[mlir] Extract RHS rows once when lowering vector.contract to dot (#130130)

The `vector.contract` op on two matrices A and B will be lowered to
individual dot products of each row and column of A and B respectively.
The existing lowering will extract each column of B for each row of A,
which leads to multiple values in the IR representing the same columns
of B.

This PR makes changes to the `ContractOpToDotLowering` to make sure that
the columns of B are only ever extracted once, so then the SSA values
representing the extracted columns are then re-used in the IR for later
dot products.

I have updated the existing vector-contract-to-dot-transforms test.

0 files changed, 0 insertions, 0 deletions