[llvm] [Loads] Support dereferenceable assumption with variable size. (PR #128436)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

ping :) 

> Could you pls add a test in `early_exit_legality.ll` to show that the dereferencability and alignment bundles allow early exit vectorization without the need for statically allocated arrays (the existing tests in the patch show why predication wouldn’t be needed). It works as expected when I tried, will be useful just to showcase that additional benefit.

I added some deref assumption tests with early exits and constant sizes in 0afbf1721346faca3dbcd659acf2c558c26146fb and added one with non-constant sizes to this patch

I'll share a patch soon that updates LAA to use info from deref assumptions in the code there .

https://github.com/llvm/llvm-project/pull/128436