Vectorizer for types with different size

[Li, Pan2]

Hi Richard Biener,

Recently I am try to enable the RISC-V auto-vec for the lrint family, which is trying to convert the HF/SF/DF to long type.

Then I found the vectorizer can only act on the types with the same data size. For example, DF to DI (long in RV64) works
well for standard pattern name lrintmn2 but fails on other combinations like SF to DI.

However, according the legacy hook TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION may help to resolve the problem
but I would like to learn if there is any plan that the middle-end would like to support the types with different size before we
start to implement the hook.

I also have a try for ARM for this, you can reference this link https://godbolt.org/z/o41hr9rY9.

Thanks in advance and have a great day, ;)!

Pan