onnx2webnn

ONNX → WebNN lowering crate extracted from webnn-graph. ONNX operators lower directly to rustnn MLGraphBuilder; full-graph validation runs via ORT CPU build() (onnx-runtime feature). There is no JSON IR and no on-disk graph export — success means builder.build() returns Ok(MLGraph).

Supported ONNX opset range: 11–18 (see MIN_SUPPORTED_OPSET / MAX_SUPPORTED_OPSET in src/onnx/convert.rs).

Build

cargo build
# or
cargo build --release

make build, make test, make fmt, and make check are defined in the repo Makefile.

Convert

cargo run -- convert --input model.onnx --optimize --override-dim batch_size=1

Dynamic ONNX inputs (unresolved symbolic dims kept as WebNN dynamic metadata):

cargo run -- convert --input model.onnx `
  --experimental-dynamic-inputs `
  --override-dim batch_size=1 `
  --override-dim sequence_length=1

If model.dims.json sits beside the ONNX file and no overrides were passed on the CLI, dimension bindings are loaded from that sidecar (freeDimensionOverrides or a flat JSON object).

Flag	Purpose
--input	Input .onnx path (required)
--optimize	Constant folding and shape propagation
--override-dim NAME=VALUE	Bind a symbolic dim (repeatable)
--override-dims-file	JSON overrides (freeDimensionOverrides or flat object)
--experimental-dynamic-inputs	Preserve unresolved symbolic dims as dynamic metadata
--debug	Verbose conversion logging (global)

On success the CLI prints ✓ ORT graph build succeeded for ….

Library API:

use onnx2webnn::{convert_onnx, ConvertOptions};

let graph = convert_onnx("model.onnx", ConvertOptions::default())?;

Layout

Path	Purpose
src/onnx/convert.rs	ONNX load, optional folding, lowering, ORT build()
src/onnx/builder.rs	OnnxBuilder — operand map and MLGraphBuilder bridge
src/onnx/builder_helpers.rs	Shared lowering helpers
src/onnx/shape_inference.rs	Static shape/type propagation
src/onnx/constant_folding.rs	Constant folding driver (with --optimize)
src/onnx/constant_folding/evaluators/	Per-op fold evaluators
src/onnx/ops/	ONNX op handlers (activation, conv, pool, reshape, …)
src/protos.rs	ONNX protobuf types
src/debug.rs	Debug logging toggle

Dependencies

• rustnn (../rustnn, onnx-runtime) — MLGraphBuilder, shape inference, ORT build() validation
• webnn-onnx-utils — ONNX protos, op names, data types

Related

• webnn-graph — DSL parser, validator, JS/HTML emit (source of the extracted lowering code)