[Mlir-commits] [mlir] [mlir][EmitC] Model lvalues as a type in EmitC (PR #91475)

[Simon Camphausen]

simon-camp wrote:

As this is a major breaking change, which possibly impacts many of the users of the EmitC dialect I would suggest to post a PSA on discourse and wait for a while before finally merging this PR. Suggestions welcome.

> PSA: Modelling memory of EmitC variables 
> 
> WIth [PR 91475](https://github.com/llvm/llvm-project/pull/91475) explicit variables will be modeled as lvalues in the type system. This introduces some breaking changes to multiple operations. 
>
> - `emitc.variable` and `emitc.global` ops are restricted to return `emitc.array` or `emitc.lvalue` types
>   - the result of the `emitc.variable` op can be materialized as SSA values with the `emitc.load` op 
> - Taking the address of a value is restricted to operands with lvalue type 
> - Conversion from lvalues into SSA values is done with the new `emitc.load` op 
> - The var operand of the `emitc.assign` op is restricted to lvalue type 
> - The result of the `emitc.subscript` and `emitc.get_global` ops is a lvalue type 
>   - results can be materialized as SSA values with the `emitc.load` op

https://github.com/llvm/llvm-project/pull/91475