diff --git a/mlir/include/mlir/IR/PatternMatch.h b/mlir/include/mlir/IR/PatternMatch.h
--- a/mlir/include/mlir/IR/PatternMatch.h
+++ b/mlir/include/mlir/IR/PatternMatch.h
@@ -790,6 +790,27 @@
     return *this;
   }
 
+  // Add a matchAndRewrite style pattern represented as a C function pointer.
+  template <typename OpType>
+  OwningRewritePatternList &
+  insert(LogicalResult (*implFn)(OpType, PatternRewriter &rewriter)) {
+    struct Folder final : public OpRewritePattern<OpType> {
+      Folder(LogicalResult (*implFn)(OpType, PatternRewriter &rewriter),
+             MLIRContext *context)
+          : OpRewritePattern<OpType>(context), implFn(implFn) {}
+
+      LogicalResult matchAndRewrite(OpType op,
+                                    PatternRewriter &rewriter) const override {
+        return implFn(op, rewriter);
+      }
+
+    private:
+      LogicalResult (*implFn)(OpType, PatternRewriter &rewriter);
+    };
+    insert(std::make_unique<Folder>(std::move(implFn), getContext()));
+    return *this;
+  }
+
 private:
   /// Add an instance of the pattern type 'T'. Return a reference to `this` for
   /// chaining insertions.
diff --git a/mlir/lib/Dialect/Math/Transforms/ExpandTanh.cpp b/mlir/lib/Dialect/Math/Transforms/ExpandTanh.cpp
--- a/mlir/lib/Dialect/Math/Transforms/ExpandTanh.cpp
+++ b/mlir/lib/Dialect/Math/Transforms/ExpandTanh.cpp
@@ -15,51 +15,42 @@
 #include "mlir/Dialect/StandardOps/IR/Ops.h"
 #include "mlir/IR/Builders.h"
 #include "mlir/Transforms/DialectConversion.h"
-
 using namespace mlir;
 
-namespace {
 /// Expands tanh op into
 ///   1) 1-exp^{-2x} / 1+exp^{-2x}, if x => 0
 ///   2) exp^{2x}-1 / exp^{2x}+1  , if x < 0
-struct TanhOpConverter : public OpRewritePattern<math::TanhOp> {
-public:
-  using OpRewritePattern::OpRewritePattern;
-
-  LogicalResult matchAndRewrite(math::TanhOp op,
-                                PatternRewriter &rewriter) const final {
-    auto floatType = op.operand().getType();
-    Location loc = op.getLoc();
-    auto floatOne = rewriter.getFloatAttr(floatType, 1.0);
-    auto floatTwo = rewriter.getFloatAttr(floatType, 2.0);
-    Value one = rewriter.create<ConstantOp>(loc, floatOne);
-    Value two = rewriter.create<ConstantOp>(loc, floatTwo);
-    Value doubledX = rewriter.create<MulFOp>(loc, op.operand(), two);
-
-    // Case 1: tanh(x) = 1-exp^{-2x} / 1+exp^{-2x}
-    Value negDoubledX = rewriter.create<NegFOp>(loc, doubledX);
-    Value exp2x = rewriter.create<math::ExpOp>(loc, negDoubledX);
-    Value dividend = rewriter.create<SubFOp>(loc, one, exp2x);
-    Value divisor = rewriter.create<AddFOp>(loc, one, exp2x);
-    Value positiveRes = rewriter.create<DivFOp>(loc, dividend, divisor);
-
-    // Case 2: tanh(x) = exp^{2x}-1 / exp^{2x}+1
-    exp2x = rewriter.create<math::ExpOp>(loc, doubledX);
-    dividend = rewriter.create<SubFOp>(loc, exp2x, one);
-    divisor = rewriter.create<AddFOp>(loc, exp2x, one);
-    Value negativeRes = rewriter.create<DivFOp>(loc, dividend, divisor);
-
-    // tanh(x) = x >= 0 ? positiveRes : negativeRes
-    auto floatZero = rewriter.getFloatAttr(floatType, 0.0);
-    Value zero = rewriter.create<ConstantOp>(loc, floatZero);
-    Value cmpRes =
-        rewriter.create<CmpFOp>(loc, CmpFPredicate::OGE, op.operand(), zero);
-    rewriter.replaceOpWithNewOp<SelectOp>(op, cmpRes, positiveRes, negativeRes);
-    return success();
-  }
-};
-} // namespace
+static LogicalResult convertTanhOp(math::TanhOp op, PatternRewriter &rewriter) {
+  auto floatType = op.operand().getType();
+  Location loc = op.getLoc();
+  auto floatOne = rewriter.getFloatAttr(floatType, 1.0);
+  auto floatTwo = rewriter.getFloatAttr(floatType, 2.0);
+  Value one = rewriter.create<ConstantOp>(loc, floatOne);
+  Value two = rewriter.create<ConstantOp>(loc, floatTwo);
+  Value doubledX = rewriter.create<MulFOp>(loc, op.operand(), two);
+
+  // Case 1: tanh(x) = 1-exp^{-2x} / 1+exp^{-2x}
+  Value negDoubledX = rewriter.create<NegFOp>(loc, doubledX);
+  Value exp2x = rewriter.create<math::ExpOp>(loc, negDoubledX);
+  Value dividend = rewriter.create<SubFOp>(loc, one, exp2x);
+  Value divisor = rewriter.create<AddFOp>(loc, one, exp2x);
+  Value positiveRes = rewriter.create<DivFOp>(loc, dividend, divisor);
+
+  // Case 2: tanh(x) = exp^{2x}-1 / exp^{2x}+1
+  exp2x = rewriter.create<math::ExpOp>(loc, doubledX);
+  dividend = rewriter.create<SubFOp>(loc, exp2x, one);
+  divisor = rewriter.create<AddFOp>(loc, exp2x, one);
+  Value negativeRes = rewriter.create<DivFOp>(loc, dividend, divisor);
+
+  // tanh(x) = x >= 0 ? positiveRes : negativeRes
+  auto floatZero = rewriter.getFloatAttr(floatType, 0.0);
+  Value zero = rewriter.create<ConstantOp>(loc, floatZero);
+  Value cmpRes =
+      rewriter.create<CmpFOp>(loc, CmpFPredicate::OGE, op.operand(), zero);
+  rewriter.replaceOpWithNewOp<SelectOp>(op, cmpRes, positiveRes, negativeRes);
+  return success();
+}
 
 void mlir::populateExpandTanhPattern(OwningRewritePatternList &patterns) {
-  patterns.insert<TanhOpConverter>(patterns.getContext());
+  patterns.insert(convertTanhOp);
 }