Another bug, this time in --deallocate-buffers. The input is the following function (toy fft).

```
func @fft(%arg0: memref<?xf32>) -> memref<?xf32> {
%c0 = constant 0 : index
%c1 = constant 1 : index
%0 = dim %arg0, %c0 : memref<?xf32>
%1 = and %0, %c1 : index
%2 = cmpi "eq", %1, %c0 : index
assert %2, "@fft: size of input data is not power of 2."
%3 = shift_right_signed %0, %c1 : index
%4 = call @subtensor(%arg0, %c0, %3) : (memref<?xf32>, index, index) -> memref<?xf32>
%5 = call @subtensor(%arg0, %3, %3) : (memref<?xf32>, index, index) -> memref<?xf32>
%6:2 = call @bf(%3, %4, %5) : (index, memref<?xf32>, memref<?xf32>) -> (memref<?xf32>, memref<?xf32>)
%7 = cmpi "sgt", %3, %c1 : index
cond_br %7, ^bb1, ^bb2(%6#0, %6#1 : memref<?xf32>, memref<?xf32>)
^bb1: // pred: ^bb0
%8 = call @fft(%6#0) : (memref<?xf32>) -> memref<?xf32>
%9 = call @fft(%6#1) : (memref<?xf32>) -> memref<?xf32>
br ^bb2(%8, %9 : memref<?xf32>, memref<?xf32>)
^bb2(%10: memref<?xf32>, %11: memref<?xf32>): // 2 preds: ^bb0, ^bb1
%12 = call @tensor_concat(%10, %11) : (memref<?xf32>, memref<?xf32>) -> memref<?xf32>
%13 = call @bitrev(%12) : (memref<?xf32>) -> memref<?xf32>
%14 = index_cast %0 : index to i32
%15 = sitofp %14 : i32 to f32
%16 = alloc(%0) : memref<?xf32>
%c0_0 = constant 0 : index
%c1_1 = constant 1 : index
scf.parallel (%arg1) = (%c0_0) to (%0) step (%c1_1) {
%17 = load %13[%arg1] : memref<?xf32>
%18 = divf %17, %15 : f32
store %18, %16[%arg1] : memref<?xf32>
scf.yield
}
return %16 : memref<?xf32>
}
```

The output of `mlir-opt --buffer-deallocation`

is unchanged. I believe this is incorrect. For instance, variables %8, %9 should be deleted (they were created by a function call, and must be deallocated by the caller, under the given calling convention).

Dumitru