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Re: [PATCH] Fix PR ada/33788
On Jan 14, 2008 12:15 PM, Richard Kenner <kenner@vlsi1.ultra.nyu.edu> wrote:
> > > > I wonder if we will ever see BLKmode or VOIDmode -
> > >
> > > I don't think either is valid for NOP_EXPR.
> >
> > But we nowhere check this
>
> That may be, but as far as I can tell, lots of things will fail if such
> a NOP_EXPR were to show up.
>
> > If you extract from a bitfield and have BIT_FIELD_REF_UNSIGNED unset
> > then it better should. Even though it is not documented. ...which we also
> > should do.
>
> In the NOP_EXPR or as part of *generating* the NOP_EXPR? Don't lots of the
> compiler assume that a non-mode-changing NOP_EXPR doesn't generate code?
something like NOP_EXPR<int, BIT_FIELD_REF <int, ...>>. And yes,
probably there are inconsistencies regarding the assumption that a
NOP_EXPR that doesn't change mode creates (or creates not) code.
See the various bitfield related wrong-code bugs we have. See the interesting
and inconsistently used reduce-bit-field-operations langhook.
It's a mess and I like to not add to it in stage3.
Richard.