Adds utility to convert slice bounds to a FlatAffineConstraints representation.
Adds utility to FlatAffineConstraints to promote loop IV symbol identifiers to dim identifiers.
PiperOrigin-RevId: 236973261
- fix for the mod detection
- simplify/avoid the mod at construction (if the dividend is already known to be less
than the divisor), since the information is available at hand there
PiperOrigin-RevId: 236882988
- fix out of bounds test case
- -memref-bound-check on the test/Transforms/loop-fusion.mlir no longer reports any
errors, before or after -loop-fusion is run
PiperOrigin-RevId: 236757658
- this was detected when memref-bound-check was run on the output of the
loop-fusion pass
- the addition (to represent ceildiv as a floordiv) had to be performed only
for the constant term of the constraint
- update test cases
- memref-bound-check no longer returns an error on the output of this test case
PiperOrigin-RevId: 236731137
*) Breaks fusion pass into multiple sub passes over nodes in data dependence graph:
- first pass fuses single-use producers into their unique consumer.
- second pass enables fusing for input-reuse by fusing sibling nodes which read from the same memref, but which do not share dependence edges.
- third pass fuses remaining producers into their consumers (Note that the sibling fusion pass may have transformed a producer with multiple uses into a single-use producer).
*) Fusion for input reuse is enabled by computing a sibling node slice using the load/load accesses to the same memref, and fusion safety is guaranteed by checking that the sibling node memref write region (to a different memref) is preserved.
*) Enables output vector and output matrix computations from KFAC patches-second-moment operation to fuse into a single loop nest and reuse input from the image patches operation.
*) Adds a generic loop utilitiy for finding all sequential loops in a loop nest.
*) Adds and updates unit tests.
PiperOrigin-RevId: 236350987
- compute slices precisely where the destination iteration depends on multiple source
iterations (instead of over-approximating to the whole source loop extent)
- update unionBoundingBox to deal with input with non-matching symbols
- reenable disabled backend test case
PiperOrigin-RevId: 234714069
*) Adds utility to LoopUtils to perform loop interchange of two AffineForOps.
*) Adds utility to LoopUtils to sink a loop to a specified depth within a loop nest, using a series of loop interchanges.
*) Computes dependences between all loads and stores in the loop nest, and classifies each loop as parallel or sequential.
*) Computes loop interchange permutation required to sink sequential loops (and raise parallel loop nests) while preserving relative order among them.
*) Checks each dependence against the permutation to make sure that dependences would not be violated by the loop interchange transformation.
*) Calls loop interchange in LoopFusion pass on consumer loop nests before fusing in producers, sinking loops with loop carried dependences deeper into the consumer loop nest.
*) Adds and updates related unit tests.
PiperOrigin-RevId: 234158370
Update FlatAffineConstraints::getLower/UpperBounds to project to the identifier for which bounds are being computed. This change enables computing bounds on an identifier which were previously dependent on the bounds of another identifier.
PiperOrigin-RevId: 234017514
*) After a private memref buffer is created for a fused loop nest, dependences on the old memref are reduced, which can open up fusion opportunities. In these cases, users of the old memref are added back to the worklist to be reconsidered for fusion.
*) Fixed a bug in fusion insertion point dependence check where the memref being privatized was being skipped from the check.
PiperOrigin-RevId: 232477853
index remapping
- generate a sequence of single result affine_apply's for the index remapping
(instead of one multi result affine_apply)
- update dma-generate and loop-fusion test cases; while on this, change test cases
to use single result affine apply ops
- some fusion comment fix/cleanup
PiperOrigin-RevId: 230985830
- update fusion cost model to fuse while tolerating a certain amount of redundant
computation; add cl option -fusion-compute-tolerance
evaluate memory footprint and intermediate memory reduction
- emit debug info from -loop-fusion showing what was fused and why
- introduce function to compute memory footprint for a loop nest
- getMemRefRegion readability update - NFC
PiperOrigin-RevId: 230541857
- the size of the private memref created for the slice should be based on
the memref region accessed at the depth at which the slice is being
materialized, i.e., symbolic in the outer IVs up until that depth, as opposed
to the region accessed based on the entire domain.
- leads to a significant contraction of the temporary / intermediate memref
whenever the memref isn't reduced to a single scalar (through store fwd'ing).
Other changes
- update to promoteIfSingleIteration - avoid introducing unnecessary identity
map affine_apply from IV; makes it much easier to write and read test cases
and pass output for all passes that use promoteIfSingleIteration; loop-fusion
test cases become much simpler
- fix replaceAllMemrefUsesWith bug that was exposed by the above update -
'domInstFilter' could be one of the ops erased due to a memref replacement in
it.
- fix getConstantBoundOnDimSize bug: a division by the coefficient of the identifier was
missing (the latter need not always be 1); add lbFloorDivisors output argument
- rename getBoundingConstantSizeAndShape -> getConstantBoundingSizeAndShape
PiperOrigin-RevId: 230405218
*) Do not remove loop nests which write to memrefs which escape the function.
*) Do not remove memrefs which escape the function (e.g. are used in the return instruction).
PiperOrigin-RevId: 230398630
- detected with memref-bound-check
- fixes b/123072438; while on this, fix another test case which was reported
out of bounds
PiperOrigin-RevId: 229978187
*) Enables reduction of private memref size based on MemRef region accessed by fused slice.
*) Enables maximal fusion by creating a private memref to break a fusion-preventing dependence.
*) Adds maximal fusion flag to enable fusing as much as possible (though it still fuses the minimum cost computation slice).
PiperOrigin-RevId: 229936698
*) Adds support for fusing into consumer loop nests with multiple loads from the same memref.
*) Adds support for reducing slice loop trip count by projecting out destination loop IVs greater than destination loop depth.
*) Removes dependence on src loop depth and simplifies cost model computation.
PiperOrigin-RevId: 229575126
*) LoopFusion: Adds fusion cost function which compares the cost of the fused loop nest, with the cost of the two unfused loop nests to determine if it is profitable to fuse the candidate loop nests. The fusion cost function is run for various combinations for src/dst loop depths attempting find the minimum cost setting for src/dst loop depths which does not increase the computational cost when the loop nests are fused. Combinations of src/dst loop depth are evaluated attempting to maximize loop depth (i.e. take a bigger computation slice from the source loop nest, and insert it deeper in the destination loop nest for better locality).
*) LoopFusion: Adds utility to compute op instance count for loop nests, sliced loop nests, and to compute the cost of a loop nest fused with another sliced loop nest.
*) LoopFusion: canonicalizes slice bound AffineMaps (and updates related tests).
*) Analysis::Utils: Splits getBackwardComputationSlice into two functions: one which calculates and returns the slice loop bounds for analysis by LoopFusion, and the other for insertion of the computation slice (ones fusion has calculated the min-cost src/dst loop depths).
*) Test: Adds multiple unit tests to test the new functionality.
PiperOrigin-RevId: 229219757
- refactor toAffineFromEq and the code surrounding it; refactor code into
FlatAffineConstraints::getSliceBounds
- add FlatAffineConstraints methods to detect identifiers as mod's and div's of other
identifiers
- add FlatAffineConstraints::getConstantLower/UpperBound
- Address b/122118218 (don't assert on invalid fusion depths cmdline flags -
instead, don't do anything; change cmdline flags
src-loop-depth -> fusion-src-loop-depth
- AffineExpr/Map print method update: don't fail on null instances (since we have
a wrapper around a pointer, it's avoidable); rationale: dump/print methods should
never fail if possible.
- Update memref-dataflow-opt to add an optimization to avoid a unnecessary call to
IsRangeOneToOne when it's trivially going to be true.
- Add additional test cases to exercise the new support
- update a few existing test cases since the maps are now generated uniformly with
all destination loop operands appearing for the backward slice
- Fix projectOut - fix wrong range for getBestElimCandidate.
- Fix for getConstantBoundOnDimSize() - didn't show up in any test cases since
we didn't have any non-hyperrectangular ones.
PiperOrigin-RevId: 228265152
- this is CL 1/2 that does a clean up and gets rid of one limitation in an
underlying method - as a result, fusion works for more cases.
- fix bugs/incomplete impl. in toAffineMapFromEq
- fusing across rank changing reshapes for example now just works
For eg. given a rank 1 memref to rank 2 memref reshape (64 -> 8 x 8) like this,
-loop-fusion -memref-dataflow-opt now completely fuses and inlines/store-forward
to get rid of the temporary:
INPUT
// Rank 1 -> Rank 2 reshape
for %i0 = 0 to 64 {
%v = load %A[%i0]
store %v, %B[%i0 floordiv 8, i0 mod 8]
}
for %i1 = 0 to 8
for %i2 = 0 to 8
%w = load %B[%i1, i2]
"foo"(%w) : (f32) -> ()
OUTPUT
$ mlir-opt -loop-fusion -memref-dataflow-opt fuse_reshape.mlir
#map0 = (d0, d1) -> (d0 * 8 + d1)
mlfunc @fuse_reshape(%arg0: memref<64xf32>) {
for %i0 = 0 to 8 {
for %i1 = 0 to 8 {
%0 = affine_apply #map0(%i0, %i1)
%1 = load %arg0[%0] : memref<64xf32>
"foo"(%1) : (f32) -> ()
}
}
}
AFAIK, there is no polyhedral tool / compiler that can perform such fusion -
because it's not really standard loop fusion, but possible through a
generalized slicing-based approach such as ours.
PiperOrigin-RevId: 227918338
The entire compiler now looks at structural properties of the function (e.g.
does it have one block, does it contain an if/for stmt, etc) so the only thing
holding up this difference is round tripping through the parser/printer syntax.
Removing this shrinks the compile by ~140LOC.
This is step 31/n towards merging instructions and statements. The last step
is updating the docs, which I will do as a separate patch in order to split it
from this mostly mechanical patch.
PiperOrigin-RevId: 227540453
consistent and moving the using declarations over. Hopefully this is the last
truly massive patch in this refactoring.
This is step 21/n towards merging instructions and statements, NFC.
PiperOrigin-RevId: 227178245
*) Adds simple greedy fusion algorithm to drive experimentation. This algorithm greedily fuses loop nests with single-writer/single-reader memref dependences to improve locality.
*) Adds support for fusing slices of a loop nest computation: fusing one loop nest into another by adjusting the source loop nest's iteration bounds (after it is fused into the destination loop nest). This is accomplished by solving for the source loop nest's IVs in terms of the destination loop nests IVs and symbols using the dependece polyhedron, then creating AffineMaps of these functions for the loop bounds of the fused source loop.
*) Adds utility function 'insertMemRefComputationSlice' which computes and inserts computation slice from loop nest surrounding a source memref access into the loop nest surrounding the destingation memref access.
*) Adds FlatAffineConstraints::toAffineMap function which returns and AffineMap which represents an equality contraint where one dimension identifier is represented as a function of all others in the equality constraint.
*) Adds multiple fusion unit tests.
PiperOrigin-RevId: 225842944
Adds equality constraints to dependence constraint system for accesses using dims/symbols where the defining operation of the dim/symbol is a constant.
PiperOrigin-RevId: 219814740
- Builds access functions and iterations domains for each access.
- Builds dependence polyhedron constraint system which has equality constraints for equated access functions and inequality constraints for iteration domain loop bounds.
- Runs elimination on the dependence polyhedron to test if no dependence exists between the accesses.
- Adds a trivial LoopFusion transformation pass with a simple test policy to test dependence between accesses to the same memref in adjacent loops.
- The LoopFusion pass will be extended in subsequent CLs.
PiperOrigin-RevId: 219630898
MLIR Team