`isOpOperandCanBeDroppedAfterFusedLinalgs` crashes when `indexingMaps`
is empty. This can occur when `producer` only has DPS init operands and
`consumer ` only has a single DPS input operand (all operands are
ignored and nothing gets added to `indexingMaps`). This is because
`concatAffineMaps` wasn't handling the maps being empty properly.
Similar to `canOpOperandsBeDroppedImpl`, I added an early return when
the maps are of size zero. Additionally, `concatAffineMaps`'s
declaration comment says it returns an empty map when `maps` is empty
but it has no way to get the `MLIRContext` needed to construct the empty
affine map when the array is empty. So, I changed this to take the
context.
__NOTE: concatAffineMaps now takes an MLIRContext to be able to
construct an empty map in the case where `maps` is empty.__
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Signed-off-by: Ian Wood <ianwood2024@u.northwestern.edu>
Co-authored-by: Quinn Dawkins <quinn.dawkins@gmail.com>
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