[Bug middle-end/38880] New: [4.4 Regression] g++.dg/init/const7.C XFAILed

[Bug middle-end/38880] New: [4.4 Regression] g++.dg/init/const7.C XFAILed

[rguenth at gcc dot gnu dot org]

We do not fold

    (long int) &16B->y - 16


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           Summary: [4.4 Regression] g++.dg/init/const7.C XFAILed
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: xfail
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug middle-end/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2009-01-16 19:23 -------
Caused by the fix for PR36227.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-01-16 19:23:08
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug middle-end/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[rguenth at gcc dot gnu dot org]

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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug middle-end/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2009-01-16 20:37 -------
  ((char*) &(((struct s*)16)->y) - (char *)16),

That is not a valid constant expression in C++ ....


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2009-01-16 20:41 -------
http://gcc.gnu.org/ml/gcc-patches/2008-09/msg00448.html


http://gcc.gnu.org/ml/gcc-patches/2008-09/msg00581.html

Hmm, I think the front-end should be doing the trick of &16B->y into 16B + 4
just like the C front-end except in strict C++ mode.


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|middle-end                  |c++


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[jason at gcc dot gnu dot org]

-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jason at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2009-01-16 19:23:08         |2009-01-26 19:10:35
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2009-01-27 16:33 -------
Created an attachment (id=17193)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17193&action=view)
example patch

I just found this, I tried to fix this in fold but in the end agreed with
Andrew
that the C++ FE should do what the C FE does here.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[jason at redhat dot com]

------- Comment #5 from jason at redhat dot com  2009-01-27 23:25 -------
Subject: Re:  [4.4 Regression] g++.dg/init/const7.C XFAILed

rguenth at gcc dot gnu dot org wrote:
> I just found this, I tried to fix this in fold but in the end agreed with
> Andrew that the C++ FE should do what the C FE does here.

Why do it in the FE?  This seems like a language-independent optimization.

Jason


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[rguenther at suse dot de]

------- Comment #6 from rguenther at suse dot de  2009-01-28 10:39 -------
Subject: Re:  [4.4 Regression] g++.dg/init/const7.C XFAILed

On Tue, 27 Jan 2009, jason at redhat dot com wrote:

> ------- Comment #5 from jason at redhat dot com  2009-01-27 23:25 -------
> Subject: Re:  [4.4 Regression] g++.dg/init/const7.C XFAILed
> 
> rguenth at gcc dot gnu dot org wrote:
> > I just found this, I tried to fix this in fold but in the end agreed with
> > Andrew that the C++ FE should do what the C FE does here.
> 
> Why do it in the FE?  This seems like a language-independent optimization.

Do it in the FE if the FE wants it to be optimized to a constant.
Otherwise sure - it is a language-independent optimization.  But fold
isn't a proper optimizer ;)

Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[jason at redhat dot com]

------- Comment #7 from jason at redhat dot com  2009-01-28 16:29 -------
Subject: Re:  [4.4 Regression] g++.dg/init/const7.C XFAILed

rguenther at suse dot de wrote:
>> Why do it in the FE?  This seems like a language-independent optimization.
> 
> Do it in the FE if the FE wants it to be optimized to a constant.
> Otherwise sure - it is a language-independent optimization.  But fold
> isn't a proper optimizer ;)

I don't understand the distinction you're making; it seems to me that 
reducing expressions to simpler forms that are more easily optimized is 
exactly what fold is for.  I don't see the difference between this and, 
say, reducing "1 + 2" to "3".

The FE doesn't especially want this to be a constant; it isn't a valid 
constant expression in C++, because it involves a subtraction of two 
pointers.

Jason


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[rguenther at suse dot de]

------- Comment #8 from rguenther at suse dot de  2009-01-28 19:44 -------
Subject: Re:  [4.4 Regression] g++.dg/init/const7.C XFAILed

On Wed, 28 Jan 2009, jason at redhat dot com wrote:

> Subject: Re:  [4.4 Regression] g++.dg/init/const7.C XFAILed
> 
> rguenther at suse dot de wrote:
> >> Why do it in the FE?  This seems like a language-independent optimization.
> > 
> > Do it in the FE if the FE wants it to be optimized to a constant.
> > Otherwise sure - it is a language-independent optimization.  But fold
> > isn't a proper optimizer ;)
> 
> I don't understand the distinction you're making; it seems to me that 
> reducing expressions to simpler forms that are more easily optimized is 
> exactly what fold is for.  I don't see the difference between this and, 
> say, reducing "1 + 2" to "3".
> 
> The FE doesn't especially want this to be a constant; it isn't a valid 
> constant expression in C++, because it involves a subtraction of two 
> pointers.

I'll bootstrap / test my fold patch.

Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[jason at gcc dot gnu dot org]

------- Comment #9 from jason at gcc dot gnu dot org  2009-02-20 05:34 -------
New patch at http://gcc.gnu.org/ml/gcc-patches/2009-01/msg01309.html


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[jason at gcc dot gnu dot org]

------- Comment #10 from jason at gcc dot gnu dot org  2009-02-20 05:35 -------
Er, not that one, this one:
http://gcc.gnu.org/ml/gcc-patches/2009-02/msg00882.html


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[jason at gcc dot gnu dot org]

------- Comment #11 from jason at gcc dot gnu dot org  2009-02-23 21:24 -------
Subject: Bug 38880

Author: jason
Date: Mon Feb 23 21:23:58 2009
New Revision: 144395

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=144395
Log:
        PR c++/38880
        * varasm.c (initializer_constant_valid_p) [PLUS_EXPR]: Check
        narrowing_initializer_constant_valid_p.
        (narrowing_initializer_constant_valid_p): Don't return
        null_pointer_node for adding a pointer to itself.

Added:
    trunk/gcc/testsuite/g++.dg/init/static-init1.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/init/const7.C
    trunk/gcc/varasm.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880

[Bug c++/38880] [4.4 Regression] g++.dg/init/const7.C XFAILed

[jason at gcc dot gnu dot org]

------- Comment #12 from jason at gcc dot gnu dot org  2009-02-24 05:14 -------
Fixed.


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jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38880