Complex values are returned differently depending on -mpowerpc64. For example gcc.c-torture/execute/960512-1.c
__complex__ double f () In 32-bit mode, the complex value is returned in r3:r4,r5:r6. In -mpowerpc64 mixed mode, the value is returned in r3,r4. ABI breakage. Oops. -- Summary: Darwin -mpowerpc64 complex ABI breakage Product: gcc Version: 4.1.0 Status: UNCONFIRMED Keywords: wrong-code Severity: normal Priority: P2 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: dje at gcc dot gnu dot org CC: gcc-bugs at gcc dot gnu dot org GCC build triplet: powerpc-darwin GCC host triplet: powerpc-darwin GCC target triplet: powerpc-darwin http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23847