[llvm] [RISCV] Add searchable table for tune information (PR #66193)

[Wang Pengcheng via llvm-commits]

wangpc-pp wrote:

> > We collected some data that shows that different values of these variables are better on different benchmarks. Do we have the ability to override these values at compile time so that different benchmarks can specify which alignment to use?
> 
> Alignment can be overridden by frontend options `-falign-loops` and `-falign-functions`. This sets an attribute on each function or loop in IR. if those attributes are present, they are maxed with the information in TargetLowering/Subtarget.

Besides, user can set alignment per function/loop via `__attribute__(aligned(n))` or something like `__attribute__((optimize("align-loops=n")))`.

https://github.com/llvm/llvm-project/pull/66193