TensorToScalarsPasses

-convert-tensor-to-scalars

Effectively ‘unrolls’ tensors of static shape to scalars.

This pass will convert a static-shaped tensor type to a TypeRange containing product(dim) copies of the element type of the tensor. This pass currently includes two patterns:

1. It converts tensor.from_elements operations to the corresponding scalar inputs.
2. It converts tensor.insert operations by updating the ValueRange corresponding to the converted input and updating it with the scalar to be inserted.

It also applies folders greedily to simplify, e.g., extract(from_elements).

Note: The pass is designed to be run on an IR, where the only operations with tensor typed operands are tensor “management” operations such as insert/extract, with all other operations (e.g., arith operations) already taking (extracted) scalar inputs. For example, an IR where elementwise operations have been converted to scalar operations via --convert-elementwise-to-affine.

The pass might insert new tensor.from_elements operations or manually create the scalar ValueRange via inserting tensor.extract operations if any operations remain that operate on tensors. The pass currently applies irrespective of tensor size, i.e., might be very slow for large tensors.

TODO (#1023): Extend this pass to support more tensor operations, e.g., tensor.slice

Options

-max-size : Limits `unrolling` to tensors with at most max-size elements