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Parser utilities
================

A few helpers act at **parse time** (when TVMScript is turned into TIRx), letting
you inline Python-computed values, factor out reusable fragments, and bundle
parser-side state.

``T.meta_var`` — inline a Python value
--------------------------------------

``T.meta_var(x)`` tells the parser to treat ``x`` — a value computed in **Python** —
as a compile-time *meta* value and inline it directly into the IR, rather than
parse it as a script variable. It avoids a throwaway local, and it drives
metaprogramming: a plain Python ``for`` over a meta value unrolls in the parser.

.. code-block:: python

    n = T.meta_var(4)              # n is a Python int, inlined
    for j in range(n):            # unrolled at parse time
        acc[0] = acc[0] + A[tx, j]

``@T.inline`` — inline functions
--------------------------------

``@T.inline`` defines a function whose body is **inlined at each call site** during
parsing — no call appears in the generated code. It follows Python's lexical (LEGB)
scoping with late binding, so a parameter shadows an enclosing variable:

.. code-block:: python

    @T.inline
    def add_into(acc, x):
        acc[0] = acc[0] + x

    add_into(s.acc, A[tx, j])     # inlined -> s.acc[0] = s.acc[0] + A[tx, j]

``@T.meta_class`` — parser-side state objects
---------------------------------------------

``@T.meta_class`` marks a plain Python class whose **instances are parser meta
values**: their fields can hold buffers and scalars, so you can bundle related
allocations and state into one object and use it in the kernel body.

.. code-block:: python

    @T.meta_class
    class State:
        def __init__(self, smem):
            self.acc = T.alloc_local([1], "float32")
            self.buf = T.decl_buffer([64], "float16", smem, scope="shared.dyn")

    s = State(smem.data)
    s.acc[0] = T.float32(0.0)     # use its fields like ordinary buffers
    # ... s.buf[i] ...

This is handy for grouping a kernel's pipeline state (barriers, accumulators,
scratch views) instead of threading many separate locals through the body.

``T.constexpr``
---------------

``T.constexpr`` marks a compile-time kernel parameter, baked in by ``@T.jit``'s
``.specialize(...)``. See :doc:`functions` for the details.