As the following testcase shows, libffi didn't handle properly
classify_arguments of structures at byte offsets not divisible by
UNITS_PER_WORD. The following patch adjusts it to match what
config/i386/ classify_argument does for that and also ports the
PR38781 fix there (the second chunk).
This has been committed to upstream libffi already:
5651bea284
2021-06-16 Jakub Jelinek <jakub@redhat.com>
* src/x86/ffi64.c (classify_argument): For FFI_TYPE_STRUCT set words
to number of words needed for type->size + byte_offset bytes rather
than just type->size bytes. Compute pos before the loop and check
total size of the structure.
* testsuite/libffi.call/nested_struct12.c: New test.
041f741770