[Bug target/109933] __atomic_test_and_set is broken for BIG ENDIAN riscv targets

[patrick at rivosinc dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109933

--- Comment #13 from Patrick O'Neill <patrick at rivosinc dot com> ---
Created attachment 56487
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56487&action=edit
Proposed fix

Hi Rory,

Sorry that this slipped off my plate for way too long.
I just got around to refactoring the surrounding code on trunk and revised your
patch to fix this for both test_and_set along with inline subword amo
sequences.
When you have the time can you please test this using your big-endian setup?
I'll handle the little-endian testing.

Patrick