Return values in registers, with "gcc -freg-struct-return":
"---" means return in memory.
I_III C_CdC D_fDd J_JiJ T_TcT X_BcdB
i386 eax al --- eax,edx --- ---
m68k d0 d0 --- d0,d1 --- ---
mips $2 $2 --- --- --- ---
sparc %o0 %o0 --- --- --- ---
alpha $0 $0 $0 $0,$1 --- ---
hppa %r28 %r28 --- --- --- ---
arm r0 r0 --- r0,r1 --- ---
powerpc 3 3 --- 3,4 --- ---
powerpc64 --- --- --- --- --- ---
m88k r2 --- --- --- --- ---
convex s0 s0 s0 s0.l --- ---
ia64 r8 r8 f8 r8,r9 r8 ---
x86_64 eax eax xmm0 rax,rdx rax ---
s390 r2 r2 r2,r3 r2,r3 r2 ---