diff --git a/mlir/test/mlir-tblgen/pattern.mlir b/mlir/test/mlir-tblgen/pattern.mlir
--- a/mlir/test/mlir-tblgen/pattern.mlir
+++ b/mlir/test/mlir-tblgen/pattern.mlir
@@ -285,6 +285,7 @@
   // CHECK: [[V0]]
   return %2 : i32
 }
+
 // CHECK-LABEL: testConstOpMatchFailure
 func @testConstOpMatchFailure() -> (i64) {
   // CHECK-DAG: [[C0:%.+]] = constant 1
@@ -300,6 +301,20 @@
   return %2 : i64
 }
 
+// CHECK-LABEL: testConstOpMatchNonConst
+func @testConstOpMatchNonConst(%arg0 : i32) -> (i32) {
+  // CHECK-DAG: [[C0:%.+]] = constant 1
+  %0 = "test.constant"() {value = 1 : i32} : () -> i32
+
+  // CHECK: [[V0:%.+]] = "test.op_r"([[C0]], %arg0)
+  %1 = "test.op_r"(%0, %arg0) : (i32, i32) -> i32
+
+  // CHECK: [[V0]]
+  return %1 : i32
+}
+
+
+
 //===----------------------------------------------------------------------===//
 // Test Enum Attributes
 //===----------------------------------------------------------------------===//
diff --git a/mlir/tools/mlir-tblgen/RewriterGen.cpp b/mlir/tools/mlir-tblgen/RewriterGen.cpp
--- a/mlir/tools/mlir-tblgen/RewriterGen.cpp
+++ b/mlir/tools/mlir-tblgen/RewriterGen.cpp
@@ -259,6 +259,7 @@
 
   raw_indented_ostream::DelimitedScope scope(os);
 
+  os << "if(!" << opName << ") return failure();\n";
   for (int i = 0, e = tree.getNumArgs(); i != e; ++i) {
     std::string argName = formatv("arg{0}_{1}", depth, i);
     if (DagNode argTree = tree.getArgAsNestedDag(i)) {