[Bug tree-optimization/23115] New: -ftree-vectorize generates wrong code

[Bug tree-optimization/23115] New: -ftree-vectorize generates wrong code

[p dot van-hoof at qub dot ac dot uk]

The vectorizer generates wrong code for the attached example

dogbert> gcc o.c
dogbert> a.out
 this is where I should be (R = 1.0e+00)...
dogbert> gcc -O1 -ftree-vectorize o.c
dogbert> a.out
 I should not be here (R = -1.0e+300)...
dogbert> gcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/usr/local/gcc410
--enable-languages=c,c++,f95
Thread model: posix
gcc version 4.1.0 20050725 (experimental)

This behavior shows up on the mainline, but not the 4.0 branch. I could
reproduce the problem on i686-pc-linux-gnu, x86_64-unknown-linux-gnu, and
sparc-sun-solaris2.9, so doesn't seem to be target specific.

-- 
           Summary: -ftree-vectorize generates wrong code
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: p dot van-hoof at qub dot ac dot uk
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23115

[Bug tree-optimization/23115] -ftree-vectorize generates wrong code

[p dot van-hoof at qub dot ac dot uk]

------- Additional Comments From p dot van-hoof at qub dot ac dot uk  2005-07-28 18:40 -------
Created an attachment (id=9380)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=9380&action=view)
code that triggers the bug


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23115

[Bug tree-optimization/23115] [4.1 Regression] -ftree-vectorize generates wrong code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-28 18:51 -------
This is caused by tree if conversion.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |wrong-code
   Last reconfirmed|0000-00-00 00:00:00         |2005-07-28 18:51:44
               date|                            |
            Summary|-ftree-vectorize generates  |[4.1 Regression] -ftree-
                   |wrong code                  |vectorize generates wrong
                   |                            |code
   Target Milestone|---                         |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23115

[Bug tree-optimization/23115] [4.1 Regression] -ftree-vectorize generates wrong code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-08 20:03 -------
Before:
  if (x_16 < x_26) goto <L3>; else goto <L14>;

<L14>:;

  # x_4 = PHI <x_26(1), x_16(2)>;
<L3>:;
  if (x_16 > n_17) goto <L6>; else goto <L15>;

<L15>:;

  # n_5 = PHI <n_17(3), x_16(4)>;
<L6>:;

After:
  x_4 = x_16 < x_26 ? x_26 : x_16;
  n_5 = 1 ? n_17 : x_16;

That 1 is just wrong.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23115

[Bug tree-optimization/23115] [4.1 Regression] -ftree-vectorize generates wrong code

[janis at gcc dot gnu dot org]

------- Additional Comments From janis at gcc dot gnu dot org  2005-09-09 22:18 -------
A regression hunt of mainline on powerpc-linux shows that the test starts
failing with a merge from tree-cleanup-branch on 20050409.  The test passes,
however, with a compiler built after the final patch was added to that branch
on 20050401; looks like it could be a merge problem.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dnovillo at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23115

[Bug tree-optimization/23115] [4.1 Regression] -ftree-vectorize generates wrong code

[dpatel at apple dot com]

------- Additional Comments From dpatel at apple dot com  2005-09-30 23:52 -------
Assign this bug to me. Thanks.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23115

[Bug tree-optimization/23115] [4.1 Regression] -ftree-vectorize generates wrong code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-30 23:54 -------
(In reply to comment #5)
> Assign this bug to me. Thanks.
Done, you also now have the premissions to do that yourself.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |dpatel at apple dot com
                   |dot org                     |
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23115