Re: suspect code in fold-const.c

[Eric Botcazou <ebotcazou at adacore dot com>]

> this code from fold-const.c starts on line 13811.
> 
>          else if (TREE_INT_CST_HIGH (arg1) == signed_max_hi
>               && TREE_INT_CST_LOW (arg1) == signed_max_lo
>               && TYPE_UNSIGNED (arg1_type)
>               /* We will flip the signedness of the comparison operator
>              associated with the mode of arg1, so the sign bit is
>              specified by this mode.  Check that arg1 is the signed
>              max associated with this sign bit.  */
>               && width == GET_MODE_BITSIZE (TYPE_MODE (arg1_type))
>               /* signed_type does not work on pointer types.  */
>               && INTEGRAL_TYPE_P (arg1_type))

with width defined as:

	unsigned int width = TYPE_PRECISION (arg1_type);

> it seems that the check on bitsize should really be a check on the
> precision of the variable.   If this seems right, i will correct this on
> the trunk and make the appropriate changes to the wide-int branch.

Do you mean

  && width == GET_MODE_PRECISION (TYPE_MODE (arg1_type))

instead?  If so, that would probably make sense, but there are a few other 
places with the same TYPE_PRECISION/GET_MODE_BITSIZE check, in particular the 
very similar transformation done in fold_single_bit_test_into_sign_test.

-- 
Eric Botcazou