1 files changed, 11 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
index 08446ccaa9fc..28ae4f0a0aad 100644
--- a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
@@ -260,6 +260,17 @@ static bool populateDependencyMatrix(CharMatrix &DepMatrix, unsigned Level,
           Dep.push_back('I');
         }
 
+        // If all the elements of any direction vector have only '*', legality
+        // can't be proven. Exit early to save compile time.
+        if (all_of(Dep, [](char C) { return C == '*'; })) {
+          ORE->emit([&]() {
+            return OptimizationRemarkMissed(DEBUG_TYPE, "Dependence",
+                                            L->getStartLoc(), L->getHeader())
+                   << "All loops have dependencies in all directions.";
+          });
+          return false;
+        }
+
         // Test whether the dependency is forward or not.
         bool IsKnownForward = true;
         if (Src->getParent() != Dst->getParent()) {