[Mlir-commits] [mlir] Add pattern to fold insert_slice of extract_slice (PR #86328)

Jerry Wu llvmlistbot at llvm.org
Fri Mar 22 12:10:55 PDT 2024


https://github.com/pzread updated https://github.com/llvm/llvm-project/pull/86328

>From 2fb7b5c91d1df0b61dd7a1b1f5d3972255b40644 Mon Sep 17 00:00:00 2001
From: Jerry Wu <cheyuw at google.com>
Date: Wed, 20 Mar 2024 21:26:44 +0000
Subject: [PATCH 1/3] Fold extract_slice+insert_slice

---
 .../Tensor/Transforms/FoldTensorSubsetOps.cpp | 61 ++++++++++++++++++-
 1 file changed, 59 insertions(+), 2 deletions(-)

diff --git a/mlir/lib/Dialect/Tensor/Transforms/FoldTensorSubsetOps.cpp b/mlir/lib/Dialect/Tensor/Transforms/FoldTensorSubsetOps.cpp
index 3b8d3708bb7314..94de49b301e692 100644
--- a/mlir/lib/Dialect/Tensor/Transforms/FoldTensorSubsetOps.cpp
+++ b/mlir/lib/Dialect/Tensor/Transforms/FoldTensorSubsetOps.cpp
@@ -16,6 +16,7 @@
 #include "mlir/Dialect/Tensor/IR/Tensor.h"
 #include "mlir/Dialect/Tensor/Transforms/Passes.h"
 #include "mlir/Dialect/Tensor/Transforms/Transforms.h"
+#include "mlir/Dialect/Tensor/Utils/Utils.h"
 #include "mlir/Dialect/Utils/IndexingUtils.h"
 #include "mlir/Dialect/Vector/IR/VectorOps.h"
 #include "mlir/IR/AffineMap.h"
@@ -65,6 +66,16 @@ class InsertSliceOfTransferWriteOpFolder final
   LogicalResult matchAndRewrite(tensor::InsertSliceOp insertSliceOp,
                                 PatternRewriter &rewriter) const override;
 };
+
+class InsertSliceOfExtractSliceFolder final
+    : public OpRewritePattern<tensor::InsertSliceOp> {
+public:
+  using OpRewritePattern<tensor::InsertSliceOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(tensor::InsertSliceOp insertSliceOp,
+                                PatternRewriter &rewriter) const override;
+};
+
 } // namespace
 
 template <typename XferOp, typename ExtractOrInsertOp>
@@ -147,6 +158,52 @@ LogicalResult InsertSliceOfTransferWriteOpFolder::matchAndRewrite(
   return success();
 }
 
+LogicalResult InsertSliceOfExtractSliceFolder::matchAndRewrite(
+    tensor::InsertSliceOp insertSliceOp, PatternRewriter &rewriter) const {
+  auto extractSliceOp =
+      insertSliceOp.getSource().getDefiningOp<tensor::ExtractSliceOp>();
+  if (!extractSliceOp)
+    return failure();
+
+  if (!extractSliceOp->hasOneUse())
+    return failure();
+
+  if (!isCastLikeInsertSliceOp(insertSliceOp))
+    return failure();
+
+  llvm::SmallBitVector extractDroppedDims = extractSliceOp.getDroppedDims();
+  llvm::SmallBitVector insertExpandedDims = insertSliceOp.getDroppedDims();
+  if (extractDroppedDims.size() < insertExpandedDims.size())
+    return failure();
+
+  int64_t insertPos = 0;
+  for (int64_t extractPos = 0; extractPos < extractDroppedDims.size();
+       ++extractPos) {
+    if (insertPos == insertExpandedDims.size())
+      break;
+
+    bool isDropped = extractDroppedDims[extractPos];
+    bool isExpanded = insertExpandedDims[insertPos];
+    if (isDropped == isExpanded) {
+      insertPos += 1;
+    } else {
+      if (!isDropped && isExpanded) {
+        return failure();
+      }
+    }
+  }
+  if (insertPos != insertExpandedDims.size())
+    return failure();
+
+  rewriter.replaceOpWithNewOp<tensor::ExtractSliceOp>(
+      insertSliceOp, insertSliceOp.getType(), extractSliceOp.getSource(),
+      extractSliceOp.getMixedOffsets(), extractSliceOp.getMixedSizes(),
+      extractSliceOp.getMixedStrides());
+  rewriter.eraseOp(extractSliceOp);
+
+  return success();
+}
+
 template <typename OpTy>
 struct InsertSliceOfInsertSliceFolder : public OpRewritePattern<OpTy> {
   using OpRewritePattern<OpTy>::OpRewritePattern;
@@ -224,8 +281,8 @@ struct InsertSliceOfInsertSliceFolder : public OpRewritePattern<OpTy> {
 void tensor::populateFoldTensorSubsetOpPatterns(RewritePatternSet &patterns) {
   populateFoldTensorSubsetIntoVectorTransferPatterns(patterns);
   patterns.add<InsertSliceOfInsertSliceFolder<tensor::InsertSliceOp>,
-               InsertSliceOfInsertSliceFolder<tensor::ParallelInsertSliceOp>>(
-      patterns.getContext());
+               InsertSliceOfInsertSliceFolder<tensor::ParallelInsertSliceOp>,
+               InsertSliceOfExtractSliceFolder>(patterns.getContext());
 }
 
 void tensor::populateFoldTensorSubsetIntoVectorTransferPatterns(

>From ca2607a4532f561a76f96e3a9af9824a51bbd4df Mon Sep 17 00:00:00 2001
From: Jerry Wu <cheyuw at google.com>
Date: Thu, 21 Mar 2024 20:06:13 +0000
Subject: [PATCH 2/3] Fix isCastLikeInsertSliceOp

---
 mlir/lib/Dialect/Tensor/Utils/Utils.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mlir/lib/Dialect/Tensor/Utils/Utils.cpp b/mlir/lib/Dialect/Tensor/Utils/Utils.cpp
index 186f85d2ce20a6..4bc966f2079d8a 100644
--- a/mlir/lib/Dialect/Tensor/Utils/Utils.cpp
+++ b/mlir/lib/Dialect/Tensor/Utils/Utils.cpp
@@ -142,11 +142,13 @@ mlir::tensor::getUnPackInverseSrcPerm(UnPackOp unpackOp,
 bool mlir::tensor::isCastLikeInsertSliceOp(InsertSliceOp op) {
   llvm::SmallBitVector droppedDims = op.getDroppedDims();
   int64_t srcDim = 0;
+  RankedTensorType resultType = op.getDestType();
   // Source dims and destination dims (apart from dropped dims) must have the
   // same size.
-  for (int64_t resultDim = 0; resultDim < op.getDestType().getRank();
-       ++resultDim) {
+  for (int64_t resultDim = 0; resultDim < resultType.getRank(); ++resultDim) {
     if (droppedDims.test(resultDim)) {
+      if (resultType.getDimSize(resultDim) != 1)
+        return false;
       continue;
     }
     FailureOr<bool> equalDimSize = ValueBoundsConstraintSet::areEqual(

>From f4d6bf260e9b143df9f1f4ea161f7d44a53fe05e Mon Sep 17 00:00:00 2001
From: Jerry Wu <cheyuw at google.com>
Date: Fri, 22 Mar 2024 19:03:48 +0000
Subject: [PATCH 3/3] Add pattern to fold insert_slice of extract_slice

---
 .../Tensor/Transforms/FoldTensorSubsetOps.cpp | 37 +++++++++--
 mlir/lib/Dialect/Tensor/Utils/Utils.cpp       |  2 +
 .../Tensor/fold-tensor-subset-ops.mlir        | 65 +++++++++++++++++++
 3 files changed, 100 insertions(+), 4 deletions(-)

diff --git a/mlir/lib/Dialect/Tensor/Transforms/FoldTensorSubsetOps.cpp b/mlir/lib/Dialect/Tensor/Transforms/FoldTensorSubsetOps.cpp
index 94de49b301e692..d04d1b5eaf5c5b 100644
--- a/mlir/lib/Dialect/Tensor/Transforms/FoldTensorSubsetOps.cpp
+++ b/mlir/lib/Dialect/Tensor/Transforms/FoldTensorSubsetOps.cpp
@@ -67,6 +67,7 @@ class InsertSliceOfTransferWriteOpFolder final
                                 PatternRewriter &rewriter) const override;
 };
 
+/// Merge insert_slice operation with extract_slice operation.
 class InsertSliceOfExtractSliceFolder final
     : public OpRewritePattern<tensor::InsertSliceOp> {
 public:
@@ -158,6 +159,21 @@ LogicalResult InsertSliceOfTransferWriteOpFolder::matchAndRewrite(
   return success();
 }
 
+/// Merge insert_slice operation with extract_slice operation.
+///
+/// This can be done when the insert_slice op purely expands ranks (adds unit
+/// dims) and the extrace_slice drops corresponding unit dims. For example:
+///
+/// %extracted_slice = tensor.extract_slice %in[0, 0] [1, 8] [1, 1]
+///     : tensor<2x8xf32> to tensor<8xf32>
+/// %inserted_slice = tensor.insert_slice %extracted_slice
+///     into %dest[0, 0] [1, 8] [1, 1]
+///     : tensor<8xf32> into tensor<1x8xf32>
+///
+/// can be folded into:
+///
+/// %extracted_slice = tensor.extract_slice %in[0, 0] [1, 8] [1, 1]
+///     : tensor<2x8xf32> to tensor<1x8xf32>
 LogicalResult InsertSliceOfExtractSliceFolder::matchAndRewrite(
     tensor::InsertSliceOp insertSliceOp, PatternRewriter &rewriter) const {
   auto extractSliceOp =
@@ -165,33 +181,46 @@ LogicalResult InsertSliceOfExtractSliceFolder::matchAndRewrite(
   if (!extractSliceOp)
     return failure();
 
+  // Can't fold if the extract_slice op has other users.
   if (!extractSliceOp->hasOneUse())
     return failure();
 
+  // Check if the insert_slice op purely expands ranks (add unit dims).
   if (!isCastLikeInsertSliceOp(insertSliceOp))
     return failure();
 
   llvm::SmallBitVector extractDroppedDims = extractSliceOp.getDroppedDims();
   llvm::SmallBitVector insertExpandedDims = insertSliceOp.getDroppedDims();
+  // Can't fold if the insert_slice op expands more dims.
   if (extractDroppedDims.size() < insertExpandedDims.size())
     return failure();
 
+  // Try to match the dropped unit dims to the expanded unit dims. This is done
+  // by scanning the dims of extract_slice and find the left-most one can match
+  // the dim of insert_slice. If a match is found, advance the dim of
+  // insert_slice to match the next one.
   int64_t insertPos = 0;
   for (int64_t extractPos = 0; extractPos < extractDroppedDims.size();
        ++extractPos) {
+    // Matched all expanded dims.
     if (insertPos == insertExpandedDims.size())
       break;
 
     bool isDropped = extractDroppedDims[extractPos];
     bool isExpanded = insertExpandedDims[insertPos];
+    // Match if both sides drop/keep the dim. Advance and match the next dim of
+    // insert_slice.
     if (isDropped == isExpanded) {
       insertPos += 1;
-    } else {
-      if (!isDropped && isExpanded) {
-        return failure();
-      }
+    } else if (!isDropped && isExpanded) {
+      // Not enough dropped unit dims to match the expanded unit dims.
+      return failure();
     }
+    // If the dim is dropped by extract_slice and not by insert_slice, look the
+    // next dim of extract_slice to see if it can match the current dim of
+    // insert_slice.
   }
+  // Can't match some expanded dims.
   if (insertPos != insertExpandedDims.size())
     return failure();
 
diff --git a/mlir/lib/Dialect/Tensor/Utils/Utils.cpp b/mlir/lib/Dialect/Tensor/Utils/Utils.cpp
index 4bc966f2079d8a..2dd91e2f7a1700 100644
--- a/mlir/lib/Dialect/Tensor/Utils/Utils.cpp
+++ b/mlir/lib/Dialect/Tensor/Utils/Utils.cpp
@@ -147,6 +147,8 @@ bool mlir::tensor::isCastLikeInsertSliceOp(InsertSliceOp op) {
   // same size.
   for (int64_t resultDim = 0; resultDim < resultType.getRank(); ++resultDim) {
     if (droppedDims.test(resultDim)) {
+      // InsertSlice may expand unit dimensions that result from inserting a
+      // size-1 slice into a non-size-1 result dimension.
       if (resultType.getDimSize(resultDim) != 1)
         return false;
       continue;
diff --git a/mlir/test/Dialect/Tensor/fold-tensor-subset-ops.mlir b/mlir/test/Dialect/Tensor/fold-tensor-subset-ops.mlir
index f2e529b4cac950..bb1df99d4c97ee 100644
--- a/mlir/test/Dialect/Tensor/fold-tensor-subset-ops.mlir
+++ b/mlir/test/Dialect/Tensor/fold-tensor-subset-ops.mlir
@@ -390,3 +390,68 @@ func.func @parallel_insert_slice_of_insert_slice_dynamic(
   }
   return %0: tensor<12x34xf32>
 }
+
+// -----
+
+func.func @fold_casting_insert_slice_of_extract_slice(%in : tensor<?x8x2x8xf32>, %dest : tensor<8x1x8xf32>) -> tensor<8x1x8xf32> {
+  %extracted_slice = tensor.extract_slice %in[0, 0, 0, 0] [1, 8, 1, 8] [1, 1, 1, 1] : tensor<?x8x2x8xf32> to tensor<8x8xf32>
+  %inserted_slice = tensor.insert_slice %extracted_slice into %dest[0, 0, 0] [8, 1, 8] [1, 1, 1] : tensor<8x8xf32> into tensor<8x1x8xf32>
+  return %inserted_slice : tensor<8x1x8xf32>
+}
+// CHECK-LABEL: func.func @fold_casting_insert_slice_of_extract_slice(
+// CHECK-SAME:      %[[ARG0:.*]]: tensor<?x8x2x8xf32>
+// CHECK:         %[[EXTRACTED_SLICE:.*]] = tensor.extract_slice %[[ARG0]][0, 0, 0, 0] [1, 8, 1, 8] [1, 1, 1, 1]
+// CHECK-SAME:      : tensor<?x8x2x8xf32> to tensor<8x1x8xf32>
+// CHECK:         return %[[EXTRACTED_SLICE]] : tensor<8x1x8xf32>
+
+// -----
+
+func.func @fold_casting_insert_slice_of_strided_extract_slice(%in : tensor<?x8x2x8xf32>, %dest : tensor<1x4x8xf32>) -> tensor<1x4x8xf32> {
+  %extracted_slice = tensor.extract_slice %in[0, 0, 0, 0] [1, 4, 1, 8] [1, 2, 1, 1] : tensor<?x8x2x8xf32> to tensor<4x8xf32>
+  %inserted_slice = tensor.insert_slice %extracted_slice into %dest[0, 0, 0] [1, 4, 8] [1, 1, 1] : tensor<4x8xf32> into tensor<1x4x8xf32>
+  return %inserted_slice : tensor<1x4x8xf32>
+}
+// CHECK-LABEL: func.func @fold_casting_insert_slice_of_strided_extract_slice(
+// CHECK-SAME:      %[[ARG0:.*]]: tensor<?x8x2x8xf32>
+// CHECK:         %[[EXTRACTED_SLICE:.*]] = tensor.extract_slice %[[ARG0]][0, 0, 0, 0] [1, 4, 1, 8] [1, 2, 1, 1]
+// CHECK-SAME:      : tensor<?x8x2x8xf32> to tensor<1x4x8xf32>
+// CHECK:         return %[[EXTRACTED_SLICE]] : tensor<1x4x8xf32>
+
+// -----
+
+func.func @no_fold_more_unit_dims_insert_slice_of_extract_slice(%in : tensor<?x8x8xf32>, %dest : tensor<1x1x8x8xf32>) -> tensor<1x1x8x8xf32> {
+  %extracted_slice = tensor.extract_slice %in[0, 0, 0] [1, 8, 8] [1, 1, 1] : tensor<?x8x8xf32> to tensor<8x8xf32>
+  %inserted_slice = tensor.insert_slice %extracted_slice into %dest[0, 0, 0, 0] [1, 1, 8, 8] [1, 1, 1, 1] : tensor<8x8xf32> into tensor<1x1x8x8xf32>
+  return %inserted_slice : tensor<1x1x8x8xf32>
+}
+// CHECK-LABEL: func.func @no_fold_more_unit_dims_insert_slice_of_extract_slice(
+// CHECK-SAME:      %[[ARG0:.*]]: tensor<?x8x8xf32>
+// CHECK:         %[[EXTRACTED_SLICE:.*]] = tensor.extract_slice %[[ARG0]]
+// CHECK:         %[[INSERTED_SLICE:.*]] = tensor.insert_slice %[[EXTRACTED_SLICE]]
+// CHECK:         return %[[INSERTED_SLICE]] : tensor<1x1x8x8xf32>
+
+// -----
+
+func.func @no_fold_strided_insert_slice_of_extract_slice(%in : tensor<?x8x2x8xf32>, %dest : tensor<1x4x4xf32>) -> tensor<1x4x4xf32> {
+  %extracted_slice = tensor.extract_slice %in[0, 0, 0, 0] [1, 8, 1, 8] [1, 1, 1, 1] : tensor<?x8x2x8xf32> to tensor<8x8xf32>
+  %inserted_slice = tensor.insert_slice %extracted_slice into %dest[0, 0, 0] [1, 8, 8] [1, 2, 2] : tensor<8x8xf32> into tensor<1x4x4xf32>
+  return %inserted_slice : tensor<1x4x4xf32>
+}
+// CHECK-LABEL: func.func @no_fold_strided_insert_slice_of_extract_slice(
+// CHECK-SAME:      %[[ARG0:.*]]: tensor<?x8x2x8xf32>
+// CHECK:         %[[EXTRACTED_SLICE:.*]] = tensor.extract_slice %[[ARG0]]
+// CHECK:         %[[INSERTED_SLICE:.*]] = tensor.insert_slice %[[EXTRACTED_SLICE]]
+// CHECK:         return %[[INSERTED_SLICE]] : tensor<1x4x4xf32>
+
+// -----
+
+func.func @no_fold_non_casting_insert_slice_of_extract_slice(%in : tensor<1x1x1x8x8xf32>, %dest : tensor<2x8x8xf32>) -> tensor<2x8x8xf32> {
+  %extracted_slice = tensor.extract_slice %in[0, 0, 0, 0, 0] [1, 1, 1, 8, 8] [1, 1, 1, 1, 1] : tensor<1x1x1x8x8xf32> to tensor<8x8xf32>
+  %inserted_slice = tensor.insert_slice %extracted_slice into %dest[0, 0, 0] [1, 8, 8] [1, 1, 1] : tensor<8x8xf32> into tensor<2x8x8xf32>
+  return %inserted_slice : tensor<2x8x8xf32>
+}
+// CHECK-LABEL: func.func @no_fold_non_casting_insert_slice_of_extract_slice(
+// CHECK-SAME:      %[[ARG0:.*]]: tensor<1x1x1x8x8xf32>
+// CHECK:         %[[EXTRACTED_SLICE:.*]] = tensor.extract_slice %[[ARG0]]
+// CHECK:         %[[INSERTED_SLICE:.*]] = tensor.insert_slice %[[EXTRACTED_SLICE]]
+// CHECK:         return %[[INSERTED_SLICE]] : tensor<2x8x8xf32>



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