[Issue]: Model compilation fails with more than one dynamic dimension specified

Problem description

MIGraphX fails to compile even simple models when more than one dynamic dimension is specified.

The compilation usually fails with this error message:

RuntimeError: src/shape.cpp:391: lens: SHAPE: lens() called on a dynamic shape

Also, the MIGRAPHX_ENABLE_FULL_DYNAMIC environment variable doesn't help whether or not it's set to 1.

Steps to reproduce

import math
import migraphx
import torch

EMBEDDING_COUNT = 32
EMBEDDING_DIM = 16
BATCH_SIZE = 4

torch.inference_mode(True)
torch.cuda.set_device("cuda:0")

model = torch.nn.Embedding(EMBEDDING_COUNT, EMBEDDING_DIM)
model.eval()
input_batch = torch.arange(math.ceil(EMBEDDING_COUNT / 2)).repeat(BATCH_SIZE, 1).contiguous()

torch.onnx.export(
    model,
    (input_batch,),
    "model.onnx",
    external_data=False,
    dynamo=True,
    dynamic_shapes=[
        {0: torch.export.Dim.DYNAMIC, 1: torch.export.Dim.DYNAMIC},
    ],
)

migraphx_model = migraphx.parse_onnx("model.onnx", map_dyn_input_dims={
    "input": [
        migraphx.shape.dynamic_dimension(1, BATCH_SIZE, {BATCH_SIZE}),
        migraphx.shape.dynamic_dimension(1, 64, {1}),
    ],
})
migraphx_model.compile(migraphx.get_target("gpu"), offload_copy=False)

We want to note that we've observed the same issue with larger models, but we've created this reproducer script with a single node for simpler analysis.

Environment

OS: Debian GNU/Linux 12 (bookworm)
CPU: AMD Ryzen 9 9950X
GPU: AMD Radeon AI PRO R9700
ROCm version: 7.2.1
MIGraphX version: 2.16.0.dev+20250912-17-406-gb91f1c0c0