------- Comment #7 from mikulas at artax dot karlin dot mff dot cuni dot cz
2009-08-10 19:36 -------
Worse, try to return these structures with -freg-struct-return and it also
follows this inconsistent pattern, some are returned in EAX:EDX, some are
returned in ST(0).
It is even inconsistent between GCC releases:
struct {
float a[1];
float a[0];
}
is returned in EAX on GCC-3.3 and in ST(0) on GCC-3.4 and GCC-4.
It is much worse than regparm inconsistency because some operating systems (for
example FreeBSD) use -freg-struct-return as a default calling convention and
GCC generates incompatible code for them.
Where is this "-freg-struct-return" thing documented. The documentation in
manpage, "Return 'struct' and 'union' values in registers when possible." is
really inadequate.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41017
