[mlir][shape] Add a func to populate ShapeToShape patterns.

mlir/include/mlir/Dialect/Shape/Transforms/Passes.h

 
 #ifndef MLIR_DIALECT_SHAPE_TRANSFORMS_PASSES_H_
 #define MLIR_DIALECT_SHAPE_TRANSFORMS_PASSES_H_
 
 #include <memory>
 
 namespace mlir {
 
+class MLIRContext;
+class OwningRewritePatternList;
 class Pass;
 
 /// Creates an instance of the ShapeToShapeLowering pass that legalizes Shape
 /// dialect to be convertible to Standard. For example, `shape.num_elements` get
 /// transformed to `shape.reduce`, which can be lowered to SCF and Standard.
 std::unique_ptr<Pass> createShapeToShapeLowering();
 
+/// Collects a set of patterns to rewrite ops within the Shape dialect.
+void populateShapeRewritePatterns(MLIRContext *context,
+                                  OwningRewritePatternList &patterns);
 } // end namespace mlir
 
 #endif // MLIR_DIALECT_SHAPE_TRANSFORMS_PASSES_H_

mlir/lib/Dialect/Shape/Transforms/ShapeToShapeLowering.cpp

 namespace {
 struct ShapeToShapeLowering
     : public ShapeToShapeLoweringBase<ShapeToShapeLowering> {
   void runOnFunction() override;
 };
 } // namespace
 
 void ShapeToShapeLowering::runOnFunction() {
+  MLIRContext &ctx = getContext();
+
   OwningRewritePatternList patterns;
-  patterns.insert<NumElementsOpConverter>(&getContext());
+  populateShapeRewritePatterns(&ctx, patterns);
 
   ConversionTarget target(getContext());
   target.addLegalDialect<ShapeDialect>();
   target.addIllegalOp<NumElementsOp>();
   if (failed(mlir::applyPartialConversion(getFunction(), target, patterns)))
     signalPassFailure();
 }
 
+void mlir::populateShapeRewritePatterns(MLIRContext *context,
+                                        OwningRewritePatternList &patterns) {
+  patterns.insert<NumElementsOpConverter>(context);
+}
+
 std::unique_ptr<Pass> mlir::createShapeToShapeLowering() {
   return std::make_unique<ShapeToShapeLowering>();
 }