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Re: PING^2: Fwd: SSA range class and removal of VR_ANTI_RANGEs
- From: Aldy Hernandez <aldyh at redhat dot com>
- To: Richard Biener <richard dot guenther at gmail dot com>, "MacLeod, Andrew" <amacleod at redhat dot com>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>, Jeff Law <law at redhat dot com>
- Date: Fri, 21 Jul 2017 15:30:17 -0400
- Subject: Re: PING^2: Fwd: SSA range class and removal of VR_ANTI_RANGEs
- Authentication-results: sourceware.org; auth=none
- References: <CAGm3qMWqyuY+j2dq2ej3=W45M1S2_4cgOOk3cxmYt==t-3MQeg@mail.gmail.com> <CAFiYyc2DmiPes3Er=q1j3ywyOX7rk-aKsiU_XJkNz1d680UL1g@mail.gmail.com>
On Mon, Jul 17, 2017 at 6:23 AM, Richard Biener
<richard.guenther@gmail.com> wrote:
> On Mon, Jul 17, 2017 at 8:51 AM, Aldy Hernandez <aldyh@redhat.com> wrote:
>> How does this look?
>
> It's a change that on its own doesn't look worthwhile to me.
>
> So please post the changes that will build ontop of this. Like removing
> anti-ranges from VRP or your on-demand value-range stuff.
>
> Thanks,
> Richard.
>From the looks of it, we can have a variety of VRP ranges that are not
representable at all with the an integer range class. For instance, I
see the following ranges built in set_value_range():
[INT, (nop_expr SSA)]
[INT, (plus_expr SSA INT)]
[(negate_expr SSA), (negate_expr SSA)]
[(plus_expr (negate_expr SSA INT)),
(plus_expr (negate_expr SSA) INT)]
[SSA, SSA]
So...I guess the first suggestion is out of the question ;-).
Aldy