[Bug tree-optimization/34123] New: [4.3 Regression] verify_ssa failed (definition in block 11 does not dominate use in block 7)

[Bug tree-optimization/34123] New: [4.3 Regression] verify_ssa failed (definition in block 11 does not dominate use in block 7)

[tbm at cyrius dot com]

With current trunk:

(sid)tbm@coconut0:~$ /usr/lib/gcc-snapshot/bin/gcc -c -O -ftree-loop-linear
md2.c
md2.c: In function 'MD2Transform':
md2.c:6: error: definition in block 11 does not dominate use in block 7
for SSA_NAME: t_20 in statement:
t_10 = PHI <t_20(7), 0(2)>
PHI argument
t_20
for PHI node
t_10 = PHI <t_20(7), 0(2)>
md2.c:6: internal compiler error: verify_ssa failed
Please submit a full bug report,

I originally thought this was the same as PR31037 and didn't file a PR
but the other testcases work now while this one still fails.


-- 
           Summary: [4.3 Regression] verify_ssa failed (definition in block
                    11 does not dominate use in block 7)
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tbm at cyrius dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed (definition in block 11 does not dominate use in block 7)

[tbm at cyrius dot com]

------- Comment #1 from tbm at cyrius dot com  2007-11-16 19:08 -------
/* Testcase by Martin Michlmayr <tbm@cyrius.com> */

static unsigned char sbox[] = {
};
void MD2Transform (unsigned char state[16])
{
  unsigned char t = 0;
  int i, j;
  for (i = 0; i < 16; i++)
    {
      for (j = 0; j < 2; j++)
        t = (state[j] ^= sbox[t]);
      t += i;
    }
}


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed (definition in block 11 does not dominate use in block 7)

[tbm at cyrius dot com]

------- Comment #2 from tbm at cyrius dot com  2007-11-16 19:14 -------
This was introduced between 20070422 and 20070515.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed (definition in block 11 does not dominate use in block 7)

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2007-11-17 12:37 -------
Confirmed.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |spop at gcc dot gnu dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-11-17 12:37:41
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed with -ftree-loop-linear

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
            Summary|[4.3 Regression] verify_ssa |[4.3 Regression] verify_ssa
                   |failed (definition in block |failed with -ftree-loop-
                   |11 does not dominate use in |linear
                   |block 7)                    |
   Target Milestone|---                         |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed with -ftree-loop-linear

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2007-11-20 10:59 -------
The testcase is wrong, static unsigned char sbox[] = {}; means zero sized
array.
But using sbox[256] makes the testcase valid and the problem is still there.
This looks like a bug in can_convert_to_perfect_nest, this loop (at least
unless
earlier passes don't realize that sbox[i] == 0 for any i) can't be converted
into a perfect nest.
The basic block which is after the inner loop is:

<bb 5>:
# t_30 = PHI <t_16(4)>
D.1558_19 = (unsigned char) i_39;
t_20 = t_30 + D.1558_19;
i_21 = i_39 + 1;
if (i_21 <= 15)
  goto <bb 6>;
else
  goto <bb 8>;

<bb 6>:

<bb 7>:
# i_39 = PHI <0(2), i_21(6)>
# SMT.4_10 = PHI <SMT.4_26(D)(2), SMT.4_28(6)>
# t_29 = PHI <0(2), t_20(6)>
goto <bb 4>;

can_convert_to_perfect_nest walks the statements of these bbs and is satisfied
with all of them, the first two stmts in bb5 are satisfied by:

2234                          tree step = evolution_part_in_loop_num (scev,
loop->num);
2235                          if (step && step != chrec_dont_know 
2236                              && TREE_CODE (step) == INTEGER_CST)
2237                            continue;

- step is for both integer_one_node, the third stmt is of course correctly a
stmt_is_bumper_for_loop and the last one is exit_condition.  But nothing scans
the PHIs which are relevant here.  # t_30 = PHI <t_16(4)> in bb5 sets t_30 to
t_16, which is computed by inner loop.  And # t_29 = PHI <0(2), t_20(6)>
in bb7 sets t_29 used in the inner loop to t_20 set in bb5 (i.e. in the bb
which prevents perfect nest).  Should the PHIs be walked similarly to how
stmts are walked?


-- 

jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed with -ftree-loop-linear

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed with -ftree-loop-linear

[spop at gcc dot gnu dot org]

------- Comment #5 from spop at gcc dot gnu dot org  2007-12-15 20:37 -------
Subject: Re:  [4.3 Regression] verify_ssa failed with -ftree-loop-linear

I have a fix for this one, cleaning up the complex logic in
can_convert_to_perfect_nest.

Sebastian


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed with -ftree-loop-linear

[spop at gcc dot gnu dot org]

------- Comment #6 from spop at gcc dot gnu dot org  2007-12-17 19:15 -------
Subject: Re:  [4.3 Regression] verify_ssa failed with -ftree-loop-linear

Patch is here:
http://gcc.gnu.org/ml/gcc-patches/2007-12/msg00735.html
test result on amd64-linux is here:
http://gcc.gnu.org/ml/gcc-patches/2007-12/msg00752.html
waiting for approval.

Sebastian


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed with -ftree-loop-linear

[spop at gcc dot gnu dot org]

------- Comment #7 from spop at gcc dot gnu dot org  2007-12-18 19:40 -------
Subject: Bug 34123

Author: spop
Date: Tue Dec 18 19:40:35 2007
New Revision: 131040

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=131040
Log:
2007-12-18  Sebastian Pop  <sebastian.pop@amd.com>

        PR tree-optimization/34123
        * lambda-code.c (can_duplicate_iv): New.
        (cannot_convert_modify_to_perfect_nest): New.
        (cannot_convert_bb_to_perfect_nest): New.
        (can_convert_to_perfect_nest): Split up.

        * gcc.dg/tree-ssa/pr34123.c: New test.


Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/pr34123.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/lambda-code.c
    trunk/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123

[Bug tree-optimization/34123] [4.3 Regression] verify_ssa failed with -ftree-loop-linear

[spop at gcc dot gnu dot org]

------- Comment #8 from spop at gcc dot gnu dot org  2007-12-18 19:42 -------
Fixed.


-- 

spop at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34123