[llvm] [RISCV] Add a command line option to disable cost per use for compressed registers. (PR #83320)

[Craig Topper via llvm-commits]

topperc wrote:

> @topperc Could you please provide some performance data with the flag enabled? Looks like enabling the flag leads to ~16% execution time regression and ~20% code size regression.

I can try to get some numbers. I only had some specific examples where it seemed to cause something bad. Here's an example where enabling it reduces the number of spills https://godbolt.org/z/M4YTad6cf though it does increase the code size.

https://github.com/llvm/llvm-project/pull/83320