[Bug c/38774] New: ice in df_refs_verify, at df-scan.c:4307

[Bug c/38774] New: ice in df_refs_verify, at df-scan.c:4307

[regehr at cs dot utah dot edu]

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This is seen using r143187 on Ubuntu Hardy on x86.

PR 32431 reports a similar failure but at a different line number, and for the
68HC11 target.

regehr@john-home:~/volatile/tmp117$ current-gcc -c -O2 -march=i686 small.c
small.c: In function ‘foo’:
small.c:17: internal compiler error: in df_refs_verify, at df-scan.c:4307
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

regehr@john-home:~/volatile/tmp117$ cat small.c

int safe_add_func_int64_t_s_s (int _si1, int _si2)
{
  return 1 > 9223372036854775807LL - _si2 && 1 - _si2 ? : 1 + _si2;
}

volatile int g_55;

void func_42 (int p_43, int p_44, int p_46, int p_47)
{
  p_44 & 1 && g_55, !1;
}

void foo (int p_38)
{
  int l_84 = 0;
  func_42 (1, safe_add_func_int64_t_s_s (p_38, 1 >= safe (1)), l_84, 1);
}

regehr@john-home:~/volatile/tmp117$ current-gcc -v

Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../configure --program-prefix=current-
--enable-languages=c,c++ --prefix=/home/regehr : (reconfigured) ../configure
--program-prefix=current- --enable-languages=c,c++ --prefix=/home/regehr :
(reconfigured) ../configure --program-prefix=current- --enable-languages=c,c++
--prefix=/home/regehr : (reconfigured) ../configure --program-prefix=current-
--prefix=/home/regehr --enable-languages=c,c++ --no-create --no-recursion :
(reconfigured) ../configure --program-prefix=current- --prefix=/home/regehr
--enable-languages=c,c++ --no-create --no-recursion : (reconfigured)
../configure --program-prefix=current- --prefix=/home/regehr
--enable-languages=c,c++ --no-create --no-recursion : (reconfigured)
../configure --program-prefix=current- --prefix=/home/regehr
--enable-languages=c,c++ --no-create --no-recursion : (reconfigured)
../configure --program-prefix=current- --prefix=/home/regehr
--enable-languages=c,c++ --no-create --no-recursion
Thread model: posix
gcc version 4.4.0 20090108 (experimental) (GCC)


-- 
           Summary: ice in df_refs_verify, at df-scan.c:4307
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: regehr at cs dot utah dot edu
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774

[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2009-01-09 10:33 -------
Confirmed.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |zadeck at naturalbridge dot
                   |                            |com
             Status|UNCONFIRMED                 |NEW
          Component|c                           |rtl-optimization
     Ever Confirmed|0                           |1
           Keywords|                            |ice-checking, ice-on-valid-
                   |                            |code
           Priority|P3                          |P2
   Last reconfirmed|0000-00-00 00:00:00         |2009-01-09 10:33:26
               date|                            |
            Summary|ice in df_refs_verify, at   |[4.4 Regression] ice in
                   |df-scan.c:4307              |df_refs_verify, at df-
                   |                            |scan.c:4307
   Target Milestone|---                         |4.4.0
            Version|unknown                     |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774

[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307

[zadeck at naturalbridge dot com]

------- Comment #2 from zadeck at naturalbridge dot com  2009-01-09 12:41 -------
i will have my best people work on it.


-- 

zadeck at naturalbridge dot com changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774

[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307

[zadeck at naturalbridge dot com]

------- Comment #3 from zadeck at naturalbridge dot com  2009-01-10 01:57 -------
Created an attachment (id=17068)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17068&action=view)
patch to cause df to verify after every patch

this is a combine bug.  The df verification fails after combine makes some
modification to the cc arg of insn 28 in the foo function that bypasses the
implicit and explicit calls to mark the insn as being changed. 

I am looking into trying to figure out what path thru combine is doing this.  
However, if some combine expert (or just someone who wants to prove that they
have better skill with the debugger than I do) wants to get there first, be my
guest.   I have attached a patch that improves some of the debugging and causes
df to verify after every pass.   This patch causes the failure to move from
being in ira, to the start of if conversion after combine.  



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774

[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2009-01-13 18:07 -------
Simplified testcase:
extern int bar (void);
volatile int g;

int
foo (void)
{
  int a = 1 >= bar ();
  if ((1 > 9223372036854775807LL - a && 1 - a ? : 1 + a) & 1)
    return g;
  return 0;
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774

[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307

[jakub at gcc dot gnu dot org]

------- Comment #5 from jakub at gcc dot gnu dot org  2009-01-13 20:39 -------
The single CC user is modified, then those changes are reverted, but
unfortunately they aren't reverted by putting back the old content, but instead
tweaking the new comparison with PUT_CODE.
          SUBST (*cc_use, gen_rtx_fmt_ee (new_code, GET_MODE (*cc_use),
                                          dest, const0_rtx));   
          other_changed = 1;
...
              if ((recog_for_combine (&pat, other_insn, &note) < 0
                   && ! check_asm_operands (pat)))
                {
                  PUT_CODE (*cc_use, old_code);
                  other_changed = 0;

We should insert put there the old *cc_use rtx.  I'll test a patch.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774

[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307

[jakub at gcc dot gnu dot org]

------- Comment #6 from jakub at gcc dot gnu dot org  2009-01-13 20:57 -------
Created an attachment (id=17094)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17094&action=view)
gcc44-pr38774.patch

Patch I'm going to bootstrap/regtest.  Fixes the testcase on both i686-linux
and x86_64-linux.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|zadeck at naturalbridge dot |jakub at gcc dot gnu dot org
                   |com                         |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774

[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307

[pinskia at gcc dot gnu dot org]

------- Comment #7 from pinskia at gcc dot gnu dot org  2009-01-13 20:59 -------
(In reply to comment #6)
> Created an attachment (id=17094)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17094&action=view) [edit]
> gcc44-pr38774.patch
> 
> Patch I'm going to bootstrap/regtest.  Fixes the testcase on both i686-linux
> and x86_64-linux.

Do you think the testcase could go into gcc.dg/torture/ instead of just gcc.dg
and remove the -O2 part of dg-options ?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774

[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307

[jakub at gcc dot gnu dot org]

------- Comment #8 from jakub at gcc dot gnu dot org  2009-01-13 22:36 -------
Subject: Bug 38774

Author: jakub
Date: Tue Jan 13 22:36:06 2009
New Revision: 143355

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=143355
Log:
        PR rtl-optimization/38774
        * combine.c (simplify_set): When undoing cc_use change, don't do
        PUT_CODE on the newly created comparison, but instead put back the
        old comparison.

        * gcc.dg/torture/pr38774.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr38774.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/combine.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774

[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307

[jakub at gcc dot gnu dot org]

------- Comment #9 from jakub at gcc dot gnu dot org  2009-01-13 22:38 -------
Fixed.


-- 

jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774