This PR applies the same fix from #166569 to `memref.subview`. That PR
fixed the issue for `tensor.extract_slice`, and this one addresses the
identical problem for `memref.subview`.
The runtime verification for `memref.subview` incorrectly rejects valid
empty subviews (size=0) starting at the memref boundary.
**Example that demonstrates the issue:**
```mlir
func.func @subview_with_empty_slice(%memref: memref<10x4x1xf32, strided<[?, ?, ?], offset: ?>>,
%dim_0: index,
%dim_1: index,
%dim_2: index,
%offset: index) {
// When called with: offset=10, dim_0=0, dim_1=4, dim_2=1
// Runtime verification fails: "offset 0 is out-of-bounds"
%subview = memref.subview %memref[%offset, 0, 0] [%dim_0, %dim_1, %dim_2] [1, 1, 1] :
memref<10x4x1xf32, strided<[?, ?, ?], offset: ?>> to
memref<?x?x?xf32, strided<[?, ?, ?], offset: ?>>
return
}
```
When `%offset=10` and `%dim_0=0`, we're creating an empty subview (zero
elements along dimension 0) starting at the boundary. The current
verification enforces `offset < dim_size`, which evaluates to `10 < 10`
and fails. I feel this should be valid since no memory is accessed.
**The fix:**
Same as #166569 - make the offset check conditional on subview size:
- Empty subview (size == 0): allow `0 <= offset <= dim_size`
- Non-empty subview (size > 0): require `0 <= offset < dim_size`
Please see #166569 for motivation and rationale.
---
Co-authored-by: Hanumanth Hanumantharayappa <hhanuman@ah-hhanuman-l.dhcp.mathworks.com>
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