c.slli/c.srli/c.srai allow a 5-bit shift in RV32C and a 6-bit shift in RV64C.
This patch adds uimmlog2xlennonzero to reflect this constraint as well as
tests.
Differential Revision: https://reviews.llvm.org/D41216
Patch by Shiva Chen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320799 91177308-0d34-0410-b5e6-96231b3b80d8