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Memref prefetch side effect #151261

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Memref prefetch side effect #151261

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7078f7d
add MemWrite side effect to memref.prefetch
AlexandreEichenberger Jul 30, 2025
3f91e0f
update
AlexandreEichenberger Jul 30, 2025
3a7212a
added memref.prefetch MemWrite side effect
AlexandreEichenberger Jul 30, 2025
daaabfb
Merge branch 'main' into memref-prefetch-side-effect
AlexandreEichenberger Jul 31, 2025
23b37c5
update
AlexandreEichenberger Aug 1, 2025
429910e
added comments to responde to review
AlexandreEichenberger Aug 1, 2025
0c3cdcb
Merge branch 'main' into memref-prefetch-side-effect
AlexandreEichenberger Aug 4, 2025
9c410c6
Merge branch 'main' into memref-prefetch-side-effect
AlexandreEichenberger Aug 4, 2025
789c474
Merge branch 'main' into memref-prefetch-side-effect
AlexandreEichenberger Aug 5, 2025
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6 changes: 5 additions & 1 deletion mlir/include/mlir/Dialect/MemRef/IR/MemRefOps.td
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Original file line number Diff line number Diff line change
Expand Up @@ -1351,7 +1351,11 @@ def MemRef_PrefetchOp : MemRef_Op<"prefetch"> {
instruction cache.
}];

let arguments = (ins AnyMemRef:$memref, Variadic<Index>:$indices,
// The memref argument is labeled with a MemWrite side effect to enforce a
// relative ordering of the prefetch and other memory operations targeting
// that memory stream.
let arguments = (ins Arg<AnyMemRef, "prefetch address", [MemWrite]> :$memref,
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Why do you need to "write to the buffer" semantically here?
(it's worth a comment, as this may not be intuitive!)

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Good suggestion, will add a comment. It's basically to ensure that dead-code analysis does not remove the operation. It is inline with making that operation a "volatile" so that it remains in place with respect to the other load/store of the prefetched data.

Variadic<Index>:$indices,
BoolAttr:$isWrite,
ConfinedAttr<I32Attr, [IntMinValue<0>,
IntMaxValue<3>]>:$localityHint,
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10 changes: 9 additions & 1 deletion mlir/test/Dialect/Bufferization/Transforms/OwnershipBasedBufferDeallocation/misc-other.mlir
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Expand Up @@ -17,4 +17,12 @@ func.func @func_with_assert(%arg0: index, %arg1: index) {
func.func @func_with_assume_alignment(%arg0: memref<128xi8>) {
%0 = memref.assume_alignment %arg0, 64 : memref<128xi8>
return
}
}

// CHECK-LABEL: func @func_with_prefetch(
// CHECK: memref.prefetch %arg0[%c0, %c0], read, locality<1>, data : memref<4x8xf32>
func.func @func_with_prefetch(%arg0: memref<4x8xf32>) {
%c0 = arith.constant 0 : index
memref.prefetch %arg0[%c0, %c0], read, locality<1>, data : memref<4x8xf32>
return
}