[compiler-rt] [XRay][RISC-V] Guard trampoline FP saves behind float ABI (PR #214390)

[Mark Zhuang via llvm-commits]

zqb-all wrote:

Thanks for the question. I'm not familiar with XRay either. 
In my opinion, the XRay runtime and the instrumented program should share the same ABI. If that ABI is lp64, then by the ABI contract FP registers aren't used across function boundaries. XRay sleds sit at entry/exit, so even if a function uses FP internally per its -march, XRay doesn't need to save/restore FP registers
But would be good to wait for someone more familiar with XRay to confirm this.

https://github.com/llvm/llvm-project/pull/214390