tvm_ffi.dtype

class tvm_ffi.dtype(content)

Bases: str

Lightweight data type in TVM FFI.

It behaves like a Python str but also carries an internal FFI representation. You can construct it from strings, NumPy/ML dtypes, or via from_dlpack_data_type().

Parameters:

• dtype_str – The string representation of the dtype.

• content (Any)

Return type:

dtype

Examples

import tvm_ffi

# Create from string
f32 = tvm_ffi.dtype("float32")
assert f32.bits == 32
assert f32.itemsize == 4

# Adjust lanes to create vector types
v4f32 = f32.with_lanes(4)
assert v4f32 == "float32x4"

# Round-trip from a DLPack (code, bits, lanes) triple
f16 = tvm_ffi.dtype.from_dlpack_data_type((2, 16, 1))
assert f16 == "float16"

Note

This class subclasses str so it can be directly passed into other array api’s dtype arguments.

__init__()

Methods

from_dlpack_data_type(dltype_data_type)	Create a dtype from a DLPack data type tuple.
with_lanes(lanes)	Create a new dtype with the given number of lanes.

Attributes

bits	Number of bits of the scalar base type.
itemsize	Size of one element in bytes.
lanes	Number of lanes (for vector types).
type_code	Integer DLDataTypeCode of the scalar base type.

static from_dlpack_data_type(dltype_data_type)

Create a dtype from a DLPack data type tuple.

Parameters:

dltype_data_type (tuple[int, int, int]) – The DLPack data type tuple (type_code, bits, lanes).

Return type:

dtype

Returns:

dtype – The created dtype.

Examples

import tvm_ffi

# Create float16 and int8 directly from DLPack triples
f16 = tvm_ffi.dtype.from_dlpack_data_type((2, 16, 1))
i8 = tvm_ffi.dtype.from_dlpack_data_type((0, 8, 1))
assert f16 == "float16"
assert i8 == "int8"

See also

tvm_ffi.dtype

User-facing dtype wrapper.

tvm_ffi.dtype.with_lanes()

Create vector dtypes from a scalar base.

with_lanes(lanes)

Create a new dtype with the given number of lanes.

Parameters:

lanes (int) – The number of lanes for the resulting vector type.

Return type:

dtype

Returns:

dtype – The new dtype with the given number of lanes.

Examples

import tvm_ffi

f32 = tvm_ffi.dtype("float32")
v4f32 = f32.with_lanes(4)
assert v4f32 == "float32x4"
assert v4f32.bits == f32.bits and v4f32.lanes == 4

See also

tvm_ffi.dtype.from_dlpack_data_type()

Construct from a DLPack (code, bits, lanes) triple.

property itemsize: int

Size of one element in bytes.

The size is computed as bits * lanes // 8. When the number of lanes is greater than 1, the itemsize represents the byte size of the vector element.

Examples

import tvm_ffi

assert tvm_ffi.dtype("float32").itemsize == 4
assert tvm_ffi.dtype("float32").with_lanes(4).itemsize == 16

See also

tvm_ffi.dtype.bits

Bit width of the scalar base type.

tvm_ffi.dtype.lanes

Number of lanes for vector types.

tvm_ffi.dtype.with_lanes()

Create a vector dtype from a scalar base.

property type_code: int

Integer DLDataTypeCode of the scalar base type.

Examples

import tvm_ffi

f32 = tvm_ffi.dtype("float32")
# The type code is an integer following DLPack conventions
assert isinstance(f32.type_code, int)
# Consistent with constructing from an explicit (code, bits, lanes)
assert f32.type_code == tvm_ffi.dtype.from_dlpack_data_type((2, 32, 1)).type_code

See also

tvm_ffi.dtype.from_dlpack_data_type()

Construct a dtype from a DLPack (code, bits, lanes) triple.

property bits: int

Number of bits of the scalar base type.

Examples

import tvm_ffi

assert tvm_ffi.dtype("int8").bits == 8
v4f32 = tvm_ffi.dtype("float32").with_lanes(4)
assert v4f32.bits == 32  # per-lane bit width

See also

tvm_ffi.dtype.itemsize

Byte size accounting for lanes.

tvm_ffi.dtype.lanes

Number of lanes for vector types.

property lanes: int

Number of lanes (for vector types).

Returns 1 for scalar dtypes and the lane count for vector dtypes created via tvm_ffi.dtype.with_lanes().

Examples

import tvm_ffi

assert tvm_ffi.dtype("float32").lanes == 1
assert tvm_ffi.dtype("float32").with_lanes(4).lanes == 4

See also

tvm_ffi.dtype.with_lanes()

Create a vector dtype from a scalar base.

tvm_ffi.dtype.itemsize

Byte size accounting for lanes.