[Bug middle-end/52925] New: [4.5/4.6 Regression] var-tracking never terminates

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52925

             Bug #: 52925
           Summary: [4.5/4.6 Regression] var-tracking never terminates
    Classification: Unclassified
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: rguenth@gcc.gnu.org


gcc  -O2   -g    -S bug-756235_t.c

hangs forever in

#0  0x0000000001176db4 in htab_mod_1 (x=99, y=59, inv=363980280, shift=5)
    at /space/rguenther/src/svn/gcc-4_6-branch/libiberty/hashtab.c:257
#1  0x0000000001176e50 in htab_mod_m2 (hash=99, htab=0x1a79900)
    at /space/rguenther/src/svn/gcc-4_6-branch/libiberty/hashtab.c:282
#2  0x00000000011779b3 in htab_find_slot_with_hash (htab=0x1a79900, 
    element=0x1b77fb0, hash=99, insert=INSERT)
    at /space/rguenther/src/svn/gcc-4_6-branch/libiberty/hashtab.c:671
#3  0x0000000000c93ad7 in vars_copy (dst=0x1a79900, src=0x1a7a850)
    at /space/rguenther/src/svn/gcc-4_6-branch/gcc/var-tracking.c:1601
#4  0x0000000000c9344b in shared_hash_unshare (vars=0x1a948e8)
    at /space/rguenther/src/svn/gcc-4_6-branch/gcc/var-tracking.c:1404
#5  0x0000000000c93520 in shared_hash_find_slot_unshare_1 (pvars=0x1bd6748, 
    dv=0x1b77cb0, dvhash=67, ins=INSERT)
    at /space/rguenther/src/svn/gcc-4_6-branch/gcc/var-tracking.c:1440
#6  0x0000000000c9357e in shared_hash_find_slot_unshare (pvars=0x1bd6748, 
    dv=0x1b77cb0, ins=INSERT)
    at /space/rguenther/src/svn/gcc-4_6-branch/gcc/var-tracking.c:1448
#7  0x0000000000ca22fb in set_variable_part (set=0x1bd6598, 
    loc=0x7ffff5bc9528, dv=0x1b77cb0, offset=0, 
    initialized=VAR_INIT_STATUS_INITIALIZED, set_src=0x0, iopt=INSERT)
    at /space/rguenther/src/svn/gcc-4_6-branch/gcc/var-tracking.c:6730
#8  0x0000000000c947c9 in val_store (set=0x1bd6598, val=0x1b77cb0, 
    loc=0x7ffff5bc9528, insn=0x7ffff504f870, modified=0 '\000')
    at /space/rguenther/src/svn/gcc-4_6-branch/gcc/var-tracking.c:1889
#9  0x0000000000c9f7b3 in compute_bb_dataflow (bb=0x7ffff4209dd0)
    at /space/rguenther/src/svn/gcc-4_6-branch/gcc/var-tracking.c:5824
#10 0x0000000000ca08ab in vt_find_locations ()

with no progress.  Maybe works in 4.7 by luck.