For reg+imm SVE addressing mode imm is implictly scaled by VL,
making them impractical for truely immediate offsets. However, if
the offset can be unscaled based on the storage element type we
can use the reg+reg SVE addressing mode and thus either reduce the
number of generate add instructions or replace them with a mov
instruction that can be hoisted from the hot code path.
Differential Revision: https://reviews.llvm.org/D106744
Many of the tests have used NEXT when DAG is more approprite. In
some cases single DAG lines have been used. Note that these are
manual tests because they're to complex for update_llc_test_checks.py
and so it's worth not relying too much on the ordered output.
I've also made the CHECK lines more uniform when it comes to the
ordering of things like LO/HI.
Paul Walker