Commit Graph

11 Commits

Author SHA1 Message Date
Uday Bondhugula d59a95a05c Fix missing check for dependent DMAs in pipeline-data-transfer
- adding a conservative check for now (TODO: use the dependence analysis pass
  once the latter is extended to deal with DMA ops). resolve an existing bug on
  a test case.

- update test cases

PiperOrigin-RevId: 224869526
2019-03-29 14:24:53 -07:00
Uday Bondhugula 2ef57806ba Update/fix -pipeline-data-transfer; fix b/120770946
- fix replaceAllMemRefUsesWith call to replace only inside loop body.
- handle the case where DMA buffers are dynamic; extend doubleBuffer() method
  to handle dynamically shaped DMA buffers (pass the right operands to AllocOp)
- place alloc's for DMA buffers at the depth at which pipelining is being done
  (instead of at top-level)
- add more test cases

PiperOrigin-RevId: 224852231
2019-03-29 14:24:22 -07:00
Uday Bondhugula b6c03917ad Remove allocations for memref's that become dead as a result of double
buffering in the auto DMA overlap pass.

This is done online in the pass.

PiperOrigin-RevId: 222313640
2019-03-29 14:05:19 -07:00
Nicolas Vasilache cde8248753 [MLIR] Make upper bound implementation exclusive
This CL implement exclusive upper bound behavior as per b/116854378.
A followup CL will update the semantics of the for loop.

PiperOrigin-RevId: 220448963
2019-03-29 13:49:49 -07:00
Alex Zinenko aae372ecb8 Drop trivial identity affine mappings in MemRef construction.
As per MLIR spec, the absence of affine maps in MemRef type is interpreted as
an implicit identity affine map.  Therefore, MemRef types declared with
explicit or implicit identity map should be considered equal at the MemRefType
level.  During MemRefType construction, drop trivial identity affine map
compositions.  A trivial identity composition consists of a single unbounded
identity map.  It is unclear whether affine maps should be composed in-place to
a single map during MemRef type construction, so non-trivial compositions that
could have been simplified to an identity are NOT removed.  We chose to drop
the trivial identity map rather than inject it in places that assume its
present implicitly because it makes the code simpler by reducing boilerplate;
identity mappings are obvious defaults.

Update tests that were checking for the presence of trivial identity map
compositions in the outputs.

PiperOrigin-RevId: 218862454
2019-03-29 13:41:47 -07:00
Uday Bondhugula 18e666702c Generalize / improve DMA transfer overlap; nested and multiple DMA support; resolve
multiple TODOs.

- replace the fake test pass (that worked on just the first loop in the
  MLFunction) to perform DMA pipelining on all suitable loops.
- nested DMAs work now (DMAs in an outer loop, more DMAs in nested inner loops)
- fix bugs / assumptions: correctly copy memory space and elemental type of source
  memref for double buffering.
- correctly identify matching start/finish statements, handle multiple DMAs per
  loop.
- introduce dominates/properlyDominates utitilies for MLFunction statements.
- move checkDominancePreservationOnShifts to LoopAnalysis.h; rename it
  getShiftValidity
- refactor getContainingStmtPos -> findAncestorStmtInBlock - move into
  Analysis/Utils.h; has two users.
- other improvements / cleanup for related API/utilities
- add size argument to dma_wait - for nested DMAs or in general, it makes it
  easy to obtain the size to use when lowering the dma_wait since we wouldn't
  want to identify the matching dma_start, and more importantly, in general/in the
  future, there may not always be a dma_start dominating the dma_wait.
- add debug information in the pass

PiperOrigin-RevId: 217734892
2019-03-29 13:32:28 -07:00
Uday Bondhugula 86eac4618c Create private exclusive / single use affine computation slice for an op stmt.
- add util to create a private / exclusive / single use affine
  computation slice for an op stmt (see method doc comment); a single
  multi-result affine_apply op is prepended to the op stmt to provide all
  results needed for its operands as a function of loop iterators and symbols.
- use it for DMA pipelining (to create private slices for DMA start stmt's);
  resolve TODOs/feature request (b/117159533)
- move createComposedAffineApplyOp to Transforms/Utils; free it from taking a
  memref as input / generalize it.

PiperOrigin-RevId: 216926818
2019-03-29 13:29:21 -07:00
Uday Bondhugula 82e55750d2 Add target independent standard DMA ops: dma.start, dma.wait
Add target independent standard DMA ops: dma.start, dma.wait. Update pipeline
data transfer to use these to detect DMA ops.

While on this
- return failure from mlir-opt::performActions if a pass generates invalid output
- improve error message for verify 'n' operand traits

PiperOrigin-RevId: 216429885
2019-03-29 13:26:10 -07:00
Chris Lattner d2d89cbc19 Rename affineint type to index type. The name 'index' may not be perfect, but is better than the old name. Here is some justification:
1) affineint (as it is named) is not a type suitable for general computation (e.g. the multiply/adds in an integer matmul).  It has undefined width and is undefined on overflow.  They are used as the indices for forstmt because they are intended to be used as indexes inside the loop.

2) It can be used in both cfg and ml functions, and in cfg functions.  As you mention, “symbols” are not affine, and we use affineint values for symbols.

3) Integers aren’t affine, the algorithms applied to them can be. :)

4) The only suitable use for affineint in MLIR is for indexes and dimension sizes (i.e. the bounds of those indexes).

PiperOrigin-RevId: 216057974
2019-03-29 13:24:16 -07:00
Uday Bondhugula 6cfdb756b1 Introduce memref replacement/rewrite support: to replace an existing memref
with a new one (of a potentially different rank/shape) with an optional index
remapping.

- introduce Utils::replaceAllMemRefUsesWith
- use this for DMA double buffering

(This CL also adds a few temporary utilities / code that will be done away with
once:
1) abstract DMA op's are added
2) memref deferencing side-effect / trait is available on op's
3) b/117159533 is resolved (memref index computation slices).
PiperOrigin-RevId: 215831373
2019-03-29 13:23:19 -07:00
Uday Bondhugula 041817a45e Introduce loop body skewing / loop pipelining / loop shifting utility.
- loopBodySkew shifts statements of a loop body by stmt-wise delays, and is
  typically meant to be used to:
  - allow overlap of non-blocking start/wait until completion operations with
    other computation
  - allow shifting of statements (for better register
    reuse/locality/parallelism)
  - software pipelining (when applied to the innermost loop)
- an additional argument specifies whether to unroll the prologue and epilogue.
- add method to check SSA dominance preservation.
- add a fake loop pipeline pass to test this utility.

Sample input/output are below. While on this, fix/add following:

- fix minor bug in getAddMulPureAffineExpr
- add additional builder methods for common affine map cases
- fix const_operand_iterator's for ForStmt, etc. When there is no such thing
  as 'const MLValue', the iterator shouldn't be returning const MLValue's.
  Returning MLValue is const correct.

Sample input/output examples:

1) Simplest case: shift second statement by one.

Input:

for %i = 0 to 7 {
  %y = "foo"(%i) : (affineint) -> affineint
  %x = "bar"(%i) : (affineint) -> affineint
}

Output:

#map0 = (d0) -> (d0 - 1)
mlfunc @loop_nest_simple1() {
  %c8 = constant 8 : affineint
  %c0 = constant 0 : affineint
  %0 = "foo"(%c0) : (affineint) -> affineint
  for %i0 = 1 to 7 {
    %1 = "foo"(%i0) : (affineint) -> affineint
    %2 = affine_apply #map0(%i0)
    %3 = "bar"(%2) : (affineint) -> affineint
  }
  %4 = affine_apply #map0(%c8)
  %5 = "bar"(%4) : (affineint) -> affineint
  return
}

2) DMA overlap: shift dma.wait and compute by one.

Input
  for %i = 0 to 7 {
    %pingpong = affine_apply (d0) -> (d0 mod 2) (%i)
    "dma.enqueue"(%pingpong) : (affineint) -> affineint
    %pongping = affine_apply (d0) -> (d0 mod 2) (%i)
    "dma.wait"(%pongping) : (affineint) -> affineint
    "compute1"(%pongping) : (affineint) -> affineint
  }

Output

#map0 = (d0) -> (d0 mod 2)
#map1 = (d0) -> (d0 - 1)
#map2 = ()[s0] -> (s0 + 7)
mlfunc @loop_nest_dma() {
  %c8 = constant 8 : affineint
  %c0 = constant 0 : affineint
  %0 = affine_apply #map0(%c0)
  %1 = "dma.enqueue"(%0) : (affineint) -> affineint
  for %i0 = 1 to 7 {
    %2 = affine_apply #map0(%i0)
    %3 = "dma.enqueue"(%2) : (affineint) -> affineint
    %4 = affine_apply #map1(%i0)
    %5 = affine_apply #map0(%4)
    %6 = "dma.wait"(%5) : (affineint) -> affineint
    %7 = "compute1"(%5) : (affineint) -> affineint
  }
  %8 = affine_apply #map1(%c8)
  %9 = affine_apply #map0(%8)
  %10 = "dma.wait"(%9) : (affineint) -> affineint
  %11 = "compute1"(%9) : (affineint) -> affineint
  return
}

3) With arbitrary affine bound maps:

Shift last two statements by two.

Input:

  for %i = %N to ()[s0] -> (s0 + 7)()[%N] {
    %y = "foo"(%i) : (affineint) -> affineint
    %x = "bar"(%i) : (affineint) -> affineint
    %z = "foo_bar"(%i) : (affineint) -> (affineint)
    "bar_foo"(%i) : (affineint) -> (affineint)
  }

Output

#map0 = ()[s0] -> (s0 + 1)
#map1 = ()[s0] -> (s0 + 2)
#map2 = ()[s0] -> (s0 + 7)
#map3 = (d0) -> (d0 - 2)
#map4 = ()[s0] -> (s0 + 8)
#map5 = ()[s0] -> (s0 + 9)

  for %i0 = %arg0 to #map0()[%arg0] {
    %0 = "foo"(%i0) : (affineint) -> affineint
    %1 = "bar"(%i0) : (affineint) -> affineint
  }
  for %i1 = #map1()[%arg0] to #map2()[%arg0] {
    %2 = "foo"(%i1) : (affineint) -> affineint
    %3 = "bar"(%i1) : (affineint) -> affineint
    %4 = affine_apply #map3(%i1)
    %5 = "foo_bar"(%4) : (affineint) -> affineint
    %6 = "bar_foo"(%4) : (affineint) -> affineint
  }
  for %i2 = #map4()[%arg0] to #map5()[%arg0] {
    %7 = affine_apply #map3(%i2)
    %8 = "foo_bar"(%7) : (affineint) -> affineint
    %9 = "bar_foo"(%7) : (affineint) -> affineint
  }

4) Shift one by zero, second by one, third by two

  for %i = 0 to 7 {
    %y = "foo"(%i) : (affineint) -> affineint
    %x = "bar"(%i) : (affineint) -> affineint
    %z = "foobar"(%i) : (affineint) -> affineint
  }

#map0 = (d0) -> (d0 - 1)
#map1 = (d0) -> (d0 - 2)
#map2 = ()[s0] -> (s0 + 7)

  %c9 = constant 9 : affineint
  %c8 = constant 8 : affineint
  %c1 = constant 1 : affineint
  %c0 = constant 0 : affineint
  %0 = "foo"(%c0) : (affineint) -> affineint
  %1 = "foo"(%c1) : (affineint) -> affineint
  %2 = affine_apply #map0(%c1)
  %3 = "bar"(%2) : (affineint) -> affineint
  for %i0 = 2 to 7 {
    %4 = "foo"(%i0) : (affineint) -> affineint
    %5 = affine_apply #map0(%i0)
    %6 = "bar"(%5) : (affineint) -> affineint
    %7 = affine_apply #map1(%i0)
    %8 = "foobar"(%7) : (affineint) -> affineint
  }
  %9 = affine_apply #map0(%c8)
  %10 = "bar"(%9) : (affineint) -> affineint
  %11 = affine_apply #map1(%c8)
  %12 = "foobar"(%11) : (affineint) -> affineint
  %13 = affine_apply #map1(%c9)
  %14 = "foobar"(%13) : (affineint) -> affineint

5) SSA dominance violated; no shifting if a shift is specified for the second
statement.

  for %i = 0 to 7 {
    %x = "foo"(%i) : (affineint) -> affineint
    "bar"(%x) : (affineint) -> affineint
  }

PiperOrigin-RevId: 214975731
2019-03-29 13:21:26 -07:00