http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39386
Georg-Johann Lay <gjl at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |gjl at gcc dot gnu.org
Known to fail| |
--- Comment #10 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2011-07-23
10:08:33 UTC ---
The problem arises from the following insns:
*ashlqi3
ashlhi3
ashlsi3
ashrqi3
ashrhi3
ashrsi3
*lshrqi3
lshrhi3
lshrsi3
For variable shifts the first constraint alternative is "=r,0,r"
avr.c:out_shift_with_cnt() reads
else if (register_operand (operands[2], QImode))
{
if (reg_unused_after (insn, operands[2]))
op[3] = op[2];
else
{
op[3] = tmp_reg_rtx;
if (!len)
strcat (str, (AS2 (mov,%3,%2) CR_TAB));
}
}
so that in the very rare, pathological case of op0 = op1 = op2 and op2 is
unused after the insn, wrong code gets generated. Fix is:
if (reg_unused_after (insn, operands[2])
&& !reg_overlap_mentioned_p (operands[0], operands[2]))
or something like that.
