[Bug rtl-optimization/58668] [4.8/4.9 regression] internal compiler error: in cond_exec_process_insns, at ifcvt.c:339

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58668

--- Comment #6 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> I think the problem is that ifcvt relies on consistent counting of insns,
> but the various functions count different things.

What kind of insns is responsible for the discrepancy that leads to the ICE?

> I guess best would be to count/skip/etc. the same things consistently, the
> problem is that some of the functions have other uses etc.

In any case, this would be a sensible approach.

> 1) let count_bb_insns not count insns with USE or CLOBBER PATTERNs

Agreed.

> 2) perhaps not count any JUMP_INSNs in flow_find_cross_jump if dir_p == NULL
> (i.e.
> when called from ifcvt)?
> 3) perhaps not count USE/CLOBBER insns in flow_find_head_matching_sequence if
> stop_after is non-zero?

I'd first make the functions behave the same wrt USE and CLOBBER insns.

> 4) perhaps add also skip_use argument to first_active_insn and if TRUE,
> ignore USE insns and for both {first,last}_active_insn if skip_use is TRUE,
> also ignore CLOBBER insns
>
> 5) in find_active_insn_{before,after} ignore USE/CLOBBER insns
> and document this properly?

I'm less sure about these ones: does their behavior need to be in keeping with
the insns counting?