[Bug target/99092] Using -O3 and -fprefetch-loop-arrays to compile BLAS on Apple M1 fails

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99092

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
hmmm, see https://gcc.gnu.org/legacy-ml/gcc-patches/2014-07/msg00612.html :
"When it comes to emitting the pattern, always use "prfm" -- the prfum
form can be generated from the prfm mnemonic when the offset implies
this is necessary."

>From readin the ARM ARM, it does look like the prfm mnemonic should accept the
unscaled 9bit signed value.  Just like how ldr vs ldur.
So the bug is in LLVM assembler I think.