[onnx] Accept keep_aspect_ratio_policy=stretch in Resize parser

src/onnx/parse_resize.cpp

@@ -267,20 +267,28 @@ struct parse_resize : op_parser<parse_resize>
         void set_aspect_ratio_policy(const onnx_parser::attribute_map& attr,
                                      const std::vector<instruction_ref>& args) const
         {
-            // TODO: Add support for this instead of keeping it as a check
-            if(contains(attr, "keep_aspect_ratio_policy"))
+            // Attribute introduced in opset 18; not present in opset <= 17.
+            if(not contains(attr, "keep_aspect_ratio_policy"))
+                return;
+
+            // 'stretch' is the opset-18 default and matches the existing per-axis
+            // semantics, so accept it as a no-op.
+            if(attr.at("keep_aspect_ratio_policy").s() == "stretch")
+                return;
+
+            // TODO: Add support for 'not_larger' and 'not_smaller' policies.
+            shape last_arg_shape     = args.back()->get_shape();
+            size_t last_arg_elements = last_arg_shape.elements();
+            // Check if the last arg is 'sizes' input.
+            // This attribute is only relevant if 'sizes' input is used.
+            // The shape constraints for 'sizes' are below:
+            if(last_arg_shape.type() == shape::int64_type and
+               (last_arg_elements == args.front()->get_shape().ndim() or
+                (is_axes_used() and last_arg_elements == r_attr.axes.size())))
             {
-                shape last_arg_shape     = args.back()->get_shape();
-                size_t last_arg_elements = last_arg_shape.elements();
-                // Check if the last arg is 'sizes' input.
-                // This attribute is only relevant if 'sizes' input is used.
-                // The shape constraints for 'sizes' are below:
-                if(last_arg_shape.type() == shape::int64_type and
-                   (last_arg_elements == args.front()->get_shape().ndim() or
-                    (is_axes_used() and last_arg_elements == r_attr.axes.size())))
-                {
-                    MIGRAPHX_THROW("PARSE_RESIZE: keep_aspect_ratio_policy is not supported!");
-                }
+                MIGRAPHX_THROW("PARSE_RESIZE: keep_aspect_ratio_policy=\"" +
+                               attr.at("keep_aspect_ratio_policy").s() +
+                               "\" is not supported (only \"stretch\" is accepted)");
             }
         }
 

test/onnx/gen_onnx.py

@@ -14248,6 +14248,9 @@ def resize_upsample_pc_test():
 
 @onnx_test()
 def resize_aspect_ratio_err_test():
+    # The 'stretch' policy is now accepted as a no-op (matches pre-Resize-18
+    # semantics already implemented). This negative test exercises a policy
+    # value that is still unsupported.
     sizes = np.array([1, 1, 3, 5], dtype=np.int64)
     size_tensor = helper.make_tensor(name='sizes',
                                       data_type=TensorProto.INT64,
@@ -14262,12 +14265,36 @@ def resize_aspect_ratio_err_test():
                                  outputs=['Y'],
                                  coordinate_transformation_mode='asymmetric',
                                  mode='nearest',
-                                 keep_aspect_ratio_policy='stretch',
+                                 keep_aspect_ratio_policy='not_larger',
                                  nearest_mode='ceil')
 
     return ([node], [X], [Y], [size_tensor])
 
 
+@onnx_test()
+def resize_aspect_ratio_stretch_test():
+    # 'stretch' is the Resize-18 default and matches pre-18 per-axis semantics.
+    # ORT injects it for opset-18 exports, so the parser must accept it as a no-op.
+    sizes = np.array([1, 1, 4, 8], dtype=np.int64)
+    size_tensor = helper.make_tensor(name='sizes',
+                                     data_type=TensorProto.INT64,
+                                     dims=sizes.shape,
+                                     vals=sizes.flatten().astype(np.int64))
+
+    X = helper.make_tensor_value_info('X', TensorProto.FLOAT, [1, 1, 2, 4])
+    Y = helper.make_tensor_value_info('Y', TensorProto.FLOAT, [1, 1, 4, 8])
+
+    node = onnx.helper.make_node('Resize',
+                                 inputs=['X', '', '', 'sizes'],
+                                 outputs=['Y'],
+                                 coordinate_transformation_mode='asymmetric',
+                                 mode='nearest',
+                                 keep_aspect_ratio_policy='stretch',
+                                 nearest_mode='floor')
+
+    return ([node], [X], [Y], [size_tensor])
+
+
 @onnx_test()
 def resize_invalid_mode_test():
     # Resize with unsupported mode "quadratic" should fail during parsing

test/onnx/parse/resize_aspect_ratio_stretch_test.cpp

@@ -0,0 +1,55 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015-2026 Advanced Micro Devices, Inc. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <onnx_test.hpp>
+
+TEST_CASE(resize_aspect_ratio_stretch_test)
+{
+    migraphx::program p;
+    auto* mm = p.get_main_module();
+
+    // These are from the ONNX file but not used by the 1-input resize
+    std::vector<int64_t> out_len = {1, 1, 4, 8};
+    migraphx::shape so{migraphx::shape::int64_type, {4}};
+    mm->add_literal(migraphx::literal(so, out_len));
+
+    migraphx::shape sx{migraphx::shape::float_type, {1, 1, 2, 4}};
+    auto inx = mm->add_parameter("X", sx);
+
+    mm->add_instruction(migraphx::make_op("undefined"));
+
+    // keep_aspect_ratio_policy="stretch" is accepted as a no-op: it is the
+    // Resize-18 default and matches the existing per-axis semantics.
+    auto r =
+        mm->add_instruction(migraphx::make_op("resize",
+                                              {{"sizes", {1, 1, 4, 8}},
+                                               {"nearest_mode", "floor"},
+                                               {"coordinate_transformation_mode", "asymmetric"}}),
+                            inx);
+    mm->add_return({r});
+
+    auto prog = read_onnx("resize_aspect_ratio_stretch_test.onnx");
+
+    EXPECT(p == prog);
+}