Bug in binop rotate ?

[Andrew Hutchinson <andrewhutchinson at cox dot net>]

I have been adding rotate capability to AVR port and have come across 
what I think is bug in
optabs.c: expand_binop()

This occurs during a rotate expansion. For example

target  = op0  rotated by op1

In the particular situation (code extract below) it tries a reverse 
rotate of (bits - op1). Where this expression is expanded as a simple 
integer,
a negation or subtraction depending on type of op1 and target.

The expansion of the subtraction is using the mode of the target - I 
believe it should be using the mode of op1.
The mode of the rotation  amount need not be the same as the target.

target:DI = Op0:DI rotate op1:HI

In my testcase it is not and I get  asserts latter in simplfy_rtx.

The negation mode looks equally wrong.

Am I mistaken?


 /* If we were trying to rotate, and that didn't work, try rotating
    the other direction before falling back to shifts and bitwise-or.  */
 if (((binoptab == rotl_optab
   && optab_handler (rotr_optab, mode)->insn_code != CODE_FOR_nothing)
      || (binoptab == rotr_optab
      && optab_handler (rotl_optab, mode)->insn_code != CODE_FOR_nothing))
     && mclass == MODE_INT)
   {
     optab otheroptab = (binoptab == rotl_optab ? rotr_optab : rotl_optab);
     rtx newop1;
     unsigned int bits = GET_MODE_BITSIZE (mode);

     if (CONST_INT_P (op1))
   newop1 = GEN_INT (bits - INTVAL (op1));
     else if (targetm.shift_truncation_mask (mode) == bits - 1)
   newop1 = negate_rtx (mode, op1);
     else
   newop1 = expand_binop (mode, sub_optab,
                  GEN_INT (bits), op1,
                  NULL_RTX, unsignedp, OPTAB_DIRECT);