> On Fri, 2 Oct 2015, Jan Hubicka wrote: > > > > There must be a reason why I allowed modes to differ there btw ;) > > > > Thinking about it, I guess reason is that incomplete types do not have > > resonable modes set, so requiring modes to match will prevent complete > > and incomplete types to match. > > Hmm. I still think that the mode shouldn't be relevant. Isn't this > only about the cases where the aggregate ends up not having its address > taken and thus we don't allocate a stack slot for it but end up > using a register with mode? ISTR expansion has special cases dealing > with some of the mismatch cases and a fallback spilling to the stack. > > I think we should fix that rather than disallowing aggregate assignments > (which are memory ops to GIMPLE) based on the mode of the aggregate.
THe ICE we get is: +===========================GNAT BUG DETECTED==============================+^M | 6.0.0 20150929 (experimental) (powerpc64-unknown-linux-gnu) GCC error: |^M | in convert_move, at expr.c:282 |^M | Error detected around /home/jh/trunk/gcc/testsuite/gnat.dg/overriding_ops.ads:7:4|^M | Please submit a bug report; see http://gcc.gnu.org/bugs.html. |^M | Use a subject line meaningful to you and us to track the bug. |^M | Include the entire contents of this bug box in the report. |^M | Include the exact command that you entered. |^M | Also include sources listed below. |^M +==========================================================================+^M which is: void convert_move (rtx to, rtx from, int unsignedp) { machine_mode to_mode = GET_MODE (to); machine_mode from_mode = GET_MODE (from); int to_real = SCALAR_FLOAT_MODE_P (to_mode); int from_real = SCALAR_FLOAT_MODE_P (from_mode); enum insn_code code; rtx libcall; /* rtx code for making an equivalent value. */ enum rtx_code equiv_code = (unsignedp < 0 ? UNKNOWN : (unsignedp ? ZERO_EXTEND : SIGN_EXTEND)); gcc_assert (to_real == from_real); gcc_assert (to_mode != BLKmode); gcc_assert (from_mode != BLKmode); so specifically we do not allow any RTL conversion from and to BLKmode and if one of them is, we die. I guess it is because convert_move does not know size of argument and does not expect it to be equivalent. We can fix this earlier upstream when expanding assignment by adding appropriate subreg I think, but I would rather do things step by step - first get with removal of TYPE_CANONICAL and doing this second. I think one needs to fix expand_move and also probably an expansion of calls/memory statemetns that also take loads/stores as parameters. With TYPE_CANONICAL I think only case we get TYPE_CANONICAL equivalent for aggregates of different mode would LTO and then we would ICE the same way here; I guess no one tried to mix these Ada aggregates hard enough to trigger it. Honza
