[all-commits] [llvm/llvm-project] cbe7c4: [mlir][memref] Fix runtime verification for memref...

[Hanumanth via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: cbe7c49e93b630d3388dba2663b08a3c5c1bc8b6
      https://github.com/llvm/llvm-project/commit/cbe7c49e93b630d3388dba2663b08a3c5c1bc8b6
  Author: Hanumanth <hhanuman at mathworks.com>
  Date:   2025-10-27 (Mon, 27 Oct 2025)

  Changed paths:
    M mlir/lib/Dialect/MemRef/Transforms/RuntimeOpVerification.cpp
    M mlir/test/Integration/Dialect/MemRef/subview-runtime-verification.mlir

  Log Message:
  -----------
  [mlir][memref] Fix runtime verification for memref.subview when size dimension value is 0 (#164897)

Previously, the runtime verification pass would insert assertion
statements with conditions that always evaluate to false for
semantically valid `memref.subview` operations where one of the
dimensions had a size of 0.

The `memref.subview` runtime verification logic was unconditionally
generating checks for the position of the last element (`offset + (size
- 1) * stride`). When `size` is 0, this causes the assertion condition
to always be false, leading to runtime failures even though the
operation is semantically valid.

This patch fixes the issue by making the `lastPos` check conditional.
The offset is always verified, but the endpoint check is only performed
when `size > 0` to avoid generating spurious assert statements.

This issue was discovered through a LiteRT model, where a dynamic shape
calculation resulted in a zero-sized dimension being passed to
`memref.subview`. The following is a simplified IR snippet from the
model. After running the runtime verification pass, an assertion that
always fails is generated because the SSA value `%5` becomes 0.

```mlir
module {
  memref.global "private" constant @__constant_2xi32 : memref<2xi32> = dense<-1> {alignment = 64 : i64}
  memref.global "private" constant @__constant_1xi32 : memref<1xi32> = dense<0> {alignment = 64 : i64}
  func.func @simpleRepro(%arg0: memref<10x4x1xf32, strided<[?, ?, ?], offset: ?>>) -> memref<?x?x?xf32, strided<[?, ?, ?], offset: ?>> {
    %c2 = arith.constant 2 : index
    %c4 = arith.constant 4 : index
    %c1 = arith.constant 1 : index
    %c10 = arith.constant 10 : index
    %c0 = arith.constant 0 : index
    %c-1 = arith.constant -1 : index
    %0 = memref.get_global @__constant_1xi32 : memref<1xi32>
    %1 = memref.get_global @__constant_2xi32 : memref<2xi32>
    %alloca = memref.alloca() {alignment = 64 : i64} : memref<3xi32>
    %subview = memref.subview %alloca[0] [1] [1] : memref<3xi32> to memref<1xi32, strided<[1]>>
    memref.copy %0, %subview : memref<1xi32> to memref<1xi32, strided<[1]>>
    %subview_0 = memref.subview %alloca[1] [2] [1] : memref<3xi32> to memref<2xi32, strided<[1], offset: 1>>
    memref.copy %1, %subview_0 : memref<2xi32> to memref<2xi32, strided<[1], offset: 1>>
    %2 = memref.load %alloca[%c0] : memref<3xi32>
    %3 = index.casts %2 : i32 to index
    %4 = arith.cmpi eq, %3, %c-1 : index
    %5 = arith.select %4, %c10, %3 : index
    %6 = memref.load %alloca[%c1] : memref<3xi32>
    %7 = index.casts %6 : i32 to index
    %8 = arith.cmpi eq, %7, %c-1 : index
    %9 = arith.select %8, %c4, %7 : index
    %10 = memref.load %alloca[%c2] : memref<3xi32>
    %11 = index.casts %10 : i32 to index
    %12 = arith.cmpi eq, %11, %c-1 : index
    %13 = arith.select %12, %c1, %11 : index
    %subview_1 = memref.subview %arg0[0, 0, 0] [%5, %9, %13] [1, 1, 1] : memref<10x4x1xf32, strided<[?, ?, ?], offset: ?>> to memref<?x?x?xf32, strided<[?, ?, ?], offset: ?>>
    return %subview_1 : memref<?x?x?xf32, strided<[?, ?, ?], offset: ?>>
  }
}
```

P.S. This is a similar issue to the one fixed for `tensor.extract_slice`
in https://github.com/llvm/llvm-project/pull/164878

---------

Co-authored-by: Hanumanth Hanumantharayappa <hhanuman at ah-hhanuman-l.dhcp.mathworks.com>



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