diff --git a/mlir/lib/Analysis/AffineStructures.cpp b/mlir/lib/Analysis/AffineStructures.cpp
--- a/mlir/lib/Analysis/AffineStructures.cpp
+++ b/mlir/lib/Analysis/AffineStructures.cpp
@@ -3568,8 +3568,11 @@
     // zero coefficients everywhere.
     for (unsigned i = getNumDimAndSymbolIds(), e = getNumIds(); i < e; ++i) {
       if (!memo[i] && !isColZero(*this, /*pos=*/i)) {
-        LLVM_DEBUG(llvm::dbgs() << "one or more local exprs do not have an "
-                                   "explicit representation");
+        LLVM_DEBUG(llvm::dbgs()
+                   << "local variable at position "
+                   << i - getNumDimAndSymbolIds()
+                   << " does not have an explicit representation:\n");
+        LLVM_DEBUG(this->dump());
         return IntegerSet();
       }
     }