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[mlir][memref] canonicalization for erasing copying subview to identical subview #125852

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[mlir][memref] canonicalization for erasing copying subview to identical subview #125852

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588d44c
canonicalization for erasing copying subview to identical subview
fschlimb Feb 5, 2025
c78b154
clang-format
fschlimb Feb 5, 2025
011b2b4
more readable by smiplification
fschlimb Feb 7, 2025
c8845af
Merge branch 'main' into canonicalize_copy_subview
fschlimb Feb 27, 2025
438e6e6
Update mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
fschlimb Feb 28, 2025
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18 changes: 16 additions & 2 deletions mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -824,8 +824,22 @@ struct FoldSelfCopy : public OpRewritePattern<CopyOp> {

LogicalResult matchAndRewrite(CopyOp copyOp,
PatternRewriter &rewriter) const override {
if (copyOp.getSource() != copyOp.getTarget())
return failure();
if (copyOp.getSource() != copyOp.getTarget()) {
// We can still fold if source and target are similar SubViews.
auto source = copyOp.getSource().getDefiningOp<SubViewOp>();
auto target = copyOp.getTarget().getDefiningOp<SubViewOp>();
if (!source || !target)
return failure();
if (source.getSource() != target.getSource() ||
source.getOffsets() != target.getOffsets() ||
source.getStaticOffsets() != target.getStaticOffsets() ||
source.getStrides() != target.getStrides() ||
source.getStaticStrides() != target.getStaticStrides()) {
// By copy semantics, sizes of source and target must be the same
// -> no need to check sizes.
return failure();
}
}

rewriter.eraseOp(copyOp);
return success();
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30 changes: 30 additions & 0 deletions mlir/test/Dialect/MemRef/canonicalize.mlir
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Original file line number Diff line number Diff line change
Expand Up @@ -704,6 +704,36 @@ func.func @self_copy(%m1: memref<?xf32>) {

// -----

func.func @self_copy_subview(%arg0: memref<?xf32>, %arg1: memref<?xf32>, %s: index) {
%c3 = arith.constant 3: index
%0 = memref.subview %arg0[3] [4] [2] : memref<?xf32> to memref<4xf32, strided<[2], offset: 3>>
%1 = memref.subview %arg0[%c3] [4] [2] : memref<?xf32> to memref<4xf32, strided<[2], offset: ?>>
%2 = memref.subview %arg0[%c3] [4] [%s] : memref<?xf32> to memref<4xf32, strided<[?], offset: ?>>
%3 = memref.subview %arg0[3] [4] [%s] : memref<?xf32> to memref<4xf32, strided<[?], offset: 3>>
%4 = memref.subview %arg1[3] [4] [%s] : memref<?xf32> to memref<4xf32, strided<[?], offset: 3>>
// erase (source and destination subviews render the same)
memref.copy %0, %1 : memref<4xf32, strided<[2], offset: 3>> to memref<4xf32, strided<[2], offset: ?>>
// keep (strides differ)
memref.copy %2, %1 : memref<4xf32, strided<[?], offset: ?>> to memref<4xf32, strided<[2], offset: ?>>
// erase (source and destination subviews render the same)
memref.copy %2, %3 : memref<4xf32, strided<[?], offset: ?>> to memref<4xf32, strided<[?], offset: 3>>
// keep (source and destination differ)
memref.copy %3, %4 : memref<4xf32, strided<[?], offset: 3>> to memref<4xf32, strided<[?], offset: 3>>
return
}

// CHECK-LABEL: func.func @self_copy_subview(
// CHECK-SAME: [[varg0:%.*]]: memref<?xf32>, [[varg1:%.*]]: memref<?xf32>, [[varg2:%.*]]: index) {
// CHECK: [[vsubview:%.*]] = memref.subview [[varg0]][3] [4] [2]
// CHECK: [[vsubview_0:%.*]] = memref.subview [[varg0]][3] [4] [[[varg2]]]
// CHECK: [[vsubview_1:%.*]] = memref.subview [[varg0]][3] [4] [[[varg2]]]
// CHECK: [[vsubview_2:%.*]] = memref.subview [[varg1]][3] [4] [[[varg2]]]
// CHECK-NEXT: memref.copy [[vsubview_0]], [[vsubview]]
// CHECK-NEXT: memref.copy [[vsubview_1]], [[vsubview_2]]
// CHECK-NEXT: return

// -----

// CHECK-LABEL: func @empty_copy
// CHECK-NEXT: return
func.func @empty_copy(%m1: memref<0x10xf32>, %m2: memref<?x10xf32>) {
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