1 files changed, 23 insertions, 4 deletions

diff --git a/polly/lib/Analysis/ScopInfo.cpp b/polly/lib/Analysis/ScopInfo.cpp
index b61d9fa81d7..f3271c20334 100644
--- a/polly/lib/Analysis/ScopInfo.cpp
+++ b/polly/lib/Analysis/ScopInfo.cpp
@@ -3618,8 +3618,15 @@ void Scop::buildSchedule(ScopDetection &SD, LoopInfo &LI) {
   Loop *L = getLoopSurroundingRegion(getRegion(), LI);
   LoopStackTy LoopStack({LoopStackElementTy(L, nullptr, 0)});
   buildSchedule(getRegion().getNode(), LoopStack, SD, LI);
-  assert(LoopStack.size() == 1 && LoopStack.back().L == L);
-  Schedule = LoopStack[0].Schedule;
+  assert(!LoopStack.empty());
+  if (LoopStack.size() == 1 && LoopStack.back().L == L) {
+    Schedule = LoopStack[0].Schedule;
+  } else {
+    // If something went wrong we have to cleanup.
+    assert(!hasFeasibleRuntimeContext());
+    while (!LoopStack.empty())
+      isl_schedule_free(LoopStack.pop_back_val().Schedule);
+  }
 }
 
 /// To generate a schedule for the elements in a Region we traverse the Region
@@ -3662,9 +3669,22 @@ void Scop::buildSchedule(Region *R, LoopStackTy &LoopStack, ScopDetection &SD,
   // iterator. If it is set we have to explore the next sub-region/block from
   // the iterator (if any) to guarantee progress. If it is not set we first try
   // the next queued sub-region/blocks.
+  unsigned RemainingWork = WorkList.size() + DelayList.size() + 1;
   while (!WorkList.empty() || !DelayList.empty()) {
+    Loop *LastLoop = LoopStack.back().L;
     RegionNode *RN;
 
+    // FIXME: We will bail out if we cannot make progress. So far that is only
+    //        known to happen in the presence of infinite loops without an exit
+    //        edge. For such cases there is no region covering only the loop and
+    //        our reasoning fails.
+    if (WorkList.size() + DelayList.size() >= RemainingWork) {
+      invalidate(INFINITELOOP, R->getEntry()->getTerminator()->getDebugLoc());
+      LastLoop = nullptr;
+    }
+
+    RemainingWork = WorkList.size() + DelayList.size();
+
     if ((LastRNWaiting && !WorkList.empty()) || DelayList.size() == 0) {
       RN = WorkList.front();
       WorkList.pop_front();
@@ -3678,9 +3698,8 @@ void Scop::buildSchedule(Region *R, LoopStackTy &LoopStack, ScopDetection &SD,
     if (!getRegion().contains(L))
       L = OuterScopLoop;
 
-    Loop *LastLoop = LoopStack.back().L;
     if (LastLoop != L) {
-      if (!LastLoop->contains(L)) {
+      if (LastLoop && !LastLoop->contains(L)) {
         LastRNWaiting = true;
         DelayList.push_back(RN);
         continue;