2 files changed, 38 insertions, 0 deletions
diff --git a/polly/lib/Analysis/ScopDetection.cpp b/polly/lib/Analysis/ScopDetection.cpp
index bd68ef5c817..4c5c95af6e6 100644
--- a/polly/lib/Analysis/ScopDetection.cpp
+++ b/polly/lib/Analysis/ScopDetection.cpp
@@ -1297,6 +1297,18 @@ bool ScopDetection::isValidLoop(Loop *L, DetectionContext &Context) const {
   if (!hasExitingBlocks(L))
     return invalid<ReportLoopHasNoExit>(Context, /*Assert=*/true, L);
 
+  // The algorithm for domain construction assumes that loops has only a single
+  // exit block (and hence corresponds to a subregion). Note that we cannot use
+  // L->getExitBlock() because it does not check whether all exiting edges point
+  // to the same BB.
+  SmallVector<BasicBlock *, 4> ExitBlocks;
+  L->getExitBlocks(ExitBlocks);
+  BasicBlock *TheExitBlock = ExitBlocks[0];
+  for (BasicBlock *ExitBB : ExitBlocks) {
+    if (TheExitBlock != ExitBB)
+      return invalid<ReportLoopHasMultipleExits>(Context, /*Assert=*/true, L);
+  }
+
   if (canUseISLTripCount(L, Context))
     return true;
 
diff --git a/polly/lib/Analysis/ScopDetectionDiagnostic.cpp b/polly/lib/Analysis/ScopDetectionDiagnostic.cpp
index ac1e751e32d..a0c371237c4 100644
--- a/polly/lib/Analysis/ScopDetectionDiagnostic.cpp
+++ b/polly/lib/Analysis/ScopDetectionDiagnostic.cpp
@@ -71,6 +71,7 @@ Statistic RejectStatistics[] = {
     SCOP_STAT(LastAffFunc, ""),
     SCOP_STAT(LoopBound, "Uncomputable loop bounds"),
     SCOP_STAT(LoopHasNoExit, "Loop without exit"),
+    SCOP_STAT(LoopHasMultipleExits, "Loop with multiple exits"),
     SCOP_STAT(LoopOnlySomeLatches, "Not all loop latches in scop"),
     SCOP_STAT(FuncCall, "Function call with side effects"),
     SCOP_STAT(NonSimpleMemoryAccess,
@@ -496,6 +497,31 @@ std::string ReportLoopHasNoExit::getEndUserMessage() const {
 }
 
 //===----------------------------------------------------------------------===//
+// ReportLoopHasMultipleExits.
+
+std::string ReportLoopHasMultipleExits::getRemarkName() const {
+  return "ReportLoopHasMultipleExits";
+}
+
+const Value *ReportLoopHasMultipleExits::getRemarkBB() const {
+  return L->getHeader();
+}
+
+std::string ReportLoopHasMultipleExits::getMessage() const {
+  return "Loop " + L->getHeader()->getName() + " has multiple exits.";
+}
+
+bool ReportLoopHasMultipleExits::classof(const RejectReason *RR) {
+  return RR->getKind() == RejectReasonKind::LoopHasMultipleExits;
+}
+
+const DebugLoc &ReportLoopHasMultipleExits::getDebugLoc() const { return Loc; }
+
+std::string ReportLoopHasMultipleExits::getEndUserMessage() const {
+  return "Loop cannot be handled because it has multiple exits.";
+}
+
+//===----------------------------------------------------------------------===//
 // ReportLoopOnlySomeLatches
 
 std::string ReportLoopOnlySomeLatches::getRemarkName() const {