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[mlir][arith] Only fold splats for static shape result types #93102

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Merged
merged 1 commit into from
May 23, 2024
Merged

[mlir][arith] Only fold splats for static shape result types #93102

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5 changes: 4 additions & 1 deletion mlir/include/mlir/Dialect/CommonFolders.h
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Original file line number Diff line number Diff line change
Expand Up @@ -298,7 +298,10 @@ Attribute constFoldCastOp(ArrayRef<Attribute> operands, Type resType,
calculate(op.getSplatValue<ElementValueT>(), castStatus);
if (!castStatus)
return {};
return DenseElementsAttr::get(cast<ShapedType>(resType), elementResult);
auto shapedResType = cast<ShapedType>(resType);
if (!shapedResType.hasStaticShape())
return {};
return DenseElementsAttr::get(shapedResType, elementResult);
}
if (auto op = dyn_cast<ElementsAttr>(operands[0])) {
// Operand is ElementsAttr-derived; perform an element-wise fold by
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8 changes: 8 additions & 0 deletions mlir/test/Dialect/Arith/canonicalize.mlir
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Expand Up @@ -2950,6 +2950,14 @@ func.func @unsignedExtendConstantResource() -> tensor<i16> {
return %ext : tensor<i16>
}

// Just checks that this doesn't crash.
// CHECK-LABEL: @signedExtendSplatAsDynamicShape
func.func @signedExtendSplatAsDynamicShape() -> tensor<?xi64> {
%splat = arith.constant dense<5> : tensor<2xi16>
%extsplat = arith.extsi %splat : tensor<2xi16> to tensor<?xi64>
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I'm surprised this is even allowed at the level of artith. Shouldn't we change the verifier to reject this extend + 'shape cast' pattern instead?

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Makes sense. I'll rewrite it so that it's rejected during verification.

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That might be a different can of worms. This is an obvious things to fix for now. Maybe we should land this first.

return %extsplat : tensor<?xi64>
}

// CHECK-LABEL: @extsi_i0
// CHECK: %[[ZERO:.*]] = arith.constant 0 : i16
// CHECK: return %[[ZERO]] : i16
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