[Bug tree-optimization/42873] New: [4.5 Regression] deadlock in var tracking in recent builds

[Bug tree-optimization/42873] New: [4.5 Regression] deadlock in var tracking in recent builds

[zsojka at seznam dot cz]

This can be related to pr41371, but I think it is not duplicate. This one ends
in endless loop, as can be seen from -fdump-rtl-vartrack dumps - there are
about 50 lines periodically repeating.
I thought it's a dup of pr41371, but the compilation (of nonreduced testcase)
didn't finish even after one week.
Reduced testcase compilation finishes "in miliseconds" with -fno-var-tracking,
but takes forever without it. It's not slowly eating memory, so it never
crashes.

Command line:
gcc -O3 -g -fgcse-sm -ftracer testcase.c

Tested revisions (x86_64):
r156217 - fail
r156038 - fail
r155945 - fail (x86)
r155920 - fail
r155917 - fail
r155902 - OK
r155844 - OK (x86)
r155833 - OK
r155363 - OK
r154886 - OK
r153685 - OK
4.4 branch, r155365 - OK

Output (manually terminated):
$ time
/mnt/svn/gcc-trunk/binary-155920-lto/libexec/gcc/x86_64-unknown-linux-gnu/4.5.0/cc1
-v -O3 -g -fgcse-sm -ftracer testcase.c
ignoring nonexistent directory "/usr/local/include"
ignoring nonexistent directory
"/mnt/svn/gcc-trunk/binary-155920-lto/lib/gcc/x86_64-unknown-linux-gnu/4.5.0/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /mnt/svn/gcc-trunk/binary-155920-lto/include

/mnt/svn/gcc-trunk/binary-155920-lto/lib/gcc/x86_64-unknown-linux-gnu/4.5.0/include

/mnt/svn/gcc-trunk/binary-155920-lto/lib/gcc/x86_64-unknown-linux-gnu/4.5.0/include-fixed
 /usr/include
End of search list.
 baz bar foo
Analyzing compilation unit
Performing interprocedural optimizations
 <visibility> <*free_lang_data> <early_local_cleanups> <whole-program> <cp>
<inline> <static-var> <pure-const>Assembling functions:
 foo^C

real    76m32.295s
user    74m33.830s
sys     0m0.730s


-- 
           Summary: [4.5 Regression] deadlock in var tracking in recent
                    builds
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zsojka at seznam dot cz
  GCC host triplet: x86(_64)-pc-linux-gnu
GCC target triplet: x86(_64)-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42873

[Bug tree-optimization/42873] [4.5 Regression] deadlock in var tracking in recent builds

[zsojka at seznam dot cz]

------- Comment #1 from zsojka at seznam dot cz  2010-01-26 14:19 -------
Created an attachment (id=19713)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19713&action=view)
reduced testcase

Command line:
gcc -O3 -g -fgcse-sm -ftracer pr42873.c -c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42873

[Bug debug/42873] [4.5 Regression] deadlock in var tracking in recent builds

[jakub at gcc dot gnu dot org]

-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
          Component|tree-optimization           |debug
     Ever Confirmed|0                           |1
      Known to fail|                            |4.5.0
      Known to work|                            |4.4.3
           Priority|P3                          |P1
   Last reconfirmed|0000-00-00 00:00:00         |2010-01-26 15:02:37
               date|                            |
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42873

[Bug debug/42873] [4.5 Regression] deadlock in var tracking in recent builds

[zsojka at seznam dot cz]

------- Comment #2 from zsojka at seznam dot cz  2010-01-26 19:41 -------
Since http://gcc.gnu.org/viewcvs?view=revision&revision=155917


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42873

[Bug debug/42873] [4.5 Regression] deadlock in var tracking in recent builds

[jakub at gcc dot gnu dot org]

------- Comment #3 from jakub at gcc dot gnu dot org  2010-01-29 10:28 -------
Seems s is alternating between VALUE 1 and VALUE 11:
dataflow difference found: old and new follow:
  name: s
    offset 0
      (value/s/u:DI 1 @0x2ff4100/0x3009f40)
  name: s
    offset 0
      (value/s/u:DI 11 @0x2ff4478/0x3013980)
...
dataflow difference found: old and new follow:
  name: s
    offset 0
      (value/s/u:DI 11 @0x2ff4478/0x3013980)
  name: s
    offset 0
      (value/s/u:DI 1 @0x2ff4100/0x3009f40)

Both VALUE 1 and 11 are created for (reg/v/f:DI 5 di [orig:177 s ] [177])
which is a fn parameter and hasn't been ever modified within the function,
supposedly just 1 and 11 are created in different bbs.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42873

[Bug debug/42873] [4.5 Regression] deadlock in var tracking in recent builds

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2010-01-29 11:27 -------
When doing dataflow_set_merge where s variable is in VALUE 1 in one hash table
and in VALUE 11 in the other hash table, apparently always the one that is
first wins, as VALUE 11 has var->var_part[0].loc_chain->loc VALUE 1 and vice
versa, so intersect_loc_chains just picks the first one.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42873

[Bug debug/42873] [4.5 Regression] deadlock in var tracking in recent builds

[jakub at gcc dot gnu dot org]

------- Comment #5 from jakub at gcc dot gnu dot org  2010-03-18 20:17 -------
Subject: Bug 42873

Author: jakub
Date: Thu Mar 18 20:16:48 2010
New Revision: 157548

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=157548
Log:
        PR debug/42873
        * var-tracking.c (canonicalize_vars_star): New.
        (dataflow_post_merge_adjust): Use it.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/var-tracking.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42873

[Bug debug/42873] [4.5 Regression] deadlock in var tracking in recent builds

[jakub at gcc dot gnu dot org]

------- Comment #6 from jakub at gcc dot gnu dot org  2010-03-18 20:31 -------
Fixed, thanks Alex.


-- 

jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42873