## Summary
Restructure TVMScript to be dialect-agnostic at the script-core layer
while letting each extension dialect (TIRX, Relax) own its own
per-dialect script subtree. IR is below script in the dependency
stack and is NOT a peer dialect — its script handlers stay in the
shared core.
This PR folds together two coupled refactors that were initially
opened as separate PRs (#19478 and the original #19479); they
share rename / relocation surface so they ship as one cohesive
change.
## What this PR does
### Per-dialect script subtree (originally #19479)
- Moves per-dialect printer + builder from
`src/script/{printer,ir_builder}/{tirx,relax}/` to
`src/{tirx,relax}/script/{printer,builder}/`.
- Tightens `src/script/*.cc` CMake glob to the dialect-free core.
- Refactors `IRBuilder::DeclFunction` to dispatch via FFI registry
(`script.ir_builder.decl_function.<type-key>`); removes
cross-dialect includes from the shared core.
- Adds `tvm.script.register_dialect` API + `__getattr__` + a
`sys.meta_path` finder for Python-side dialect discovery.
In-tree dialects (tirx, relax) registered centrally in
`python/tvm/__init__.py`.
- Drops the obsolete static re-export shims at
`python/tvm/script/{parser,ir_builder}/{tirx,relax}/`.
### Dialect-agnostic printer config (originally #19478)
- Relocates `include/tvm/ir/script_printer.h` →
`include/tvm/script/printer/config.h` next to the rest of the
printer's public surface. The header is not IR-specific.
- Renames `TVM_SCRIPT_REPR` → `TVM_REGISTER_SCRIPT_AS_REPR` for
clarity (the macro registers Script as the kRepr callback +
per-type vtable dispatch). Aligns with the `TVM_REGISTER_*`
family.
- Drops dialect-hardcoded `PrinterConfig` fields (`tir_prefix`,
`relax_prefix`, `show_all_struct_info`, `buffer_dtype`) in favor
of a generic `ffi::Map<String, Any> extra_config` keyed by
`"<dialect>.<knob>"`. Each call site reads via the templated
accessor `config->GetExtraConfig<T>("...", default)`.
- Promotes `std::string` config fields to `ffi::String`.
After this lands, the script-printer core knows nothing specific
about any dialect — new dialects plug in via the registry pattern
with zero core edits. Public Python API surface unchanged.
Tianqi Chen
7504e3ed1a