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From: "amacleod at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/102844] [9/10/11/12 Regression] DOM jump threading not copying block that became non-empty
Date: Wed, 20 Oct 2021 12:49:28 +0000	[thread overview]
Message-ID: <bug-102844-4-HzX4Y4IuRr@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-102844-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102844

--- Comment #22 from Andrew Macleod <amacleod at redhat dot com> ---
(In reply to Richard Biener from comment #20)
> (In reply to Aldy Hernandez from comment #18)
> > (In reply to rguenther@suse.de from comment #17)
> > > On Wed, 20 Oct 2021, aldyh at gcc dot gnu.org wrote:
> > 
> > > > Silly question, why is the SSA form invalid on entry to VRP2?  That's just
> > > > asking for trouble.  Is this related to how asserts work?
> > > 
> > > Well, DOM threading creates invalid SSA (definition not dominating use).
> > > Doesn't have to do anything with VRP or asserts.
> > 
> > Ah, I see.
> > 
> > BTW, if this is still the case in mainline, this is bound to be a problem
> > for the ranger.  Andrew, won't we get an UNDEFINED / unreachable if we query
> > the non dominating use at this point?
> 
> Well, invalid IL is invalid - there's no need to "cope" with it.  We have to
> fix the (forward) threading code.

Indeed, invalid is invalid.

And it depends. Any on-entry range is the union of all incoming blocks. If we
query a use that has no def anywhere in the dominator tree , then you will get
UNDEFINED. If the def is on at least one incoming path, then you will get the
def or some derivative of it.

  parent reply	other threads:[~2021-10-20 12:49 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-19 17:45 [Bug c/102844] New: gcc-9.x miscompiles unsigned char expression in switch breiten at lexmark dot com
2021-10-19 17:58 ` [Bug tree-optimization/102844] [9/10/11/12 Regression] " pinskia at gcc dot gnu.org
2021-10-19 18:11 ` pinskia at gcc dot gnu.org
2021-10-19 18:13 ` pinskia at gcc dot gnu.org
2021-10-19 18:23 ` [Bug tree-optimization/102844] [9/10/11/12 Regression] vrp inserting assert causes miscompiling when doing update_ssa pinskia at gcc dot gnu.org
2021-10-20  7:10 ` rguenth at gcc dot gnu.org
2021-10-20  7:44 ` rguenth at gcc dot gnu.org
2021-10-20  7:49 ` rguenth at gcc dot gnu.org
2021-10-20  8:08 ` marxin at gcc dot gnu.org
2021-10-20  8:28 ` rguenth at gcc dot gnu.org
2021-10-20  8:33 ` marxin at gcc dot gnu.org
2021-10-20  8:59 ` rguenth at gcc dot gnu.org
2021-10-20  9:00 ` rguenth at gcc dot gnu.org
2021-10-20  9:03 ` rguenth at gcc dot gnu.org
2021-10-20  9:08 ` rguenth at gcc dot gnu.org
2021-10-20  9:19 ` rguenth at gcc dot gnu.org
2021-10-20  9:21 ` aldyh at gcc dot gnu.org
2021-10-20  9:30 ` rguenther at suse dot de
2021-10-20  9:47 ` aldyh at gcc dot gnu.org
2021-10-20  9:50 ` rguenth at gcc dot gnu.org
2021-10-20  9:50 ` rguenth at gcc dot gnu.org
2021-10-20 10:56 ` marxin at gcc dot gnu.org
2021-10-20 12:49 ` amacleod at redhat dot com [this message]
2021-10-20 16:13 ` [Bug tree-optimization/102844] [9/10/11/12 Regression] DOM jump threading not copying block that became non-empty law at gcc dot gnu.org
2021-10-21  6:02 ` rguenth at gcc dot gnu.org
2022-05-20  8:24 ` [Bug tree-optimization/102844] [9/10/11/12/13 " rguenth at gcc dot gnu.org
2022-05-20 12:01 ` aldyh at gcc dot gnu.org
2022-05-20 15:11 ` law at gcc dot gnu.org
2022-05-20 15:33 ` aldyh at gcc dot gnu.org
2022-05-27  9:46 ` [Bug tree-optimization/102844] [10/11/12/13 " rguenth at gcc dot gnu.org
2022-06-28 10:46 ` jakub at gcc dot gnu.org
2023-01-19 13:26 ` rguenth at gcc dot gnu.org
2023-07-07 10:41 ` [Bug tree-optimization/102844] [11/12/13/14 " rguenth at gcc dot gnu.org
2023-09-19 11:24 ` rguenth at gcc dot gnu.org
2023-09-19 11:25 ` [Bug tree-optimization/102844] [11/12/13 " rguenth at gcc dot gnu.org

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