pub fn compiler_barrier()Expand description
Compiler-only barrier: ordinary RAM accesses are not moved across it in either direction, so stores before it land before an MMIO store after it and accesses after it follow an MMIO read before it.
The pinned MIPS-I backend lowers even a single-thread compiler fence to
SYNC, which the R3000 lacks, so the target uses an empty asm! with its
default memory clobber. Do not add nomem or readonly: both would drop
the guarantee.