[Mlir-commits] [mlir] [mlir][TOSA] restore unrealized casts when lowering rescale ops (PR #141096)

[Thomas Preud'homme]

RoboTux wrote:

Hi Artem,

First of all my apologies for the trouble my commit caused. How do you manage to lower those unrealized cast? When the only way to convey signedness was through signed/unsigned type we had unrealized_conversion_cast legalization failure for i8->ui8 when lowering from Arith to SPIR-V. I've just tried again with your patch and a rescale from i8 to ui8 and I'm getting:

rescale.mlir:6:8: error: failed to legalize operation 'builtin.unrealized_conversion_cast'

Is unrealized_conversion_cast the correct way to cast between signed/unsigned and signless type? If yes then it's just a bug in the SPIR-V conversion and this patch is fine.

https://github.com/llvm/llvm-project/pull/141096