[Bug debug/63135] New: [4.9 regression] Infinite loop in var-tracking

[krebbel at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63135

            Bug ID: 63135
           Summary: [4.9 regression] Infinite loop in var-tracking
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: krebbel at gcc dot gnu.org

Created attachment 33435
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33435&action=edit
Preprocessed zsh 5.0.6 source file

zsh compilation runs into infinite loop on S/390:

cc1 builtin.i -m64 -mzarch -march=z900 -g  -O2 -fstack-protector-all -o
builtin.s

reghunt indicates that the failure started to appear with r208165 and for
mainline got fixed (or papered over) with r211007. However, it still fails with
GCC 4.9 branch.

(gdb) bt
#0  0x000000008088f8ea in dv_uid (dv=0x812accb8) at
/home/andreas/clean/gcc/gcc/var-tracking.c:443
#1  dv_htab_hash (dv=0x812accb8) at
/home/andreas/clean/gcc/gcc/var-tracking.c:461
#2  dv_htab_hash (dv=0x812accb8) at
/home/andreas/clean/gcc/gcc/var-tracking.c:1604
#3  vars_copy (src=..., dst=...) at
/home/andreas/clean/gcc/gcc/var-tracking.c:1816
#4  shared_hash_unshare (vars=0x81258960) at
/home/andreas/clean/gcc/gcc/var-tracking.c:1610
#5  0x0000000080895d34 in shared_hash_find_slot_unshare_1 (ins=INSERT,
dvhash=169, dv=0x81188080, 
    pvars=0x81187758) at /home/andreas/clean/gcc/gcc/var-tracking.c:1646
#6  shared_hash_find_slot_unshare (ins=INSERT, dv=0x81188080, pvars=0x81187758)
    at /home/andreas/clean/gcc/gcc/var-tracking.c:1654
#7  set_variable_part (set=0x81187620, loc=0x3fff6e1e8b8, dv=0x81188080,
offset=0, 
    initialized=VAR_INIT_STATUS_INITIALIZED, set_src=0x0, iopt=INSERT)
    at /home/andreas/clean/gcc/gcc/var-tracking.c:7768
#8  0x000000008089625a in var_mem_decl_set (set=0x81187620, loc=0x3fff6e1e8b8, 
    initialized=<optimized out>, dv=0x81188080, offset=<optimized out>,
set_src=0x0, iopt=INSERT)
    at /home/andreas/clean/gcc/gcc/var-tracking.c:2341
#9  0x000000008089acd0 in val_bind (modified=<optimized out>, loc=<optimized
out>, 
    val=<optimized out>, set=<optimized out>) at
/home/andreas/clean/gcc/gcc/var-tracking.c:2455
#10 val_resolve (set=0x81187620, val=0x81188080, loc=0x3fff6e1e8b8,
insn=<optimized out>)
    at /home/andreas/clean/gcc/gcc/var-tracking.c:2653
#11 0x000000008089b8b6 in compute_bb_dataflow (bb=0x3fff6cbcc30)
    at /home/andreas/clean/gcc/gcc/var-tracking.c:6718
#12 0x000000008089cba4 in vt_find_locations () at
/home/andreas/clean/gcc/gcc/var-tracking.c:7070
#13 0x000000008089f0ca in variable_tracking_main_1 ()
    at /home/andreas/clean/gcc/gcc/var-tracking.c:10294