[NFC] Factor out predecessors collection into a separate method
It may be reused in a different piece of logic.
Differential Revision: https://reviews.llvm.org/D50890
Reviewed By: reames
llvm-svn: 340250
diff --git a/llvm/lib/Analysis/MustExecute.cpp b/llvm/lib/Analysis/MustExecute.cpp
index ab09100..79ec8e4 100644
--- a/llvm/lib/Analysis/MustExecute.cpp
+++ b/llvm/lib/Analysis/MustExecute.cpp
@@ -98,19 +98,13 @@
return SimpleCst->isAllOnesValue();
}
-
-bool LoopSafetyInfo::allLoopPathsLeadToBlock(const Loop *CurLoop,
- const BasicBlock *BB,
- const DominatorTree *DT) const {
+void LoopSafetyInfo::collectTransitivePredecessors(
+ const Loop *CurLoop, const BasicBlock *BB,
+ SmallPtrSetImpl<const BasicBlock *> &Predecessors) const {
+ assert(Predecessors.empty() && "Garbage in predecessors set?");
assert(CurLoop->contains(BB) && "Should only be called for loop blocks!");
-
- // Fast path: header is always reached once the loop is entered.
if (BB == CurLoop->getHeader())
- return true;
-
- // Collect all transitive predecessors of BB in the same loop. This set will
- // be a subset of the blocks within the loop.
- SmallPtrSet<const BasicBlock *, 4> Predecessors;
+ return;
SmallVector<const BasicBlock *, 4> WorkList;
for (auto *Pred : predecessors(BB)) {
Predecessors.insert(Pred);
@@ -132,6 +126,21 @@
if (Predecessors.insert(PredPred).second)
WorkList.push_back(PredPred);
}
+}
+
+bool LoopSafetyInfo::allLoopPathsLeadToBlock(const Loop *CurLoop,
+ const BasicBlock *BB,
+ const DominatorTree *DT) const {
+ assert(CurLoop->contains(BB) && "Should only be called for loop blocks!");
+
+ // Fast path: header is always reached once the loop is entered.
+ if (BB == CurLoop->getHeader())
+ return true;
+
+ // Collect all transitive predecessors of BB in the same loop. This set will
+ // be a subset of the blocks within the loop.
+ SmallPtrSet<const BasicBlock *, 4> Predecessors;
+ collectTransitivePredecessors(CurLoop, BB, Predecessors);
// Make sure that all successors of all predecessors of BB are either:
// 1) BB,