On Fri, Oct 13, 2017 at 05:08:51PM +0100, Richard Sandiford wrote:
> Yeah, I agree this'll change the handling of paradoxical subregs that
> occupy more words than the SUBREG_REG, but I think the new version is
> correct. The comment says:
>
> /* If the destination is anything other than CC0, PC, a REG or a SUBREG
> of a REG that occupies all of the REG, the insn uses DEST if
> it is mentioned in the destination or the source. Otherwise, we
> need just check the source. */
>
> and a paradoxical subreg does occupy all of the SUBREG_REG.
I don't think a paradoxical subreg is allowed to refer to more than one
word at all? At least that is how I read the documentation. For example
the very first line of the subreg documentation:
@code{subreg} expressions are used to refer to a register in a machine
mode other than its natural one, or to refer to one register of
a multi-part @code{reg} that actually refers to several registers.
Segher
