[Bug target/81823] New: [RX] Improve support for atomics other than SImode

["olegendo at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81823

            Bug ID: 81823
           Summary: [RX] Improve support for atomics other than SImode
           Product: gcc
           Version: 7.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: olegendo at gcc dot gnu.org
  Target Milestone: ---
            Target: rx*-*-*

Atomics that perform arithmetic are only implemented for SImode.  It should be
extended to support QImode and HImode in the same way.

Moreover, when doing atomic ior, xor, and operations with constants that
consist of only one bit, the following instructions can be used:

   ior -> bset
   xor -> bnot
   and -> bclr

Although the memory operand of those instructions is always a byte, it can also
be used on wider types by adjusting the byte offset (depending on the current
endian mode).

The bset, bnot and bclr instructions are very useful when dealing with GPIO
port registers.