Fold memref.expand_shape and memref.collapse_shape ops

[arnab-oss]

Summary

Fold memref.expand_shape and memref.collapse_shape ops into
their memref/affine load/store ops.

[arnab-oss]

Discarding unnecessary changes.

[nicolasvasilache]

Thanks for improving this part of the codebase @arnab-oss!
Here is a first batch of comments.

[nicolasvasilache]

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

31

nit: typo: "of a load/store" here and below

56

Please generalize this a bit and add as a helper in include/mlir/Dialect/Utils/IndexingUtils.h, this will be useful in other places too.

I am surprised there isn't already something like this, I only see utilities to linearize / delinearize atm.

67

This feels like a linearization similar to the one in IndexingUtils.h but more generally applicable.
Could you try generalizing the AffineExpr building part into a new IndexingUtils.h and compose that with the extra reorderings?

The more it looks like:

AffineExpr srcIndexExpr = linearAffineExpression(suffixProduct);
SmallVector<Value> dynamicIndices = gather(indices, groups);
sourceIndices.push_back(rewriter.create<AffineApplyOp>(...));

the better the composability and overall code idiom power.

108

Same comments as above but for a delinearized form.

178

Have not yet looked at this deeply but please consider a similar type of refactoring / reuse as proposed above if possible.
I'll come back to it once the first batch of comments is resolved.
(I see you are merely moving code here but if there are opportunities to improve I'd take them).

245

Looking at the amount of code below I am wondering if you are going overboard with templates.

Seems it would be quite fewer code to have 3 separate LoadOpOfXXXFolder and inline the impl at the right place.
What you save in not typing the pattern decl and the matchAndRewrite decl you pay at least 4-5x the price in the extra indirection and templating logic.

[bondhugula]

This would be a great enhancement for code generation! -- to be able to de-abstract these ops out if/when needed. Would have been great to have these from the start!

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

2

Update summary line: memref.subview -> memref aliasing ops.

[nicolasvasilache]

In D128986#3640925, @bondhugula wrote:

This would be a great enhancement for code generation! -- to be able to de-abstract these ops out if/when needed. Would have been great to have these from the start!

Feel free to contribute when you need something ! :)

[arnab-oss]

Addressed review comments.

[arnab-oss]

Addressd review comments.

[arnab-oss]

ping @nicolasvasilache can you please re-review?

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

178

I feel this part of the code usage is specific to this case, and is not beneficial to expose it as a utility function.

[bondhugula]

It looks like the commit summary has got into the title, and the former is missing!

[nicolasvasilache]

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

123

This seems super artificial, I would rather duplicate this affine builder

void AffineLoadOp::build(OpBuilder &builder, OperationState &result,
                         Value memref, ValueRange indices) {

to allow taking ArrayRef<OpFoldResult> and just pass fill your sourceIndices with b.getIndexAttr(0).

178

faire enough, thanks for looking into it.

270

This decl, its def can be folded in all its uses now I think.
This would be the part that reduces the code size.

496

I think you can now:

llvm::TypeSwitch<Operation *, void>(loadOp)
        .Case<affine::LoadOp, memref::LoadOp>([&](auto op) {
          rewriter.replaceOpWithNewOp<decltype(op)>(
            loadOp, expandShapeOp.getViewSource(), sourceIndices);
        })
        .Default([](Operation *) { ;});

And drop all the overloads and decls?

[nicolasvasilache]

mlir/test/Dialect/MemRef/fold-memref-alias-ops.mlir

278

Please also add some tests for memref.load/store and vector.transfer.

[arnab-oss]

@nicolasvasilache can you please take a look at my comments?

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

123

Hi, I'm sorry I do not get your comment. Can you please elaborate?

270

I think I cannot unify all the cases involving different varieties of load/store ops, as their build functions expect different kinds and numbers of arguments.

496

I think this is not possible. Please take a look at my comment above.

[nicolasvasilache]

Sorry was OOO the last 2 weeks, replied inline.

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

496

This is precisely why I used a specific TypeSwitch + auto + decltype to resolve the type inside the Case lambda. To spell it more, you should be able to:

llvm::TypeSwitch<Operation *, void>(loadOp)
        .Case<affine::LoadOp, memref::LoadOp>([&](auto op) {
          rewriter.replaceOpWithNewOp<decltype(op)>(
            loadOp, expandShapeOp.getViewSource(), sourceIndices);
        })
        .Case<vector::TransferReadOp>([&](auto transferReadOp) {
          if (transferReadOp.getTransferRank() == 0) {
            // TODO: Propagate the error.
            return;
          }
          rewriter.replaceOpWithNewOp<vector::TransferReadOp>(
              transferReadOp, transferReadOp.getVectorType(), subViewOp.source(),
              sourceIndices,
              getPermutationMapAttr(rewriter.getContext(), subViewOp,
                                    transferReadOp.getPermutationMap()),
              transferReadOp.getPadding(),
              /*mask=*/Value(), transferReadOp.getInBoundsAttr());
        })
        .Default([](Operation *) { ;});

Did you try and hit compilation errors? If so, could you paste the error message ?

[arnab-oss]

I'm getting the following error:

/home2/arnab/llvm-project/mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp:447:30: error: ‘class mlir::vector::TransferReadOp’ has no member named ‘getValue’
  447 |             storeOp, storeOp.getValue(), subViewOp.source(), sourceIndices);

AffineStoreOp and memref::StoreOp have the getValue(), but vector::TransferReadOp does not.

[nicolasvasilache]

In D128986#3718717, @arnab-oss wrote:

I'm getting the following error:

/home2/arnab/llvm-project/mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp:447:30: error: ‘class mlir::vector::TransferReadOp’ has no member named ‘getValue’
  447 |             storeOp, storeOp.getValue(), subViewOp.source(), sourceIndices);

AffineStoreOp and memref::StoreOp have the getValue(), but vector::TransferReadOp does not.

Sorry I missed this.. This seems like the type of errors that the TypeSwitch solution I suggested should easily handle .. Can you post another WIP PR which shows how you are trying to do this?
In any case, adding a getValue to TransferReadOp or renaming the result vector to value is also an easy normalization of APIs.

If you find this really difficult, please just add more tests as requested and feel free to land as is.
I can pick up the slack in a followup commit.

[bondhugula]

In D128986#3718717, @arnab-oss wrote:

I'm getting the following error:

/home2/arnab/llvm-project/mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp:447:30: error: ‘class mlir::vector::TransferReadOp’ has no member named ‘getValue’
  447 |             storeOp, storeOp.getValue(), subViewOp.source(), sourceIndices);

AffineStoreOp and memref::StoreOp have the getValue(), but vector::TransferReadOp does not.

You can just make the APIs (accessor names here) consistent.

[bondhugula]

mlir/include/mlir/Dialect/MemRef/Transforms/Passes.h

41–42

This comment is outdated.

96

This one as well. Please update the doc comments to reflect the generalization.

[bondhugula]

There are still several style and efficiency issues (unnecessary copies).

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

50–51

This would lead to unnecessary copies - please don't use SmallVector's by copy this way; groups is only read below. Normally const ref, but ArrayRef here.

97

Likewise.

[bondhugula]

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

50–51

Sorry, looks like I didn't see the RHS here. This is a SmallVector returned from a function. So this is correct as is.

97

Nothing to change.

[arnab-oss]

Addressed comments

[arnab-oss]

@nicolasvasilache I've made the required changes in the API. Also added tests featuring memref.load/store. However I've not handled folding related to vector transfer ops, so no tests involving those ops.

[bondhugula]

mlir/include/mlir/Dialect/Vector/IR/VectorOps.td

1488–1490

Doc comment here. You can mention that this is added for uniformity with other similar ops.

1488–1490

Nit: This will fit in a single line.

[bondhugula]

mlir/include/mlir/Dialect/Utils/IndexingUtils.h

18

You don't need this include. Please use fwd decl.

[arnab-oss]

Addressed comments.

[nicolasvasilache]

utils/arcanist/clang-format.sh

54

please revert this change

[arnab-oss]

Removed wrong changes in clang-format.sh

[nicolasvasilache]

@arnab-oss thanks for refactoring to a nicer outcome.

Please address the last 2 points I raised and let's ship this!

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

344

Please add an llvm_unreachable here and all other places below, we don't want to silently fail if/when new ops get added in the future.

mlir/tools/mlir-vulkan-runner/mlir-vulkan-runner.cpp

50

Seems unrelated to this PR.
Even if it has no effects on the logic, I'd rather keep separate pieces separate.

[arnab-oss]

Addressed comments by nicolas.

[arnab-oss]

Minor changes.

[bondhugula]

A few minor things.

1. Please add a commit summary; it's currently blank.
2. Drop the full stop at the end of the commit title.
3. There is a whitespace issue in the test case file: $ git diff --check HEAD~.

mlir/test/Dialect/MemRef/fold-memref-alias-ops.mlir

418–419

Indent by two to be consistent.

[arnab-oss]

Minor NFC changes.

mlir/include/mlir/Dialect/MemRef/Transforms/Passes.h

 namespace memref {
 class AllocOp;
 //===----------------------------------------------------------------------===//
 // Patterns
 //===----------------------------------------------------------------------===//
 
 /// Collects a set of patterns to rewrite ops within the memref dialect.
 void populateExpandOpsPatterns(RewritePatternSet &patterns);
 
-/// Appends patterns for folding memref.subview ops into consumer load/store ops
-/// into `patterns`.
-void populateFoldSubViewOpPatterns(RewritePatternSet &patterns);
+/// Appends patterns for folding memref aliasing ops into consumer load/store
+/// ops into `patterns`.
+void populateFoldMemRefAliasOpPatterns(RewritePatternSet &patterns);
 
 /// Appends patterns that resolve `memref.dim` operations with values that are
 /// defined by operations that implement the
 /// `ReifyRankedShapeTypeShapeOpInterface`, in terms of shapes of its input
 /// operands.
 void populateResolveRankedShapeTypeResultDimsPatterns(
     RewritePatternSet &patterns);
 

 // Passes
 //===----------------------------------------------------------------------===//
 
 /// Creates an instance of the ExpandOps pass that legalizes memref dialect ops
 /// to be convertible to LLVM. For example, `memref.reshape` gets converted to
 /// `memref_reinterpret_cast`.
 std::unique_ptr<Pass> createExpandOpsPass();
 
-/// Creates an operation pass to fold memref.subview ops into consumer
+/// Creates an operation pass to fold memref aliasing ops into consumer
 /// load/store ops into `patterns`.
-std::unique_ptr<Pass> createFoldSubViewOpsPass();
+std::unique_ptr<Pass> createFoldMemRefAliasOpsPass();
 
 /// Creates an interprocedural pass to normalize memrefs to have a trivial
 /// (identity) layout map.
 std::unique_ptr<OperationPass<ModuleOp>> createNormalizeMemRefsPass();
 
 /// Creates an operation pass to resolve `memref.dim` operations with values
 /// that are defined by operations that implement the
 /// `ReifyRankedShapeTypeShapeOpInterface`, in terms of shapes of its input

mlir/include/mlir/Dialect/MemRef/Transforms/Passes.td

 
 include "mlir/Pass/PassBase.td"
 
 def ExpandOps : Pass<"memref-expand"> {
   let summary = "Legalize memref operations to be convertible to LLVM.";
   let constructor = "mlir::memref::createExpandOpsPass()";
 }
 
-def FoldSubViewOps : Pass<"fold-memref-subview-ops"> {
-  let summary = "Fold memref.subview ops into consumer load/store ops";
+def FoldMemRefAliasOps : Pass<"fold-memref-alias-ops"> {
+  let summary = "Fold memref alias ops into consumer load/store ops";
   let description = [{
-    The pass folds loading/storing from/to subview ops to loading/storing
+    The pass folds loading/storing from/to memref aliasing ops to loading/storing
     from/to the original memref.
   }];
-  let constructor = "mlir::memref::createFoldSubViewOpsPass()";
+  let constructor = "mlir::memref::createFoldMemRefAliasOpsPass()";
   let dependentDialects = [
       "AffineDialect", "memref::MemRefDialect", "vector::VectorDialect"
   ];
 }
 
 def NormalizeMemRefs : Pass<"normalize-memrefs", "ModuleOp"> {
   let summary = "Normalize memrefs";
    let description = [{

mlir/include/mlir/Dialect/Utils/IndexingUtils.h

 //===- IndexingUtils.h - Helpers related to index computations --*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This header file defines utilities and common canonicalization patterns for
 // reshape operations.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef MLIR_DIALECT_UTILS_INDEXINGUTILS_H
 #define MLIR_DIALECT_UTILS_INDEXINGUTILS_H
 
+#include "mlir/IR/Builders.h"
 #include "mlir/Support/LLVM.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
 
 namespace mlir {
 class ArrayAttr;
 
 /// Computes and returns the linearized index of 'offsets' w.r.t. 'basis'.
 int64_t linearize(ArrayRef<int64_t> offsets, ArrayRef<int64_t> basis);
for (const auto &en : enumerate(permutation))
     auxVec[en.index()] = inVec[en.value()];
   inVec = auxVec;
 }
 
 /// Helper that returns a subset of `arrayAttr` as a vector of int64_t.
 SmallVector<int64_t, 4> getI64SubArray(ArrayAttr arrayAttr,
                                        unsigned dropFront = 0,
                                        unsigned dropBack = 0);
+
+/// Computes and returns linearized affine expression w.r.t. `basis`.
+mlir::AffineExpr getLinearAffineExpr(ArrayRef<int64_t> basis, mlir::Builder &b);
+
+/// Given the strides in the dimension space, returns the affine expressions for
+/// vector-space offsets in each dimension for a de-linearized index.
+SmallVector<mlir::AffineExpr, 4>
+getDelinearizedAffineExpr(ArrayRef<int64_t> strides, mlir::Builder &b);
+
 } // namespace mlir
 
 #endif // MLIR_DIALECT_UTILS_INDEXINGUTILS_H

mlir/include/mlir/Dialect/Vector/IR/VectorOps.td

OpBuilder<(ins "Value":$vector,
                    CArg<"Optional<ArrayRef<bool>>", "::llvm::None">:$inBounds)>,
     /// 4. Builder with type inference that sets an empty mask and sets permutation
     /// map to 'getMinorIdentityMap'.
     OpBuilder<(ins "Value":$vector,
                    "Value":$dest,
                    "ValueRange":$indices,
                    CArg<"Optional<ArrayRef<bool>>", "::llvm::None">:$inBounds)>,
   ];
+
+  let extraClassDeclaration = [{
+    /// This method is added to maintain uniformity with load/store
+    ///  ops of other dialects.
+    Value getValue() { return getVector(); }
+  }];
+
   let hasFolder = 1;
   let hasCanonicalizer = 1;
   let hasCustomAssemblyFormat = 1;
   let hasVerifier = 1;
 }
 
 def Vector_LoadOp : Vector_Op<"load"> {
   let summary = "reads an n-D slice of memory into an n-D vector";

mlir/lib/Dialect/MemRef/Transforms/CMakeLists.txt

 add_mlir_dialect_library(MLIRMemRefTransforms
   ComposeSubView.cpp
   ExpandOps.cpp
-  FoldSubViewOps.cpp
+  FoldMemRefAliasOps.cpp
   MultiBuffer.cpp
   NormalizeMemRefs.cpp
   ResolveShapedTypeResultDims.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${MLIR_MAIN_INCLUDE_DIR}/mlir/Dialect/MemRef
 
   DEPENDS

mlir/lib/Dialect/MemRef/Transforms/FoldMemRefAliasOps.cpp

+//===- FoldMemRefAliasOps.cpp - Fold memref alias ops -----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This transformation pass folds loading/storing from/to subview ops into
+// loading/storing from/to the original memref.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PassDetail.h"
+#include "mlir/Dialect/Affine/IR/AffineOps.h"
+#include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
+#include "mlir/Dialect/MemRef/IR/MemRef.h"
+#include "mlir/Dialect/MemRef/Transforms/Passes.h"
+#include "mlir/Dialect/Utils/IndexingUtils.h"
+#include "mlir/Dialect/Vector/IR/VectorOps.h"
+#include "mlir/IR/BuiltinTypes.h"
+#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
+#include "llvm/ADT/SmallBitVector.h"
+#include "llvm/ADT/TypeSwitch.h"
+
+using namespace mlir;
+
+//===----------------------------------------------------------------------===//
+// Utility functions
+//===----------------------------------------------------------------------===//
+
+/// Given the 'indices' of a load/store operation where the memref is a result
+/// of a expand_shape op, returns the indices w.r.t to the source memref of the
+/// expand_shape op. For example
+///
+/// %0 = ... : memref<12x42xf32>
+/// %1 = memref.expand_shape %0 [[0, 1], [2]]
+///    : memref<12x42xf32> into memref<2x6x42xf32>
+/// %2 = load %1[%i1, %i2, %i3] : memref<2x6x42xf32
+///
+/// could be folded into
+///
+/// %2 = load %0[6 * i1 + i2, %i3] :
+///          memref<12x42xf32>
+static LogicalResult
+resolveSourceIndicesExpandShape(Location loc, PatternRewriter &rewriter,
+                                memref::ExpandShapeOp expandShapeOp,
+                                ValueRange indices,
+                                SmallVectorImpl<Value> &sourceIndices) {
+  for (SmallVector<int64_t, 2> groups :
+       expandShapeOp.getReassociationIndices()) {
+    assert(!groups.empty() && "association indices groups cannot be empty");
+    unsigned groupSize = groups.size();
+    SmallVector<int64_t> suffixProduct(groupSize);
+    // Calculate suffix product of dimension sizes for all dimensions of expand
+    // shape op result.
+    suffixProduct[groupSize - 1] = 1;
+    for (unsigned i = groupSize - 1; i > 0; i--)
+      suffixProduct[i - 1] =
+          suffixProduct[i] *
+          expandShapeOp.getType().cast<MemRefType>().getDimSize(groups[i]);
+    SmallVector<Value> dynamicIndices(groupSize);
+    for (unsigned i = 0; i < groupSize; i++)
+      dynamicIndices[i] = indices[groups[i]];
+    // Construct the expression for the index value w.r.t to expand shape op
+    // source corresponding the indices wrt to expand shape op result.
+    AffineExpr srcIndexExpr = getLinearAffineExpr(suffixProduct, rewriter);
+    sourceIndices.push_back(rewriter.create<AffineApplyOp>(
+        loc,
+        AffineMap::get(/*numDims=*/groupSize, /*numSymbols=*/0, srcIndexExpr),
+        dynamicIndices));
+  }
+  return success();
+}
+
+/// Given the 'indices' of a load/store operation where the memref is a result
+/// of a collapse_shape op, returns the indices w.r.t to the source memref of
+/// the collapse_shape op. For example
+///
+/// %0 = ... : memref<2x6x42xf32>
+/// %1 = memref.collapse_shape %0 [[0, 1], [2]]
+///    : memref<2x6x42xf32> into memref<12x42xf32>
+/// %2 = load %1[%i1, %i2] : memref<12x42xf32>
+///
+/// could be folded into
+///
+/// %2 = load %0[%i1 / 6, %i1 % 6, %i2] :
+///          memref<2x6x42xf32>
+static LogicalResult
+resolveSourceIndicesCollapseShape(Location loc, PatternRewriter &rewriter,
+                                  memref::CollapseShapeOp collapseShapeOp,
+                                  ValueRange indices,
+                                  SmallVectorImpl<Value> &sourceIndices) {
+  unsigned cnt = 0;
+  SmallVector<Value> tmp(indices.size());
+  SmallVector<Value> dynamicIndices;
+  for (SmallVector<int64_t, 2> groups :
+       collapseShapeOp.getReassociationIndices()) {
+    assert(!groups.empty() && "association indices groups cannot be empty");
+    dynamicIndices.push_back(indices[cnt++]);
+    unsigned groupSize = groups.size();
+    SmallVector<int64_t> suffixProduct(groupSize);
+    // Calculate suffix product for all collapse op source dimension sizes.
+    suffixProduct[groupSize - 1] = 1;
+    for (unsigned i = groupSize - 1; i > 0; i--)
+      suffixProduct[i - 1] =
+          suffixProduct[i] * collapseShapeOp.getSrcType().getDimSize(groups[i]);
+    // Derive the index values along all dimensions of the source corresponding
+    // to the index wrt to collapsed shape op output.
+    SmallVector<AffineExpr, 4> srcIndexExpr =
+        getDelinearizedAffineExpr(suffixProduct, rewriter);
+    for (unsigned i = 0; i < groupSize; i++)
+      sourceIndices.push_back(rewriter.create<AffineApplyOp>(
+          loc, AffineMap::get(/*numDims=*/1, /*numSymbols=*/0, srcIndexExpr[i]),
+          dynamicIndices));
+    dynamicIndices.clear();
+  }
+  if (collapseShapeOp.getReassociationIndices().empty()) {
+    auto zeroAffineMap = rewriter.getConstantAffineMap(0);
+    unsigned srcRank =
+        collapseShapeOp.getViewSource().getType().cast<MemRefType>().getRank();
+    for (unsigned i = 0; i < srcRank; i++)
+      sourceIndices.push_back(
+          rewriter.create<AffineApplyOp>(loc, zeroAffineMap, dynamicIndices));
+  }
+  return success();
+}
+
+/// Given the 'indices' of an load/store operation where the memref is a result
+/// of a subview op, returns the indices w.r.t to the source memref of the
+/// subview op. For example
+///
+/// %0 = ... : memref<12x42xf32>
+/// %1 = subview %0[%arg0, %arg1][][%stride1, %stride2] : memref<12x42xf32> to
+///          memref<4x4xf32, offset=?, strides=[?, ?]>
+/// %2 = load %1[%i1, %i2] : memref<4x4xf32, offset=?, strides=[?, ?]>
+///
+/// could be folded into
+///
+/// %2 = load %0[%arg0 + %i1 * %stride1][%arg1 + %i2 * %stride2] :
+///          memref<12x42xf32>
+static LogicalResult
+resolveSourceIndicesSubView(Location loc, PatternRewriter &rewriter,
+                            memref::SubViewOp subViewOp, ValueRange indices,
+                            SmallVectorImpl<Value> &sourceIndices) {
+  SmallVector<OpFoldResult> mixedOffsets = subViewOp.getMixedOffsets();
+  SmallVector<OpFoldResult> mixedSizes = subViewOp.getMixedSizes();
+  SmallVector<OpFoldResult> mixedStrides = subViewOp.getMixedStrides();
+
+  SmallVector<Value> useIndices;
+  // Check if this is rank-reducing case. Then for every unit-dim size add a
+  // zero to the indices.
+  unsigned resultDim = 0;
+  llvm::SmallBitVector unusedDims = subViewOp.getDroppedDims();
+  for (auto dim : llvm::seq<unsigned>(0, subViewOp.getSourceType().getRank())) {
+    if (unusedDims.test(dim))
+      useIndices.push_back(rewriter.create<arith::ConstantIndexOp>(loc, 0));
+    else
+      useIndices.push_back(indices[resultDim++]);
+  }
+  if (useIndices.size() != mixedOffsets.size())
+    return failure();
+  sourceIndices.resize(useIndices.size());
+  for (auto index : llvm::seq<size_t>(0, mixedOffsets.size())) {
+    SmallVector<Value> dynamicOperands;
+    AffineExpr expr = rewriter.getAffineDimExpr(0);
+    unsigned numSymbols = 0;
+    dynamicOperands.push_back(useIndices[index]);
+
+    // Multiply the stride;
+    if (auto attr = mixedStrides[index].dyn_cast<Attribute>()) {
+      expr = expr * attr.cast<IntegerAttr>().getInt();
+    } else {
+      dynamicOperands.push_back(mixedStrides[index].get<Value>());
+      expr = expr * rewriter.getAffineSymbolExpr(numSymbols++);
+    }
+
+    // Add the offset.
+    if (auto attr = mixedOffsets[index].dyn_cast<Attribute>()) {
+      expr = expr + attr.cast<IntegerAttr>().getInt();
+    } else {
+      dynamicOperands.push_back(mixedOffsets[index].get<Value>());
+      expr = expr + rewriter.getAffineSymbolExpr(numSymbols++);
+    }
+    Location loc = subViewOp.getLoc();
+    sourceIndices[index] = rewriter.create<AffineApplyOp>(
+        loc, AffineMap::get(1, numSymbols, expr), dynamicOperands);
+  }
+  return success();
+}
+
+/// Helpers to access the memref operand for each op.
+template <typename LoadOrStoreOpTy>
+static Value getMemRefOperand(LoadOrStoreOpTy op) {
+  return op.getMemref();
+}
+
+static Value getMemRefOperand(vector::TransferReadOp op) {
+  return op.getSource();
+}
+
+static Value getMemRefOperand(vector::TransferWriteOp op) {
+  return op.getSource();
+}
+
+/// Given the permutation map of the original
+/// `vector.transfer_read`/`vector.transfer_write` operations compute the
+/// permutation map to use after the subview is folded with it.
+static AffineMapAttr getPermutationMapAttr(MLIRContext *context,
+                                           memref::SubViewOp subViewOp,
+                                           AffineMap currPermutationMap) {
+  llvm::SmallBitVector unusedDims = subViewOp.getDroppedDims();
+  SmallVector<AffineExpr> exprs;
+  int64_t sourceRank = subViewOp.getSourceType().getRank();
+  for (auto dim : llvm::seq<int64_t>(0, sourceRank)) {
+    if (unusedDims.test(dim))
+      continue;
+    exprs.push_back(getAffineDimExpr(dim, context));
+  }
+  auto resultDimToSourceDimMap = AffineMap::get(sourceRank, 0, exprs, context);
+  return AffineMapAttr::get(
+      currPermutationMap.compose(resultDimToSourceDimMap));
+}
+
+//===----------------------------------------------------------------------===//
+// Patterns
+//===----------------------------------------------------------------------===//
+
+namespace {
+/// Merges subview operation with load/transferRead operation.
+template <typename OpTy>
+class LoadOpOfSubViewOpFolder final : public OpRewritePattern<OpTy> {
+public:
+  using OpRewritePattern<OpTy>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(OpTy loadOp,
+                                PatternRewriter &rewriter) const override;
+};
+
+/// Merges expand_shape operation with load/transferRead operation.
+template <typename OpTy>
+class LoadOpOfExpandShapeOpFolder final : public OpRewritePattern<OpTy> {
+public:
+  using OpRewritePattern<OpTy>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(OpTy loadOp,
+                                PatternRewriter &rewriter) const override;
+};
+
+/// Merges collapse_shape operation with load/transferRead operation.
+template <typename OpTy>
+class LoadOpOfCollapseShapeOpFolder final : public OpRewritePattern<OpTy> {
+public:
+  using OpRewritePattern<OpTy>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(OpTy loadOp,
+                                PatternRewriter &rewriter) const override;
+};
+
+/// Merges subview operation with store/transferWriteOp operation.
+template <typename OpTy>
+class StoreOpOfSubViewOpFolder final : public OpRewritePattern<OpTy> {
+public:
+  using OpRewritePattern<OpTy>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(OpTy storeOp,
+                                PatternRewriter &rewriter) const override;
+};
+
+/// Merges expand_shape operation with store/transferWriteOp operation.
+template <typename OpTy>
+class StoreOpOfExpandShapeOpFolder final : public OpRewritePattern<OpTy> {
+public:
+  using OpRewritePattern<OpTy>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(OpTy storeOp,
+                                PatternRewriter &rewriter) const override;
+};
+
+/// Merges collapse_shape operation with store/transferWriteOp operation.
+template <typename OpTy>
+class StoreOpOfCollapseShapeOpFolder final : public OpRewritePattern<OpTy> {
+public:
+  using OpRewritePattern<OpTy>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(OpTy storeOp,
+                                PatternRewriter &rewriter) const override;
+};
+
+} // namespace
+
+static SmallVector<Value>
+calculateExpandedAccessIndices(AffineMap affineMap, SmallVector<Value> indices,
+                               Location loc, PatternRewriter &rewriter) {
+  SmallVector<Value> expandedIndices;
+  for (unsigned i = 0, e = affineMap.getNumResults(); i < e; i++)
+    expandedIndices.push_back(
+        rewriter.create<AffineApplyOp>(loc, affineMap.getSubMap({i}), indices));
+  return expandedIndices;
+}
+
+template <typename OpTy>
+LogicalResult LoadOpOfSubViewOpFolder<OpTy>::matchAndRewrite(
+    OpTy loadOp, PatternRewriter &rewriter) const {
+  auto subViewOp =
+      getMemRefOperand(loadOp).template getDefiningOp<memref::SubViewOp>();
+
+  if (!subViewOp)
+    return failure();
+
+  SmallVector<Value> indices(loadOp.getIndices().begin(),
+                             loadOp.getIndices().end());
+  // For affine ops, we need to apply the map to get the operands to get the
+  // "actual" indices.
+  if (auto affineLoadOp = dyn_cast<AffineLoadOp>(loadOp.getOperation())) {
+    AffineMap affineMap = affineLoadOp.getAffineMap();
+    auto expandedIndices = calculateExpandedAccessIndices(
+        affineMap, indices, loadOp.getLoc(), rewriter);
+    indices.assign(expandedIndices.begin(), expandedIndices.end());
+  }
+  SmallVector<Value, 4> sourceIndices;
+  if (failed(resolveSourceIndicesSubView(loadOp.getLoc(), rewriter, subViewOp,
+                                         indices, sourceIndices)))
+    return failure();
+  llvm::TypeSwitch<Operation *, void>(loadOp)
+      .Case<AffineLoadOp, memref::LoadOp>([&](auto op) {
+        rewriter.replaceOpWithNewOp<decltype(op)>(loadOp, subViewOp.source(),
+                                                  sourceIndices);
+      })
+      .Case([&](vector::TransferReadOp transferReadOp) {
+        if (transferReadOp.getTransferRank() == 0) {
+          // TODO: Propagate the error.
+          return;
+        }
+        rewriter.replaceOpWithNewOp<vector::TransferReadOp>(
+            transferReadOp, transferReadOp.getVectorType(), subViewOp.source(),
+            sourceIndices,
+            getPermutationMapAttr(rewriter.getContext(), subViewOp,
+                                  transferReadOp.getPermutationMap()),
+            transferReadOp.getPadding(),
+            /*mask=*/Value(), transferReadOp.getInBoundsAttr());
+      })
+      .Default([](Operation *) { ; });
+  return success();
+}
+
+template <typename OpTy>
+LogicalResult LoadOpOfExpandShapeOpFolder<OpTy>::matchAndRewrite(
+    OpTy loadOp, PatternRewriter &rewriter) const {
+  auto expandShapeOp =
+      getMemRefOperand(loadOp).template getDefiningOp<memref::ExpandShapeOp>();
+
+  if (!expandShapeOp)
+    return failure();
+
+  SmallVector<Value> indices(loadOp.getIndices().begin(),
+                             loadOp.getIndices().end());
+  // For affine ops, we need to apply the map to get the operands to get the
+  // "actual" indices.
+  if (auto affineLoadOp = dyn_cast<AffineLoadOp>(loadOp.getOperation())) {
+    AffineMap affineMap = affineLoadOp.getAffineMap();
+    auto expandedIndices = calculateExpandedAccessIndices(
+        affineMap, indices, loadOp.getLoc(), rewriter);
+    indices.assign(expandedIndices.begin(), expandedIndices.end());
+  }
+  SmallVector<Value, 4> sourceIndices;
+  if (failed(resolveSourceIndicesExpandShape(
+          loadOp.getLoc(), rewriter, expandShapeOp, indices, sourceIndices)))
+    return failure();
+  llvm::TypeSwitch<Operation *, void>(loadOp)
+      .Case<AffineLoadOp, memref::LoadOp>([&](auto op) {
+        rewriter.replaceOpWithNewOp<decltype(op)>(
+            loadOp, expandShapeOp.getViewSource(), sourceIndices);
+      })
+      .Default([](Operation *) { ; });
+  return success();
+}
+
+template <typename OpTy>
+LogicalResult LoadOpOfCollapseShapeOpFolder<OpTy>::matchAndRewrite(
+    OpTy loadOp, PatternRewriter &rewriter) const {
+  auto collapseShapeOp = getMemRefOperand(loadOp)
+                             .template getDefiningOp<memref::CollapseShapeOp>();
+
+  if (!collapseShapeOp)
+    return failure();
+
+  SmallVector<Value> indices(loadOp.getIndices().begin(),
+                             loadOp.getIndices().end());
+  // For affine ops, we need to apply the map to get the operands to get the
+  // "actual" indices.
+  if (auto affineLoadOp = dyn_cast<AffineLoadOp>(loadOp.getOperation())) {
+    AffineMap affineMap = affineLoadOp.getAffineMap();
+    auto expandedIndices = calculateExpandedAccessIndices(
+        affineMap, indices, loadOp.getLoc(), rewriter);
+    indices.assign(expandedIndices.begin(), expandedIndices.end());
+  }
+  SmallVector<Value, 4> sourceIndices;
+  if (failed(resolveSourceIndicesCollapseShape(
+          loadOp.getLoc(), rewriter, collapseShapeOp, indices, sourceIndices)))
+    return failure();
+  llvm::TypeSwitch<Operation *, void>(loadOp)
+      .Case<AffineLoadOp, memref::LoadOp>([&](auto op) {
+        rewriter.replaceOpWithNewOp<decltype(op)>(
+            loadOp, collapseShapeOp.getViewSource(), sourceIndices);
+      })
+      .Default([](Operation *) { ; });
+  return success();
+}
+
+template <typename OpTy>
+LogicalResult StoreOpOfSubViewOpFolder<OpTy>::matchAndRewrite(
+    OpTy storeOp, PatternRewriter &rewriter) const {
+  auto subViewOp =
+      getMemRefOperand(storeOp).template getDefiningOp<memref::SubViewOp>();
+
+  if (!subViewOp)
+    return failure();
+
+  SmallVector<Value> indices(storeOp.getIndices().begin(),
+                             storeOp.getIndices().end());
+  // For affine ops, we need to apply the map to get the operands to get the
+  // "actual" indices.
+  if (auto affineStoreOp = dyn_cast<AffineStoreOp>(storeOp.getOperation())) {
+    AffineMap affineMap = affineStoreOp.getAffineMap();
+    auto expandedIndices = calculateExpandedAccessIndices(
+        affineMap, indices, storeOp.getLoc(), rewriter);
+    indices.assign(expandedIndices.begin(), expandedIndices.end());
+  }
+  SmallVector<Value, 4> sourceIndices;
+  if (failed(resolveSourceIndicesSubView(storeOp.getLoc(), rewriter, subViewOp,
+                                         indices, sourceIndices)))
+    return failure();
+  llvm::TypeSwitch<Operation *, void>(storeOp)
+      .Case<AffineStoreOp, memref::StoreOp>([&](auto op) {
+        rewriter.replaceOpWithNewOp<decltype(op)>(
+            storeOp, storeOp.getValue(), subViewOp.source(), sourceIndices);
+      })
+      .Case([&](vector::TransferWriteOp op) {
+        // TODO: support 0-d corner case.
+        if (op.getTransferRank() == 0)
+          return;
+        rewriter.replaceOpWithNewOp<vector::TransferWriteOp>(
+            op, op.getValue(), subViewOp.source(), sourceIndices,
+            getPermutationMapAttr(rewriter.getContext(), subViewOp,
+                                  op.getPermutationMap()),
+            op.getInBoundsAttr());
+      })
+      .Default([](Operation *) { ; });
+  return success();
+}
+
+template <typename OpTy>
+LogicalResult StoreOpOfExpandShapeOpFolder<OpTy>::matchAndRewrite(
+    OpTy storeOp, PatternRewriter &rewriter) const {
+  auto expandShapeOp =
+      getMemRefOperand(storeOp).template getDefiningOp<memref::ExpandShapeOp>();
+
+  if (!expandShapeOp)
+    return failure();
+
+  SmallVector<Value> indices(storeOp.getIndices().begin(),
+                             storeOp.getIndices().end());
+  // For affine ops, we need to apply the map to get the operands to get the
+  // "actual" indices.
+  if (auto affineStoreOp = dyn_cast<AffineStoreOp>(storeOp.getOperation())) {
+    AffineMap affineMap = affineStoreOp.getAffineMap();
+    auto expandedIndices = calculateExpandedAccessIndices(
+        affineMap, indices, storeOp.getLoc(), rewriter);
+    indices.assign(expandedIndices.begin(), expandedIndices.end());
+  }
+  SmallVector<Value, 4> sourceIndices;
+  if (failed(resolveSourceIndicesExpandShape(
+          storeOp.getLoc(), rewriter, expandShapeOp, indices, sourceIndices)))
+    return failure();
+  llvm::TypeSwitch<Operation *, void>(storeOp)
+      .Case<AffineStoreOp, memref::StoreOp>([&](auto op) {
+        rewriter.replaceOpWithNewOp<decltype(op)>(storeOp, storeOp.getValue(),
+                                                  expandShapeOp.getViewSource(),
+                                                  sourceIndices);
+      })
+      .Default([](Operation *) { ; });
+  return success();
+}
+
+template <typename OpTy>
+LogicalResult StoreOpOfCollapseShapeOpFolder<OpTy>::matchAndRewrite(
+    OpTy storeOp, PatternRewriter &rewriter) const {
+  auto collapseShapeOp = getMemRefOperand(storeOp)
+                             .template getDefiningOp<memref::CollapseShapeOp>();
+
+  if (!collapseShapeOp)
+    return failure();
+
+  SmallVector<Value> indices(storeOp.getIndices().begin(),
+                             storeOp.getIndices().end());
+  // For affine ops, we need to apply the map to get the operands to get the
+  // "actual" indices.
+  if (auto affineStoreOp = dyn_cast<AffineStoreOp>(storeOp.getOperation())) {
+    AffineMap affineMap = affineStoreOp.getAffineMap();
+    auto expandedIndices = calculateExpandedAccessIndices(
+        affineMap, indices, storeOp.getLoc(), rewriter);
+    indices.assign(expandedIndices.begin(), expandedIndices.end());
+  }
+  SmallVector<Value, 4> sourceIndices;
+  if (failed(resolveSourceIndicesCollapseShape(
+          storeOp.getLoc(), rewriter, collapseShapeOp, indices, sourceIndices)))
+    return failure();
+  llvm::TypeSwitch<Operation *, void>(storeOp)
+      .Case<AffineStoreOp, memref::StoreOp>([&](auto op) {
+        rewriter.replaceOpWithNewOp<decltype(op)>(
+            storeOp, storeOp.getValue(), collapseShapeOp.getViewSource(),
+            sourceIndices);
+      })
+      .Default([](Operation *) { ; });
+  return success();
+}
+
+void memref::populateFoldMemRefAliasOpPatterns(RewritePatternSet &patterns) {
+  patterns.add<LoadOpOfSubViewOpFolder<AffineLoadOp>,
+               LoadOpOfSubViewOpFolder<memref::LoadOp>,
+               LoadOpOfSubViewOpFolder<vector::TransferReadOp>,
+               StoreOpOfSubViewOpFolder<AffineStoreOp>,
+               StoreOpOfSubViewOpFolder<memref::StoreOp>,
+               StoreOpOfSubViewOpFolder<vector::TransferWriteOp>,
+               LoadOpOfExpandShapeOpFolder<AffineLoadOp>,
+               LoadOpOfExpandShapeOpFolder<memref::LoadOp>,
+               StoreOpOfExpandShapeOpFolder<AffineStoreOp>,
+               StoreOpOfExpandShapeOpFolder<memref::StoreOp>,
+               LoadOpOfCollapseShapeOpFolder<AffineLoadOp>,
+               LoadOpOfCollapseShapeOpFolder<memref::LoadOp>,
+               StoreOpOfCollapseShapeOpFolder<AffineStoreOp>,
+               StoreOpOfCollapseShapeOpFolder<memref::StoreOp>>(
+      patterns.getContext());
+}
+
+//===----------------------------------------------------------------------===//
+// Pass registration
+//===----------------------------------------------------------------------===//
+
+namespace {
+
+#define GEN_PASS_CLASSES
+#include "mlir/Dialect/MemRef/Transforms/Passes.h.inc"
+
+struct FoldMemRefAliasOpsPass final
+    : public FoldMemRefAliasOpsBase<FoldMemRefAliasOpsPass> {
+  void runOnOperation() override;
+};
+
+} // namespace
+
+void FoldMemRefAliasOpsPass::runOnOperation() {
+  RewritePatternSet patterns(&getContext());
+  memref::populateFoldMemRefAliasOpPatterns(patterns);
+  (void)applyPatternsAndFoldGreedily(getOperation()->getRegions(),
+                                     std::move(patterns));
+}
+
+std::unique_ptr<Pass> memref::createFoldMemRefAliasOpsPass() {
+  return std::make_unique<FoldMemRefAliasOpsPass>();
+}

mlir/lib/Dialect/MemRef/Transforms/FoldSubViewOps.cpp

-//===- FoldSubViewOps.cpp - Fold memref.subview ops -----------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This transformation pass folds loading/storing from/to subview ops into
-// loading/storing from/to the original memref.
-//
-//===----------------------------------------------------------------------===//
-
-#include "PassDetail.h"
-#include "mlir/Dialect/Affine/IR/AffineOps.h"
-#include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
-#include "mlir/Dialect/MemRef/IR/MemRef.h"
-#include "mlir/Dialect/MemRef/Transforms/Passes.h"
-#include "mlir/Dialect/Vector/IR/VectorOps.h"
-#include "mlir/IR/BuiltinTypes.h"
-#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
-#include "llvm/ADT/SmallBitVector.h"
-
-using namespace mlir;
-
-//===----------------------------------------------------------------------===//
-// Utility functions
-//===----------------------------------------------------------------------===//
-
-/// Given the 'indices' of an load/store operation where the memref is a result
-/// of a subview op, returns the indices w.r.t to the source memref of the
-/// subview op. For example
-///
-/// %0 = ... : memref<12x42xf32>
-/// %1 = subview %0[%arg0, %arg1][][%stride1, %stride2] : memref<12x42xf32> to
-///          memref<4x4xf32, offset=?, strides=[?, ?]>
-/// %2 = load %1[%i1, %i2] : memref<4x4xf32, offset=?, strides=[?, ?]>
-///
-/// could be folded into
-///
-/// %2 = load %0[%arg0 + %i1 * %stride1][%arg1 + %i2 * %stride2] :
-///          memref<12x42xf32>
-static LogicalResult
-resolveSourceIndices(Location loc, PatternRewriter &rewriter,
-                     memref::SubViewOp subViewOp, ValueRange indices,
-                     SmallVectorImpl<Value> &sourceIndices) {
-  SmallVector<OpFoldResult> mixedOffsets = subViewOp.getMixedOffsets();
-  SmallVector<OpFoldResult> mixedSizes = subViewOp.getMixedSizes();
-  SmallVector<OpFoldResult> mixedStrides = subViewOp.getMixedStrides();
-
-  SmallVector<Value> useIndices;
-  // Check if this is rank-reducing case. Then for every unit-dim size add a
-  // zero to the indices.
-  unsigned resultDim = 0;
-  llvm::SmallBitVector unusedDims = subViewOp.getDroppedDims();
-  for (auto dim : llvm::seq<unsigned>(0, subViewOp.getSourceType().getRank())) {
-    if (unusedDims.test(dim))
-      useIndices.push_back(rewriter.create<arith::ConstantIndexOp>(loc, 0));
-    else
-      useIndices.push_back(indices[resultDim++]);
-  }
-  if (useIndices.size() != mixedOffsets.size())
-    return failure();
-  sourceIndices.resize(useIndices.size());
-  for (auto index : llvm::seq<size_t>(0, mixedOffsets.size())) {
-    SmallVector<Value> dynamicOperands;
-    AffineExpr expr = rewriter.getAffineDimExpr(0);
-    unsigned numSymbols = 0;
-    dynamicOperands.push_back(useIndices[index]);
-
-    // Multiply the stride;
-    if (auto attr = mixedStrides[index].dyn_cast<Attribute>()) {
-      expr = expr * attr.cast<IntegerAttr>().getInt();
-    } else {
-      dynamicOperands.push_back(mixedStrides[index].get<Value>());
-      expr = expr * rewriter.getAffineSymbolExpr(numSymbols++);
-    }
-
-    // Add the offset.
-    if (auto attr = mixedOffsets[index].dyn_cast<Attribute>()) {
-      expr = expr + attr.cast<IntegerAttr>().getInt();
-    } else {
-      dynamicOperands.push_back(mixedOffsets[index].get<Value>());
-      expr = expr + rewriter.getAffineSymbolExpr(numSymbols++);
-    }
-    Location loc = subViewOp.getLoc();
-    sourceIndices[index] = rewriter.create<AffineApplyOp>(
-        loc, AffineMap::get(1, numSymbols, expr), dynamicOperands);
-  }
-  return success();
-}
-
-/// Helpers to access the memref operand for each op.
-template <typename LoadOrStoreOpTy>
-static Value getMemRefOperand(LoadOrStoreOpTy op) {
-  return op.getMemref();
-}
-
-static Value getMemRefOperand(vector::TransferReadOp op) {
-  return op.getSource();
-}
-
-static Value getMemRefOperand(vector::TransferWriteOp op) {
-  return op.getSource();
-}
-
-/// Given the permutation map of the original
-/// `vector.transfer_read`/`vector.transfer_write` operations compute the
-/// permutation map to use after the subview is folded with it.
-static AffineMapAttr getPermutationMapAttr(MLIRContext *context,
-                                           memref::SubViewOp subViewOp,
-                                           AffineMap currPermutationMap) {
-  llvm::SmallBitVector unusedDims = subViewOp.getDroppedDims();
-  SmallVector<AffineExpr> exprs;
-  int64_t sourceRank = subViewOp.getSourceType().getRank();
-  for (auto dim : llvm::seq<int64_t>(0, sourceRank)) {
-    if (unusedDims.test(dim))
-      continue;
-    exprs.push_back(getAffineDimExpr(dim, context));
-  }
-  auto resultDimToSourceDimMap = AffineMap::get(sourceRank, 0, exprs, context);
-  return AffineMapAttr::get(
-      currPermutationMap.compose(resultDimToSourceDimMap));
-}
-
-//===----------------------------------------------------------------------===//
-// Patterns
-//===----------------------------------------------------------------------===//
-
-namespace {
-/// Merges subview operation with load/transferRead operation.
-template <typename OpTy>
-class LoadOpOfSubViewFolder final : public OpRewritePattern<OpTy> {
-public:
-  using OpRewritePattern<OpTy>::OpRewritePattern;
-
-  LogicalResult matchAndRewrite(OpTy loadOp,
-                                PatternRewriter &rewriter) const override;
-
-private:
-  void replaceOp(OpTy loadOp, memref::SubViewOp subViewOp,
-                 ArrayRef<Value> sourceIndices,
-                 PatternRewriter &rewriter) const;
-};
-
-/// Merges subview operation with store/transferWriteOp operation.
-template <typename OpTy>
-class StoreOpOfSubViewFolder final : public OpRewritePattern<OpTy> {
-public:
-  using OpRewritePattern<OpTy>::OpRewritePattern;
-
-  LogicalResult matchAndRewrite(OpTy storeOp,
-                                PatternRewriter &rewriter) const override;
-
-private:
-  void replaceOp(OpTy storeOp, memref::SubViewOp subViewOp,
-                 ArrayRef<Value> sourceIndices,
-                 PatternRewriter &rewriter) const;
-};
-
-template <typename LoadOpTy>
-void LoadOpOfSubViewFolder<LoadOpTy>::replaceOp(
-    LoadOpTy loadOp, memref::SubViewOp subViewOp, ArrayRef<Value> sourceIndices,
-    PatternRewriter &rewriter) const {
-  rewriter.replaceOpWithNewOp<LoadOpTy>(loadOp, subViewOp.getSource(),
-                                        sourceIndices);
-}
-
-template <>
-void LoadOpOfSubViewFolder<vector::TransferReadOp>::replaceOp(
-    vector::TransferReadOp transferReadOp, memref::SubViewOp subViewOp,
-    ArrayRef<Value> sourceIndices, PatternRewriter &rewriter) const {
-  // TODO: support 0-d corner case.
-  if (transferReadOp.getTransferRank() == 0)
-    return;
-  rewriter.replaceOpWithNewOp<vector::TransferReadOp>(
-      transferReadOp, transferReadOp.getVectorType(), subViewOp.getSource(),
-      sourceIndices,
-      getPermutationMapAttr(rewriter.getContext(), subViewOp,
-                            transferReadOp.getPermutationMap()),
-      transferReadOp.getPadding(),
-      /*mask=*/Value(), transferReadOp.getInBoundsAttr());
-}
-
-template <typename StoreOpTy>
-void StoreOpOfSubViewFolder<StoreOpTy>::replaceOp(
-    StoreOpTy storeOp, memref::SubViewOp subViewOp,
-    ArrayRef<Value> sourceIndices, PatternRewriter &rewriter) const {
-  rewriter.replaceOpWithNewOp<StoreOpTy>(storeOp, storeOp.getValue(),
-                                         subViewOp.getSource(), sourceIndices);
-}
-
-template <>
-void StoreOpOfSubViewFolder<vector::TransferWriteOp>::replaceOp(
-    vector::TransferWriteOp transferWriteOp, memref::SubViewOp subViewOp,
-    ArrayRef<Value> sourceIndices, PatternRewriter &rewriter) const {
-  // TODO: support 0-d corner case.
-  if (transferWriteOp.getTransferRank() == 0)
-    return;
-  rewriter.replaceOpWithNewOp<vector::TransferWriteOp>(
-      transferWriteOp, transferWriteOp.getVector(), subViewOp.getSource(),
-      sourceIndices,
-      getPermutationMapAttr(rewriter.getContext(), subViewOp,
-                            transferWriteOp.getPermutationMap()),
-      transferWriteOp.getInBoundsAttr());
-}
-} // namespace
-
-template <typename OpTy>
-LogicalResult
-LoadOpOfSubViewFolder<OpTy>::matchAndRewrite(OpTy loadOp,
-                                             PatternRewriter &rewriter) const {
-  auto subViewOp =
-      getMemRefOperand(loadOp).template getDefiningOp<memref::SubViewOp>();
-  if (!subViewOp)
-    return failure();
-
-  SmallVector<Value, 4> sourceIndices;
-  if (failed(resolveSourceIndices(loadOp.getLoc(), rewriter, subViewOp,
-                                  loadOp.getIndices(), sourceIndices)))
-    return failure();
-
-  replaceOp(loadOp, subViewOp, sourceIndices, rewriter);
-  return success();
-}
-
-template <typename OpTy>
-LogicalResult
-StoreOpOfSubViewFolder<OpTy>::matchAndRewrite(OpTy storeOp,
-                                              PatternRewriter &rewriter) const {
-  auto subViewOp =
-      getMemRefOperand(storeOp).template getDefiningOp<memref::SubViewOp>();
-  if (!subViewOp)
-    return failure();
-
-  SmallVector<Value, 4> sourceIndices;
-  if (failed(resolveSourceIndices(storeOp.getLoc(), rewriter, subViewOp,
-                                  storeOp.getIndices(), sourceIndices)))
-    return failure();
-
-  replaceOp(storeOp, subViewOp, sourceIndices, rewriter);
-  return success();
-}
-
-void memref::populateFoldSubViewOpPatterns(RewritePatternSet &patterns) {
-  patterns.add<LoadOpOfSubViewFolder<AffineLoadOp>,
-               LoadOpOfSubViewFolder<memref::LoadOp>,
-               LoadOpOfSubViewFolder<vector::TransferReadOp>,
-               StoreOpOfSubViewFolder<AffineStoreOp>,
-               StoreOpOfSubViewFolder<memref::StoreOp>,
-               StoreOpOfSubViewFolder<vector::TransferWriteOp>>(
-      patterns.getContext());
-}
-
-//===----------------------------------------------------------------------===//
-// Pass registration
-//===----------------------------------------------------------------------===//
-
-namespace {
-
-struct FoldSubViewOpsPass final
-    : public FoldSubViewOpsBase<FoldSubViewOpsPass> {
-  void runOnOperation() override;
-};
-
-} // namespace
-
-void FoldSubViewOpsPass::runOnOperation() {
-  RewritePatternSet patterns(&getContext());
-  memref::populateFoldSubViewOpPatterns(patterns);
-  (void)applyPatternsAndFoldGreedily(getOperation(), std::move(patterns));
-}
-
-std::unique_ptr<Pass> memref::createFoldSubViewOpsPass() {
-  return std::make_unique<FoldSubViewOpsPass>();
-}

mlir/lib/Dialect/Utils/IndexingUtils.cpp

 //===- IndexingUtils.cpp - Helpers related to index computations ----------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "mlir/Dialect/Utils/IndexingUtils.h"
 
+#include "mlir/IR/AffineExpr.h"
+#include "mlir/IR/Builders.h"
 #include "mlir/IR/BuiltinAttributes.h"
 
 int64_t mlir::linearize(ArrayRef<int64_t> offsets, ArrayRef<int64_t> basis) {
   assert(offsets.size() == basis.size());
   int64_t linearIndex = 0;
   for (unsigned idx = 0, e = basis.size(); idx < e; ++idx)
     linearIndex += offsets[idx] * basis[idx];
   return linearIndex;
llvm::SmallVector<int64_t, 4> mlir::getI64SubArray(ArrayAttr arrayAttr,
   auto range = arrayAttr.getAsRange<IntegerAttr>();
   SmallVector<int64_t, 4> res;
   res.reserve(arrayAttr.size() - dropFront - dropBack);
   for (auto it = range.begin() + dropFront, eit = range.end() - dropBack;
        it != eit; ++it)
     res.push_back((*it).getValue().getSExtValue());
   return res;
 }
+
+mlir::AffineExpr mlir::getLinearAffineExpr(ArrayRef<int64_t> basis,
+                                           mlir::Builder &b) {
+  AffineExpr resultExpr = b.getAffineDimExpr(0);
+  resultExpr = resultExpr * basis[0];
+  for (unsigned i = 1; i < basis.size(); i++)
+    resultExpr = resultExpr + b.getAffineDimExpr(i) * basis[i];
+  return resultExpr;
+}
+
+llvm::SmallVector<mlir::AffineExpr, 4>
+mlir::getDelinearizedAffineExpr(mlir::ArrayRef<int64_t> strides, Builder &b) {
+  AffineExpr resultExpr = b.getAffineDimExpr(0);
+  int64_t rank = strides.size();
+  SmallVector<AffineExpr, 4> vectorOffsets(rank);
+  vectorOffsets[0] = resultExpr.floorDiv(strides[0]);
+  resultExpr = resultExpr % strides[0];
+  for (unsigned i = 1; i < rank; i++) {
+    vectorOffsets[i] = resultExpr.floorDiv(strides[i]);
+    resultExpr = resultExpr % strides[i];
+  }
+  return vectorOffsets;
+}

mlir/test/Dialect/MemRef/fold-memref-alias-ops.mlir

-// RUN: mlir-opt -fold-memref-subview-ops -split-input-file %s -o - | FileCheck %s
+// RUN: mlir-opt -fold-memref-alias-ops -split-input-file %s -o - | FileCheck %s
 
 func.func @fold_static_stride_subview_with_load(%arg0 : memref<12x32xf32>, %arg1 : index, %arg2 : index, %arg3 : index, %arg4 : index) -> f32 {
   %0 = memref.subview %arg0[%arg1, %arg2][4, 4][2, 3] : memref<12x32xf32> to memref<4x4xf32, offset:?, strides: [64, 3]>
   %1 = memref.load %0[%arg3, %arg4] : memref<4x4xf32, offset:?, strides: [64, 3]>
   return %1 : f32
 }
 //  CHECK-DAG: #[[MAP0:.+]] = affine_map<(d0)[s0] -> (d0 * 2 + s0)>
 //  CHECK-DAG: #[[MAP1:.+]] = affine_map<(d0)[s0] -> (d0 * 3 + s0)>
func.func @fold_static_stride_subview_with_affine_load_store(%arg0 : memref<12x32xf32>, %arg1 : index, %arg2 : index, %arg3 : index, %arg4 : index) -> f32 {
   // CHECK-NEXT: affine.load
   affine.store %1, %0[%arg3, %arg4] : memref<4x4xf32, offset:?, strides: [64, 3]>
   // CHECK-NEXT: affine.apply
   // CHECK-NEXT: affine.apply
   // CHECK-NEXT: affine.store
   // CHECK-NEXT: return
   return %1 : f32
 }
+
+// -----
+
+// CHECK-DAG: #[[$MAP:.*]] = affine_map<(d0, d1) -> (d0 * 6 + d1)>
+// CHECK-LABEL: fold_static_stride_subview_with_affine_load_store_expand_shape
+// CHECK-SAME: (%[[ARG0:.*]]: memref<12x32xf32>, %[[ARG1:.*]]: index, %[[ARG2:.*]]: index, %[[ARG3:.*]]: index) -> f32 {
+func.func @fold_static_stride_subview_with_affine_load_store_expand_shape(%arg0 : memref<12x32xf32>, %arg1 : index, %arg2 : index, %arg3 : index) -> f32 {
+  %0 = memref.expand_shape %arg0 [[0, 1], [2]] : memref<12x32xf32> into memref<2x6x32xf32>
+  %1 = affine.load %0[%arg1, %arg2, %arg3] : memref<2x6x32xf32>
+  return %1 : f32
+}
+// CHECK: %[[INDEX:.*]] = affine.apply #[[$MAP]](%[[ARG1]], %[[ARG2]])
+// CHECK-NEXT: %[[RESULT:.*]] = affine.load %[[ARG0]][%[[INDEX]], %[[ARG3]]] : memref<12x32xf32>
+// CHECK-NEXT: return %[[RESULT]] : f32
+
+// -----
+
+// CHECK-DAG: #[[$MAP0:.*]] = affine_map<(d0) -> (d0 floordiv 6)>
+// CHECK-DAG: #[[$MAP1:.*]] = affine_map<(d0) -> (d0 mod 6)>
+// CHECK-LABEL: @fold_static_stride_subview_with_affine_load_store_collapse_shape
+// CHECK-SAME: (%[[ARG0:.*]]: memref<2x6x32xf32>, %[[ARG1:.*]]: index, %[[ARG2:.*]]: index)
+func.func @fold_static_stride_subview_with_affine_load_store_collapse_shape(%arg0 : memref<2x6x32xf32>, %arg1 : index, %arg2 : index) -> f32 {
+  %0 = memref.collapse_shape %arg0 [[0, 1], [2]] : memref<2x6x32xf32> into memref<12x32xf32>
+  %1 = affine.load %0[%arg1, %arg2] : memref<12x32xf32>
+  return %1 : f32
+}
+// CHECK-NEXT: %[[MODIFIED_INDEX0:.*]] = affine.apply #[[$MAP0]](%[[ARG1]])
+// CHECK-NEXT: %[[MODIFIED_INDEX1:.*]] = affine.apply #[[$MAP1]](%[[ARG1]])
+// CHECK-NEXT: %[[RESULT:.*]] = affine.load %[[ARG0]][%[[MODIFIED_INDEX0]], %[[MODIFIED_INDEX1]], %[[ARG2]]] : memref<2x6x32xf32>
+// CHECK-NEXT: return %[[RESULT]] : f32
+
+// -----
+
+// CHECK-DAG: #[[$MAP:.*]] = affine_map<(d0, d1, d2) -> (d0 * 6 + d1 * 3 + d2)>
+// CHECK-LABEL: fold_static_stride_subview_with_affine_load_store_expand_shape_3d
+// CHECK-SAME: (%[[ARG0:.*]]: memref<12x32xf32>, %[[ARG1:.*]]: index, %[[ARG2:.*]]: index, %[[ARG3:.*]]: index, %[[ARG4:.*]]: index) -> f32 {
+func.func @fold_static_stride_subview_with_affine_load_store_expand_shape_3d(%arg0 : memref<12x32xf32>, %arg1 : index, %arg2 : index, %arg3 : index, %arg4: index) -> f32 {
+  %0 = memref.expand_shape %arg0 [[0, 1, 2], [3]] : memref<12x32xf32> into memref<2x2x3x32xf32>
+  %1 = affine.load %0[%arg1, %arg2, %arg3, %arg4] : memref<2x2x3x32xf32>
+  return %1 : f32
+}
+// CHECK: %[[INDEX:.*]] = affine.apply #[[$MAP]](%[[ARG1]], %[[ARG2]], %[[ARG3]])
+// CHECK-NEXT: %[[RESULT:.*]] = affine.load %[[ARG0]][%[[INDEX]], %[[ARG4]]] : memref<12x32xf32>
+// CHECK-NEXT: return %[[RESULT]] : f32
+
+// -----
+
+// CHECK-DAG: #[[$MAP0:.*]] = affine_map<(d0, d1) -> (d0 * 1024 + d1)>
+// CHECK-DAG: #[[$MAP1:.*]] = affine_map<(d0, d1) -> (d0 + d1)>
+// CHECK-LABEL: fold_static_stride_subview_with_affine_load_store_expand_shape
+// CHECK-SAME: (%[[ARG0:.*]]: memref<1024x1024xf32>, %[[ARG1:.*]]: memref<1xf32>, %[[ARG2:.*]]: index)
+func.func @fold_static_stride_subview_with_affine_load_store_expand_shape(%arg0: memref<1024x1024xf32>, %arg1: memref<1xf32>, %arg2: index) -> f32 {
+  %0 = memref.expand_shape %arg0 [[0, 1], [2, 3]] : memref<1024x1024xf32> into memref<1x1024x1024x1xf32>
+  affine.for %arg3 = 0 to 1 {
+    affine.for %arg4 = 0 to 1024 {
+      affine.for %arg5 = 0 to 1020 {
+        affine.for %arg6 = 0 to 1 {
+          %1 = affine.load %0[%arg3, %arg4, %arg5, %arg6] : memref<1x1024x1024x1xf32>
+          affine.store %1, %arg1[%arg2] : memref<1xf32>
+        }
+      }
+    }
+  }
+  %2 = affine.load %arg1[%arg2] : memref<1xf32>
+  return %2 : f32
+}
+// CHECK-NEXT: affine.for %[[ARG3:.*]] = 0 to 1 {
+// CHECK-NEXT:  affine.for %[[ARG4:.*]] = 0 to 1024 {
+// CHECK-NEXT:   affine.for %[[ARG5:.*]] = 0 to 1020 {
+// CHECK-NEXT:    affine.for %[[ARG6:.*]] = 0 to 1 {
+// CHECK-NEXT:     %[[IDX1:.*]] = affine.apply #[[$MAP0]](%[[ARG3]], %[[ARG4]])
+// CHECK-NEXT:     %[[IDX2:.*]] = affine.apply #[[$MAP1]](%[[ARG5]], %[[ARG6]])
+// CHECK-NEXT:     affine.load %[[ARG0]][%[[IDX1]], %[[IDX2]]] : memref<1024x1024xf32>
+
+// -----
+
+// CHECK-DAG: #[[$MAP0:.*]] = affine_map<(d0, d1, d2, d3) -> (d1 + d0)>
+// CHECK-DAG: #[[$MAP1:.*]] = affine_map<(d0, d1) -> (d0 * 1024 + d1)>
+// CHECK-DAG: #[[$MAP2:.*]] = affine_map<(d0, d1) -> (d0 + d1)>
+// CHECK-LABEL: fold_static_stride_subview_with_affine_load_store_expand_shape_when_access_index_is_an_expression
+// CHECK-SAME: (%[[ARG0:.*]]: memref<1024x1024xf32>, %[[ARG1:.*]]: memref<1xf32>, %[[ARG2:.*]]: index)
+func.func @fold_static_stride_subview_with_affine_load_store_expand_shape_when_access_index_is_an_expression(%arg0: memref<1024x1024xf32>, %arg1: memref<1xf32>, %arg2: index) -> f32 {
+  %0 = memref.expand_shape %arg0 [[0, 1], [2, 3]] : memref<1024x1024xf32> into memref<1x1024x1024x1xf32>
+  affine.for %arg3 = 0 to 1 {
+    affine.for %arg4 = 0 to 1024 {
+      affine.for %arg5 = 0 to 1020 {
+        affine.for %arg6 = 0 to 1 {
+          %1 = affine.load %0[%arg3, %arg4 + %arg3, %arg5, %arg6] : memref<1x1024x1024x1xf32>
+          affine.store %1, %arg1[%arg2] : memref<1xf32>
+        }
+      }
+    }
+  }
+  %2 = affine.load %arg1[%arg2] : memref<1xf32>
+  return %2 : f32
+}
+// CHECK-NEXT: affine.for %[[ARG3:.*]] = 0 to 1 {
+// CHECK-NEXT:  affine.for %[[ARG4:.*]] = 0 to 1024 {
+// CHECK-NEXT:   affine.for %[[ARG5:.*]] = 0 to 1020 {
+// CHECK-NEXT:    affine.for %[[ARG6:.*]] = 0 to 1 {
+// CHECK-NEXT:      %[[TMP1:.*]] = affine.apply #[[$MAP0]](%[[ARG3]], %[[ARG4]], %[[ARG5]], %[[ARG6]])
+// CHECK-NEXT:      %[[TMP2:.*]] = affine.apply #[[$MAP1]](%[[ARG3]], %[[TMP1]])
+// CHECK-NEXT:      %[[TMP3:.*]] = affine.apply #map2(%[[ARG5]], %[[ARG6]])
+// CHECK-NEXT:      affine.load %[[ARG0]][%[[TMP2]], %[[TMP3]]] : memref<1024x1024xf32>
+
+// -----
+
+// CHECK-DAG: #[[$MAP0:.*]] = affine_map<(d0, d1) -> (d0 * 1024 + d1)>
+// CHECK-DAG: #[[$MAP1:.*]] = affine_map<(d0, d1) -> (d0 + d1)>
+// CHECK-LABEL: fold_static_stride_subview_with_affine_load_store_expand_shape_with_constant_access_index
+// CHECK-SAME: (%[[ARG0:.*]]: memref<1024x1024xf32>, %[[ARG1:.*]]: memref<1xf32>, %[[ARG2:.*]]: index)
+func.func @fold_static_stride_subview_with_affine_load_store_expand_shape_with_constant_access_index(%arg0: memref<1024x1024xf32>, %arg1: memref<1xf32>, %arg2: index) -> f32 {
+  %0 = memref.expand_shape %arg0 [[0, 1], [2, 3]] : memref<1024x1024xf32> into memref<1x1024x1024x1xf32>
+  %cst = arith.constant 0 : index
+  affine.for %arg3 = 0 to 1 {
+    affine.for %arg4 = 0 to 1024 {
+      affine.for %arg5 = 0 to 1020 {
+        affine.for %arg6 = 0 to 1 {
+          %1 = memref.load %0[%arg3, %cst, %arg5, %arg6] : memref<1x1024x1024x1xf32>
+          memref.store %1, %arg1[%arg2] : memref<1xf32>
+        }
+      }
+    }
+  }
+  %2 = memref.load %arg1[%arg2] : memref<1xf32>
+  return %2 : f32
+}
+// CHECK-NEXT:   %[[ZERO:.*]] = arith.constant 0 : index
+// CHECK-NEXT:   affine.for %[[ARG3:.*]] = 0 to 1 {
+// CHECK-NEXT:   affine.for %[[ARG4:.*]] = 0 to 1024 {
+// CHECK-NEXT:    affine.for %[[ARG5:.*]] = 0 to 1020 {
+// CHECK-NEXT:     affine.for %[[ARG6:.*]] = 0 to 1 {
+// CHECK-NEXT:      %[[TMP1:.*]] = affine.apply #[[$MAP0]](%[[ARG3]], %[[ZERO]])
+// CHECK-NEXT:      %[[TMP2:.*]] = affine.apply #[[$MAP1]](%[[ARG5]], %[[ARG6]])
+// CHECK-NEXT:      memref.load %[[ARG0]][%[[TMP1]], %[[TMP2]]] : memref<1024x1024xf32>
+
+// -----
+
+// CHECK-LABEL: fold_static_stride_subview_with_affine_load_store_collapse_shape_with_0d_result
+// CHECK-SAME: (%[[ARG0:.*]]: memref<1xf32>, %[[ARG1:.*]]: memref<1xf32>)
+func.func @fold_static_stride_subview_with_affine_load_store_collapse_shape_with_0d_result(%arg0: memref<1xf32>, %arg1: memref<1xf32>) -> memref<1xf32> {
+  %0 = memref.collapse_shape %arg0 [] : memref<1xf32> into memref<f32>
+  affine.for %arg2 = 0 to 3 {
+   %1 = affine.load %0[] : memref<f32> 
+   affine.store %1, %arg1[0] : memref<1xf32>
+  }
+  return %arg1 : memref<1xf32>
+}
+// CHECK-NEXT: %[[ZERO:.*]] = arith.constant 0 : index
+// CHECK-NEXT: affine.for %{{.*}} = 0 to 3 {
+// CHECK-NEXT:  affine.load %[[ARG0]][%[[ZERO]]] : memref<1xf32>

mlir/tools/mlir-vulkan-runner/mlir-vulkan-runner.cpp

 
 using namespace mlir;
 
 static LogicalResult runMLIRPasses(ModuleOp module) {
   PassManager passManager(module.getContext());
   applyPassManagerCLOptions(passManager);
 
   passManager.addPass(createGpuKernelOutliningPass());
-  passManager.addPass(memref::createFoldSubViewOpsPass());
-
-  passManager.addPass(createConvertGPUToSPIRVPass(/*mapMemorySpace=*/true));
+  passManager.addPass(memref::createFoldMemRefAliasOpsPass());
+  passManager.addPass(createConvertGPUToSPIRVPass());
   OpPassManager &modulePM = passManager.nest<spirv::ModuleOp>();
   modulePM.addPass(spirv::createLowerABIAttributesPass());
   modulePM.addPass(spirv::createUpdateVersionCapabilityExtensionPass());
 
   passManager.addPass(createConvertGpuLaunchFuncToVulkanLaunchFuncPass());
   LowerToLLVMOptions llvmOptions(module.getContext(), DataLayout(module));
   passManager.addPass(createMemRefToLLVMPass());
   passManager.nest<func::FuncOp>().addPass(LLVM::createRequestCWrappersPass());

utils/arcanist/clang-format.sh

 # message on line 1, char 1 with file content edited using clang-format-diff.py
 #
 # We do not use git-clang-format because it wants to modify the index,
 # and arc is already holding the lock.
 #
 # We do not look for clang-format-diff or clang-format-diff.py in the PATH
 # because whether/how these are installed differs between distributions,
 # and we have an executable copy in the tree anyway.
-arc_base_commit=$(arc which --show-base)
+arc_base_commit=$(/opt/arcanist/bin/arc which --show-base)
 git diff-index -U0 "${arc_base_commit}" "${src_file}" \
   | clang/tools/clang-format/clang-format-diff.py -style file -i -p1
 
 cp -p "${src_file}" "${formatted_file}"
 cp -p "${original_file}" "${src_file}"
 if ! diff -q "${src_file}" "${formatted_file}" > /dev/null ; then
   echo "autofix"
   echo "clang-format suggested style edits found:"
   echo "1,1"  # line,char of start of replacement.
   cat "${src_file}"
   echo ">>>>"
   cat "${formatted_file}"
   echo "<<<<"
 fi