[Bug rtl-optimization/69102] [4.9/5/6 Regression] ICE: in move_op_ascend, at sel-sched.c:6138 with -fselective-scheduling2

[rth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69102

--- Comment #2 from Richard Henderson <rth at gcc dot gnu.org> ---
The only additional deps in this entire function by the
quoted patch are three sequential insns involved in a call
that use REG_ARGS_SIZE.  But all of these are well-removed
from the ICE.

The instruction that is producing the ICE is

(gdb) call debug_insn(insn)
([((3;ax=0x5;)type:use;count:2;)prio:0;orig_bb:3;];seqno:14;)

which ought to have dependencies only in setting of EAX.  Whether
this is actually so, I can't quite tell from 

  if (has_dep_p[DEPS_IN_INSN])
    /* We have some dependency that cannot be discarded.  */
    return MOVEUP_EXPR_NULL;

But regardless, sel-sched.c appears to be not handling valid
dependency info.