[llvm] [GlobalISel] Refactor Combiner MatchData & Apply C++ Code Handling (PR #92239)

[Pierre van Houtryve via llvm-commits]

Pierre-vh wrote:

> Awesome! Thanks for doing this so quickly.
> 
> ```
> unsigned SomeMatchData;
> if (match(SomeMatchData))
>   apply(SomeMatchData)
> ```
> 
> Do the match and apply functions get inlined into this?

They probably will be inlined if it's possible (simplified example: https://godbolt.org/z/17vY68hx3), but it's all in one big switch so maybe size constraints will prevent everything from being inlined all the time

https://github.com/llvm/llvm-project/pull/92239