http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50762
--- Comment #8 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2011-11-09
18:52:16 UTC ---
(In reply to comment #7)
> Redefining "j" constraint as "define_address_constraint" results in:
Yes, it needs to be define_address_constraint.
> pr50762.c:48:1: error: unrecognizable insn:
> (insn 29 28 30 3 (set (reg:DI 0 ax [77])
> (zero_extend:DI (const_int 1 [0x1]))) pr50762.c:35 -1
> (expr_list:REG_DEAD (reg/v:SI 59 [ p_60 ])
> (nil)))
> pr50762.c:48:1: internal compiler error: in extract_insn, at recog.c:2137
> Please submit a full bug report,
That's odd.
> So, _why_ reload insists on pushing zero_extended constant to the register?
> I'd
> expect that (const_int 1) is pushed into the register.
>
> And finally, (zero_extend:DI (const_int 1 [0x1])) equals to (const_int 1
> [0x1]), so why this RTX isn't simplified on-the-fly?
The zero_extend is a fixed part of the insn pattern in question:
(define_insn "*lea_4_zext"
[(set (match_operand:DI 0 "register_operand" "=r")
(zero_extend:DI
(match_operand:SI 1 "lea_address_operand" "p")))]
Reload only ever changes what is *inside* the operands. It does not change the
fixed parts of the pattern (outside of operands).
What I would have expected to happen is for reload to load the (const_int 1)
into an SImode register, and then zero-extend that one ...
Not sure why that doesn't happen. I'll have a look.
