C++ LabelDecl::getStmt方法代码示例

/// VerifyJumps - Verify each element of the Jumps array to see if they are
/// valid, emitting diagnostics if not.
void JumpScopeChecker::VerifyJumps() {
  while (!Jumps.empty()) {
    Stmt *Jump = Jumps.pop_back_val();

    // With a goto,
    if (GotoStmt *GS = dyn_cast<GotoStmt>(Jump)) {
      CheckJump(GS, GS->getLabel()->getStmt(), GS->getGotoLoc(),
                diag::err_goto_into_protected_scope,
                diag::warn_goto_into_protected_scope,
                diag::warn_cxx98_compat_goto_into_protected_scope);
      continue;
    }

    // We only get indirect gotos here when they have a constant target.
    if (IndirectGotoStmt *IGS = dyn_cast<IndirectGotoStmt>(Jump)) {
      LabelDecl *Target = IGS->getConstantTarget();
      CheckJump(IGS, Target->getStmt(), IGS->getGotoLoc(),
                diag::err_goto_into_protected_scope,
                diag::warn_goto_into_protected_scope,
                diag::warn_cxx98_compat_goto_into_protected_scope);
      continue;
    }

    SwitchStmt *SS = cast<SwitchStmt>(Jump);
    for (SwitchCase *SC = SS->getSwitchCaseList(); SC;
         SC = SC->getNextSwitchCase()) {
      assert(LabelAndGotoScopes.count(SC) && "Case not visited?");
      CheckJump(SS, SC, SC->getLocStart(),
                diag::err_switch_into_protected_scope, 0,
                diag::warn_cxx98_compat_switch_into_protected_scope);
    }
  }
}

/// VerifyIndirectJumps - Verify whether any possible indirect jump
/// might cross a protection boundary.  Unlike direct jumps, indirect
/// jumps count cleanups as protection boundaries:  since there's no
/// way to know where the jump is going, we can't implicitly run the
/// right cleanups the way we can with direct jumps.
///
/// Thus, an indirect jump is "trivial" if it bypasses no
/// initializations and no teardowns.  More formally, an indirect jump
/// from A to B is trivial if the path out from A to DCA(A,B) is
/// trivial and the path in from DCA(A,B) to B is trivial, where
/// DCA(A,B) is the deepest common ancestor of A and B.
/// Jump-triviality is transitive but asymmetric.
///
/// A path in is trivial if none of the entered scopes have an InDiag.
/// A path out is trivial is none of the exited scopes have an OutDiag.
///
/// Under these definitions, this function checks that the indirect
/// jump between A and B is trivial for every indirect goto statement A
/// and every label B whose address was taken in the function.
void JumpScopeChecker::VerifyIndirectJumps() {
  if (IndirectJumps.empty()) return;

  // If there aren't any address-of-label expressions in this function,
  // complain about the first indirect goto.
  if (IndirectJumpTargets.empty()) {
    S.Diag(IndirectJumps[0]->getGotoLoc(),
           diag::err_indirect_goto_without_addrlabel);
    return;
  }

  // Collect a single representative of every scope containing an
  // indirect goto.  For most code bases, this substantially cuts
  // down on the number of jump sites we'll have to consider later.
  typedef std::pair<unsigned, IndirectGotoStmt*> JumpScope;
  SmallVector<JumpScope, 32> JumpScopes;
  {
    llvm::DenseMap<unsigned, IndirectGotoStmt*> JumpScopesMap;
    for (SmallVectorImpl<IndirectGotoStmt*>::iterator
           I = IndirectJumps.begin(), E = IndirectJumps.end(); I != E; ++I) {
      IndirectGotoStmt *IG = *I;
      assert(LabelAndGotoScopes.count(IG) &&
             "indirect jump didn't get added to scopes?");
      unsigned IGScope = LabelAndGotoScopes[IG];
      IndirectGotoStmt *&Entry = JumpScopesMap[IGScope];
      if (!Entry) Entry = IG;
    }
    JumpScopes.reserve(JumpScopesMap.size());
    for (llvm::DenseMap<unsigned, IndirectGotoStmt*>::iterator
           I = JumpScopesMap.begin(), E = JumpScopesMap.end(); I != E; ++I)
      JumpScopes.push_back(*I);
  }

  // Collect a single representative of every scope containing a
  // label whose address was taken somewhere in the function.
  // For most code bases, there will be only one such scope.
  llvm::DenseMap<unsigned, LabelDecl*> TargetScopes;
  for (SmallVectorImpl<LabelDecl*>::iterator
         I = IndirectJumpTargets.begin(), E = IndirectJumpTargets.end();
       I != E; ++I) {
    LabelDecl *TheLabel = *I;
    assert(LabelAndGotoScopes.count(TheLabel->getStmt()) &&
           "Referenced label didn't get added to scopes?");
    unsigned LabelScope = LabelAndGotoScopes[TheLabel->getStmt()];
    LabelDecl *&Target = TargetScopes[LabelScope];
    if (!Target) Target = TheLabel;
  }

  // For each target scope, make sure it's trivially reachable from
  // every scope containing a jump site.
  //
  // A path between scopes always consists of exitting zero or more
  // scopes, then entering zero or more scopes.  We build a set of
  // of scopes S from which the target scope can be trivially
  // entered, then verify that every jump scope can be trivially
  // exitted to reach a scope in S.
  llvm::BitVector Reachable(Scopes.size(), false);
  for (llvm::DenseMap<unsigned,LabelDecl*>::iterator
         TI = TargetScopes.begin(), TE = TargetScopes.end(); TI != TE; ++TI) {
    unsigned TargetScope = TI->first;
    LabelDecl *TargetLabel = TI->second;

    Reachable.reset();

    // Mark all the enclosing scopes from which you can safely jump
    // into the target scope.  'Min' will end up being the index of
    // the shallowest such scope.
    unsigned Min = TargetScope;
    while (true) {
      Reachable.set(Min);

      // Don't go beyond the outermost scope.
      if (Min == 0) break;

      // Stop if we can't trivially enter the current scope.
      if (Scopes[Min].InDiag) break;

      Min = Scopes[Min].ParentScope;
    }

    // Walk through all the jump sites, checking that they can trivially
//.........这里部分代码省略.........