Hi DJ,
The patch below is to fix a snafu I made whilst fixing some problems
with the RL78 port a while ago. GCC was generating
(SUBREG (SYMBOL_REF) <n>) which made no sense to me, so I had the
movqi expander just fail when it encountered them. Now that I have
more idea about why they are created - installing symbolic values into
bitfields or packed structure fields - I have found that it is
necessary to support them. Failure is not an option as GCC will just
silently omit generating any code at all.
Tested with an rl78-elf toolchain without any regressions. OK to
apply ?
Cheers
Nick
gcc/ChangeLog
2014-04-01 Nick Clifton <ni...@redhat.com>
* config/rl78/rl78-expand.md (movqi): Handle (SUBREG (SYMBOL_REF))
properly.
Index: gcc/config/rl78/rl78-expand.md
===================================================================
--- gcc/config/rl78/rl78-expand.md (revision 209009)
+++ gcc/config/rl78/rl78-expand.md (working copy)
@@ -30,18 +30,23 @@
if (rl78_far_p (operands[0]) && rl78_far_p (operands[1]))
operands[1] = copy_to_mode_reg (QImode, operands[1]);
- /* FIXME: Not sure how GCC can generate (SUBREG (SYMBOL_REF)),
- but it does. Since this makes no sense, reject it here. */
+ /* GCC can generate (SUBREG (SYMBOL_REF)) when it has to store a symbol
+ into a bitfield, or a packed ordinary field. We can handle this
+ provided that the destination is a register. If not, then load the
+ source into a register first. */
if (GET_CODE (operands[1]) == SUBREG
- && GET_CODE (XEXP (operands[1], 0)) == SYMBOL_REF)
- FAIL;
+ && GET_CODE (XEXP (operands[1], 0)) == SYMBOL_REF
+ && ! REG_P (operands[0]))
+ operands[1] = copy_to_mode_reg (QImode, operands[1]);
+
/* Similarly for (SUBREG (CONST (PLUS (SYMBOL_REF)))).
cf. g++.dg/abi/packed.C. */
if (GET_CODE (operands[1]) == SUBREG
&& GET_CODE (XEXP (operands[1], 0)) == CONST
&& GET_CODE (XEXP (XEXP (operands[1], 0), 0)) == PLUS
- && GET_CODE (XEXP (XEXP (XEXP (operands[1], 0), 0), 0)) == SYMBOL_REF)
- FAIL;
+ && GET_CODE (XEXP (XEXP (XEXP (operands[1], 0), 0), 0)) == SYMBOL_REF
+ && ! REG_P (operands[0]))
+ operands[1] = copy_to_mode_reg (QImode, operands[1]);
if (CONST_INT_P (operands[1]) && ! IN_RANGE (INTVAL (operands[1]), (-1 <<
8) + 1, (1 << 8) - 1))
FAIL;
