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torch-mlir/test/Dialect/Torch/maximize-value-semantics.mlir

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Make MaximizeValueSemantics a bit smarter. This adds a pattern to MaximizeValueSemantics which does a simple abstract interpretation within a block, which handles simple cases of `torch.overwrite_tensor`, enough to remove all the unnecessary uses of non-value tensors in ResNet right now. Before/after IR: [gist](https://gist.github.com/silvasean/a3e1ef625b19dfc63579f73cd3b543b6) Also, - Split `torch.copy.tensor` into `torch.copy.to_tensor` and `torch.copy.to_vtensor` which convert between value and non-value semantic tensors. This is a much cleaner factorization as they have very separate use cases and properties (e.g. different side effects) - Remove the various canonicalization patterns they had, which were confusing because they resulted in limited forms of maximizing value semantics throughout the pipeline. We should structure our compilation pipeline such that only MaximizeValueSemantics should be maximizing value semantics. - Adjust pass pipeline to only run MaximizeValueSemantics once. - Make OverwriteTensorOp `$value` always be a value tensor and `$overwritten` be a non-value tensor.
2021-06-19 04:47:47 +08:00
// RUN: npcomp-opt -split-input-file -allow-unregistered-dialect %s -torch-maximize-value-semantics | FileCheck %s
// CHECK-LABEL: func @torch.copy.tensor$basic(
// CHECK-SAME: %[[ARG0:.*]]: !torch.vtensor) -> (!torch.vtensor, !torch.vtensor) {
// CHECK: return %[[ARG0]], %[[ARG0]] : !torch.vtensor, !torch.vtensor
func @torch.copy.tensor$basic(%arg0: !torch.vtensor) -> (!torch.vtensor, !torch.vtensor) {
%0 = torch.copy.to_tensor %arg0 : !torch.tensor
%1 = torch.copy.to_vtensor %0 : !torch.vtensor
%2 = torch.copy.to_vtensor %0 : !torch.vtensor
return %1, %2 : !torch.vtensor, !torch.vtensor
}
// CHECK-LABEL: func @one_mutation_in_a_block(
// CHECK-SAME: %[[ARG0:.*]]: !torch.vtensor,
// CHECK-SAME: %[[ARG1:.*]]: !torch.vtensor) -> (!torch.vtensor, !torch.vtensor) {
// CHECK: return %[[ARG0]], %[[ARG1]] : !torch.vtensor, !torch.vtensor
func @one_mutation_in_a_block(%arg0: !torch.vtensor, %arg1: !torch.vtensor) -> (!torch.vtensor, !torch.vtensor) {
%0 = torch.copy.to_tensor %arg0 : !torch.tensor
%equal_to_arg0 = torch.copy.to_vtensor %0 : !torch.vtensor
torch.overwrite.tensor %arg1 overwrites %0 : !torch.vtensor, !torch.tensor
%equal_to_arg1 = torch.copy.to_vtensor %0 : !torch.vtensor
return %equal_to_arg0, %equal_to_arg1 : !torch.vtensor, !torch.vtensor
}
// CHECK-LABEL: func @multiple_mutations_in_a_block(
// CHECK-SAME: %[[ARG0:.*]]: !torch.vtensor, %[[ARG1:.*]]: !torch.vtensor,
// CHECK-SAME: %[[ARG2:.*]]: !torch.vtensor) -> (!torch.vtensor, !torch.vtensor, !torch.vtensor, !torch.vtensor) {
// CHECK: return %[[ARG0]], %[[ARG1]], %[[ARG1]], %[[ARG2]] : !torch.vtensor, !torch.vtensor, !torch.vtensor, !torch.vtensor
func @multiple_mutations_in_a_block(%arg0: !torch.vtensor, %arg1: !torch.vtensor, %arg2: !torch.vtensor) -> (!torch.vtensor, !torch.vtensor, !torch.vtensor, !torch.vtensor) {
// The mutable tensor we are overwriting.
%tensor = torch.copy.to_tensor %arg0 : !torch.tensor
// The original value.
%equal_to_arg0 = torch.copy.to_vtensor %tensor : !torch.vtensor
// Overwrite with %arg1
torch.overwrite.tensor %arg1 overwrites %tensor : !torch.vtensor, !torch.tensor
%equal_to_arg1 = torch.copy.to_vtensor %tensor : !torch.vtensor
%equal_to_arg1_again = torch.copy.to_vtensor %tensor : !torch.vtensor
// Overwrite with %arg2
torch.overwrite.tensor %arg2 overwrites %tensor : !torch.vtensor, !torch.tensor
%equal_to_arg2 = torch.copy.to_vtensor %tensor : !torch.vtensor
return %equal_to_arg0, %equal_to_arg1, %equal_to_arg1_again, %equal_to_arg2 : !torch.vtensor, !torch.vtensor, !torch.vtensor, !torch.vtensor
}
// CHECK-LABEL: func @unmodeled_mutation(
// CHECK: torch.overwrite.tensor
func @unmodeled_mutation(%arg0: !torch.vtensor, %arg1: !torch.vtensor) -> !torch.vtensor {
%0 = torch.copy.to_tensor %arg0 : !torch.tensor
torch.overwrite.tensor %arg1 overwrites %0 : !torch.vtensor, !torch.tensor
"some.op"(%0) : (!torch.tensor) -> ()
%result = torch.copy.to_vtensor %0 : !torch.vtensor
return %result : !torch.vtensor
}
// We don't yet handle nontrivial cases involving control flow.
// CHECK-LABEL: func @unimplemented_control_flow(
// CHECK: torch.copy.to_vtensor
func @unimplemented_control_flow(%arg0: !torch.vtensor, %arg1: !torch.vtensor, %cond: !torch.bool) -> (!torch.vtensor, !torch.vtensor) {
%tensor = torch.copy.to_tensor %arg0 : !torch.tensor
%equal_to_arg0 = torch.copy.to_vtensor %tensor : !torch.vtensor
torch.prim.If %cond -> () {
torch.overwrite.tensor %arg1 overwrites %tensor : !torch.vtensor, !torch.tensor
torch.prim.If.yield
} else {
torch.prim.If.yield
}
%equal_to_arg1 = torch.copy.to_vtensor %tensor : !torch.vtensor
return %equal_to_arg0, %equal_to_arg1 : !torch.vtensor, !torch.vtensor
Introduce `!torch.tensor` / `!torch.vtensor` types. This removes our reliance on the numpy dialect and avoids our off-label use of the builtin tnesor type for modeling unknown dtypes. The `!torch.vtensor` (`ValueTensorType`) type is a value-semantic tensor. The `!torch.tensor` (`NonValueTensorType`) type is a non-value-semantic tensor. The new types look as follows syntactically: ``` // Least-static-information, non-value-semantic tensor. !torch.tensor // Explicit form of least-static-information variant. !torch.tensor<*,unk> // Least-static-information, value-semantic tensor. !torch.vtensor // Explicit form of least-static-information variant. !torch.vtensor<*,unk> // Fixed-set of allowable element types, with first-class support for // Torch's frontend signedness semantics. !torch.tensor<*,si32> // First-class support for unknown dtypes. !torch.tensor<[?,?,?],unk> // Standard MLIR representation of `?` for unknown dimensions. !torch.tensor<[?,2,?,4],unk> // Statically shaped / dtyped example. !torch.vtensor<[1,2,3,4],f32> ``` This required fairly significant changes throughout the compiler, but overall it is a big cleanup. We now have a much clearer layering of "the Torch frontend lowering" vs "lowering to std + linalg + etc.". At the C++ level, there is `ValueTensorType`, `NonValueTensorType`. We also have a helper `BaseTensorType` (kind of like ShapedType) which interoperates with those two. Included changes: - New `torch.tensor(dense<0.0> : tensor<5xf32>) : !torch.tensor` op for creating torch tensor literals in the frontend. - Consistently use signedness for the types (except i1 which I didn't touch -- we need to sort out the situation with !basicpy.BoolType there anyway so will be attending to that soon) - Frontend can annotate whether an argument to the function has value semantics. We currently require this, as our backend contract does not currently allow us to even model the non-value-semantic case. Before, the value-semantic assumption was randomly injected in the middle of the pass pipeline. - Move ArrayToTensor (now called MaximizeValueSemantics) and RefinePublicReturn passes to torch dialect. - The TorchToStd and TorchToLinalg passes are now type conversions from `!torch.vtensor` to `tensor` and use the dialect conversion infra. The overall conversion pipeline is set up following the best practices of the "Type Conversions the Not-So-Hard Way" talk. This required introducing `torch-func-builtin-tensorize` and `torch-finalizing-builtin-tensorize` passes analogous to the upstream bufferization passes with the corresponding names (mostly just copypasta from there). - Misc Torch-level canonicalizations -- we now cleanly layer the lowering to std later in the pipeline, so we are gradually lessening our reliance on random std constant folding before we get to that point. Recommended review order: - New types in TorchTypes.td/TorchTypes.h/TorchDialect.cpp - New ops in TorchOps.td / TorchOps.cpp - Less important / more mechanical stuff - Frontend changes. - Pass changes/additions in `Torch/Transforms` and `Conversion/`
2021-05-21 08:07:18 +08:00
}
Generalize support for elementwise ops. We plumb through e2e a fair number of interesting cases: - unary, binary, ternary elementwise ops - ops like `torch.aten.add.Tensor` that also take a scalar parameter - static size-1 broadcasting We allow the static size-1 broadcasting case, but emit a runtime error in the case of dynamic size-1 broadcasting. This seems like a sweet spot subset of things that can be lowered directly to linalg, while not being overly constraining to users. This is consistent with what IREE is doing for CHLO->Linalg lowering as well ([code](https://github.com/google/iree/blob/50bf7a87e465d2048c527bc27724edde40519b7e/iree/compiler/InputConversion/MHLO/BroadcastingToLinalgPatterns.cpp#L1)). To test the static size-1 case, we added support for the `torch.aten.unsqueeze` op and lowering for it through `linalg.tensor_expand_shape`. This involved a generalization of `MaximizeValueSemantics` able to handle it (the solution there also works for `torch.aten.flatten.using_ints` which we need for ResNet anyway) Also, a few minor additional changes: - Add `VerifyInvariantsBeforeBackendLowering` pass, which catches a large class of errors before we get to backend lowering (now that we are doing dialect conversion, the errors are way nicer if we just emit them up front rather than in the guts of a random pattern). - Minor change to RefBackend to allow `linalg.tensor_expand_shape`. Recommended review order: - e2e tests in elementwise.py - `ConvertElementwiseOp` in TorchToLinalg.cpp + elementwise.mlir test - `ConvertAtenUnsqueezeOp` in TorchToLinalg.cpp + unsqueeze.mlir test - RefineTypes.cpp + tests - MaximizeValueSemantics changes + test - VerifyInvariantsBeforeBackendLowering pass + test
2021-06-26 08:25:09 +08:00
// CHECK-LABEL: func @viewlike$basic_unsqueeze(
// CHECK-SAME: %[[ARG:.*]]: !torch.vtensor) -> !torch.vtensor {
// CHECK: %[[INT0:.*]] = torch.constant.int 0
// CHECK: %[[UNSQUEEZE:.*]] = torch.aten.unsqueeze %[[ARG]], %[[INT0]] : !torch.vtensor, !torch.int -> !torch.vtensor
// CHECK: return %[[UNSQUEEZE]] : !torch.vtensor
func @viewlike$basic_unsqueeze(%arg0: !torch.vtensor) -> !torch.vtensor {
%int0 = torch.constant.int 0
%0 = torch.copy.to_tensor %arg0 : !torch.tensor
%1 = torch.aten.unsqueeze %0, %int0 : !torch.tensor, !torch.int -> !torch.tensor
%2 = torch.copy.to_vtensor %1 : !torch.vtensor
return %2 : !torch.vtensor
}
// CHECK-LABEL: func @viewlike$basic_flatten(
// CHECK-SAME: %[[ARG:.*]]: !torch.vtensor) -> !torch.vtensor {
// CHECK: %[[INT0:.*]] = torch.constant.int 0
// CHECK: %[[INTM1:.*]] = torch.constant.int -1
// CHECK: %[[FLATTEN:.*]] = torch.aten.flatten.using_ints %[[ARG]], %[[INT0]], %[[INTM1]] : !torch.vtensor, !torch.int, !torch.int -> !torch.vtensor
// CHECK: return %[[FLATTEN]] : !torch.vtensor
func @viewlike$basic_flatten(%arg0: !torch.vtensor) -> !torch.vtensor {
%start = torch.constant.int 0
%end = torch.constant.int -1
%0 = torch.copy.to_tensor %arg0 : !torch.tensor
%1 = torch.aten.flatten.using_ints %0, %start, %end : !torch.tensor, !torch.int, !torch.int -> !torch.tensor
%2 = torch.copy.to_vtensor %1 : !torch.vtensor
return %2 : !torch.vtensor
}
// CHECK-LABEL: func @viewlike$transitive(
// CHECK-SAME: %[[ARG:.*]]: !torch.vtensor) -> !torch.vtensor {
// CHECK: %[[INT0:.*]] = torch.constant.int 0
// CHECK: %[[UNSQUEEZE0:.*]] = torch.aten.unsqueeze %[[ARG]], %[[INT0]] : !torch.vtensor, !torch.int -> !torch.vtensor
// CHECK: %[[UNSQUEEZE1:.*]] = torch.aten.unsqueeze %[[UNSQUEEZE0]], %[[INT0]] : !torch.vtensor, !torch.int -> !torch.vtensor
// CHECK: return %[[UNSQUEEZE1]] : !torch.vtensor
func @viewlike$transitive(%arg0: !torch.vtensor) -> !torch.vtensor {
%int0 = torch.constant.int 0
%0 = torch.copy.to_tensor %arg0 : !torch.tensor
%1 = torch.aten.unsqueeze %0, %int0 : !torch.tensor, !torch.int -> !torch.tensor
%2 = torch.aten.unsqueeze %1, %int0 : !torch.tensor, !torch.int -> !torch.tensor
%3 = torch.copy.to_vtensor %2 : !torch.vtensor
return %3 : !torch.vtensor
}
// CHECK-LABEL: func @viewlike$transitive_tree(
// CHECK-SAME: %[[ARG:.*]]: !torch.vtensor) -> (!torch.vtensor, !torch.vtensor) {
// CHECK: %[[INT0:.*]] = torch.constant.int 0
// CHECK: %[[UNSQUEEZE0:.*]] = torch.aten.unsqueeze %[[ARG]], %[[INT0]] : !torch.vtensor, !torch.int -> !torch.vtensor
// CHECK: %[[RET0:.*]] = torch.aten.unsqueeze %[[UNSQUEEZE0]], %[[INT0]] : !torch.vtensor, !torch.int -> !torch.vtensor
// CHECK: %[[RET1:.*]] = torch.aten.unsqueeze %[[UNSQUEEZE0]], %[[INT0]] : !torch.vtensor, !torch.int -> !torch.vtensor
// CHECK: return %[[RET0]], %[[RET1]] : !torch.vtensor, !torch.vtensor
func @viewlike$transitive_tree(%arg0: !torch.vtensor) -> (!torch.vtensor, !torch.vtensor) {
%int0 = torch.constant.int 0
%0 = torch.copy.to_tensor %arg0 : !torch.tensor
// %1 has two users.
%1 = torch.aten.unsqueeze %0, %int0 : !torch.tensor, !torch.int -> !torch.tensor
%2 = torch.aten.unsqueeze %1, %int0 : !torch.tensor, !torch.int -> !torch.tensor
%3 = torch.copy.to_vtensor %2 : !torch.vtensor
%4 = torch.aten.unsqueeze %1, %int0 : !torch.tensor, !torch.int -> !torch.tensor
%5 = torch.copy.to_vtensor %4 : !torch.vtensor
return %3, %5 : !torch.vtensor, !torch.vtensor
}
// CHECK-LABEL: func @viewlike$unmodeled_op(
// CHECK-SAME: %[[ARG:.*]]: !torch.vtensor) -> !torch.vtensor {
// CHECK: %[[UNSQUEEZE:.*]] = torch.aten.unsqueeze {{.*}} : !torch.tensor, !torch.int -> !torch.tensor
// CHECK: "some.op"(%[[UNSQUEEZE]]) : (!torch.tensor) -> ()
func @viewlike$unmodeled_op(%arg0: !torch.vtensor) -> !torch.vtensor {
%int0 = torch.constant.int 0
%0 = torch.copy.to_tensor %arg0 : !torch.tensor
%1 = torch.aten.unsqueeze %0, %int0 : !torch.tensor, !torch.int -> !torch.tensor
"some.op"(%1) : (!torch.tensor) -> ()
%2 = torch.copy.to_vtensor %1 : !torch.vtensor
return %2 : !torch.vtensor
}