[Bug target/59794] [4.7/4.8/4.9 Regression] i386 backend fails to detect MMX/SSE/AVX return value

["hjl.tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59794

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rth at gcc dot gnu.org
            Summary|i386 backend fails to       |[4.7/4.8/4.9 Regression]
                   |detect SSE/AVX return value |i386 backend fails to
                   |                            |detect MMX/SSE/AVX return
                   |                            |value

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> ---
This is a regression:

[hjl@gnu-6 tmp]$ cat m1.i
typedef int __v2si __attribute__ ((__vector_size__ (8)));

extern __v2si y;

__v2si
foo ()
{
  return y;
}
[hjl@gnu-6 tmp]$ cc -S -mno-mmx m1.i -m32
[hjl@gnu-6 tmp]$ 

This may be caused by r83533.  ix86_struct_value_rtx sees BLKmode
when SSE is disabled and DImode when MMX is disabled.