axelera.runtime.postamble

The Postamble object handed to op.load (see the Postamble class).

Summary​

Postamble​

Names a fast kernel for op.load to run a model's postamble.

When a model is compiled, most of the network runs on the AIPU, but the compiler leaves a trailing piece as a small graph in the .axm (its postamble_graph): the model-specific decode or activation that turns the device's output into the model's declared results: for example YOLO box decoding, or a softmax. That graph is the postamble (the mirror of the preamble the compiler leaves in front of the network).

op.load runs the postamble on onnxruntime unless you hand it a Postamble naming a kernel to run in the graph's place. Two ways to feed that kernel, trading effort for speed:

• kernel=MyKernel: simplest. The runtime unpads the AIPU's raw output and dequantizes it to float tensors, and your kernel runs on those.
• fused_kernel=MyKernel: fastest. Your kernel is handed the AIPU's raw int8 output and does the unpad and dequantize itself, fused with the decode in one pass (how the built-in YOLO kernels avoid building large float tensors).

An empty Postamble() asks for the onnxruntime postamble and suppresses the automatic choice. Omitting the argument leaves that choice open, so a model whose .axm carries framework metadata gets the matching kernel from .optimized(). Those are different requests, which is why this class defines no __bool__: an empty Postamble is a statement of intent, not the absence of one, and code that tested it for truth would silently treat it as "no opinion".

Name the kernel as a class, as the bare name of a built-in kernel ('ClassificationPostamble'), or as a "module:ClassName" string for a kernel of your own, which op.load imports. A class is stored as its import path, so a Postamble always holds a name a generated recipe can import. Any **kwargs are the kernel's own parameters (e.g. num_classes), passed to it when it is built.

Raises:

• ValueError: if both kernel and fused_kernel are given; if kernel parameters are given with neither slot to receive them; or if a kernel class cannot be named importably (defined in __main__, or inside a function).

Constructor:

__init__(kernel: Any = None, fused_kernel: Any = None, **kwargs: Any)

Methods:

as_spec​

as_spec() -> dict[str, Any]

Return this Postamble as plain data, for a manifest or a recipe.

An empty Postamble is an empty mapping, not an absent one: the two are different requests, and only the caller's own choice belongs in a package.

classmethod from_spec​

from_spec(spec: dict[str, Any]) -> Postamble

Rebuild a Postamble from as_spec output.