C++ Optional::abandon方法代码示例

bool CGSCCAnalysisManagerModuleProxy::Result::invalidate(
    Module &M, const PreservedAnalyses &PA,
    ModuleAnalysisManager::Invalidator &Inv) {
  // If literally everything is preserved, we're done.
  if (PA.areAllPreserved())
    return false; // This is still a valid proxy.

  // If this proxy or the call graph is going to be invalidated, we also need
  // to clear all the keys coming from that analysis.
  //
  // We also directly invalidate the FAM's module proxy if necessary, and if
  // that proxy isn't preserved we can't preserve this proxy either. We rely on
  // it to handle module -> function analysis invalidation in the face of
  // structural changes and so if it's unavailable we conservatively clear the
  // entire SCC layer as well rather than trying to do invalidation ourselves.
  auto PAC = PA.getChecker<CGSCCAnalysisManagerModuleProxy>();
  if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Module>>()) ||
      Inv.invalidate<LazyCallGraphAnalysis>(M, PA) ||
      Inv.invalidate<FunctionAnalysisManagerModuleProxy>(M, PA)) {
    InnerAM->clear();

    // And the proxy itself should be marked as invalid so that we can observe
    // the new call graph. This isn't strictly necessary because we cheat
    // above, but is still useful.
    return true;
  }

  // Directly check if the relevant set is preserved so we can short circuit
  // invalidating SCCs below.
  bool AreSCCAnalysesPreserved =
      PA.allAnalysesInSetPreserved<AllAnalysesOn<LazyCallGraph::SCC>>();

  // Ok, we have a graph, so we can propagate the invalidation down into it.
  G->buildRefSCCs();
  for (auto &RC : G->postorder_ref_sccs())
    for (auto &C : RC) {
      Optional<PreservedAnalyses> InnerPA;

      // Check to see whether the preserved set needs to be adjusted based on
      // module-level analysis invalidation triggering deferred invalidation
      // for this SCC.
      if (auto *OuterProxy =
              InnerAM->getCachedResult<ModuleAnalysisManagerCGSCCProxy>(C))
        for (const auto &OuterInvalidationPair :
             OuterProxy->getOuterInvalidations()) {
          AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
          const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
          if (Inv.invalidate(OuterAnalysisID, M, PA)) {
            if (!InnerPA)
              InnerPA = PA;
            for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
              InnerPA->abandon(InnerAnalysisID);
          }
        }

      // Check if we needed a custom PA set. If so we'll need to run the inner
      // invalidation.
      if (InnerPA) {
        InnerAM->invalidate(C, *InnerPA);
        continue;
      }

      // Otherwise we only need to do invalidation if the original PA set didn't
      // preserve all SCC analyses.
      if (!AreSCCAnalysesPreserved)
        InnerAM->invalidate(C, PA);
    }

  // Return false to indicate that this result is still a valid proxy.
  return false;
}

bool LoopAnalysisManagerFunctionProxy::Result::invalidate(
    Function &F, const PreservedAnalyses &PA,
    FunctionAnalysisManager::Invalidator &Inv) {
  // First compute the sequence of IR units covered by this proxy. We will want
  // to visit this in postorder, but because this is a tree structure we can do
  // this by building a preorder sequence and walking it in reverse.
  SmallVector<Loop *, 4> PreOrderLoops, PreOrderWorklist;
  // Note that we want to walk the roots in reverse order because we will end
  // up reversing the preorder sequence. However, it happens that the loop nest
  // roots are in reverse order within the LoopInfo object. So we just walk
  // forward here.
  // FIXME: If we change the order of LoopInfo we will want to add a reverse
  // here.
  for (Loop *RootL : *LI) {
    assert(PreOrderWorklist.empty() &&
           "Must start with an empty preorder walk worklist.");
    PreOrderWorklist.push_back(RootL);
    do {
      Loop *L = PreOrderWorklist.pop_back_val();
      PreOrderWorklist.append(L->begin(), L->end());
      PreOrderLoops.push_back(L);
    } while (!PreOrderWorklist.empty());
  }

  // If this proxy or the loop info is going to be invalidated, we also need
  // to clear all the keys coming from that analysis. We also completely blow
  // away the loop analyses if any of the standard analyses provided by the
  // loop pass manager go away so that loop analyses can freely use these
  // without worrying about declaring dependencies on them etc.
  // FIXME: It isn't clear if this is the right tradeoff. We could instead make
  // loop analyses declare any dependencies on these and use the more general
  // invalidation logic below to act on that.
  auto PAC = PA.getChecker<LoopAnalysisManagerFunctionProxy>();
  if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
      Inv.invalidate<AAManager>(F, PA) ||
      Inv.invalidate<AssumptionAnalysis>(F, PA) ||
      Inv.invalidate<DominatorTreeAnalysis>(F, PA) ||
      Inv.invalidate<LoopAnalysis>(F, PA) ||
      Inv.invalidate<ScalarEvolutionAnalysis>(F, PA)) {
    // Note that the LoopInfo may be stale at this point, however the loop
    // objects themselves remain the only viable keys that could be in the
    // analysis manager's cache. So we just walk the keys and forcibly clear
    // those results. Note that the order doesn't matter here as this will just
    // directly destroy the results without calling methods on them.
    for (Loop *L : PreOrderLoops)
      InnerAM->clear(*L);

    // We also need to null out the inner AM so that when the object gets
    // destroyed as invalid we don't try to clear the inner AM again. At that
    // point we won't be able to reliably walk the loops for this function and
    // only clear results associated with those loops the way we do here.
    // FIXME: Making InnerAM null at this point isn't very nice. Most analyses
    // try to remain valid during invalidation. Maybe we should add an
    // `IsClean` flag?
    InnerAM = nullptr;

    // Now return true to indicate this *is* invalid and a fresh proxy result
    // needs to be built. This is especially important given the null InnerAM.
    return true;
  }

  // Directly check if the relevant set is preserved so we can short circuit
  // invalidating loops.
  bool AreLoopAnalysesPreserved =
      PA.allAnalysesInSetPreserved<AllAnalysesOn<Loop>>();

  // Since we have a valid LoopInfo we can actually leave the cached results in
  // the analysis manager associated with the Loop keys, but we need to
  // propagate any necessary invalidation logic into them. We'd like to
  // invalidate things in roughly the same order as they were put into the
  // cache and so we walk the preorder list in reverse to form a valid
  // postorder.
  for (Loop *L : reverse(PreOrderLoops)) {
    Optional<PreservedAnalyses> InnerPA;

    // Check to see whether the preserved set needs to be adjusted based on
    // function-level analysis invalidation triggering deferred invalidation
    // for this loop.
    if (auto *OuterProxy =
            InnerAM->getCachedResult<FunctionAnalysisManagerLoopProxy>(*L))
      for (const auto &OuterInvalidationPair :
           OuterProxy->getOuterInvalidations()) {
        AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
        const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
        if (Inv.invalidate(OuterAnalysisID, F, PA)) {
          if (!InnerPA)
            InnerPA = PA;
          for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
            InnerPA->abandon(InnerAnalysisID);
        }
      }

    // Check if we needed a custom PA set. If so we'll need to run the inner
    // invalidation.
    if (InnerPA) {
      InnerAM->invalidate(*L, *InnerPA);
      continue;
    }

    // Otherwise we only need to do invalidation if the original PA set didn't
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