[all-commits] [llvm/llvm-project] 50653e: [tosa] : Enhance tosa.slice folding for dynamic di...

[Sayan Saha via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 50653e5a0d1db1b7a9451cb98fb1b56224449d72
      https://github.com/llvm/llvm-project/commit/50653e5a0d1db1b7a9451cb98fb1b56224449d72
  Author: Sayan Saha <sayans at mathworks.com>
  Date:   2026-03-04 (Wed, 04 Mar 2026)

  Changed paths:
    M mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp
    M mlir/test/Dialect/Tosa/canonicalize.mlir

  Log Message:
  -----------
  [tosa] : Enhance tosa.slice folding for dynamic dims. (#184615)

Source IR:
```
func.func @main(%arg0: tensor<?x112x64x112xf32>) -> tensor<?x113x65x112xf32> {
    %0 = tosa.const_shape  {values = dense<[0, 0, 1, 1, 1, 1, 0, 0]> : tensor<8xindex>} : () -> !tosa.shape<8>
    %1 = "tosa.const"() <{values = dense<0.000000e+00> : tensor<1xf32>}> : () -> tensor<1xf32>
    %2 = tosa.pad %arg0, %0, %1 : (tensor<?x112x64x112xf32>, !tosa.shape<8>, tensor<1xf32>) -> tensor<?x114x66x112xf32>
    %3 = tosa.const_shape  {values = dense<0> : tensor<4xindex>} : () -> !tosa.shape<4>
    %4 = tosa.const_shape  {values = dense<[-1, 113, 65, 112]> : tensor<4xindex>} : () -> !tosa.shape<4>
    %5 = tosa.slice %2, %3, %4 : (tensor<?x114x66x112xf32>, !tosa.shape<4>, !tosa.shape<4>) -> tensor<?x113x65x112xf32>
    return %5 : tensor<?x113x65x112xf32>
  }
```

when canonicalized produces

```
$> mlir-opt --canonicalize

func.func @main(%arg0: tensor<?x112x64x112xf32>) -> tensor<?x113x65x112xf32> {
    %0 = tosa.const_shape  {values = dense<0> : tensor<4xindex>} : () -> !tosa.shape<4>
    %1 = tosa.const_shape  {values = dense<[-1, 113, 65, 112]> : tensor<4xindex>} : () -> !tosa.shape<4>
    %2 = "tosa.const"() <{values = dense<0.000000e+00> : tensor<1xf32>}> : () -> tensor<1xf32>
    %3 = tosa.const_shape  {values = dense<[0, 0, 1, 0, 1, 0, 0, 0]> : tensor<8xindex>} : () -> !tosa.shape<8>
    %4 = tosa.pad %arg0, %3, %2 : (tensor<?x112x64x112xf32>, !tosa.shape<8>, tensor<1xf32>) -> tensor<?x113x65x112xf32>
    %5 = tosa.slice %4, %0, %1 : (tensor<?x113x65x112xf32>, !tosa.shape<4>, !tosa.shape<4>) -> tensor<?x113x65x112xf32>
    return %5 : tensor<?x113x65x112xf32>
  }
```

because of the `PadSliceOptimization`. Note that the `tosa.slice` op
after the optimization is essentially a no-op. This change, enhances the
folder to fold such `tosa.slice` ops. After this change canonicalization
produces

```
func.func @main(%arg0: tensor<?x112x64x112xf32>) -> tensor<?x113x65x112xf32> {
    %0 = "tosa.const"() <{values = dense<0.000000e+00> : tensor<1xf32>}> : () -> tensor<1xf32>
    %1 = tosa.const_shape  {values = dense<[0, 0, 1, 0, 1, 0, 0, 0]> : tensor<8xindex>} : () -> !tosa.shape<8>
    %2 = tosa.pad %arg0, %1, %0 : (tensor<?x112x64x112xf32>, !tosa.shape<8>, tensor<1xf32>) -> tensor<?x113x65x112xf32>
    return %2 : tensor<?x113x65x112xf32>
  }
```



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