This is helps on architectures where i8,i16 are not legal but we have byte, and
short loads/stores. Allowing us to merge copies like the one below on ARM.
copy(char *a, char *b, int n) {
do {
int t0 = a[0];
int t1 = a[1];
b[0] = t0;
b[1] = t1;
radar://13536387
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178546 91177308-0d34-0410-b5e6-96231b3b80d8
