Make getPredecessorWithUniqueSuccessorForBB return the unique successor
in addition to the predecessor.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101374 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index b8bcdd4..9e10137 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -4654,21 +4654,21 @@
/// successor from which BB is reachable, or null if no such block is
/// found.
///
-BasicBlock *
+std::pair<BasicBlock *, BasicBlock *>
ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) {
// If the block has a unique predecessor, then there is no path from the
// predecessor to the block that does not go through the direct edge
// from the predecessor to the block.
if (BasicBlock *Pred = BB->getSinglePredecessor())
- return Pred;
+ return std::make_pair(Pred, BB);
// A loop's header is defined to be a block that dominates the loop.
// If the header has a unique predecessor outside the loop, it must be
// a block that has exactly one successor that can reach the loop.
if (Loop *L = LI->getLoopFor(BB))
- return getLoopPredecessor(L);
+ return std::make_pair(getLoopPredecessor(L), L->getHeader());
- return 0;
+ return std::pair<BasicBlock *, BasicBlock *>();
}
/// HasSameValue - SCEV structural equivalence is usually sufficient for
@@ -4852,24 +4852,22 @@
// (interprocedural conditions notwithstanding).
if (!L) return false;
- BasicBlock *Predecessor = getLoopPredecessor(L);
- BasicBlock *PredecessorDest = L->getHeader();
-
// Starting at the loop predecessor, climb up the predecessor chain, as long
// as there are predecessors that can be found that have unique successors
// leading to the original header.
- for (; Predecessor;
- PredecessorDest = Predecessor,
- Predecessor = getPredecessorWithUniqueSuccessorForBB(Predecessor)) {
+ for (std::pair<BasicBlock *, BasicBlock *>
+ Pair(getLoopPredecessor(L), L->getHeader());
+ Pair.first;
+ Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
BranchInst *LoopEntryPredicate =
- dyn_cast<BranchInst>(Predecessor->getTerminator());
+ dyn_cast<BranchInst>(Pair.first->getTerminator());
if (!LoopEntryPredicate ||
LoopEntryPredicate->isUnconditional())
continue;
if (isImpliedCond(LoopEntryPredicate->getCondition(), Pred, LHS, RHS,
- LoopEntryPredicate->getSuccessor(0) != PredecessorDest))
+ LoopEntryPredicate->getSuccessor(0) != Pair.second))
return true;
}