void ExpressionList::optimize(AnalysisResultConstPtr ar) {
  bool changed = false;
  size_t i = m_exps.size();
  if (m_kind != ListKindParam) {
    size_t skip = m_kind == ListKindLeft ? 0 : i - 1;
    while (i--) {
      if (i != skip) {
        ExpressionPtr &e = m_exps[i];
        if (!e || e->getContainedEffects() == NoEffect) {
          removeElement(i);
          changed = true;
        } else if (e->is(KindOfExpressionList)) {
          ExpressionListPtr el(static_pointer_cast<ExpressionList>(e));
          removeElement(i);
          for (size_t j = el->getCount(); j--; ) {
            insertElement((*el)[j], i);
          }
          changed = true;
        } else if (e->getLocalEffects() == NoEffect) {
          e = e->unneeded();
          // changed already handled by unneeded
        }
      }
    }
    if (m_exps.size() == 1) {
      m_kind = ListKindWrapped;
    } else if (m_kind == ListKindLeft && m_exps[0]->isScalar()) {
      ExpressionPtr e = m_exps[0];
      removeElement(0);
      addElement(e);
      m_kind = ListKindWrapped;
    }
  } else {
    if (hasContext(UnsetContext) &&
        ar->getPhase() >= AnalysisResult::PostOptimize) {
      while (i--) {
        ExpressionPtr &e = m_exps[i];
        if (e->is(Expression::KindOfSimpleVariable)) {
          SimpleVariablePtr var = dynamic_pointer_cast<SimpleVariable>(e);
          if (var->checkUnused()) {
            const std::string &name = var->getName();
            VariableTablePtr variables = getScope()->getVariables();
            if (!variables->isNeeded(name)) {
              removeElement(i);
              changed = true;
            }
          }
        }
      }
    }
  }
  if (changed) {
    getScope()->addUpdates(BlockScope::UseKindCaller);
  }
}
示例#2
0
bool Expression::CheckNeeded(ExpressionPtr variable, ExpressionPtr value) {
  // if the value may involve object, consider the variable as "needed"
  // so that objects are not destructed prematurely.
  bool needed = true;
  if (value) needed = CheckNeededRHS(value);
  if (variable->is(Expression::KindOfSimpleVariable)) {
    auto var = dynamic_pointer_cast<SimpleVariable>(variable);
    const std::string &name = var->getName();
    VariableTablePtr variables = var->getScope()->getVariables();
    if (needed) {
      variables->addNeeded(name);
    } else {
      needed = variables->isNeeded(name);
    }
  }
  return needed;
}
示例#3
0
void ExpressionList::optimize(AnalysisResultConstPtr ar) {
  bool changed = false;
  size_t i = m_exps.size();
  if (m_kind != ListKindParam) {
    size_t skip = m_kind == ListKindLeft ? 0 : i - 1;
    while (i--) {
      if (i != skip) {
        ExpressionPtr &e = m_exps[i];
        if (!e || (e->getContainedEffects() == NoEffect && !e->isNoRemove())) {
          removeElement(i);
          changed = true;
        } else if (e->is(KindOfExpressionList)) {
          ExpressionListPtr el(static_pointer_cast<ExpressionList>(e));
          removeElement(i);
          for (size_t j = el->getCount(); j--; ) {
            insertElement((*el)[j], i);
          }
          changed = true;
        } else if (e->getLocalEffects() == NoEffect) {
          e = e->unneeded();
          // changed already handled by unneeded
        }
      }
    }
    if (m_exps.size() == 1) {
      // don't convert an exp-list with type assertions to
      // a ListKindWrapped
      if (!isNoRemove()) {
        m_kind = ListKindWrapped;
      }
    } else if (m_kind == ListKindLeft && m_exps[0]->isScalar()) {
      ExpressionPtr e = m_exps[0];
      removeElement(0);
      addElement(e);
      m_kind = ListKindWrapped;
    }
  } else {
    bool isUnset = hasContext(UnsetContext) &&
      // This used to be gated on ar->getPhase() >= PostOptimize
      false;
    int isGlobal = -1;
    while (i--) {
      ExpressionPtr &e = m_exps[i];
      if (isUnset) {
        if (e->is(Expression::KindOfSimpleVariable)) {
          SimpleVariablePtr var = dynamic_pointer_cast<SimpleVariable>(e);
          if (var->checkUnused()) {
            const std::string &name = var->getName();
            VariableTablePtr variables = getScope()->getVariables();
            if (!variables->isNeeded(name)) {
              removeElement(i);
              changed = true;
            }
          }
        }
      } else {
        bool global = e && (e->getContext() & Declaration) == Declaration;
        if (isGlobal < 0) {
          isGlobal = global;
        } else {
          always_assert(isGlobal == global);
        }
        if (isGlobal && e->isScalar()) {
          removeElement(i);
          changed = true;
        }
      }
    }
  }
  if (changed) {
    getScope()->addUpdates(BlockScope::UseKindCaller);
  }
}