On 11/09/11 16:32, Jakub Jelinek wrote:
> --- gcc/combine.c.jj 2011-11-08 23:35:12.000000000 +0100
> +++ gcc/combine.c 2011-11-09 10:06:27.207333364 +0100
> @@ -11397,9 +11397,12 @@ simplify_comparison (enum rtx_code code,
> later on, and then we wouldn't know whether to sign- or
> zero-extend. */
> mode = GET_MODE (XEXP (op0, 0));
> - if (mode != VOIDmode && GET_MODE_CLASS (mode) == MODE_INT
> + if (GET_MODE_CLASS (mode) == MODE_INT
> && ! unsigned_comparison_p
> - && val_signbit_known_clear_p (mode, const_op)
> + && HWI_COMPUTABLE_MODE_P (mode)
> + && ((unsigned HOST_WIDE_INT) const_op
> + < (((unsigned HOST_WIDE_INT) 1
> + << (GET_MODE_PRECISION (mode) - 1))))
> && have_insn_for (COMPARE, mode))
> {
> op0 = XEXP (op0, 0);
I guess this is OK, although it would still be nicer to use something
with a descriptive name rather than bit-fiddling, to avoid this kind of
confusion. Maybe check whether trunc_int_for_mode doesn't change the
constant? Or we could make val_signbit_known_clear_p do more extensive
checking.
Bernd
