Backend Internals

Backend Internals#

TIRx keeps the core IR and compiler machinery under tvm.tirx. A target backend owns its script namespaces, intrinsic builders, dispatch variants, pipeline additions, and code-generation support under tvm.backend.

Loading and registration#

tvm.backend.load imports a backend and calls its registration hook. A backend can register the following target-owned behavior:

  1. TVMScript namespaces such as Tx.cuda, Tx.ptx, and Tx.nki;

  2. tile-primitive dispatch implementations for that target kind;

  3. target tags and, when the target owns one, compilation-pipeline entry points; and

  4. code-generation helpers that translate backend calls to target source.

Registration imports some modules only for their side effects. Those modules are implementation surfaces, not additional kernel-authoring APIs.

CUDA ownership#

tvm.backend.cuda is divided by compiler responsibility:

Module

Responsibility

script and ptx

Construct the Tx.cuda, Tx.ptx, compatibility, and NVSHMEM namespaces.

op

Define IR builders used by the CUDA script namespaces.

tile

Register named Tx.cuda.tile instruction contracts and lowerers.

codegen and cpp

Register source-generation callbacks and CUDA C++ helpers.

transforms

Provide CUDA-specific compiler passes.

target_tags

Register named NVIDIA targets.

lang and iket

Provide reusable kernel utilities and profiling orchestration.

The PTX namespace is table-driven. A table entry defines the legal modifier and operand forms; construction creates a tirx.ptx.* call, and CUDA codegen emits the corresponding instruction. See Direct PTX Instructions for the supported public forms.

Trainium ownership#

tvm.backend.trn follows the same boundary. script and op construct the Tx.nki surface, tensor_instructions registers Tx.trn.tile instruction contracts, layout and transform lower Trainium-specific memory mappings, and pipeline assembles the Trainium pass sequence. target_tags registers the named AWS Trainium targets.

Public integration hooks are listed in Backend Extension API; target-facing CUDA and Trainium utilities are listed in CUDA Authoring and Support APIs and Trainium Authoring and Support APIs.

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