[mlir] Check FunctionOpInterface castable type

[Lewuathe]

Summary

As convertFuncOpTypes does not support other FuncOpInterface types, we should check the type to avoid assertion failure. The original issue was reported https://github.com/llvm/llvm-project/issues/61858.

[mehdi_amini]

Thanks for the fix.

mlir/lib/Transforms/Utils/DialectConversion.cpp

 
 //===----------------------------------------------------------------------===//
 // FunctionOpInterfaceSignatureConversion
 //===----------------------------------------------------------------------===//
 
 static LogicalResult convertFuncOpTypes(FunctionOpInterface funcOp,
                                         TypeConverter &typeConverter,
                                         ConversionPatternRewriter &rewriter) {
-  FunctionType type = funcOp.getFunctionType().cast<FunctionType>();
+  FunctionType type = dyn_cast<FunctionType>(funcOp.getFunctionType());
+  if (!type)
+    return failure();
 
   // Convert the original function types.
   TypeConverter::SignatureConversion result(type.getNumInputs());
   SmallVector<Type, 1> newResults;
   if (failed(typeConverter.convertSignatureArgs(type.getInputs(), result)) ||
       failed(typeConverter.convertTypes(type.getResults(), newResults)) ||
       failed(rewriter.convertRegionTypes(&funcOp.getFunctionBody(),
                                          typeConverter, &result)))

mlir/test/Transforms/test-legalize-type-conversion.mlir

 // -----
 
 // CHECK-LABEL: @recursive_type_conversion
 func.func @recursive_type_conversion() {
   // CHECK:  !test.test_rec<outer_converted_type, smpla>
   "test.type_producer"() : () -> !test.test_rec<something, test_rec<something>>
   return
 }
+
+// -----
+
+// CHECK-LABEL: @unsupported_func_op_interface
+llvm.func @unsupported_func_op_interface() {
+  // CHECK: llvm.return
+  llvm.return
+}