[Bug tree-optimization/47849] New: ICE: SIGSEGV in find_edge (cfganal.c:491) with -ftree-loop-if-convert -fno-tree-reassoc

[Bug tree-optimization/47849] New: ICE: SIGSEGV in find_edge (cfganal.c:491) with -ftree-loop-if-convert -fno-tree-reassoc

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47849

           Summary: ICE: SIGSEGV in find_edge (cfganal.c:491) with
                    -ftree-loop-if-convert -fno-tree-reassoc
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz
                CC: spop@gcc.gnu.org
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 23435
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23435
reduced testcase

Compiler output:
$ gcc -O2 -ftree-loop-if-convert -fno-tree-reassoc testcase.ctestcase.c: In
function 'foo':
testcase.c:2:1: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

(gdb) bt
#0  find_edge (pred=0x7ffff5bf2138, succ=0x0) at
/mnt/svn/gcc-trunk/gcc/cfganal.c:491
#1  0x0000000000986bd1 in remove_dead_stmt (i=0x7fffffffd6a0,
bb=0x7ffff5bf2138) at /mnt/svn/gcc-trunk/gcc/tree-ssa-dce.c:1102
#2  0x00000000009870f9 in eliminate_unnecessary_stmts () at
/mnt/svn/gcc-trunk/gcc/tree-ssa-dce.c:1203
#3  0x000000000098957f in perform_tree_ssa_dce (aggressive=1 '\001') at
/mnt/svn/gcc-trunk/gcc/tree-ssa-dce.c:1450
#4  0x00000000007f6e86 in execute_one_pass (pass=0x178ee30) at
/mnt/svn/gcc-trunk/gcc/passes.c:1556
#5  0x00000000007f7185 in execute_pass_list (pass=0x178ee30) at
/mnt/svn/gcc-trunk/gcc/passes.c:1611
#6  0x00000000007f7197 in execute_pass_list (pass=0x163bd80) at
/mnt/svn/gcc-trunk/gcc/passes.c:1612
#7  0x0000000000939fd6 in tree_rest_of_compilation (fndecl=0x7ffff5b86f00) at
/mnt/svn/gcc-trunk/gcc/tree-optimize.c:422
#8  0x0000000000b01e82 in cgraph_expand_function (node=0x7ffff5ba6000) at
/mnt/svn/gcc-trunk/gcc/cgraphunit.c:1576
#9  0x0000000000b045ca in cgraph_expand_all_functions () at
/mnt/svn/gcc-trunk/gcc/cgraphunit.c:1635
#10 cgraph_optimize () at /mnt/svn/gcc-trunk/gcc/cgraphunit.c:1899
#11 0x0000000000b04b4a in cgraph_finalize_compilation_unit () at
/mnt/svn/gcc-trunk/gcc/cgraphunit.c:1096
#12 0x000000000050974c in c_write_global_declarations () at
/mnt/svn/gcc-trunk/gcc/c-decl.c:9872
#13 0x00000000008e2f78 in compile_file (argc=15, argv=0x7fffffffda68) at
/mnt/svn/gcc-trunk/gcc/toplev.c:591
#14 do_compile (argc=15, argv=0x7fffffffda68) at
/mnt/svn/gcc-trunk/gcc/toplev.c:1900
#15 toplev_main (argc=15, argv=0x7fffffffda68) at
/mnt/svn/gcc-trunk/gcc/toplev.c:1963
#16 0x00007ffff6446bbd in __libc_start_main () from /lib/libc.so.6
#17 0x00000000004f02fd in _start ()

Tested revisions:
r170398 - crash

[Bug tree-optimization/47849] ICE: SIGSEGV in find_edge (cfganal.c:491) with -ftree-loop-if-convert -fno-tree-reassoc

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47849

Zdenek Sojka <zsojka at seznam dot cz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code
      Known to fail|                            |4.6.0

--- Comment #1 from Zdenek Sojka <zsojka at seznam dot cz> 2011-02-22 16:17:09 UTC ---
Originally, it failed with:

(testcase is testsuite/gcc.target/i386/avx-vpcmpistri-1.c)

$ gcc -O2 -mavx -ftree-loop-if-convert -fno-tree-reassoc avx-vpcmpistri-1.i     
avx-vpcmpistri-1.i: In function 'cmp_flags.constprop.1':
avx-vpcmpistri-1.i:5573:1: internal compiler error: in forward_edge_to_pdom, at
tree-ssa-dce.c:1064
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

(gdb) bt
#0  fancy_abort (file=0x117f638 "/mnt/svn/gcc-trunk/gcc/tree-ssa-dce.c",
line=1064, function=0x117fd60 "forward_edge_to_pdom")
    at /mnt/svn/gcc-trunk/gcc/diagnostic.c:892
#1  0x0000000000986ec6 in forward_edge_to_pdom (i=0x7fffffffd670,
bb=0x7ffff7f32548) at /mnt/svn/gcc-trunk/gcc/tree-ssa-dce.c:1064
#2  remove_dead_stmt (i=0x7fffffffd670, bb=0x7ffff7f32548) at
/mnt/svn/gcc-trunk/gcc/tree-ssa-dce.c:1113
#3  0x00000000009870f9 in eliminate_unnecessary_stmts () at
/mnt/svn/gcc-trunk/gcc/tree-ssa-dce.c:1203
#4  0x000000000098957f in perform_tree_ssa_dce (aggressive=1 '\001') at
/mnt/svn/gcc-trunk/gcc/tree-ssa-dce.c:1450
#5  0x00000000007f6e86 in execute_one_pass (pass=0x178ee30) at
/mnt/svn/gcc-trunk/gcc/passes.c:1556
#6  0x00000000007f7185 in execute_pass_list (pass=0x178ee30) at
/mnt/svn/gcc-trunk/gcc/passes.c:1611
#7  0x00000000007f7197 in execute_pass_list (pass=0x163bd80) at
/mnt/svn/gcc-trunk/gcc/passes.c:1612
#8  0x0000000000939fd6 in tree_rest_of_compilation (fndecl=0x7ffff5819e00) at
/mnt/svn/gcc-trunk/gcc/tree-optimize.c:422
#9  0x0000000000b01e82 in cgraph_expand_function (node=0x7ffff5916b00) at
/mnt/svn/gcc-trunk/gcc/cgraphunit.c:1576
#10 0x0000000000b045ca in cgraph_expand_all_functions () at
/mnt/svn/gcc-trunk/gcc/cgraphunit.c:1635
#11 cgraph_optimize () at /mnt/svn/gcc-trunk/gcc/cgraphunit.c:1899
#12 0x0000000000b04b4a in cgraph_finalize_compilation_unit () at
/mnt/svn/gcc-trunk/gcc/cgraphunit.c:1096
#13 0x000000000050974c in c_write_global_declarations () at
/mnt/svn/gcc-trunk/gcc/c-decl.c:9872
#14 0x00000000008e2f78 in compile_file (argc=16, argv=0x7fffffffda38) at
/mnt/svn/gcc-trunk/gcc/toplev.c:591
#15 do_compile (argc=16, argv=0x7fffffffda38) at
/mnt/svn/gcc-trunk/gcc/toplev.c:1900
#16 toplev_main (argc=16, argv=0x7fffffffda38) at
/mnt/svn/gcc-trunk/gcc/toplev.c:1963
#17 0x00007ffff6446bbd in __libc_start_main () from /lib/libc.so.6
#18 0x00000000004f02fd in _start ()

The backtrace is very similiar, so it is probably the same problem.

Apart from that, running testsuite with "-ftree-loop-if-convert
-fno-tree-reassoc" resulted in ~177 exec failures - it is probably already
reported as PR47770.

[Bug tree-optimization/47849] ICE: SIGSEGV in find_edge (cfganal.c:491) with -ftree-loop-if-convert -fno-tree-reassoc

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47849

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011.02.23 15:18:38
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-02-23 15:18:38 UTC ---
I have a patch.

[Bug tree-optimization/47849] ICE: SIGSEGV in find_edge (cfganal.c:491) with -ftree-loop-if-convert -fno-tree-reassoc

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47849

--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-02-23 16:50:00 UTC ---
Author: rguenth
Date: Wed Feb 23 16:49:52 2011
New Revision: 170441

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=170441
Log:
2011-02-23  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/47849
    * tree-if-conv.c (main_tree_if_conversion): Free postdom info.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/tree-if-conv.c

[Bug tree-optimization/47849] ICE: SIGSEGV in find_edge (cfganal.c:491) with -ftree-loop-if-convert -fno-tree-reassoc

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47849

Richard Guenther <rguenth at gcc dot gnu.org> changed:

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

--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-02-23 16:50:33 UTC ---
Fixed.