[Bug target/66750] New: [4.9/5/6] Aggregate return not generated with -m32 -mregparm=3 or with -miamcu

["julia.koval at intel dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66750

            Bug ID: 66750
           Summary: [4.9/5/6] Aggregate return not generated with -m32
                    -mregparm=3 or with -miamcu
           Product: gcc
           Version: 4.9.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: julia.koval at intel dot com
  Target Milestone: ---

Reproduce:
./gcc -Bgcc gcc.target/i386/aggregate-ret2.c -m32 -mregparm=3 -S

Generated code:
 .cfi_def_cfa 4, 4
 ret
 .cfi_endproc

Without mregparm:
 .cfi_def_cfa 4, 4
 ret     $4
 .cfi_endproc

Issue is also reproduced with mregparm=1/2 or -miamcu.

The problem is most likely in expand pass.