Codegen

Concept

Code generation turns resolved HwStmt IR into concrete kernel files and hook stubs. The output is deterministic: every run rewrites <kernel>.hpp and <kernel>.cpp, while hook impl files are sticky unless missing.

The emitter handles C++ type lowering, top-level function signatures, namespace-qualified hook calls, and variant naming. Top kernels are emitted as concrete functions suitable for Vitis entry points.

API

• kernel_files_to_str(comp_class, output_dir=".", impl_dir=None) returns generated file contents.
• HlsCodegenStep writes generated files into the build output.
• cpp_kernel_name(comp_class) derives kernel names.
• resolved_namespace(comp_class) resolves hook namespace behavior.

Example

From examples/stream_inband/poly_build.py, HlsCodegenStep is used in the build DAG to emit poly.hpp, poly.cpp, and impl stubs:

inner_dag.add(HlsCodegenStep(
    comp_class=PolyAccelComponent,
    source_artifact="source_dir",
    output_dir="gen",
    impl_dir="gen",
))

Generated files include kernel signatures and stream/regmap mappings based on the component endpoints.

Quick reference

• File set: .hpp, .cpp, and per-hook _impl.{cpp,tpp}.
• .tpp is used when hook template params are required.
• impl_dir files are created only when absent (sticky lifecycle).
• Stale .cpp/.tpp extension mismatches are treated as errors.
• Kernel top functions remain global; hook functions may be namespaced.