## Rationale
TIRx variables use inherited `ExprNode::ty` as their single semantic
type. Retaining a primitive handle surrogate erases the distinction
between scalar values, typed pointers, and true opaque pointers, then
forces later passes and code generators to reconstruct information that
the IR already owns.
## Changes
- Remove the duplicate reflected `Var::type_annotation` state and
preserve exact `PrimType` or `PointerType` through construction,
visitors, transforms, specialization, builders, printers, and code
generation.
- Keep scalar-only boundaries explicit through `PrimExpr`, `PrimVar`,
and `PrimType`; pointer-capable values remain general `Expr` or `Var`.
- Keep helper boundaries no broader than their contracts: TE tensor
variable indices use `PrimVar`, while expression deep equality recurses
through general `Expr` only where pointer-bearing `Call` arguments
require it and does not generalize private arithmetic subclasses.
- Keep core statement reflection typed as `Expr`, name general
reinterpret targets as `target_ty`, and preserve exact pointer calls in
the general vectorization path with explicit scalarization behavior.
- Delete `PrimType::Handle()` and `PrimType::IsHandle()`. True opaque
pointers use `PointerType::VoidPointerTy()`; TVMScript renders the
canonical global type as `T.handle`, standalone values as `T.handle()`,
and scoped void pointers with a keyword-only storage scope.
- Make `CodeGenSourceBase::SSAGetID` a single `Type` boundary across
source backends, without a separate primitive-type or runtime-dtype
variant.
- Keep WebGPU semantic argument classification type-aware: storage
buffers are identified from `PointerType`, POD arguments from
`PrimType`, and only the final `FunctionInfo` launch ABI is serialized
to `DLDataType`.
- Preserve exact pointer semantics at runtime boundaries, including
access pointers, packed calls and returns, external calls, storage
rewrites, and target-specific lowering.
## Migration guide
- **Variable types:** In C++, replace `var->type_annotation` with
`var->ty`; in Python, replace `var.type_annotation` with `var.ty`. The
result is the exact `Type`: scalar variables carry `PrimType`, while
pointer variables carry `PointerType`.
- **Scalar boundaries:** Use `PrimVar` and `PrimExpr` for variables and
expressions that are semantically scalar. When starting from a general
view, narrow explicitly with `var.as_or_throw<PrimVar>()` or
`expr.as_or_throw<PrimExpr>()`. Keep pointer-capable fields and call
arguments as `Var` or `Expr`. A default-constructed `PrimVar` is
nullable, so construct local scalar variables explicitly, for example
`PrimVar i("i")`.
- **Opaque pointers:** Replace `PrimType::Handle()` with
`PointerType::VoidPointerTy()`. Replace `IsHandle()` tests with explicit
`PointerType` inspection; use `PointerType(element_type, storage_scope)`
when the pointee type is known instead of erasing it to a runtime handle
dtype.
- **TVMScript handles:** Use `arg: T.handle` for a global void-pointer
annotation and `arg = T.handle()` for a standalone value. Use
`T.handle(storage_scope="shared")` for a scoped void pointer. Typed
pointers use forms such as `T.handle("float32")`, `T.handle("float32",
"global")`, or `T.handle("float32", "shared")`. Legacy
`T.handle("void")` input remains parse-compatible, but the printer
canonicalizes it to `T.handle` (or the keyword-only scoped form).
- The separate `tirx.type_annotation` intrinsic used by access-pointer
APIs is unchanged; this migration removes only the duplicate variable
field.
## Validation
- Complete native C++ test executable: 122/122 passed, including
`IRF.CountVar`.
- Relax binding-rewrite suite: 12/12 passed, including transferred-user
bookkeeping.
- Canonical typed/void/scoped TVMScript handle printer and round-trip
checks: 5/5 passed.
Tianqi Chen
adf8d6a463