[Bug rtl-optimization/37516] New: ~(-2 - a) is not being optimized into a + 1

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* [Bug rtl-optimization/37516]  New: ~(-2 - a) is not being optimized into a + 1
@ 2008-09-14  3:37 pinskia at gcc dot gnu dot org
  2008-09-14  3:37 ` [Bug rtl-optimization/37516] " pinskia at gcc dot gnu dot org
  2008-09-14  4:57 ` pinskia at gcc dot gnu dot org
  0 siblings, 2 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2008-09-14  3:37 UTC (permalink / raw)
  To: gcc-bugs

I noticed this when looking into PR 34087 with connection of a patch I wrote
for loop-doloop.c which is supposed to reduce the number of instructions.
Anyways the following two functions are equivalent but are not optimized that
way:
int f(int a)
{
  a = -2 - a;
  return -(a+1);
}

int f1(int a)
{
  return a + 1;
}


-- 
           Summary: ~(-2 - a) is not being optimized into a + 1
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [Bug rtl-optimization/37516] ~(-2 - a) is not being optimized into a + 1
  2008-09-14  3:37 [Bug rtl-optimization/37516] New: ~(-2 - a) is not being optimized into a + 1 pinskia at gcc dot gnu dot org
@ 2008-09-14  3:37 ` pinskia at gcc dot gnu dot org
  2008-09-14  4:57 ` pinskia at gcc dot gnu dot org
  1 sibling, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2008-09-14  3:37 UTC (permalink / raw)
  To: gcc-bugs



-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [Bug rtl-optimization/37516] ~(-2 - a) is not being optimized into a + 1
  2008-09-14  3:37 [Bug rtl-optimization/37516] New: ~(-2 - a) is not being optimized into a + 1 pinskia at gcc dot gnu dot org
  2008-09-14  3:37 ` [Bug rtl-optimization/37516] " pinskia at gcc dot gnu dot org
@ 2008-09-14  4:57 ` pinskia at gcc dot gnu dot org
  1 sibling, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2008-09-14  4:57 UTC (permalink / raw)
  To: gcc-bugs



------- Comment #1 from pinskia at gcc dot gnu dot org  2008-09-14 04:56 -------
That is I found this with the patch for PR 37451 included but this does not
need that patch to show the issue really.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516


^ permalink raw reply	[flat|nested] 9+ messages in thread

[parent not found: <bug-37516-4@http.gcc.gnu.org/bugzilla/>]

* [Bug rtl-optimization/37516] ~(-2 - a) is not being optimized into a + 1
       [not found] <bug-37516-4@http.gcc.gnu.org/bugzilla/>
@ 2012-02-23  8:48 ` pinskia at gcc dot gnu.org
  2012-02-23  9:17 ` rguenther at suse dot de
                   ` (4 subsequent siblings)
  5 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu.org @ 2012-02-23  8:48 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-02-23
         AssignedTo|unassigned at gcc dot       |pinskia at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-23 08:42:01 UTC ---
I have an idea on how to fix this.
basically:
~(C - X)
is the same as:
~ - (X - C)
which then can be simplified to
X - (C+1)

This should be done on both the tree level (on the pinskia/treecombine branch
in tree-ssa-fold.c) and the rtl level in simplify-rtx.c.


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [Bug rtl-optimization/37516] ~(-2 - a) is not being optimized into a + 1
       [not found] <bug-37516-4@http.gcc.gnu.org/bugzilla/>
  2012-02-23  8:48 ` pinskia at gcc dot gnu.org
@ 2012-02-23  9:17 ` rguenther at suse dot de
  2012-02-23 22:16 ` pinskia at gcc dot gnu.org
                   ` (3 subsequent siblings)
  5 siblings, 0 replies; 9+ messages in thread
From: rguenther at suse dot de @ 2012-02-23  9:17 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516

--- Comment #3 from rguenther at suse dot de <rguenther at suse dot de> 2012-02-23 08:47:55 UTC ---
On Thu, 23 Feb 2012, pinskia at gcc dot gnu.org wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516
> 
> Andrew Pinski <pinskia at gcc dot gnu.org> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>              Status|UNCONFIRMED                 |ASSIGNED
>    Last reconfirmed|                            |2012-02-23
>          AssignedTo|unassigned at gcc dot       |pinskia at gcc dot gnu.org
>                    |gnu.org                     |
>      Ever Confirmed|0                           |1
> 
> --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-23 08:42:01 UTC ---
> I have an idea on how to fix this.
> basically:
> ~(C - X)
> is the same as:
> ~ - (X - C)
> which then can be simplified to
> X - (C+1)
> 
> This should be done on both the tree level (on the pinskia/treecombine branch
> in tree-ssa-fold.c) and the rtl level in simplify-rtx.c.

Maybe get away with these old-stylish names ('tree' and 'fold') and
make it match reality, gimple-ssa-combine.c ;)

Still have to have a look at your branch - do you have a brief
overview documentation, for example on the wiki?  What I'd like
to do is have an interface that I can re-use for VN combining,
basically replace its simplify_*_expression functions.

Richard.


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [Bug rtl-optimization/37516] ~(-2 - a) is not being optimized into a + 1
       [not found] <bug-37516-4@http.gcc.gnu.org/bugzilla/>
  2012-02-23  8:48 ` pinskia at gcc dot gnu.org
  2012-02-23  9:17 ` rguenther at suse dot de
@ 2012-02-23 22:16 ` pinskia at gcc dot gnu.org
  2012-02-24  9:03 ` rguenther at suse dot de
                   ` (2 subsequent siblings)
  5 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu.org @ 2012-02-23 22:16 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-23 22:15:05 UTC ---

> Maybe get away with these old-stylish names ('tree' and 'fold') and
> make it match reality, gimple-ssa-combine.c ;)

That sounds like a good idea.  I have done that.

> 
> Still have to have a look at your branch - do you have a brief
> overview documentation, for example on the wiki?  What I'd like
> to do is have an interface that I can re-use for VN combining,
> basically replace its simplify_*_expression functions.

I don't have one yet.  But I hope to create one this weekend.

Right now replacing the VN combining with this new functionality will not work
as it scans the defs itself.  Though I am moving all the def scanning to its
own function which should allow for the code to be more modular and allow for
the VN combining to work with it.


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [Bug rtl-optimization/37516] ~(-2 - a) is not being optimized into a + 1
       [not found] <bug-37516-4@http.gcc.gnu.org/bugzilla/>
                   ` (2 preceding siblings ...)
  2012-02-23 22:16 ` pinskia at gcc dot gnu.org
@ 2012-02-24  9:03 ` rguenther at suse dot de
  2012-02-26  1:43 ` pinskia at gcc dot gnu.org
  2021-08-03 23:03 ` pinskia at gcc dot gnu.org
  5 siblings, 0 replies; 9+ messages in thread
From: rguenther at suse dot de @ 2012-02-24  9:03 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516

--- Comment #5 from rguenther at suse dot de <rguenther at suse dot de> 2012-02-24 08:38:19 UTC ---
On Thu, 23 Feb 2012, pinskia at gcc dot gnu.org wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516
> 
> --- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-23 22:15:05 UTC ---
> 
> > Maybe get away with these old-stylish names ('tree' and 'fold') and
> > make it match reality, gimple-ssa-combine.c ;)
> 
> That sounds like a good idea.  I have done that.
> 
> > 
> > Still have to have a look at your branch - do you have a brief
> > overview documentation, for example on the wiki?  What I'd like
> > to do is have an interface that I can re-use for VN combining,
> > basically replace its simplify_*_expression functions.
> 
> I don't have one yet.  But I hope to create one this weekend.
> 
> Right now replacing the VN combining with this new functionality will not work
> as it scans the defs itself.  Though I am moving all the def scanning to its
> own function which should allow for the code to be more modular and allow for
> the VN combining to work with it.

I think def scanning is ok, but all SSA names should be "valueized" via
a hook first.

Richard.


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [Bug rtl-optimization/37516] ~(-2 - a) is not being optimized into a + 1
       [not found] <bug-37516-4@http.gcc.gnu.org/bugzilla/>
                   ` (3 preceding siblings ...)
  2012-02-24  9:03 ` rguenther at suse dot de
@ 2012-02-26  1:43 ` pinskia at gcc dot gnu.org
  2021-08-03 23:03 ` pinskia at gcc dot gnu.org
  5 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu.org @ 2012-02-26  1:43 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-26 00:49:54 UTC ---
(In reply to comment #5)
> I think def scanning is ok, but all SSA names should be "valueized" via
> a hook first.

I wrote up something quickly (but I want to improve it some more and a little
more formal):
http://gcc.gnu.org/wiki/SSACombine

I am thinking about removing the _loc part of the name of the functions since
there is no function which does not take a location_t.


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [Bug rtl-optimization/37516] ~(-2 - a) is not being optimized into a + 1
       [not found] <bug-37516-4@http.gcc.gnu.org/bugzilla/>
                   ` (4 preceding siblings ...)
  2012-02-26  1:43 ` pinskia at gcc dot gnu.org
@ 2021-08-03 23:03 ` pinskia at gcc dot gnu.org
  5 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-03 23:03 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.0
         Resolution|---                         |DUPLICATE
             Status|ASSIGNED                    |RESOLVED

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed with r11-5958.

*** This bug has been marked as a duplicate of bug 96685 ***

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2021-08-03 23:03 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2008-09-14  3:37 [Bug rtl-optimization/37516] New: ~(-2 - a) is not being optimized into a + 1 pinskia at gcc dot gnu dot org
2008-09-14  3:37 ` [Bug rtl-optimization/37516] " pinskia at gcc dot gnu dot org
2008-09-14  4:57 ` pinskia at gcc dot gnu dot org
     [not found] <bug-37516-4@http.gcc.gnu.org/bugzilla/>
2012-02-23  8:48 ` pinskia at gcc dot gnu.org
2012-02-23  9:17 ` rguenther at suse dot de
2012-02-23 22:16 ` pinskia at gcc dot gnu.org
2012-02-24  9:03 ` rguenther at suse dot de
2012-02-26  1:43 ` pinskia at gcc dot gnu.org
2021-08-03 23:03 ` pinskia at gcc dot gnu.org

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