[Bug target/77599] M68K: __builtin_bswap32() isn't compiled correctly with -mshort

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77599

Jeffrey A. Law <law at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |law at redhat dot com
         Resolution|---                         |INVALID

--- Comment #2 from Jeffrey A. Law <law at redhat dot com> ---
The problem here is you're using -mshort  on *-linux-gnu which IMHO is invalid.


Linux defines int32_t as a "int".  And -mshort changes the width of an int to
16 bits, at which point anything prototyped using int32_t has just changed its
ABI in a meaningful way (similarly for uint32_t, but unsigned).  You can see
this in the .optimized dump file:

x (long unsigned int y)
{
  unsigned int _1;
  unsigned int _2;
  long unsigned int _4;

;;   basic block 2, loop depth 0, count 0, freq 10000, maybe hot
;;    prev block 0, next block 1, flags: (NEW, REACHABLE, VISITED)
;;    pred:       ENTRY [100.0%]  (FALLTHRU,EXECUTABLE)
  _1 = (unsigned int) y_3(D);
  _2 = __builtin_bswap32 (_1);
  _4 = (long unsigned int) _2;
  return _4;
}

Note the type of the _1 and _2.  They are both unsigned ints, so 16 bits. 


If you try this test on a bare metal target such as m68k-elf or without the
-mshort, you'll get the expected and desired result.