[clang] [mlir] Implement DestinationStyleOpInterface for scf::ForallOp (PR #66981)
Felix Schneider via cfe-commits
cfe-commits at lists.llvm.org
Fri Sep 22 04:57:01 PDT 2023
https://github.com/ubfx updated https://github.com/llvm/llvm-project/pull/66981
>From a84378d0f4e67cd7f68a27c87e12939fa40b65b4 Mon Sep 17 00:00:00 2001
From: Felix Schneider <fx.schn at gmail.com>
Date: Thu, 21 Sep 2023 06:13:57 +0000
Subject: [PATCH 1/3] [mlir] Implement DestinationStyleOpInterface for
scf::ForallOp
`scf::ForallOp` has `shared_outs` tensor operands which are used to
insert partial results into in the parallel terminator. The
`scf::ForallOp` returns one tensor for each `shared_out` which then
contains the combined result from all threads. Since the parallel
terminator cannot change the shape of the `shared_out`, ForallOp is a
`DestinationStyleOp` and this patch implements the interface by declaring
the `outputs` operands as `inits` in the language of the DPS interface.
For this change to work, we need to add an exception to the Pattern
that folds `tensor.cast` Ops into DPS Ops because `scf::Forall` needs
special handling of it's `BlockArgument` Type during this folding.
---
mlir/include/mlir/Dialect/SCF/IR/SCF.h | 1 +
mlir/include/mlir/Dialect/SCF/IR/SCFOps.td | 10 ++++++++++
mlir/lib/Dialect/Tensor/IR/TensorOps.cpp | 4 ++++
3 files changed, 15 insertions(+)
diff --git a/mlir/include/mlir/Dialect/SCF/IR/SCF.h b/mlir/include/mlir/Dialect/SCF/IR/SCF.h
index 915ab3016b688e7..644118ca884c6b1 100644
--- a/mlir/include/mlir/Dialect/SCF/IR/SCF.h
+++ b/mlir/include/mlir/Dialect/SCF/IR/SCF.h
@@ -19,6 +19,7 @@
#include "mlir/IR/BuiltinTypes.h"
#include "mlir/IR/RegionKindInterface.h"
#include "mlir/Interfaces/ControlFlowInterfaces.h"
+#include "mlir/Interfaces/DestinationStyleOpInterface.h"
#include "mlir/Interfaces/InferTypeOpInterface.h"
#include "mlir/Interfaces/LoopLikeInterface.h"
#include "mlir/Interfaces/ParallelCombiningOpInterface.h"
diff --git a/mlir/include/mlir/Dialect/SCF/IR/SCFOps.td b/mlir/include/mlir/Dialect/SCF/IR/SCFOps.td
index 08b71e20a2bc079..adc7b2e4170cb89 100644
--- a/mlir/include/mlir/Dialect/SCF/IR/SCFOps.td
+++ b/mlir/include/mlir/Dialect/SCF/IR/SCFOps.td
@@ -17,6 +17,7 @@ include "mlir/Interfaces/ControlFlowInterfaces.td"
include "mlir/Interfaces/LoopLikeInterface.td"
include "mlir/IR/RegionKindInterface.td"
include "mlir/Dialect/SCF/IR/DeviceMappingInterface.td"
+include "mlir/Interfaces/DestinationStyleOpInterface.td"
include "mlir/Interfaces/InferTypeOpInterface.td"
include "mlir/Interfaces/ParallelCombiningOpInterface.td"
include "mlir/Interfaces/SideEffectInterfaces.td"
@@ -333,6 +334,7 @@ def ForallOp : SCF_Op<"forall", [
RecursiveMemoryEffects,
SingleBlockImplicitTerminator<"scf::InParallelOp">,
DeclareOpInterfaceMethods<RegionBranchOpInterface>,
+ DestinationStyleOpInterface
]> {
let summary = "evaluate a block multiple times in parallel";
let description = [{
@@ -630,6 +632,14 @@ def ForallOp : SCF_Op<"forall", [
Location loc);
InParallelOp getTerminator();
+
+ // Implement this to declare all shared_outs as inits/outs to
+ // DestinationStyleOpInterface
+ std::pair<int64_t, int64_t> getDpsInitsPositionRange() {
+ int64_t numOperands = getNumOperands();
+ int64_t numOuts = getOutputs().size();
+ return {numOperands - numOuts, numOperands};
+ }
}];
}
diff --git a/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp b/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
index 3e30e320bee8f83..fa91471f33d4bd3 100644
--- a/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
+++ b/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
@@ -10,6 +10,7 @@
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/Arith/Utils/Utils.h"
#include "mlir/Dialect/Complex/IR/Complex.h"
+#include "mlir/Dialect/SCF/IR/SCF.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/Dialect/Utils/IndexingUtils.h"
#include "mlir/Dialect/Utils/ReshapeOpsUtils.h"
@@ -3970,6 +3971,9 @@ struct FoldTensorCastProducerOp
if (isa<InsertSliceOp>(op.getOperation()))
return failure();
+ if (isa<scf::ForallOp>(op.getOperation()))
+ return failure();
+
// If no operand comes from a tensor::CastOp and can be folded then fail.
bool hasTensorCastOperand =
llvm::any_of(op->getOpOperands(), [&](OpOperand &opOperand) {
>From 4e8e45878083490a9adf0fbcc1b4565081c1d7c5 Mon Sep 17 00:00:00 2001
From: Felix Schneider <fx.schn at gmail.com>
Date: Thu, 21 Sep 2023 07:52:23 +0000
Subject: [PATCH 2/3] add comment clarifying the exception for forallOp folding
with tensor.cast
---
mlir/lib/Dialect/Tensor/IR/TensorOps.cpp | 2 ++
1 file changed, 2 insertions(+)
diff --git a/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp b/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
index fa91471f33d4bd3..65a834acad8acfb 100644
--- a/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
+++ b/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
@@ -3971,6 +3971,8 @@ struct FoldTensorCastProducerOp
if (isa<InsertSliceOp>(op.getOperation()))
return failure();
+ // scf::ForallOp also has its own folding logic taking the Types of its
+ // BlockArguments into consideration.
if (isa<scf::ForallOp>(op.getOperation()))
return failure();
>From 43de77ecada804d6185ec27bca1081cbecb7c44d Mon Sep 17 00:00:00 2001
From: Felix Schneider <fx.schn at gmail.com>
Date: Fri, 22 Sep 2023 06:45:52 +0000
Subject: [PATCH 3/3] Exclude LoopLikeInterfaceOps instead of scf::ForallOp
specifically
---
mlir/lib/Dialect/Tensor/IR/TensorOps.cpp | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp b/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
index 65a834acad8acfb..f719cfed6b6dd30 100644
--- a/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
+++ b/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
@@ -10,7 +10,6 @@
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/Arith/Utils/Utils.h"
#include "mlir/Dialect/Complex/IR/Complex.h"
-#include "mlir/Dialect/SCF/IR/SCF.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/Dialect/Utils/IndexingUtils.h"
#include "mlir/Dialect/Utils/ReshapeOpsUtils.h"
@@ -23,6 +22,7 @@
#include "mlir/IR/OpDefinition.h"
#include "mlir/IR/TypeUtilities.h"
#include "mlir/Interfaces/DestinationStyleOpInterface.h"
+#include "mlir/Interfaces/LoopLikeInterface.h"
#include "mlir/Support/MathExtras.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
@@ -3971,9 +3971,9 @@ struct FoldTensorCastProducerOp
if (isa<InsertSliceOp>(op.getOperation()))
return failure();
- // scf::ForallOp also has its own folding logic taking the Types of its
- // BlockArguments into consideration.
- if (isa<scf::ForallOp>(op.getOperation()))
+ // Exclude DPS ops that are also LoopLike from this interface as they
+ // might need special handling of attached regions.
+ if (isa<LoopLikeOpInterface>(op.getOperation()))
return failure();
// If no operand comes from a tensor::CastOp and can be folded then fail.
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