[Bug libstdc++/33485] New: parallel v3: do not use __builtin_alloca, use VLA

[Bug libstdc++/33485] New: parallel v3: do not use __builtin_alloca, use VLA

[bangerth at dealii dot org]

find_template in parallel/find.h used to use a VLA, but Benjamin changed this
to use __builtin_alloca a couple of days ago because VLAs are not in C++98
and therefore trigger a warning.

He says the right thing to do is to use a VLA but make sure that the file
is recognized as a system header so that the warning is suppressed. This PR
is meant to remind him of changing things back to the VLA once he figures 
out how to flag a header as a system header :-)


-- 
           Summary: parallel v3: do not use __builtin_alloca, use VLA
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bangerth at dealii dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2007-09-19 02:37 -------
shouldn't using __extension__ fix the warning/error for VLAs?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bangerth at math dot tamu dot edu]

------- Comment #2 from bangerth at math dot tamu dot edu  2007-09-19 02:43 -------
Subject: Re:  parallel v3: do not use __builtin_alloca,
 use VLA


> shouldn't using __extension__ fix the warning/error for VLAs?

Yes, that's the other option. I guess Benjamin also wanted to find out for
good how to do this right :-)

-------------------------------------------------------------------------
Wolfgang Bangerth                email:            bangerth@math.tamu.edu
                                 www: http://www.math.tamu.edu/~bangerth/


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bkoz at gcc dot gnu dot org]

------- Comment #3 from bkoz at gcc dot gnu dot org  2007-09-19 17:05 -------

Awesome: thanks for doing these PR's Wolfgang.

Andrew, you mean the attribute?

It's my preference to use #pagma GCC system header for this. It does the least
amount of molestation. 

However, it doesn't currently work. But, I cannot get a good reproducer for
this so I can enter a c++ bug. I thought it was just adding -pedantic-errors in
one of these files but there's more going on. 


-- 

bkoz at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bkoz at redhat dot com
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-09-19 17:05:15
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2007-09-19 17:08 -------
(In reply to comment #3)
> Awesome: thanks for doing these PR's Wolfgang.
> 
> Andrew, you mean the attribute?
No.
I mean something like:

int f(int n)
{
  __extension__ int h[n];
  h[n-1] = 0;
  return h[n-1];
}

Which gets of the pedwarn also.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2007-09-26 19:06 -------
Hmm, __extension__ is lost with templates, see PR 21385.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |21385


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bkoz at gcc dot gnu dot org]

------- Comment #6 from bkoz at gcc dot gnu dot org  2007-09-26 20:43 -------

the real question for me is why #pragma GCC system header doesn't work.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bangerth at dealii dot org]

------- Comment #7 from bangerth at dealii dot org  2007-10-08 14:56 -------
I've just found a number of other places where currently a VLA
is used and we consequently get a warning with current sources if
using the right flags. These are:

quicksort.h:68
multiway_mergesort.h:142

Benjamin, as a stopgap would you mind using __builtin_alloca in these
places as well?

Thanks
  Wolfgang


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

Re: [Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[Andrew Pinski]

On 8 Oct 2007 14:56:18 -0000, bangerth at dealii dot org
<gcc-bugzilla@gcc.gnu.org> wrote:
> quicksort.h:68
> multiway_mergesort.h:142
>
> Benjamin, as a stopgap would you mind using __builtin_alloca in these
> places as well?

Why not use __extension__ in those places?

-- Pinski

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[pinskia at gmail dot com]

------- Comment #8 from pinskia at gmail dot com  2007-10-08 16:34 -------
Subject: Re:  parallel v3: do not use __builtin_alloca, use VLA

On 8 Oct 2007 14:56:18 -0000, bangerth at dealii dot org
<gcc-bugzilla@gcc.gnu.org> wrote:
> quicksort.h:68
> multiway_mergesort.h:142
>
> Benjamin, as a stopgap would you mind using __builtin_alloca in these
> places as well?

Why not use __extension__ in those places?

-- Pinski


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bkoz at gcc dot gnu dot org]

------- Comment #9 from bkoz at gcc dot gnu dot org  2007-10-08 18:11 -------

I'd rather do all these the same way. 

Wolfgang, do you have a patch?

-benjamin


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bangerth at dealii dot org]

------- Comment #10 from bangerth at dealii dot org  2007-10-08 19:15 -------
Created an attachment (id=14323)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=14323&action=view)
diffs to multiway_mergesort.h and quicksort.h

The attached diffs appear to do it for me.
W.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bkoz at gcc dot gnu dot org]

------- Comment #11 from bkoz at gcc dot gnu dot org  2007-10-08 19:55 -------

Wolfgang this is ok to check in.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bangerth at dealii dot org]

------- Comment #12 from bangerth at dealii dot org  2007-10-08 22:25 -------
I'm sorry, but I don't have a writable account any more. Can you do the
checkin for me?

Thanks
 W.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bkoz at gcc dot gnu dot org]

------- Comment #13 from bkoz at gcc dot gnu dot org  2007-10-09 21:51 -------
Subject: Bug 33485

Author: bkoz
Date: Tue Oct  9 21:51:06 2007
New Revision: 129182

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=129182
Log:
2007-10-09  Wolfgang Bangerth  <bangerth@dealii.org>

        PR libstdc++/33485 continued.
        * include/parallel/multiway_mergesort.h: Use __builtin_alloca.


Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/parallel/multiway_mergesort.h


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bkoz at gcc dot gnu dot org]

------- Comment #14 from bkoz at gcc dot gnu dot org  2009-01-13 08:42 -------
Created an attachment (id=17082)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17082&action=view)
patch for hppa check-abi fail


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[bkoz at gcc dot gnu dot org]

------- Comment #15 from bkoz at gcc dot gnu dot org  2009-01-13 10:06 -------
(From update of attachment 17082)
mistaken, part of 32666


-- 

bkoz at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #17082|1                           |0
           is patch|                            |
  Attachment #17082|0                           |1
        is obsolete|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[paolo dot carlini at oracle dot com]

------- Comment #16 from paolo dot carlini at oracle dot com  2010-02-08 11:19 -------
Can we review this issue? Two comments: 1- Now I can see only dynamic memory
allocations via new / delete everywhere, thus, no __builtin_alloca; 2- *If* one
really wanted to use VLAs, now it should be possible, because we are much
better at honoring the system header pragma. Thus, either way, I suspect this
PR could be resolved rather quickly or even immediately...


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |singler at kit dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: do not use __builtin_alloca, use VLA

[singler at kit dot edu]

------- Comment #17 from singler at kit dot edu  2010-02-09 10:49 -------
The actual problem has vanished, but maybe it would still be nice to use VLA in
the appropriate places.

We can close the bug as fixed/invalid, or reprioritize it as enhancement and
leave it open.  Both is fine with me.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485

[Bug libstdc++/33485] parallel v3: use VLAs in some places

[paolo dot carlini at oracle dot com]

------- Comment #18 from paolo dot carlini at oracle dot com  2010-02-09 11:14 -------
Ok, I changed Summary and Severity. Somebody should also double check whether
VLAs are still triggering warnings or not.


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
            Summary|parallel v3: do not use     |parallel v3: use VLAs in
                   |__builtin_alloca, use VLA   |some places


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33485