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apache--tvm/python/tvm/tir/buffer.py
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albert qing 7710dfd557 [TIR] Get read/write access precisely for opaque access. (#11110)
* [TIR] Get read/write access precisely for opaque access.

When the opaque access is wrapped with tvm_access_ptr, we can get the access_mask
from tvm_access_ptr in BlockReadWriteDetector and put this opaque access to read_regions
or write_regions according to access_mask.

* [TIR] Add parameter extent for access_ptr.

Co-authored-by: sqing <qing.siqi@intellif.com>
2022-04-28 21:00:29 +08:00

326 lines
11 KiB
Python

# Licensed to the Apache Software Foundation (ASF) under one
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# to you under the Apache License, Version 2.0 (the
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#
# http://www.apache.org/licenses/LICENSE-2.0
#
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# KIND, either express or implied. See the License for the
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"""Abstraction for array data structures."""
from numbers import Integral
import tvm._ffi
from tvm._ffi.base import string_types
from tvm.runtime import Object, convert
from tvm.ir import PrimExpr, PointerType, PrimType
from . import _ffi_api
@tvm._ffi.register_object("tir.Buffer")
class Buffer(Object):
"""Symbolic data buffer in TVM.
Buffer provide a way to represent data layout
specialization of data structure in TVM.
Do not construct directly, use :py:func:`~decl_buffer` instead.
See the documentation of :py:func:`decl_buffer` for more details.
See Also
--------
decl_buffer : Declare a buffer
"""
READ = 1
WRITE = 2
def access_ptr(self, access_mask, ptr_type="handle", content_lanes=1, offset=0, extent=None):
"""Get an access pointer to the head of buffer.
This is the recommended method to get buffer data
ptress when interacting with external functions.
Parameters
----------
access_mask : int
The access pattern MASK. Indicate whether the
access will read or write to the data content.
ptr_type : str, optional
The data type of the result pointer. Do not specify
unless we want to cast pointer to specific type.
content_lanes: int, optional
The number of lanes for the data type. This value
is greater than one for vector types.
offset: Expr, optional
The offset of pointer. We can use it to offset by
the number of elements from the address of ptr.
extent: Expr, optional
The extent of pointer.
Examples
--------
.. code-block:: python
# Get access ptr for read
buffer.access_ptr("r")
# Get access ptr for read/write with bitmask
buffer.access_ptr(Buffer.READ | Buffer.WRITE)
# Get access ptr for read/write with str flag
buffer.access_ptr("rw")
# Get access ptr for read with offset
buffer.access_ptr("r", offset = 100)
# Get access ptr for read with extent
buffer.access_ptr("r", extent = 100)
"""
if isinstance(access_mask, string_types):
mask = 0
for value in access_mask:
if value == "r":
mask = mask | Buffer.READ
elif value == "w":
mask = mask | Buffer.WRITE
else:
raise ValueError("Unknown access_mask %s" % access_mask)
access_mask = mask
offset = convert(offset)
extent = convert(extent)
return _ffi_api.BufferAccessPtr(
self, access_mask, ptr_type, content_lanes, offset, extent # type: ignore
)
def vload(self, begin, dtype=None):
"""Generate an Expr that loads dtype from begin index.
Parameters
----------
begin : Array of Expr
The beginning index in unit of Buffer.dtype
dtype : str
The data type to be loaded,
can be vector type which have lanes that is multiple of Buffer.dtype
Returns
-------
load : Expr
The corresponding load expression.
"""
begin = (begin,) if isinstance(begin, (int, PrimExpr)) else begin
dtype = dtype if dtype else self.dtype
return _ffi_api.BufferVLoad(self, begin, dtype) # type: ignore
def vstore(self, begin, value):
"""Generate a Stmt that store value into begin index.
Parameters
----------
begin : Array of Expr
The beginning index in unit of Buffer.dtype
value : Expr
The value to be stored.
Returns
-------
store : Stmt
The corresponding store stmt.
"""
begin = (begin,) if isinstance(begin, (int, PrimExpr)) else begin
return _ffi_api.BufferVStore(self, begin, value) # type: ignore
def scope(self):
"""Return the storage scope associated with this buffer.
Returns
-------
scope : str
The storage scope associated with this buffer.
"""
return _ffi_api.BufferStorageScope(self) # type: ignore
def get_flattened_buffer(self):
"""Generate a Buffer that is a flattened version of this buffer.
Returns
-------
flattened : Buffer
The corresponding flat buffer.
"""
return _ffi_api.BufferGetFlattenedBuffer(self) # type: ignore
def offset_of(self, indices):
"""Determine the offset of the provided indices in the flattened buffer.
Parameters
----------
indices : Union[PrimExpr, List[PrimExpr]]
The indices of the element in the original buffer.
Returns
-------
flattened_indices: List[PrimExpr]
The offset indices of the element in the flattened buffer.
"""
return _ffi_api.BufferOffsetOf(self, indices) # type: ignore
def decl_buffer(
shape,
dtype=None,
name="buffer",
data=None,
strides=None,
elem_offset=None,
scope="",
data_alignment=-1,
offset_factor=0,
buffer_type="",
axis_separators=None,
span=None,
):
"""Declare a new symbolic buffer.
Normally buffer is created automatically during lower and build.
This is only needed if user want to specify their own buffer layout.
See the note below for detailed discussion on usage of buffer.
Parameters
----------
shape : tuple of Expr
The shape of the buffer.
dtype : str, optional
The data type of the buffer.
name : str, optional
The name of the buffer.
data : Var, optional
The data pointer in the buffer.
strides: array of Expr
The stride of the buffer.
elem_offset: Expr, optional
The beginning offset of the array to data.
In terms of number of elements of dtype.
scope: str, optional
The storage scope of the buffer, if not global.
If scope equals empty string, it means it is global memory.
data_alignment: int, optional
The alignment of data pointer in bytes.
If -1 is passed, the alignment will be set to TVM's internal default.
offset_factor: int, optional
The factor of elem_offset field, when set,
elem_offset is required to be multiple of offset_factor.
If 0 is pssed, the alignment will be set to 1.
if non-zero is passed, we will created a Var for elem_offset if elem_offset is not None.
buffer_type: str, optional, {"", "auto_broadcast"}
auto_broadcast buffer allows one to implement broadcast computation
without considering whether dimension size equals to one.
TVM maps buffer[i][j][k] -> buffer[i][0][k] if dimension j's shape equals 1.
axis_separators : list of int, optional
If passed, a list of separators between groups of axes,
each of which is flattened to an output axis. For flat
memory spaces, should either be None, or an empty list.
span: Optional[Span]
The location of the decl_buffer creation in the source.
Returns
-------
buffer : tvm.tir.Buffer
The created buffer
Example
-------
Here's an example of how broadcast buffer can be used to define a symbolic broadcast operation,
.. code-block:: python
m0, m1, m2 = te.var("m0"), te.var("m1"), te.var("m2")
n0, n1, n2 = te.var("n0"), te.var("n1"), te.var("n2")
o0, o1, o2 = te.var("o0"), te.var("o1"), te.var("o2")
A = te.placeholder((m0, m1, m2), name='A')
B = te.placeholder((n0, n1, n2), name='B')
C = te.compute((o0, o1, o2), lambda i, j, k: A[i, j, k] + B[i, j, k], name='C')
Ab = tvm.tir.decl_buffer(A.shape, A.dtype, name="Ab", buffer_type="auto_broadcast")
Bb = tvm.tir.decl_buffer(B.shape, B.dtype, name="Bb", buffer_type="auto_broadcast")
s = te.create_schedule(C.op)
fadd = tvm.build(s, [A, B, C], target='llvm', name='bcast_add', binds={A:Ab, B:Bb})
dev = tvm.cpu(0)
a = tvm.nd.array(np.random.uniform(size=(2, 4, 3)).astype(A.dtype), dev)
b = tvm.nd.array(np.random.uniform(size=(2, 1, 3)).astype(B.dtype), dev)
c = tvm.nd.array(np.zeros((2, 4, 3), dtype=C.dtype), dev)
fadd(a, b, c)
tvm.testing.assert_allclose(c.numpy(), a.numpy() + b.numpy())
Note
----
Buffer data structure reflects the DLTensor structure in dlpack.
While DLTensor data structure is very general, it is usually helpful
to create function that only handles specific case of data structure
and make compiled function benefit from it.
If user pass strides and elem_offset is passed as None
when constructing the function, then the function will be specialized
for the DLTensor that is compact and aligned.
If user pass a fully generic symbolic array to the strides,
then the resulting function becomes fully generic.
"""
# pylint: disable=import-outside-toplevel
from .expr import Var
shape = (shape,) if isinstance(shape, (PrimExpr, Integral)) else shape
dtype = "float32" if dtype is None else dtype
strides = () if strides is None else strides
if axis_separators is None:
axis_separators = []
if offset_factor != 0 and elem_offset is None:
shape_dtype = shape[0].dtype if shape and hasattr(shape[0], "dtype") else "int32"
elem_offset = Var("%s_elem_offset" % name, shape_dtype)
if data is None:
# Bool is represented as uint1 in the IR, but stored as int8
storage_type = PrimType(dtype)
storage_type = PrimType("int8") if storage_type.dtype == "bool" else storage_type
data = Var(name, PointerType(storage_type, scope), span)
return _ffi_api.Buffer( # type: ignore
data,
dtype,
shape,
strides,
elem_offset,
name,
data_alignment,
offset_factor,
buffer_type,
axis_separators,
span,
)
@tvm._ffi.register_object("tir.DataProducer")
class DataProducer(Object):
pass