This follows similar logic in the ARM and Mips backends, and allows the free
use of s0 in functions without a dedicated frame pointer. The changes in
callee-saved-gprs.ll most clearly show the effect of this patch.
llvm-svn: 356063
Re-organise calling convention tests to prepare for ilp32f and ilp32d hard
float ABI tests. It's also clear that we need to introduce similar tests for
lp64.
llvm-svn: 354323