On 10/30/2011 08:38 AM, Tom de Vries wrote:
> On 10/29/2011 09:17 PM, Tom de Vries wrote:
>> Richard,
>>
>> I have a tentative fix for PR50764.
>>
>> In the example from the test-case, -fsched2-use-superblocks moves an insn
>> from
>> block 4 to block 3.
>>
>> 2
>> bar
>> |
>> -------+-----
>> / \
>> * *
>> 5 *------------ 3
>> abort bar
>> |
>> |
>> *
>> 4
>> return
>>
>>
>> The insn has a REG_CFA_DEF_CFA note and is frame-related.
>> ...
>> (insn/f 51 50 52 4 (set (reg:DI 39 r10)
>> (mem/c:DI (plus:DI (reg/f:DI 6 bp)
>> (const_int -8 [0xfffffffffffffff8])) [3 S8 A8])) pr50764.c:13
>> 62 {*movdi_internal_rex64}
>> (expr_list:REG_CFA_DEF_CFA (reg:DI 39 r10)
>> (nil)))
>> ...
>>
>> This causes the assert in maybe_record_trace_start to trigger:
>> ...
>> /* We ought to have the same state incoming to a given trace no
>> matter how we arrive at the trace. Anything else means we've
>> got some kind of optimization error. */
>> gcc_checking_assert (cfi_row_equal_p (cur_row, ti->beg_row));
>> ...
>>
>> The assert does not occur with -fno-tree-tail-merge, but that is due to the
>> following:
>> - -fsched-use-superblocks does not handle dead labels explicitly
>> - -freorder-blocks introduces a dead label, which is not removed until after
>> sched2
>> - -ftree-tail-merge makes a difference in which block -freorder-blocks
>> introduces the dead label. In the case of -ftree-tail-merge, the dead label
>> is introduced at the start of block 3, and block 3 and 4 end up in the same
>> ebb. In the case of -fno-tree-tail-merge, the dead label is introduced at
>> the
>> start of block 4, and block 3 and 4 don't end up in the same ebb.
>>
>> attached untested patch fixes PR50764 in a similar way as the patch for
>> PR49994,
>> which is also about an ICE in maybe_record_trace_start with
>> -fsched2-use-superblocks.
>>
>> The patch for PR49994 makes sure frame-related instructions are not moved
>> past
>> the following jump.
>>
>> Attached patch makes sure frame-related instructions are not moved past the
>> preceding jump.
>>
>> Is this the way to fix this PR?
>>
>
> Bootstrapped and reg-tested on x86_64.
>
> Ok for trunk?
>
Ping.
Thanks,
- Tom
> Thanks,
> - Tom
>
>> Thanks,
>> - Tom
>>
>> 2011-10-29 Tom de Vries <t...@codesourcery.com>
>>
>> PR rtl-optimization/50764
>> * (sched_analyze_insn): Make sure frame-related insns are not moved past
>> preceding jump.
>>
>>
>>
>
