C++ DIArray::getNumElements方法代码示例

/// Remove any debug info for global variables/functions in the given module for
/// which said global variable/function no longer exists (i.e. is null).
///
/// Debugging information is encoded in llvm IR using metadata. This is designed
/// such a way that debug info for symbols preserved even if symbols are
/// optimized away by the optimizer. This special pass removes debug info for
/// such symbols.
bool StripDeadDebugInfo::runOnModule(Module &M) {
  bool Changed = false;

  LLVMContext &C = M.getContext();

  // Find all debug info in F. This is actually overkill in terms of what we
  // want to do, but we want to try and be as resilient as possible in the face
  // of potential debug info changes by using the formal interfaces given to us
  // as much as possible.
  DebugInfoFinder F;
  F.processModule(M);

  // For each compile unit, find the live set of global variables/functions and
  // replace the current list of potentially dead global variables/functions
  // with the live list.
  SmallVector<Value *, 64> LiveGlobalVariables;
  SmallVector<Value *, 64> LiveSubprograms;
  DenseSet<const MDNode *> VisitedSet;

  for (DICompileUnit DIC : F.compile_units()) {
    assert(DIC.Verify() && "DIC must verify as a DICompileUnit.");

    // Create our live subprogram list.
    DIArray SPs = DIC.getSubprograms();
    bool SubprogramChange = false;
    for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
      DISubprogram DISP(SPs.getElement(i));
      assert(DISP.Verify() && "DISP must verify as a DISubprogram.");

      // Make sure we visit each subprogram only once.
      if (!VisitedSet.insert(DISP).second)
        continue;

      // If the function referenced by DISP is not null, the function is live.
      if (DISP.getFunction())
        LiveSubprograms.push_back(DISP);
      else
        SubprogramChange = true;
    }

    // Create our live global variable list.
    DIArray GVs = DIC.getGlobalVariables();
    bool GlobalVariableChange = false;
    for (unsigned i = 0, e = GVs.getNumElements(); i != e; ++i) {
      DIGlobalVariable DIG(GVs.getElement(i));
      assert(DIG.Verify() && "DIG must verify as DIGlobalVariable.");

      // Make sure we only visit each global variable only once.
      if (!VisitedSet.insert(DIG).second)
        continue;

      // If the global variable referenced by DIG is not null, the global
      // variable is live.
      if (DIG.getGlobal())
        LiveGlobalVariables.push_back(DIG);
      else
        GlobalVariableChange = true;
    }

    // If we found dead subprograms or global variables, replace the current
    // subprogram list/global variable list with our new live subprogram/global
    // variable list.
    if (SubprogramChange) {
      // Make sure that 9 is still the index of the subprograms. This is to make
      // sure that an assert is hit if the location of the subprogram array
      // changes. This is just to make sure that this is updated if such an
      // event occurs.
      assert(DIC->getNumOperands() >= 10 &&
             SPs == DIC->getOperand(9) &&
             "DICompileUnits is expected to store Subprograms in operand "
             "9.");
      DIC->replaceOperandWith(9, MDNode::get(C, LiveSubprograms));
      Changed = true;
    }

    if (GlobalVariableChange) {
      // Make sure that 10 is still the index of global variables. This is to
      // make sure that an assert is hit if the location of the subprogram array
      // changes. This is just to make sure that this index is updated if such
      // an event occurs.
      assert(DIC->getNumOperands() >= 11 &&
             GVs == DIC->getOperand(10) &&
             "DICompileUnits is expected to store Global Variables in operand "
             "10.");
      DIC->replaceOperandWith(10, MDNode::get(C, LiveGlobalVariables));
      Changed = true;
    }

    // Reset lists for the next iteration.
    LiveSubprograms.clear();
    LiveGlobalVariables.clear();
  }

//.........这里部分代码省略.........

void GCOVProfiler::emitProfileNotes() {
  NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
  if (!CU_Nodes) return;

  for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
    // Each compile unit gets its own .gcno file. This means that whether we run
    // this pass over the original .o's as they're produced, or run it after
    // LTO, we'll generate the same .gcno files.

    DICompileUnit CU(CU_Nodes->getOperand(i));
    std::error_code EC;
    raw_fd_ostream out(mangleName(CU, "gcno"), EC, sys::fs::F_None);
    std::string EdgeDestinations;

    DIArray SPs = CU.getSubprograms();
    unsigned FunctionIdent = 0;
    for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
      DISubprogram SP(SPs.getElement(i));
      assert((!SP || SP.isSubprogram()) &&
        "A MDNode in subprograms of a CU should be null or a DISubprogram.");
      if (!SP)
        continue;

      Function *F = SP.getFunction();
      if (!F) continue;
      if (!functionHasLines(F)) continue;

      // gcov expects every function to start with an entry block that has a
      // single successor, so split the entry block to make sure of that.
      BasicBlock &EntryBlock = F->getEntryBlock();
      BasicBlock::iterator It = EntryBlock.begin();
      while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It))
        ++It;
      EntryBlock.splitBasicBlock(It);

      Funcs.push_back(make_unique<GCOVFunction>(SP, &out, FunctionIdent++,
                                                Options.UseCfgChecksum,
                                                Options.ExitBlockBeforeBody));
      GCOVFunction &Func = *Funcs.back();

      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
        GCOVBlock &Block = Func.getBlock(BB);
        TerminatorInst *TI = BB->getTerminator();
        if (int successors = TI->getNumSuccessors()) {
          for (int i = 0; i != successors; ++i) {
            Block.addEdge(Func.getBlock(TI->getSuccessor(i)));
          }
        } else if (isa<ReturnInst>(TI)) {
          Block.addEdge(Func.getReturnBlock());
        }

        uint32_t Line = 0;
        for (BasicBlock::iterator I = BB->begin(), IE = BB->end();
             I != IE; ++I) {
          // Debug intrinsic locations correspond to the location of the
          // declaration, not necessarily any statements or expressions.
          if (isa<DbgInfoIntrinsic>(I)) continue;

          const DebugLoc &Loc = I->getDebugLoc();
          if (!Loc)
            continue;

          // Artificial lines such as calls to the global constructors.
          if (Loc.getLine() == 0) continue;

          if (Line == Loc.getLine()) continue;
          Line = Loc.getLine();
          if (SP != getDISubprogram(Loc.getScope()))
            continue;

          GCOVLines &Lines = Block.getFile(SP.getFilename());
          Lines.addLine(Loc.getLine());
        }
      }
      EdgeDestinations += Func.getEdgeDestinations();
    }

    FileChecksums.push_back(hash_value(EdgeDestinations));
    out.write("oncg", 4);
    out.write(ReversedVersion, 4);
    out.write(reinterpret_cast<char*>(&FileChecksums.back()), 4);

    for (auto &Func : Funcs) {
      Func->setCfgChecksum(FileChecksums.back());
      Func->writeOut();
    }

    out.write("\0\0\0\0\0\0\0\0", 8);  // EOF
    out.close();
  }
}

void DICompositeType::printInternal(raw_ostream &OS) const {
  DIType::printInternal(OS);
  DIArray A = getTypeArray();
  OS << " [" << A.getNumElements() << " elements]";
}