Re: [patch] MIPS/gcc: Revert removal of DImode shifts for 32-bit targets

[Richard Henderson <rth@redhat.com>]

On Fri, Sep 03, 2004 at 08:11:47AM +0100, Richard Sandiford wrote:
> But the point as I understand it is that the generic optimisers
> (e.g. simplify-rtx.c) can't tell the difference between an ASHIFT
> that came from an (ashift ...) in the instruction stream or from
> something that was generated artificially by expand_compound_operation.

That would be a bug in expand_compound_operation, I would think.

The alternative is to not add your new hook and do what you can
with the existing SHIFT_COUNT_TRUNCATED macro.  Which I recommend
that you do; I don't think you really want to have the shift bits
dependent on a cleanup / infrastructure change of this scale.



r~