[Bug c/34216] New: [4.2 regression] Optimizations cause audio distortion in GSM decompression

[Bug c/34216] New: [4.2 regression] Optimizations cause audio distortion in GSM decompression

[gcc-gnu-org at the-tilghman dot com]

We've found a serious audio distortion with the standard GSM 6.10 library, when
optimizations are turned on in gcc 4.2.  No such problem exists in gcc 4.1. 
Sorry I can't be more specific as to where the problem lies.

Asterisk bugtracker: http://bugs.digium.com/view.php?id=11243


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           Summary: [4.2 regression] Optimizations cause audio distortion in
                    GSM decompression
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: gcc-gnu-org at the-tilghman dot com
 GCC build triplet: i486-linux-gnu
  GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34216

[Bug c/34216] [4.2 regression] Optimizations cause audio distortion in GSM decompression

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2007-11-24 17:58 -------
This is obviously not very useful information.  You have to track this down
further.  The usual process is

 1) Build individual source files without optimization until you figure out
    which file triggers the failure.

 2) Play with GCC options, does -O1 work?  Does -O2
{-fno-tree-vrp,-fno-tree-pre}
    work? etc.

 3) Narrow down the routine that makes the difference

 4) Figure out if it's really a GCC problem.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34216

[Bug middle-end/34216] [4.2 regression] Optimizations cause audio distortion in GSM decompression

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2008-01-25 20:27 -------
No feedback from the reporter after two month.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34216

[Bug middle-end/34216] [4.2 regression] Optimizations cause audio distortion in GSM decompression

[gcc-gnu-org at the-tilghman dot com]

------- Comment #3 from gcc-gnu-org at the-tilghman dot com  2008-01-25 21:00 -------
Sorry, we're tracking this in our own bugtracker, as it's been reported against
our open source product.  The reporter on that bugtracker (the original
reporter of this issue) has verified that the optimization between -O2 and -O3
seems to cause this and is looking at which particular optimization causes the
issue.


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gcc-gnu-org at the-tilghman dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34216

[Bug middle-end/34216] [4.2 regression] Optimizations cause audio distortion in GSM decompression

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2008-01-25 22:16 -------
Plus the answers to Richard's questions are useful.

Also does -O3 -fno-strict-alising work?  Does -O3 -fwrapv work?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34216

[Bug middle-end/34216] [4.2 regression] Optimizations cause audio distortion in GSM decompression

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2008-01-25 22:15 -------
We still need a testcase and not just saying the audio output is incorrect.


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34216

[Bug middle-end/34216] [4.2 regression] Optimizations cause audio distortion in GSM decompression

[rguenth at gcc dot gnu dot org]

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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.2.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34216

[Bug middle-end/34216] [4.2 regression] Optimizations cause audio distortion in GSM decompression

[jsm28 at gcc dot gnu dot org]

------- Comment #6 from jsm28 at gcc dot gnu dot org  2008-05-19 20:23 -------
4.2.4 is being released, changing milestones to 4.2.5.


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jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.2.4                       |4.2.5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34216

[Bug middle-end/34216] [4.2 regression] Optimizations cause audio distortion in GSM decompression

[gcc-gnu-org at the-tilghman dot com]

------- Comment #7 from gcc-gnu-org at the-tilghman dot com  2008-07-30 18:38 -------
Fixed by adding noclobber to the assembly of the code in question.


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gcc-gnu-org at the-tilghman dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34216