On Wed, Nov 28, 2012 at 7:24 PM, Marek Polacek <pola...@redhat.com> wrote:
> On Wed, Nov 28, 2012 at 10:52:17AM +0100, Eric Botcazou wrote:
>> No, I don't think that's the problem. The above messages are admittedly a
>> bit
>> terse, they should say:
>>
>> JUMP-BYPASS: Proved reg 59 in jump_insn 15 equals constant (const_int 3
>> [0x3])
>> when BB 4 is entered from BB 9. Redirect edge 9->4 to 5.
>>
>> so you can have different constants for BB 3 and BB 9. The patch to tweak
>> the
>> dump messages along these lines is pre-approved.
>
> Ouch. Okay, I'll post a separate patch for improving the message.
>
>> The ICE in merge_latch_edges means that the loop structure and the CFG aren't
>> in sync anymore. Does the cprop pass modify the former without declaring it?
>
> I admit I'm not sure what to look at, maybe cprop should have in
> properties_destroyed PROP_loops? Well, then we need to remove one
> assert in loop-init.c. So something like:
Definitely not - that means to not preserve loops until after cprop. The goal
is to preserve loops everywhere!
Richard.
> --- gcc/cprop.c.mp 2012-11-28 16:55:03.520375191 +0100
> +++ gcc/cprop.c 2012-11-28 16:55:35.992246623 +0100
> @@ -1927,7 +1927,7 @@ struct rtl_opt_pass pass_rtl_cprop =
> TV_CPROP, /* tv_id */
> PROP_cfglayout, /* properties_required */
> 0, /* properties_provided */
> - 0, /* properties_destroyed */
> + PROP_loops, /* properties_destroyed */
> 0, /* todo_flags_start */
> TODO_df_finish | TODO_verify_rtl_sharing |
> TODO_verify_flow | TODO_ggc_collect /* todo_flags_finish */
> --- gcc/loop-init.c.mp 2012-11-28 16:55:08.924398879 +0100
> +++ gcc/loop-init.c 2012-11-28 16:55:17.684437276 +0100
> @@ -54,8 +54,6 @@ loop_optimizer_init (unsigned flags)
> }
> else
> {
> - gcc_assert (cfun->curr_properties & PROP_loops);
> -
> /* Ensure that the dominators are computed, like flow_loops_find does.
> */
> calculate_dominance_info (CDI_DOMINATORS);
>
> This quashes the ICE. I've regtested it, it caused one
> regression though:
> FAIL: gcc.dg/unroll_5.c scan-rtl-dump-times loop2_unroll "realistic
> bound: 2999999" 1
>
> But there probably is something else.
>
> Thanks for the review,
>
> Marek
