[Mlir-commits] [mlir] [mlir][SPIR-V] Lower arith.convertf to widen-then-narrow FConvert pair (PR #212817)

[Igor Wodiany]

IgWod wrote:

> spirv.FConvert requires differing component widths, so f16<->bf16 casts must bridge through f32 rather than converting directly

Where does it come from? Looking at the spec it says:

> The component type must not equal the component type in Result Type.

And also in `4.45. Changes from Version 1.6, Revision 3` it says:

> Clarify that OpFConvert operates on different types not just width.

So it sounds to me like conversion between `f16` and `bf16` is legal. 

https://github.com/llvm/llvm-project/pull/212817