The greedy pattern rewriter consists of two nested loops. `config.maxIterations` (which configurable on the CanonicalizerPass) controls the maximum number of iterations of the outer loop.
```
/// This specifies the maximum number of times the rewriter will iterate
/// between applying patterns and simplifying regions. Use `kNoLimit` to
/// disable this iteration limit.
int64_t maxIterations = 10;
```
This change adds `config.maxNumRewrites` which controls the maximum number of pattern rewrites within an iteration. (It effectively control the maximum number of iterations of the inner loop.)
This flag is meant for debugging and useful in cases where one or multiple faulty patterns can be applied indefinitely, resulting in an infinite loop.
Differential Revision: https://reviews.llvm.org/D140525
This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
Ops that were modifed in-place (`finalizeRootUpdate` was called) should be reprocessed by the GreedyPatternRewriter. This is currently not happening with `GreedyRewriteConfig::maxIterations = 1`.
Note: If your project goes into an infinite loop because of this change, you likely have one or multiple faulty patterns that modify the same operations in-place (`updateRootInplace`) indefinitely.
Differential Revision: https://reviews.llvm.org/D138038
The methods in `SideEffectUtils.h` (and their implementations in
`SideEffectUtils.cpp`) seem to have similar intent to methods already
existing in `SideEffectInterfaces.h`. Move the decleration (and
implementation) from `SideEffectUtils.h` (and `SideEffectUtils.cpp`)
into `SideEffectInterfaces.h` (and `SideEffectInterface.cpp`).
Also drop the `SideEffectInterface::hasNoEffect` method in favor of
`mlir::isMemoryEffectFree` which actually recurses into the operation
instead of just relying on the `hasRecursiveMemoryEffectTrait`
exclusively.
Differential Revision: https://reviews.llvm.org/D137857
Up until now PDL(L) has not supported dialect conversion because we had no
way of remapping values or integrating with type conversions. This commit
rectifies that by adding a new "pattern configuration" concept to PDL. This
essentially allows for attaching external configurations to patterns, which
can hook into pattern events (for now just the scope of a rewrite, but we
could also pass configs to native rewrites as well). This allows for injecting
the type converter into the conversion pattern rewriter.
Differential Revision: https://reviews.llvm.org/D133142
Without the llvm_unreachable, Windows complains about not returning a
value from mlir::isSpeculatable on all paths.
Differential Revision: https://reviews.llvm.org/D135899
This change allows analyzing ops from different block, in particular when used in programs that have `cf` branches.
Differential Revision: https://reviews.llvm.org/D135644
This patch takes the first step towards a more principled modeling of undefined behavior in MLIR as discussed in the following discourse threads:
1. https://discourse.llvm.org/t/semantics-modeling-undefined-behavior-and-side-effects/4812
2. https://discourse.llvm.org/t/rfc-mark-tensor-dim-and-memref-dim-as-side-effecting/65729
This patch in particular does the following:
1. Introduces a ConditionallySpeculatable OpInterface that dynamically determines whether an Operation can be speculated.
2. Re-defines `NoSideEffect` to allow undefined behavior, making it necessary but not sufficient for speculation. Also renames it to `NoMemoryEffect`.
3. Makes LICM respect the above semantics.
4. Changes all ops tagged with `NoSideEffect` today to additionally implement ConditionallySpeculatable and mark themselves as always speculatable. This combined trait is named `Pure`. This makes this change NFC.
For out of tree dialects:
1. Replace `NoSideEffect` with `Pure` if the operation does not have any memory effects, undefined behavior or infinite loops.
2. Replace `NoSideEffect` with `NoSideEffect` otherwise.
The next steps in this process are (I'm proposing to do these in upcoming patches):
1. Update operations like `tensor.dim`, `memref.dim`, `scf.for`, `affine.for` to implement a correct hook for `ConditionallySpeculatable`. I'm also happy to update ops in other dialects if the respective dialect owners would like to and can give me some pointers.
2. Update other passes that speculate operations to consult `ConditionallySpeculatable` in addition to `NoMemoryEffect`. I could not find any other than LICM on a quick skim, but I could have missed some.
3. Add some documentation / FAQs detailing the differences between side effects, undefined behavior, speculatabilty.
Reviewed By: rriddle, mehdi_amini
Differential Revision: https://reviews.llvm.org/D135505
This is much more explicit, and prevents annoying conflicts with op
specific accessors (which may have a different contract). This is similar
to the past rename of getType -> getFunctionType,
Fixes#58030
Differential Revision: https://reviews.llvm.org/D135007
It is useful for PatternRewriter listeners to know the values that are
replacing the op in addition to only the fact of the op being replaced
for being able to keep track of changes or for debugging.
Reviewed By: Mogball
Differential Revision: https://reviews.llvm.org/D134748
I'm planning to deprecate and eventually remove llvm::empty.
Note that no use of llvm::empty requires the ability of llvm::empty to
determine the emptiness from begin/end only.
This change add a helper function for computing a topological sorting of a list of ops. E.g. this can be useful in transforms where a subset of ops should be cloned without dominance errors.
The analysis reuses the existing implementation in TopologicalSortUtils.cpp.
Differential Revision: https://reviews.llvm.org/D131669
Added a commutativity utility pattern and a function to populate it. The pattern sorts the operands of an op in ascending order of the "key" associated with each operand iff the op is commutative. This sorting is stable.
The function is intended to be used inside passes to simplify the matching of commutative operations. After the application of the above-mentioned pattern, since the commutative operands now have a deterministic order in which they occur in an op, the matching of large DAGs becomes much simpler, i.e., requires much less number of checks to be written by a user in her/his pattern matching function.
The "key" associated with an operand is the list of the "AncestorKeys" associated with the ancestors of this operand, in a breadth-first order.
The operand of any op is produced by a set of ops and block arguments. Each of these ops and block arguments is called an "ancestor" of this operand.
Now, the "AncestorKey" associated with:
1. A block argument is `{type: BLOCK_ARGUMENT, opName: ""}`.
2. A non-constant-like op, for example, `arith.addi`, is `{type: NON_CONSTANT_OP, opName: "arith.addi"}`.
3. A constant-like op, for example, `arith.constant`, is `{type: CONSTANT_OP, opName: "arith.constant"}`.
So, if an operand, say `A`, was produced as follows:
```
`<block argument>` `<block argument>`
\ /
\ /
`arith.subi` `arith.constant`
\ /
`arith.addi`
|
returns `A`
```
Then, the block arguments and operations present in the backward slice of `A`, in the breadth-first order are:
`arith.addi`, `arith.subi`, `arith.constant`, `<block argument>`, and `<block argument>`.
Thus, the "key" associated with operand `A` is:
```
{
{type: NON_CONSTANT_OP, opName: "arith.addi"},
{type: NON_CONSTANT_OP, opName: "arith.subi"},
{type: CONSTANT_OP, opName: "arith.constant"},
{type: BLOCK_ARGUMENT, opName: ""},
{type: BLOCK_ARGUMENT, opName: ""}
}
```
Now, if "keyA" is the key associated with operand `A` and "keyB" is the key associated with operand `B`, then:
"keyA" < "keyB" iff:
1. In the first unequal pair of corresponding AncestorKeys, the AncestorKey in operand `A` is smaller, or,
2. Both the AncestorKeys in every pair are the same and the size of operand `A`'s "key" is smaller.
AncestorKeys of type `BLOCK_ARGUMENT` are considered the smallest, those of type `CONSTANT_OP`, the largest, and `NON_CONSTANT_OP` types come in between. Within the types `NON_CONSTANT_OP` and `CONSTANT_OP`, the smaller ones are the ones with smaller op names (lexicographically).
---
Some examples of such a sorting:
Assume that the sorting is being applied to `foo.commutative`, which is a commutative op.
Example 1:
> %1 = foo.const 0
> %2 = foo.mul <block argument>, <block argument>
> %3 = foo.commutative %1, %2
Here,
1. The key associated with %1 is:
```
{
{CONSTANT_OP, "foo.const"}
}
```
2. The key associated with %2 is:
```
{
{NON_CONSTANT_OP, "foo.mul"},
{BLOCK_ARGUMENT, ""},
{BLOCK_ARGUMENT, ""}
}
```
The key of %2 < the key of %1
Thus, the sorted `foo.commutative` is:
> %3 = foo.commutative %2, %1
Example 2:
> %1 = foo.const 0
> %2 = foo.mul <block argument>, <block argument>
> %3 = foo.mul %2, %1
> %4 = foo.add %2, %1
> %5 = foo.commutative %1, %2, %3, %4
Here,
1. The key associated with %1 is:
```
{
{CONSTANT_OP, "foo.const"}
}
```
2. The key associated with %2 is:
```
{
{NON_CONSTANT_OP, "foo.mul"},
{BLOCK_ARGUMENT, ""}
}
```
3. The key associated with %3 is:
```
{
{NON_CONSTANT_OP, "foo.mul"},
{NON_CONSTANT_OP, "foo.mul"},
{CONSTANT_OP, "foo.const"},
{BLOCK_ARGUMENT, ""},
{BLOCK_ARGUMENT, ""}
}
```
4. The key associated with %4 is:
```
{
{NON_CONSTANT_OP, "foo.add"},
{NON_CONSTANT_OP, "foo.mul"},
{CONSTANT_OP, "foo.const"},
{BLOCK_ARGUMENT, ""},
{BLOCK_ARGUMENT, ""}
}
```
Thus, the sorted `foo.commutative` is:
> %5 = foo.commutative %4, %3, %2, %1
Signed-off-by: Srishti Srivastava <srishti.srivastava@polymagelabs.com>
Reviewed By: Mogball
Differential Revision: https://reviews.llvm.org/D124750
Operand's defining op may not be valid for adding to the worklist under
stict mode
Reviewed By: rriddle
Differential Revision: https://reviews.llvm.org/D127180
In strict mode, only the new inserted operation is allowed to add to the
worklist. Before this change, it would add the users of a replaced op
and it didn't check if the users are allowed to be pushed into the
worklist
Reviewed By: rriddle
Differential Revision: https://reviews.llvm.org/D126899
The previous fix from af371f9f98 only applied when using a bottom-up
traversal. The change here applies the constant preprocessing logic to the
top-down case as well. This resolves the issue with the canonicalizer pass still
reordering constants, since it uses a top-down traversal by default.
Fixes#51892
Reviewed By: rriddle
Differential Revision: https://reviews.llvm.org/D125623
This patch adds a topological sort utility and pass. A topological sort reorders
the operations in a block without SSA dominance such that, as much as possible,
users of values come after their producers.
The utility function sorts topologically the operation range in a given block
with an optional user-provided callback that can be used to virtually break cycles.
The toposort pass itself recursively sorts graph regions under the target op.
Reviewed By: mehdi_amini
Differential Revision: https://reviews.llvm.org/D125063
Previously, checking that a fix point is reached was counted as a full
iteration. As this "iteration" never changes the IR, this seems counter-
intuitive.
Differential Revision: https://reviews.llvm.org/D123641
This patch revamps the BranchOpInterface a bit and allows a proper implementation of what was previously `getMutableSuccessorOperands` for operations, which internally produce arguments to some of the block arguments. A motivating example for this would be an invoke op with a error handling path:
```
invoke %function(%0)
label ^success ^error(%1 : i32)
^error(%e: !error, %arg0 : i32):
...
```
The advantages of this are that any users of `BranchOpInterface` can still argue over remaining block argument operands (such as `%1` in the example above), as well as make use of the modifying capabilities to add more operands, erase an operand etc.
The way this patch implements that functionality is via a new class called `SuccessorOperands`, which is now returned by `getSuccessorOperands`. It basically contains an `unsigned` denoting how many operator produced operands exist, as well as a `MutableOperandRange`, which are the usual forwarded operands we are used to. The produced operands are assumed to the first few block arguments, followed by the forwarded operands afterwards. The role of `SuccessorOperands` is to provide various utility functions to modify and query the successor arguments from a `BranchOpInterface`.
Differential Revision: https://reviews.llvm.org/D123062
Reland Note: Adds a fix to properly mark a commutative operation as folded if we change the order
of its operands. This was uncovered by the fact that we no longer re-process constants.
This avoids accidentally reversing the order of constants during successive
application, e.g. when running the canonicalizer. This helps reduce the number
of iterations, and also avoids unnecessary changes to input IR.
Fixes#51892
Differential Revision: https://reviews.llvm.org/D122692
This commit refactors the expected form of native constraint and rewrite
functions, and greatly reduces the necessary user complexity required when
defining a native function. Namely, this commit adds in automatic processing
of the necessary PDLValue glue code, and allows for users to define
constraint/rewrite functions using the C++ types that they actually want to
use.
As an example, lets see a simple example rewrite defined today:
```
static void rewriteFn(PatternRewriter &rewriter, PDLResultList &results,
ArrayRef<PDLValue> args) {
ValueRange operandValues = args[0].cast<ValueRange>();
TypeRange typeValues = args[1].cast<TypeRange>();
...
// Create an operation at some point and pass it back to PDL.
Operation *op = rewriter.create<SomeOp>(...);
results.push_back(op);
}
```
After this commit, that same rewrite could be defined as:
```
static Operation *rewriteFn(PatternRewriter &rewriter ValueRange operandValues,
TypeRange typeValues) {
...
// Create an operation at some point and pass it back to PDL.
return rewriter.create<SomeOp>(...);
}
```
Differential Revision: https://reviews.llvm.org/D122086
This reverts commit 59bbc7a085.
This exposes an issue breaking the contract of
`applyPatternsAndFoldGreedily` where we "converge" without applying
remaining patterns.
This avoids accidentally reversing the order of constants during successive
application, e.g. when running the canonicalizer. This helps reduce the number
of iterations, and also avoids unnecessary changes to input IR.
Fixes#51892
Differential Revision: https://reviews.llvm.org/D122692
(This was a TODO from the initial patch).
The control-flow sink utility accepts a callback that is used to sink an operation into a region.
The `moveIntoRegion` is called on the same operation and region that return true for `shouldMoveIntoRegion`.
The callback must preserve the dominance of the operation within the region. In the default control-flow
sink implementation, this is moving the operation to the start of the entry block.
Reviewed By: mehdi_amini
Differential Revision: https://reviews.llvm.org/D122445
When the current implementation merges two blocks that have operands defined outside of their block respectively, it will merge these by adding a block argument in the resulting merged block and adding successor arguments to the predecessors.
There is a special case where this is incorrect however: If one of predecessors terminator produce the operand, inserting the block argument and updating the predecessor would lead to the terminator using its own result as successor argument.
IR Example:
```
%0 = "test.producing_br"()[^bb1, ^bb2] {
operand_segment_sizes = dense<0> : vector<2 x i32>
} : () -> i32
^bb1:
"test.br"(%0)[^bb4] : (i32) -> ()
```
where `^bb1` is then merged with another block would lead to:
```
%0 = "test.producing_br"(%0)[^bb1, ^bb2]
```
This patch fixes that issue during clustering by making sure that if the operand is from an outside block, that it is not produced by the terminator of a predecessor.
Differential Revision: https://reviews.llvm.org/D121988
This removes any potential confusion with the `getType` accessors
which correspond to SSA results of an operation, and makes it
clear what the intent is (i.e. to represent the type of the function).
Differential Revision: https://reviews.llvm.org/D121762
This commit moves FuncOp out of the builtin dialect, and into the Func
dialect. This move has been planned in some capacity from the moment
we made FuncOp an operation (years ago). This commit handles the
functional aspects of the move, but various aspects are left untouched
to ease migration: func::FuncOp is re-exported into mlir to reduce
the actual API churn, the assembly format still accepts the unqualified
`func`. These temporary measures will remain for a little while to
simplify migration before being removed.
Differential Revision: https://reviews.llvm.org/D121266
During dialect conversion, target materialization is triggered to create
cast-like operations when a type mismatch occurs between the value that
replaces a rewritten operation and the type that another operations expects as
operands processed by the type conversion. First, a dummy cast is inserted to
make sure the pattern application can proceed. The decision to trigger the
user-provided materialization hook is taken later based on the result of the
dummy cast having uses. However, it only has uses if other patterns constructed
new operations using the casted value as operand. If existing (legal)
operations use the replaced value, they may have not been updated to use the
casted value yet. The conversion infra would then delete the dummy cast first,
and then would replace the uses with now-invalid (null in the bast case) value.
When deciding whether to trigger cast materialization, check for liveness the
uses not only of the casted value, but also of all the values that it replaces.
This was discovered in the finalizing bufferize pass that cleans up
mutually-cancelling casts without touching other operations. It is not
impossible that there are other scenarios where the dialect converison infra
could produce invalid operand uses because of dummy casts erased too eagerly.
Reviewed By: springerm
Differential Revision: https://reviews.llvm.org/D119937
This has been a major TODO for a very long time, and is necessary for establishing a proper
dialect-free dependency layering for the Transforms library. Code was moved to effectively
two main locations:
* Affine/
There was quite a bit of affine dialect related code in Transforms/ do to historical reasons
(of a time way into MLIR's past). The following headers were moved to:
Transforms/LoopFusionUtils.h -> Dialect/Affine/LoopFusionUtils.h
Transforms/LoopUtils.h -> Dialect/Affine/LoopUtils.h
Transforms/Utils.h -> Dialect/Affine/Utils.h
The following transforms were also moved:
AffineLoopFusion, AffinePipelineDataTransfer, LoopCoalescing
* SCF/
Only one SCF pass was in Transforms/ (likely accidentally placed here): ParallelLoopCollapsing
The SCF specific utilities in LoopUtils have been moved to SCF/Utils.h
* Misc:
mlir::moveLoopInvariantCode was also moved to LoopLikeInterface.h given
that it is a simple utility defined in terms of LoopLikeOpInterface.
Differential Revision: https://reviews.llvm.org/D117848
