13 Commits

Author SHA1 Message Date
Matthias Springer
0f3544d185 [mlir][scf] Loop peeling: Use scf.for for partial iteration
Generate an scf.for instead of an scf.if for the partial iteration. This is for consistency reasons: The peeling of linalg.tiled_loop also uses another loop for the partial iteration.

Note: Canonicalizations patterns may rewrite partial iterations to scf.if afterwards.

Differential Revision: https://reviews.llvm.org/D109568
2021-09-10 19:07:09 +09:00
Matthias Springer
c57c4f888c [mlir][linalg] linalg.tiled_loop peeling
Differential Revision: https://reviews.llvm.org/D108270
2021-09-07 09:50:08 +09:00
Matthias Springer
d18ffd61d4 [mlir][SCF] Canonicalize dim(x) where x is an iter_arg
* Add `DimOfIterArgFolder`.
* Move existing cross-dialect canonicalization patterns to `LoopCanonicalization.cpp`.
* Rename `SCFAffineOpCanonicalization` pass to `SCFForLoopCanonicalization`.
* Expand documentaton of scf.for: The type of loop-carried variables may not change with iterations. (Not even the dynamic type.)

Differential Revision: https://reviews.llvm.org/D108806
2021-08-30 01:39:56 +00:00
Matthias Springer
eedc997b7d [mlir][Analysis] Add batched version of FlatAffineConstraints::addId
* Add batched version of all `addId` variants, so that multiple IDs can be added at a time.
* Rename `addId` and variants to `insertId` and `appendId`. Most external users call `appendId`. Splitting `addId` into two functions also makes it possible to provide batched version for both. (Otherwise, the overloads are ambigious when calling `addId`.)

Differential Revision: https://reviews.llvm.org/D108532
2021-08-30 00:56:44 +00:00
Matthias Springer
a9cff97f94 [mlir][SCF] Generalize AffineMinSCFCanonicalization to min/max ops
* Add support for affine.max ops to SCF loop peeling pattern.
* Add support for affine.max ops to `AffineMinSCFCanonicalizationPattern`.
* Rename `AffineMinSCFCanonicalizationPattern` to `AffineOpSCFCanonicalizationPattern`.
* Rename `AffineMinSCFCanonicalization` pass to `SCFAffineOpCanonicalization`.

Differential Revision: https://reviews.llvm.org/D108009
2021-08-25 10:40:34 +09:00
Matthias Springer
98aa694d0d [mlir][scf] Add general affine.min canonicalization pattern
This canonicalization simplifies affine.min operations inside "for loop"-like operations (e.g., scf.for and scf.parallel) based on two invariants:
* iv >= lb
* iv < lb + step * ((ub - lb - 1) floorDiv step) + 1

This commit adds a new pass `canonicalize-scf-affine-min` (instead of being a canonicalization pattern) to avoid dependencies between the Affine dialect and the SCF dialect.

Differential Revision: https://reviews.llvm.org/D107731
2021-08-25 07:32:30 +09:00
Matthias Springer
0c36082963 [mlir][SCF] Use symbols in loop peeling rewrite
Use symbols in the affine map instead of dims. Dims should not be divided.

Differential Revision: https://reviews.llvm.org/D108431
2021-08-24 19:39:19 +09:00
Matthias Springer
bc194a5bb5 [mlir][SCF] Do not peel loops inside partial iterations
Do not apply loop peeling to loops that are contained in the partial iteration of an already peeled loop. This is to avoid code explosion when dealing with large loop nests. Can be controlled with a new pass option `skip-partial`.

Differential Revision: https://reviews.llvm.org/D108542
2021-08-23 21:35:46 +09:00
Matthias Springer
8e8b70aa84 [mlir][scf] Simplify affine.min ops after loop peeling
Simplify affine.min ops, enabling various other canonicalizations inside the peeled loop body.

affine.min ops such as:
```
map = affine_map<(d0)[s0, s1] -> (s0, -d0 + s1)>
%r = affine.min #affine.min #map(%iv)[%step, %ub]
```
are rewritten them into (in the case the peeled loop):
```
%r = %step
```

To determine how an affine.min op should be rewritten and to prove its correctness, FlatAffineConstraints is utilized.

Differential Revision: https://reviews.llvm.org/D107222
2021-08-19 17:24:53 +09:00
Tres Popp
2060155480 [mlir] NFC Replace some code snippets with equivalent method calls
Replace some code snippets With scf::ForOp methods. Additionally,
share a listener at one more point (although this pattern is still
not safe to roll back currently)

Differential Revision: https://reviews.llvm.org/D107754
2021-08-10 08:22:08 +02:00
Matthias Springer
767974f344 [mlir][scf] Fix bug in peelForLoop
Insertion point should be set before creating new operations.

Differential Revision: https://reviews.llvm.org/D107326
2021-08-04 10:20:46 +09:00
Matthias Springer
3a41ff4883 [mlir][SCF] Peel scf.for loops for even step divison
Add ForLoopBoundSpecialization pass, which specializes scf.for loops into a "main loop" where `step` divides the iteration space evenly and into an scf.if that handles the last iteration.

This transformation is useful for vectorization and loop tiling. E.g., when vectorizing loads/stores, programs will spend most of their time in the main loop, in which only unmasked loads/stores are used. Only the in the last iteration (scf.if), slower masked loads/stores are used.

Subsequent commits will apply this transformation in the SparseDialect and in Linalg's loop tiling.

Differential Revision: https://reviews.llvm.org/D105804
2021-08-03 10:21:38 +09:00
Stephan Herhut
4bcd08eb1c [mlir] Add for loop specialization
Summary:
We already had a parallel loop specialization pass that is used to
enable unrolling and consecutive vectorization by rewriting loops
whose bound is defined as a min of a constant and a dynamic value
into a loop with static bound (the constant) and the minimum as
bound, wrapped into a conditional to dispatch between the two.
This adds the same rewriting for for loops.

Differential Revision: https://reviews.llvm.org/D82189
2020-06-22 10:14:17 +02:00