http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8081
--- Comment #24 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-12 10:23:05 UTC --- Created attachment 26306 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26306 A patch for using by-reference passing (In reply to comment #23) > as alternative to rejecting this case we can lower returning variable-size > types during un-nesting to explicit passing of a return slot and using > memcpy, making the nested function return nothing. It's of course not that easy as we gimplify before un-nesting. The frontend would be responsible to arrange things that way, similar to how we pass a return slot in the C++ frontend (DECL_BY_REFERENCE on the DECL_RESULT variable). Like for the attached patch. Passes extern void abort (void); int main (int argc, char **argv) { int size = 10; typedef struct { char val[size]; } block; block a, b; block __attribute__((noinline)) retframe_block () { return *(block *) &b; } b.val[0] = -1; b.val[1] = -2; a=retframe_block (); if (a.val[0] != -1 || a.val[1] != -2) abort (); return 0; } I'm not sure if one can construct a testcase where using return-slot optimization causes wrong-code generation. Alternatively checking DECL_BY_REFERENCE on the callees DECL_RESULT instead of applying it to all VLA types could work (though not for indirect calls). -- Configure bugmail: http://gcc.gnu.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. -- To UNSUBSCRIBE, email to debian-gcc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/bug-8081-5724-ovo6x5u...@http.gcc.gnu.org/bugzilla/