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[mlir][memref] Canonicalize memref.reinterpret_cast when offset/sizes/strides are constants. #163505

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merged 4 commits into from
Oct 17, 2025
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[mlir][memref] Canonicalize memref.reinterpret_cast when offset/sizes/strides are constants. #163505

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[mlir][memref] Canonicalize memref.reinterpret_cast when offset/sizes…
NexMing Oct 15, 2025
efc5e82
Ensure that success() is returned only if the IR has been modified.
NexMing Oct 17, 2025
2f5f820
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NexMing Oct 17, 2025
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36 changes: 35 additions & 1 deletion mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2158,11 +2158,45 @@ struct ReinterpretCastOpExtractStridedMetadataFolder
return success();
}
};

struct ReinterpretCastOpConstantFolder
: public OpRewritePattern<ReinterpretCastOp> {
public:
using OpRewritePattern<ReinterpretCastOp>::OpRewritePattern;

LogicalResult matchAndRewrite(ReinterpretCastOp op,
PatternRewriter &rewriter) const override {
unsigned srcStaticCount = llvm::count_if(
llvm::concat<OpFoldResult>(op.getMixedOffsets(), op.getMixedSizes(),
op.getMixedStrides()),
[](OpFoldResult ofr) { return isa<Attribute>(ofr); });

SmallVector<OpFoldResult> offsets = {op.getConstifiedMixedOffset()};
SmallVector<OpFoldResult> sizes = op.getConstifiedMixedSizes();
SmallVector<OpFoldResult> strides = op.getConstifiedMixedStrides();

// TODO: Using counting comparison instead of direct comparison because
// getMixedValues (and therefore ReinterpretCastOp::getMixed...) returns
// IntegerAttrs, while constifyIndexValues (and therefore
// ReinterpretCastOp::getConstifiedMixed...) returns IndexAttrs.
if (srcStaticCount ==
llvm::count_if(llvm::concat<OpFoldResult>(offsets, sizes, strides),
[](OpFoldResult ofr) { return isa<Attribute>(ofr); }))
return failure();

auto newReinterpretCast = ReinterpretCastOp::create(
rewriter, op->getLoc(), op.getSource(), offsets[0], sizes, strides);

rewriter.replaceOpWithNewOp<CastOp>(op, op.getType(), newReinterpretCast);
return success();
}
};
} // namespace

void ReinterpretCastOp::getCanonicalizationPatterns(RewritePatternSet &results,
MLIRContext *context) {
results.add<ReinterpretCastOpExtractStridedMetadataFolder>(context);
results.add<ReinterpretCastOpExtractStridedMetadataFolder,
ReinterpretCastOpConstantFolder>(context);
}

FailureOr<std::optional<SmallVector<Value>>>
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30 changes: 21 additions & 9 deletions mlir/test/Dialect/MemRef/canonicalize.mlir
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Original file line number Diff line number Diff line change
Expand Up @@ -911,6 +911,21 @@ func.func @reinterpret_noop(%arg : memref<2x3x4xf32>) -> memref<2x3x4xf32> {

// -----

// CHECK-LABEL: func @reinterpret_constant_fold
// CHECK-SAME: (%[[ARG:.*]]: memref<f32>)
// CHECK: %[[RES:.*]] = memref.reinterpret_cast %[[ARG]] to offset: [0], sizes: [100, 100], strides: [100, 1]
// CHECK: %[[CAST:.*]] = memref.cast %[[RES]]
// CHECK: return %[[CAST]]
func.func @reinterpret_constant_fold(%arg0: memref<f32>) -> memref<?x?xf32, strided<[?, ?], offset: ?>> {
%c0 = arith.constant 0 : index
%c1 = arith.constant 1 : index
%c100 = arith.constant 100 : index
%reinterpret_cast = memref.reinterpret_cast %arg0 to offset: [%c0], sizes: [%c100, %c100], strides: [%c100, %c1] : memref<f32> to memref<?x?xf32, strided<[?, ?], offset: ?>>
return %reinterpret_cast : memref<?x?xf32, strided<[?, ?], offset: ?>>
}

// -----

// CHECK-LABEL: func @reinterpret_of_reinterpret
// CHECK-SAME: (%[[ARG:.*]]: memref<?xi8>, %[[SIZE1:.*]]: index, %[[SIZE2:.*]]: index)
// CHECK: %[[RES:.*]] = memref.reinterpret_cast %[[ARG]] to offset: [0], sizes: [%[[SIZE2]]], strides: [1]
Expand Down Expand Up @@ -996,10 +1011,9 @@ func.func @reinterpret_of_extract_strided_metadata_same_type(%arg0 : memref<?x?x
// when the strides don't match.
// CHECK-LABEL: func @reinterpret_of_extract_strided_metadata_w_different_stride
// CHECK-SAME: (%[[ARG:.*]]: memref<8x2xf32>)
// CHECK-DAG: %[[C0:.*]] = arith.constant 0 : index
// CHECK-DAG: %[[C1:.*]] = arith.constant 1 : index
// CHECK: %[[RES:.*]] = memref.reinterpret_cast %[[ARG]] to offset: [%[[C0]]], sizes: [4, 2, 2], strides: [1, 1, %[[C1]]]
// CHECK: return %[[RES]]
// CHECK: %[[RES:.*]] = memref.reinterpret_cast %[[ARG]] to offset: [0], sizes: [4, 2, 2], strides: [1, 1, 1]
// CHECK: %[[CAST:.*]] = memref.cast %[[RES]]
// CHECK: return %[[CAST]]
func.func @reinterpret_of_extract_strided_metadata_w_different_stride(%arg0 : memref<8x2xf32>) -> memref<?x?x?xf32, strided<[?, ?, ?], offset: ?>> {
%base, %offset, %sizes:2, %strides:2 = memref.extract_strided_metadata %arg0 : memref<8x2xf32> -> memref<f32>, index, index, index, index, index
%m2 = memref.reinterpret_cast %base to offset: [%offset], sizes: [4, 2, 2], strides: [1, 1, %strides#1] : memref<f32> to memref<?x?x?xf32, strided<[?, ?, ?], offset: ?>>
Expand All @@ -1011,11 +1025,9 @@ func.func @reinterpret_of_extract_strided_metadata_w_different_stride(%arg0 : me
// when the offset doesn't match.
// CHECK-LABEL: func @reinterpret_of_extract_strided_metadata_w_different_offset
// CHECK-SAME: (%[[ARG:.*]]: memref<8x2xf32>)
// CHECK-DAG: %[[C8:.*]] = arith.constant 8 : index
// CHECK-DAG: %[[C2:.*]] = arith.constant 2 : index
// CHECK-DAG: %[[C1:.*]] = arith.constant 1 : index
// CHECK: %[[RES:.*]] = memref.reinterpret_cast %[[ARG]] to offset: [1], sizes: [%[[C8]], %[[C2]]], strides: [%[[C2]], %[[C1]]]
// CHECK: return %[[RES]]
// CHECK: %[[RES:.*]] = memref.reinterpret_cast %[[ARG]] to offset: [1], sizes: [8, 2], strides: [2, 1]
// CHECK: %[[CAST:.*]] = memref.cast %[[RES]]
// CHECK: return %[[CAST]]
func.func @reinterpret_of_extract_strided_metadata_w_different_offset(%arg0 : memref<8x2xf32>) -> memref<?x?xf32, strided<[?, ?], offset: ?>> {
%base, %offset, %sizes:2, %strides:2 = memref.extract_strided_metadata %arg0 : memref<8x2xf32> -> memref<f32>, index, index, index, index, index
%m2 = memref.reinterpret_cast %base to offset: [1], sizes: [%sizes#0, %sizes#1], strides: [%strides#0, %strides#1] : memref<f32> to memref<?x?xf32, strided<[?, ?], offset: ?>>
Expand Down