[llvm] [RISCV] Add branch folding before branch relaxation (PR #134760)

[Philip Reames via llvm-commits]

preames wrote:

Looking at the most recent code size numbers after the commoning fix, I'm questioning the merits of this patch.  The remaining code size improvements are fairly small (the largest are 0.27% and 0.13%) and there is a compile time implication of running branch folding twice.  

@topperc @asb @wangpc-pp @michaelmaitland  What do you guys think?  Is this worthwhile?  Or should we abandon this approach?

https://github.com/llvm/llvm-project/pull/134760