[RISCV] Add tests for callee-saved GPRs, FPR32s, and FPR64s

Note that s0 need not be marked reserved if the frame pointer isn't used. For
the ILP32 and LP64 soft float ABIS that are currently support, all FPRs are
always considered temporaries.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@356061 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed