-// Note: We could use some sort of caching mecanism, but we lack the ability
-// to know when the cache is invalid, i.e., the CFG changed.
-// Assuming we have that, we can simply compute all the set of MBBs
-// that are before the save point.
-bool MachineFrameInfo::isBeforeSavePoint(const MachineFunction &MF,
- const MachineBasicBlock &MBB) const {
- // Early exit if shrink-wrapping did not kick.
- if (!Save)
- return &MBB == &MF.front();
-
- // Starting from MBB, check if there is a path leading to Save that do
- // not cross Restore.
- SmallPtrSet<const MachineBasicBlock *, 8> Visited;
- SmallVector<const MachineBasicBlock *, 8> WorkList;
- WorkList.push_back(&MBB);
- Visited.insert(&MBB);
- do {
- const MachineBasicBlock *CurBB = WorkList.pop_back_val();
- // By construction, the region that is after the save point is
- // dominated by the Save and post-dominated by the Restore.
- // If we do not reach Restore and still reach Save, this
- // means MBB is before Save.
- if (CurBB == Save)
- return true;
- if (CurBB == Restore)
- continue;
- // Enqueue all the successors not already visited.
- for (MachineBasicBlock *SuccBB : CurBB->successors())
- if (Visited.insert(SuccBB).second)
- WorkList.push_back(SuccBB);
- } while (!WorkList.empty());
- return false;
-}
-