[Bug tree-optimization/69426] [5/6 Regression] ICE: verify_ssa failed (error: missing definition) w/ -O2 (and above) -ftree-parallelize-loops=2

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69426

--- Comment #4 from vries at gcc dot gnu.org ---
(In reply to vries from comment #3)
> Reproduced (on x86_64) with 5 branch.
> 
> The ICE seems to have been triggered by removing the expand_omp_local from
> parloops and using a separate omp_expand_ssa pass.

Confirmed, the ICE can also be triggered in 4.9 by breaking at omp_expand_local
and calling verify_ssa.

With r226201 of gcc-4_9-branch:
...
Breakpoint 1, omp_expand_local (head=0x7ffff5f19958) at
4.9/src/gcc/omp-low.c:8460
8460      build_omp_regions_root (head);
(gdb) call verify_ssa (true)
parloops-pr.c: In function âmrâ:
parloops-pr.c:4:1: error: missing definition
 mr(void)
 ^
for SSA_NAME: .MEM_11 in statement:
.MEM_2 = PHI <.MEM_11(4), .MEM_7(D)(15)>
PHI argument
.MEM_11
for PHI node
.MEM_2 = PHI <.MEM_11(4), .MEM_7(D)(15)>
parloops-pr.c:4:1: internal compiler error: verify_ssa failed
0xf75836 verify_ssa(bool)
        4.9/src/gcc/tree-ssa.c:1096
...