One-Shot Bufferize currently does not support loops where a yielded
value bufferizes to a buffer that is different from the buffer of the
region iter_arg. In such a case, the bufferization fails with an error
such as:
```
Yield operand #0 is not equivalent to the corresponding iter bbArg
scf.yield %0 : tensor<5xf32>
```
One common reason for non-equivalent buffers is that an op on the path
from the region iter_arg to the terminator bufferizes out-of-place. Ops
that are analyzed earlier are more likely to bufferize in-place.
This commit adds a new heuristic that gives preference to ops that are
reachable on the reverse SSA use-def chain from a region terminator and
are within the parent region of the terminator. This is expected to work
better than the existing heuristics for loops where an iter_arg is
written to multiple times within a loop, but only one write is fed into
the terminator.
Current users of One-Shot Bufferize are not affected by this change.
"Bottom-up" is still the default heuristic. Users can switch to the new
heuristic manually.
This commit also turns the "fuzzer" pass option into a heuristic,
cleaning up the code a bit.
Cyclic function call graphs are generally not supported by One-Shot
Bufferize. However, they can be allowed when a function does not have
tensor arguments or results. This is because it is then no longer
necessary that the callee will be bufferized before the caller.
This commit removes the deallocation capabilities of
one-shot-bufferization. One-shot-bufferization should never deallocate
any memrefs as this should be entirely handled by the
ownership-based-buffer-deallocation pass going forward. This means the
`allow-return-allocs` pass option will default to true now,
`create-deallocs` defaults to false and they, as well as the escape
attribute indicating whether a memref escapes the current region, will
be removed. A new `allow-return-allocs-from-loops` option is added as a
temporary workaround for some bufferization limitations.
This reverts commit 6a91dfedeb956dfa092a6a3f411e8b02f0d5d289.
This caused problems in downstream projects. We are reverting to give
them more time for integration.
This is the first commit in a series with the goal to rework the
BufferDeallocation pass. Currently, this pass heavily relies on copies
to perform correct deallocations, which leads to very slow code and
potentially high memory usage. Additionally, there are unsupported cases
such as returning memrefs which this series of commits aims to add
support for as well.
This first commit removes the deallocation capabilities of
one-shot-bufferization.One-shot-bufferization should never deallocate any
memrefs as this should be entirely handled by the buffer-deallocation pass
going forward. This means the allow-return-allocs pass option will
default to true now, create-deallocs defaults to false and they, as well
as the escape attribute indicating whether a memref escapes the current region,
will be removed.
The documentation should w.r.t. these pass option changes should also be
updated in this commit.
Reviewed By: springerm
Differential Revision: https://reviews.llvm.org/D156662
This revision adds support for unstructured control flow to the bufferization infrastructure. In particular: regions with multiple blocks, `cf.br`, `cf.cond_br`.
Two helper templates are added to `BufferizableOpInterface.h`, which can be implemented by ops that supported unstructured control flow in their regions (e.g., `func.func`) and ops that branch to another block (e.g., `cf.br`).
A block signature is always bufferized together with the op that owns the block.
Differential Revision: https://reviews.llvm.org/D158094
To keep the pass simple, users should apply cleanup passes manually when necessary. In particular, `-cse -canonicalize` are often desireable to fold away self-copies that are created by the bufferization.
This addresses a comment in D120191.
Differential Revision: https://reviews.llvm.org/D155923
bufferization.to_memref ops are allowed in One-Shot Bufferize, but they are treated conservatively: in the absence of a memref analysis, we have to assume that the result buffer is read and written.
Note: to_memref cannot introduce any future aliases that would have to be considered during One-Shot Bufferize, because only to_tensor ops with the `restrict` attribute are supported. Such tensors are guaranteed to not alias with any other buffer after bufferization.
Differential Revision: https://reviews.llvm.org/D153365
The current bufferization on function boundaries works on `func.func`
and any call op implementing `CallOpInterface`. Then, an error is thrown
if there is a `CallOpInterface` op that is not `func.call`. This is
unnecessary and breaks the pass whenever such an op occurs (such as
`llvm.call`). This PR simply restricts the handling of call ops to
`func.call`.
Reviewed By: springerm
Differential Revision: https://reviews.llvm.org/D143724
Unranked tensors can currently not be copied. They are forced to always bufferize in-place. There is typically some other OpOperand that can bufferize out-of-place instead if needed.
Note: There is IR that cannot be bufferized with One-Shot Bufferize at the moment (see invalid test case). But it is unclear if we need to support such cases. We do not have a use case at the moment. This restriction could be loosened in the future if needed.
This change improves error handling when bufferizing IR where an unranked tensor would be copied. It also disables an optimization where an OpResult was copied instead of an OpOperand in case the OpResult is an unranked tensor (Github #60187).
Differential Revision: https://reviews.llvm.org/D142331
While it is unlikely to matter in practice, there is no reason
for this value to be larger than it should be. 64 bytes is the
size of a cache line in most machines, and we can fit a full
512-bit vector in it.
Reviewed By: springerm
Differential Revision: https://reviews.llvm.org/D139434
One of the test cases matched IR from a subsequent test case. For this reason, the test case appeared to pass while it is actually broken.
This change does not fix the test case itself. It will be fixed when we overhaul the buffer deallocation implementation. (The memory leak in this test case is an edge case.)
Differential Revision: https://reviews.llvm.org/D135046
Bufferization already makes the assumption that buffers pass function
boundaries in the strided form and uses the corresponding affine map layouts.
Switch it to use the recently introduced strided layout instead to avoid
unnecessary casts when bufferizing further operations to the memref dialect
counterparts that now largely rely on the strided layout attribute.
Depends On D133947
Reviewed By: nicolasvasilache
Differential Revision: https://reviews.llvm.org/D133951
Memref subview operation has been initially designed to work on memrefs with
strided layouts only and has never supported anything else. Port it to use the
recently added StridedLayoutAttr instead of extracting the strided from
implicitly from affine maps.
Reviewed By: nicolasvasilache
Differential Revision: https://reviews.llvm.org/D133938
This change changes the bufferization so that it utilizes the new TensorCopyInsertion pass. One-Shot Bufferize no longer calls the One-Shot Analysis. Instead, it relies on the TensorCopyInsertion pass to make the entire IR fully inplacable. The `bufferize` implementations of all ops are simplified; they no longer have to account for out-of-place bufferization decisions. These were already materialized in the IR in the form of `bufferization.alloc_tensor` ops during the TensorCopyInsertion pass.
Differential Revision: https://reviews.llvm.org/D127652
This simplifies the bufferization itself and is in preparation of connecting with the sparse compiler.
Differential Revision: https://reviews.llvm.org/D126814
No longer pass static dim sizes as an attribute. This was redundant and required extra checks in the verifier. This change also makes the op symmetrical to memref::AllocOp.
Differential Revision: https://reviews.llvm.org/D126178
This change adds a new op `alloc_tensor` to the bufferization dialect. During bufferization, this op is always lowered to a buffer allocation (unless it is "eliminated" by a pre-processing pass). It is useful to have such an op in tensor land, because it allows users to model tensor SSA use-def chains (which drive bufferization decisions) and because tensor SSA use-def chains can be analyzed by One-Shot Bufferize, while memref values cannot.
This change also replaces all uses of linalg.init_tensor in bufferization-related code with bufferization.alloc_tensor.
linalg.init_tensor and bufferization.alloc_tensor are similar, but the purpose of the former one is just to carry a shape. It does not indicate a memory allocation.
linalg.init_tensor is not suitable for modelling SSA use-def chains for bufferization purposes, because linalg.init_tensor is marked as not having side effects (in contrast to alloc_tensor). As such, it is legal to move linalg.init_tensor ops around/CSE them/etc. This is not desirable for alloc_tensor; it represents an explicit buffer allocation while still in tensor land and such allocations should not suddenly disappear or get moved around when running the canonicalizer/CSE/etc.
BEGIN_PUBLIC
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END_PUBLIC
Differential Revision: https://reviews.llvm.org/D126003
This changes replaces the `fully-dynamic-layout-maps` options (which was badly named) with two new options:
* `unknown-type-conversion` controls the layout maps on buffer types for which no layout map can be inferred.
* `function-boundary-type-conversion` controls the layout maps on buffer types inside of function signatures.
Differential Revision: https://reviews.llvm.org/D125615
The names of the functions that are supposed to be exported do not match the implementations. This is due in part to cac7aabbd8.
This change makes the implementations and declarations match and adds a couple missing declarations.
The new names follow the pattern of the existing `verify` functions where the prefix is maintained as `_mlir_ciface_` but the suffix follows the new naming convention.
Reviewed By: rriddle
Differential Revision: https://reviews.llvm.org/D124891
* Move Module Bufferization to the bufferization dialect. The implementation is split into `OneShotModuleBufferize.cpp` and `FuncBufferizableOpInterfaceImpl.cpp`, so that the external model implementation can be easily moved to the func dialect in the future.
* Split and clean up test cases. A few test cases are still remaining in Linalg and will be updated separately.
* `linalg.inplaceable` is renamed to `bufferization.writable` to accurately reflect its current usage.
* Attributes and their verifiers are moved from the Linalg dialect to the Bufferization dialect.
* Expand documentation.
* Add a new flag to One-Shot Bufferize to allow for function boundary bufferization.
Differential Revision: https://reviews.llvm.org/D122229
