr::deleted() {
  Map->UpdateForDeletedBlock(cast<BasicBlock>(getValPtr()));
}

void MMIAddrLabelMapCallbackPtr::allUsesReplacedWith(Value *V2) {
  Map->UpdateForRAUWBlock(cast<BasicBlock>(getValPtr()), cast<BasicBlock>(V2));
}


//===----------------------------------------------------------------------===//

MachineModuleInfo::MachineModuleInfo(const MCAsmInfo &MAI,
                                     const MCRegisterInfo &MRI,
                                     const MCObjectFileInfo *MOFI)
  : ImmutablePass(ID), Context(&MAI, &MRI, MOFI, nullptr, false) {
  initializeMachineModuleInfoPass(*PassRegistry::getPassRegistry());
}

MachineModuleInfo::MachineModuleInfo()
  : ImmutablePass(ID), Context(nullptr, nullptr, nullptr) {
  llvm_unreachable("This MachineModuleInfo constructor should never be called, "
                   "MMI should always be explicitly constructed by "
                   "LLVMTargetMachine");
}

MachineModuleInfo::~MachineModuleInfo() {
}

bool MachineModuleInfo::doInitialization(Module &M) {

  ObjFileMMI = nullptr;
  CurCallSite = 0;
  CallsEHReturn = 0;
  CallsUnwindInit = 0;
  DbgInfoAvailable = UsesVAFloatArgument = UsesMorestackAddr = false;
  // Always emit some info, by default "no personality" info.
  Personalities.push_back(nullptr);
  PersonalityTypeCache = EHPersonality::Unknown;
  AddrLabelSymbols = nullptr;
  TheModule = nullptr;

  return false;
}

bool MachineModuleInfo::doFinalization(Module &M) {

  Personalities.clear();

  delete AddrLabelSymbols;
  AddrLabelSymbols = nullptr;

  Context.reset();

  delete ObjFileMMI;
  ObjFileMMI = nullptr;

  return false;
}

/// EndFunction - Discard function meta information.
///
void MachineModuleInfo::EndFunction() {
  // Clean up frame info.
  FrameInstructions.clear();

  // Clean up exception info.
  LandingPads.clear();
  CallSiteMap.clear();
  TypeInfos.clear();
  FilterIds.clear();
  FilterEnds.clear();
  CallsEHReturn = 0;
  CallsUnwindInit = 0;
  VariableDbgInfos.clear();
}

/// AnalyzeModule - Scan the module for global debug information.
///
void MachineModuleInfo::AnalyzeModule(const Module &M) {
  // Insert functions in the llvm.used array (but not llvm.compiler.used) into
  // UsedFunctions.
  const GlobalVariable *GV = M.getGlobalVariable("llvm.used");
  if (!GV || !GV->hasInitializer()) return;

  // Should be an array of 'i8*'.
  const ConstantArray *InitList = cast<ConstantArray>(GV->getInitializer());

  for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i)
    if (const Function *F =
          dyn_cast<Function>(InitList->getOperand(i)->stripPointerCasts()))
      UsedFunctions.insert(F);
}

//===- Address of Block Management ----------------------------------------===//


/// getAddrLabelSymbol - Return the symbol to be used for the specified basic
/// block when its address is taken.  This cannot be its normal LBB label
/// because the block may be accessed outside its containing function.
MCSymbol *MachineModuleInfo::getAddrLabelSymbol(const BasicBlock *BB) {
  // Lazily create AddrLabelSymbols.
  if (!AddrLabelSymbols)
    AddrLabelSymbols = new MMIAddrLabelMap(Context);
  return AddrLabelSymbols->getAddrLabelSymbol(const_cast<BasicBlock*>(BB));
}

/// getAddrLabelSymbolToEmit - Return the symbol to be used for the specified
/// basic block when its address is taken.  If other blocks were RAUW'd to
/// this one, we may have to emit them as well, return the whole set.
std::vector<MCSymbol*> MachineModuleInfo::
getAddrLabelSymbolToEmit(const BasicBlock *BB) {
  // Lazily create AddrLabelSymbols.
  if (!AddrLabelSymbols)
    AddrLabelSymbols = new MMIAddrLabelMap(Context);
 return AddrLabelSymbols->getAddrLabelSymbolToEmit(const_cast<BasicBlock*>(BB));
}


/// takeDeletedSymbolsForFunction - If the specified function has had any
/// references to address-taken blocks generated, but the block got deleted,
/// return the symbol now so we can emit it.  This prevents emitting a
/// reference to a symbol that has no definition.
void MachineModuleInfo::
takeDeletedSymbolsForFunction(const Function *F,
                              std::vector<MCSymbol*> &Result) {
  // If no blocks have had their addresses taken, we're done.
  if (!AddrLabelSymbols) return;
  return AddrLabelSymbols->
     takeDeletedSymbolsForFunction(const_cast<Function*>(F), Result);
}

//===- EH -----------------------------------------------------------------===//

/// getOrCreateLandingPadInfo - Find or create an LandingPadInfo for the
/// specified MachineBasicBlock.
LandingPadInfo &MachineModuleInfo::getOrCreateLandingPadInfo
    (MachineBasicBlock *LandingPad) {
  unsigned N = LandingPads.size();
  for (unsigned i = 0; i < N; ++i) {
    LandingPadInfo &LP = LandingPads[i];
    if (LP.LandingPadBlock == LandingPad)
      return LP;
  }

  LandingPads.push_back(LandingPadInfo(LandingPad));
  return LandingPads[N];
}

/// addInvoke - Provide the begin and end labels of an invoke style call and
/// associate it with a try landing pad block.
void MachineModuleInfo::addInvoke(MachineBasicBlock *LandingPad,
                                  MCSymbol *BeginLabel, MCSymbol *EndLabel) {
  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
  LP.BeginLabels.push_back(BeginLabel);
  LP.EndLabels.push_back(EndLabel);
}

/// addLandingPad - Provide the label of a try LandingPad block.
///
MCSymbol *MachineModuleInfo::addLandingPad(MachineBasicBlock *LandingPad) {
  MCSymbol *LandingPadLabel = Context.CreateTempSymbol();
  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
  LP.LandingPadLabel = LandingPadLabel;
  return LandingPadLabel;
}

/// addPersonality - Provide the personality function for the exception
/// information.
void MachineModuleInfo::addPersonality(MachineBasicBlock *LandingPad,
                                       const Function *Personality) {
  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
  LP.Personality = Personality;

  for (unsigned i = 0; i < Personalities.size(); ++i)
    if (Personalities[i] == Personality)
      return;

  // If this is the first personality we're adding go
  // ahead and add it at the beginning.
  if (!Personalities[0])
    Personalities[0] = Personality;
  else
    Personalities.push_back(Personality);
}

/// addCatchTypeInfo - Provide the catch typeinfo for a landing pad.
///
void MachineModuleInfo::
addCatchTypeInfo(MachineBasicBlock *LandingPad,
                 ArrayRef<const GlobalValue *> TyInfo) {
  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
  for (unsigned N = TyInfo.size(); N; --N)
    LP.TypeIds.push_back(getTypeIDFor(TyInfo[N - 1]));
}

/// addFilterTypeInfo - Provide the filter typeinfo for a landing pad.
///
void MachineModuleInfo::
addFilterTypeInfo(MachineBasicBlock *LandingPad,
                  ArrayRef<const GlobalValue *> TyInfo) {
  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
  std::vector<unsigned> IdsInFilter(TyInfo.size());
  for (unsigned I = 0, E = TyInfo.size(); I != E; ++I)
    IdsInFilter[I] = getTypeIDFor(TyInfo[I]);
  LP.TypeIds.push_back(getFilterIDFor(IdsInFilter));
}

/// addCleanup - Add a cleanup action for a landing pad.
///
void MachineModuleInfo::addCleanup(MachineBasicBlock *LandingPad) {
  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
  LP.TypeIds.push_back(0);
}

MCSymbol *
MachineModuleInfo::addClauseForLandingPad(MachineBasicBlock *LandingPad) {
  MCSymbol *ClauseLabel = Context.CreateTempSymbol();
  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
  LP.ClauseLabels.push_back(ClauseLabel);
  return ClauseLabel;
}

/// TidyLandingPads - Remap landing pad labels and remove any deleted landing
/// pads.
void MachineModuleInfo::TidyLandingPads(DenseMap<MCSymbol*, uintptr_t> *LPMap) {
  for (unsigned i = 0; i != LandingPads.size(); ) {
    LandingPadInfo &LandingPad = LandingPads[i];
    if (LandingPad.LandingPadLabel &&
        !LandingPad.LandingPadLabel->isDefined() &&
        (!LPMap || (*LPMap)[LandingPad.LandingPadLabel] == 0))
      LandingPad.LandingPadLabel = nullptr;

    // Special case: we *should* emit LPs with null LP MBB. This indicates
    // "nounwind" case.
    if (!LandingPad.LandingPadLabel && LandingPad.LandingPadBlock) {
      LandingPads.erase(LandingPads.begin() + i);
      continue;
    }

    for (unsigned j = 0, e = LandingPads[i].BeginLabels.size(); j != e; ++j) {
      MCSymbol *BeginLabel = LandingPad.BeginLabels[j];
      MCSymbol *EndLabel = LandingPad.EndLabels[j];
      if ((BeginLabel->isDefined() ||
           (LPMap && (*LPMap)[BeginLabel] != 0)) &&
          (EndLabel->isDefined() ||
           (LPMap && (*LPMap)[EndLabel] != 0))) continue;

      LandingPad.BeginLabels.erase(LandingPad.BeginLabels.begin() + j);
      LandingPad.EndLabels.erase(LandingPad.EndLabels.begin() + j);
      --j, --e;
    }

    // Remove landing pads with no try-ranges.
    if (LandingPads[i].BeginLabels.empty()) {
      LandingPads.erase(LandingPads.begin() + i);
      continue;
    }

    // If there is no landing pad, ensure that the list of typeids is empty.
    // If the only typeid is a cleanup, this is the same as having no typeids.
    if (!LandingPad.LandingPadBlock ||
        (LandingPad.TypeIds.size() == 1 && !LandingPad.TypeIds[0]))
      LandingPad.TypeIds.clear();
    ++i;
  }
}

/// setCallSiteLandingPad - Map the landing pad's EH symbol to the call site
/// indexes.
void MachineModuleInfo::setCallSiteLandingPad(MCSymbol *Sym,
                                              ArrayRef<unsigned> Sites) {
  LPadToCallSiteMap[Sym].append(Sites.begin(), Sites.end());
}

/// getTypeIDFor - Return the type id for the specified typeinfo.  This is
/// function wide.
unsigned MachineModuleInfo::getTypeIDFor(const GlobalValue *TI) {
  for (unsigned i = 0, N = TypeInfos.size(); i != N; ++i)
    if (TypeInfos[i] == TI) return i + 1;

  TypeInfos.push_back(TI);
  return TypeInfos.size();
}

/// getFilterIDFor - Return the filter id for the specified typeinfos.  This is
/// function wide.
int MachineModuleInfo::getFilterIDFor(std::vector<unsigned> &TyIds) {
  // If the new filter coincides with the tail of an existing filter, then
  // re-use the existing filter.  Folding filters more than this requires
  // re-ordering filters and/or their elements - probably not worth it.
  for (std::vector<unsigned>::iterator I = FilterEnds.begin(),
       E = FilterEnds.end(); I != E; ++I) {
    unsigned i = *I, j = TyIds.size();

    while (i && j)
      if (FilterIds[--i] != TyIds[--j])
        goto try_next;

    if (!j)
      // The new filter coincides with range [i, end) of the existing filter.
      return -(1 + i);

try_next:;
  }

  // Add the new filter.
  int FilterID = -(1 + FilterIds.size());
  FilterIds.reserve(FilterIds.size() + TyIds.size() + 1);
  FilterIds.insert(FilterIds.end(), TyIds.begin(), TyIds.end());
  FilterEnds.push_back(FilterIds.size());
  FilterIds.push_back(0); // terminator
  return FilterID;
}

/// getPersonality - Return the personality function for the current function.
const Function *MachineModuleInfo::getPersonality() const {
  for (const LandingPadInfo &LPI : LandingPads)
    if (LPI.Personality)
      return LPI.Personality;
  return nullptr;
}

EHPersonality MachineModuleInfo::getPersonalityType() {
  if (PersonalityTypeCache == EHPersonality::Unknown)
    PersonalityTypeCache = classifyEHPersonality(getPersonality());
  return PersonalityTypeCache;
}
/// getPersonalityIndex - Return unique index for current personality
/// function. NULL/first personality function should always get zero index.
unsigned MachineModuleInfo::getPersonalityIndex() const {
  const Function* Personality = nullptr;

  // Scan landing pads. If there is at least one non-NULL personality - use it.
  for (unsigned i = 0, e = LandingPads.size(); i != e; ++i)
    if (LandingPads[i].Personality) {
      Personality = LandingPads[i].Personality;
      break;
    }

  for (unsigned i = 0, e = Personalities.size(); i < e; ++i) {
    if (Personalities[i] == Personality)
      return i;
  }

  // This will happen if the current personality function is
  // in the zero index.
  return 0;
}