[llvm] [AMDGPU] gfx1251 cost model (PR #203682)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

> ⚠️ undef deprecator found issues in your code. ⚠️
> You can test this locally with the following command:
> 
> The following files introduce new uses of undef:
> 
>     * llvm/test/Analysis/CostModel/AMDGPU/add-sub.ll
> 
> 
> [Undef](https://llvm.org/docs/LangRef.html#undefined-values) is now deprecated and should only be used in the rare cases where no replacement is possible. For example, a load of uninitialized memory yields `undef`. You should use `poison` values for placeholders instead.
> 
> In tests, avoid using `undef` and having tests that trigger undefined behavior. If you need an operand with some unimportant value, you can add a new argument to the function and use that instead.
> 
> For example, this is considered a bad practice:
> 
> ```llvm
> define void @fn() {
>   ...
>   br i1 undef, ...
> }
> ```
> 
> Please use the following instead:
> 
> ```llvm
> define void @fn(i1 %cond) {
>   ...
>   br i1 %cond, ...
> }
> ```
> 
> Please refer to the [Undefined Behavior Manual](https://llvm.org/docs/UndefinedBehavior.html) for more information.

Ignoring this. It was undef and it is undef. Tests didn't change, only checks and run lines. I.e., this is unrelated.

https://github.com/llvm/llvm-project/pull/203682