This CL revisits the composition of AffineApplyOp for the special case where a symbol
itself comes from an AffineApplyOp.
This is achieved by rewriting such symbols into dims to allow composition to occur mathematically.
The implementation is also refactored to improve readability.
Rationale for locally rewriting symbols as dims:
================================================
The mathematical composition of AffineMap must always concatenate symbols
because it does not have enough information to do otherwise. For example,
composing `(d0)[s0] -> (d0 + s0)` with itself must produce
`(d0)[s0, s1] -> (d0 + s0 + s1)`.
The result is only equivalent to `(d0)[s0] -> (d0 + 2 * s0)` when
applied to the same mlir::Value* for both s0 and s1.
As a consequence mathematical composition of AffineMap always concatenates
symbols.
When AffineMaps are used in AffineApplyOp however, they may specify
composition via symbols, which is ambiguous mathematically. This corner case
is handled by locally rewriting such symbols that come from AffineApplyOp
into dims and composing through dims.
PiperOrigin-RevId: 239791597
This CL removes the dependency of LowerVectorTransfers on the AST version of EDSCs which will be retired.
This exhibited a pretty fundamental staging difference in AST-based vs declarative based emission.
Since the delayed creation with an AST was staged, the loop order came into existence after the clipping expressions were computed.
This now changes as the loops first need to be created declaratively in fixed order and then the clipping expressions are created.
Also, due to lack of staging, coalescing cannot be done on the fly anymore and
needs to be done either as a pre-pass (current implementation) or as a local transformation on the generated IR (future work).
Tests are updated accordingly.
PiperOrigin-RevId: 238971631
- emit a note on the loop being parallel instead of setting a loop attribute
- rename the pass -test-detect-parallel (from -detect-parallel)
PiperOrigin-RevId: 238122847
- fix for getConstantBoundOnDimSize: floordiv -> ceildiv for extent
- make getConstantBoundOnDimSize also return the identifier upper bound
- fix unionBoundingBox to correctly use the divisor and upper bound identified by
getConstantBoundOnDimSize
- deal with loop step correctly in addAffineForOpDomain (covers most cases now)
- fully compose bound map / operands and simplify/canonicalize before adding
dim/symbol to FlatAffineConstraints; fixes false positives in -memref-bound-check; add
test case there
- expose mlir::isTopLevelSymbol from AffineOps
PiperOrigin-RevId: 238050395
multi-result upper bounds, complete TODOs, fix/improve test cases.
- complete TODOs for loop unroll/unroll-and-jam. Something as simple as
"for %i = 0 to %N" wasn't being unrolled earlier (unless it had been written
as "for %i = ()[s0] -> (0)()[%N] to %N"; addressed now.
- update/replace getTripCountExpr with buildTripCountMapAndOperands; makes it
more powerful as it composes inputs into it
- getCleanupLowerBound and getUnrolledLoopUpperBound actually needed the same
code; refactor and remove one.
- reorganize test cases, write previous ones better; most of these changes are
"label replacements".
- fix wrongly labeled test cases in unroll-jam.mlir
PiperOrigin-RevId: 238014653
- compute tile sizes based on a simple model that looks at memory footprints
(instead of using the hardcoded default value)
- adjust tile sizes to make them factors of trip counts based on an option
- update loop fusion CL options to allow setting maximal fusion at pass creation
- change an emitError to emitWarning (since it's not a hard error unless the client
treats it that way, in which case, it can emit one)
$ mlir-opt -debug-only=loop-tile -loop-tile test/Transforms/loop-tiling.mlir
test/Transforms/loop-tiling.mlir:81:3: note: using tile sizes [4 4 5 ]
for %i = 0 to 256 {
for %i0 = 0 to 256 step 4 {
for %i1 = 0 to 256 step 4 {
for %i2 = 0 to 250 step 5 {
for %i3 = #map4(%i0) to #map11(%i0) {
for %i4 = #map4(%i1) to #map11(%i1) {
for %i5 = #map4(%i2) to #map12(%i2) {
%0 = load %arg0[%i3, %i5] : memref<8x8xvector<64xf32>>
%1 = load %arg1[%i5, %i4] : memref<8x8xvector<64xf32>>
%2 = load %arg2[%i3, %i4] : memref<8x8xvector<64xf32>>
%3 = mulf %0, %1 : vector<64xf32>
%4 = addf %2, %3 : vector<64xf32>
store %4, %arg2[%i3, %i4] : memref<8x8xvector<64xf32>>
}
}
}
}
}
}
PiperOrigin-RevId: 237461836
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
- detect all parallel loops based on dep information and mark them with a
"parallel" attribute
- add mlir::isLoopParallel(OpPointer<AffineForOp> ...), and refactor an existing method
to use that (reuse some code from @andydavis (cl/236007073) for this)
- a simple/meaningful way to test memref dep test as well
Ex:
$ mlir-opt -detect-parallel test/Transforms/parallelism-detection.mlir
#map1 = ()[s0] -> (s0)
func @foo(%arg0: index) {
%0 = alloc() : memref<1024x1024xvector<64xf32>>
%1 = alloc() : memref<1024x1024xvector<64xf32>>
%2 = alloc() : memref<1024x1024xvector<64xf32>>
for %i0 = 0 to %arg0 {
for %i1 = 0 to %arg0 {
for %i2 = 0 to %arg0 {
%3 = load %0[%i0, %i2] : memref<1024x1024xvector<64xf32>>
%4 = load %1[%i2, %i1] : memref<1024x1024xvector<64xf32>>
%5 = load %2[%i0, %i1] : memref<1024x1024xvector<64xf32>>
%6 = mulf %3, %4 : vector<64xf32>
%7 = addf %5, %6 : vector<64xf32>
store %7, %2[%i0, %i1] : memref<1024x1024xvector<64xf32>>
} {parallel: false}
} {parallel: true}
} {parallel: true}
return
}
PiperOrigin-RevId: 236367368
*) 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
- handle floordiv/mod's in loop bounds for all analysis purposes
- allows fusion slicing to be more powerful
- add simple test cases based on -memref-bound-check
- fusion based test cases in follow up CLs
PiperOrigin-RevId: 236328551
- detect more trivially redundant constraints in
FlatAffineConstraints::removeTrivialRedundantConstraints. Redundancy due to
constraints that only differ in the constant part (eg., 32i + 64j - 3 >= 0, 32 +
64j - 8 >= 0) is now detected. The method is still linear-time and does
a single scan over the FlatAffineConstraints buffer. This detection is useful
and needed to eliminate redundant constraints generated after FM elimination.
- update GCDTightenInequalities so that we also normalize by the GCD while at
it. This way more constraints will show up as redundant (232i - 203 >= 0
becomes i - 1 >= 0 instead of 232i - 232 >= 0) without having to call
normalizeConstraintsByGCD.
- In FourierMotzkinEliminate, call GCDTightenInequalities and
normalizeConstraintsByGCD before calling removeTrivialRedundantConstraints()
- so that more redundant constraints are detected. As a result, redundancy
due to constraints like i - 5 >= 0, i - 7 >= 0, 2i - 5 >= 0, 232i - 203 >=
0 is now detected (here only i >= 7 is non-redundant).
As a result of these, a -memref-bound-check on the added test case runs in 16ms
instead of 1.35s (opt build) and no longer returns a conservative result.
PiperOrigin-RevId: 235983550
- 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
- hoist DMAs past all loops immediately surrounding the region that the latter
is invariant on - do this at DMA generation time itself
PiperOrigin-RevId: 234628447
generation pass to make it drop certain assumptions, complete TODOs.
- multiple fixes for getMemoryFootprintBytes
- pass loopDepth correctly from getMemoryFootprintBytes()
- use union while computing memory footprints
- bug fixes for addAffineForOpDomain
- take into account loop step
- add domains of other loop IVs in turn that might have been used in the bounds
- dma-generate: drop assumption of "non-unit stride loops being tile space loops
and skipping those and recursing to inner depths"; DMA generation is now purely
based on available fast mem capacity and memory footprint's calculated
- handle memory region compute failures/bailouts correctly from dma-generate
- loop tiling cleanup/NFC
- update some debug and error messages to use emitNote/emitError in
pipeline-data-transfer pass - NFC
PiperOrigin-RevId: 234245969
*) 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
- for the DMA transfers being pipelined through double buffering, generate
deallocs for the double buffers being alloc'ed
This change is along the lines of cl/233502632. We initially wanted to experiment with
scoped allocation - so the deallocation's were usually not necessary; however, they are
needed even with scoped allocations in some situations - for eg. when the enclosing loop
gets unrolled. The dealloc serves as an end of lifetime marker.
PiperOrigin-RevId: 233653463
- for the DMA buffers being allocated (and their tags), generate corresponding deallocs
- minor related update to replaceAllMemRefUsesWith and PipelineDataTransfer pass
Code generation for DMA transfers was being done with the initial simplifying
assumption that the alloc's would map to scoped allocations, and so no
deallocations would be necessary. Drop this assumption to generalize. Note that
even with scoped allocations, unrolling loops that have scoped allocations
could create a series of allocations and exhaustion of fast memory. Having a
end of lifetime marker like a dealloc in fact allows creating new scopes if
necessary when lowering to a backend and still utilize scoped allocation.
DMA buffers created by -dma-generate are guaranteed to have either
non-overlapping lifetimes or nested lifetimes.
PiperOrigin-RevId: 233502632
- determine symbols for the memref region correctly
- this wasn't exposed earlier since we didn't have any test cases where the
portion of the nest being DMAed for was non-hyperrectangular (i.e., bounds of
one IV depending on other IVs within that part)
PiperOrigin-RevId: 233493872
* AffineStructures has moved to IR.
* simplifyAffineExpr/simplifyAffineMap/getFlattenedAffineExpr have moved to IR.
* makeComposedAffineApply/fullyComposeAffineMapAndOperands have moved to AffineOps.
* ComposeAffineMaps is replaced by AffineApplyOp::canonicalize and deleted.
PiperOrigin-RevId: 232586468
*) 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
loops), (2) take into account fast memory space capacity and lower 'dmaDepth'
to fit, (3) add location information for debug info / errors
- change dma-generate pass to work on blocks of instructions (start/end
iterators) instead of 'for' loops; complete TODOs - allows DMA generation for
straightline blocks of operation instructions interspersed b/w loops
- take into account fast memory capacity: check whether memory footprint fits
in fastMemoryCapacity parameter, and recurse/lower the depth at which DMA
generation is performed until it does fit in the provided memory
- add location information to MemRefRegion; any insufficient fast memory
capacity errors or debug info w.r.t dma generation shows location information
- allow DMA generation pass to be instantiated with a fast memory capacity
option (besides command line flag)
- change getMemRefRegion to return unique_ptr's
- change getMemRefFootprintBytes to work on a 'Block' instead of 'ForInst'
- other helper methods; add postDomInstFilter option for
replaceAllMemRefUsesWith; drop forInst->walkOps, add Block::walkOps methods
Eg. output
$ mlir-opt -dma-generate -dma-fast-mem-capacity=1 /tmp/single.mlir
/tmp/single.mlir:9:13: error: Total size of all DMA buffers' for this block exceeds fast memory capacity
for %i3 = (d0) -> (d0)(%i1) to (d0) -> (d0 + 32)(%i1) {
^
$ mlir-opt -debug-only=dma-generate -dma-generate -dma-fast-mem-capacity=400 /tmp/single.mlir
/tmp/single.mlir:9:13: note: 8 KiB of DMA buffers in fast memory space for this block
for %i3 = (d0) -> (d0)(%i1) to (d0) -> (d0 + 32)(%i1) {
PiperOrigin-RevId: 232297044
Nicolas Vasilache