[PATCH][Polly] Re: 0001-Fixup-assert-fails-caused-by-incorrect-LoopInfo-update

[Tobias Grosser]

On 09/02/2013 08:30 AM, Star Tan wrote:
>
>
>
>
> At 2013-09-02 16:34:24,"Tobias Grosser" <tobias at grosser.es> wrote:
>
>> On 09/01/2013 08:01 PM, Star Tan wrote:
>>> At 2013-08-25 02:10:02,"Tobias Grosser" <tobias at grosser.es> wrote:
>>>> On 08/23/2013 08:25 AM, Star Tan wrote:
>>>>>    Hi all,
>>>>>
>>>>>
>>>>>    I have attached a patch file to fix up the CodeGen assert fail, which is also reported in a recent bug  http://llvm.org/bugs/show_bug.cgi?id=16944
>>>>
>>>> Hi Star Tan,
>>>>
>>>> thanks for looking into this bug. The patch itself looks good and the
>>>> testcase is nicely small.
>>>>
>>>> However, when running the test with 'opt' I get:
>>>>
>>>> PHINode should have one entry for each predecessor of its parent basic
>>>> block!
>>>>      %indvar = phi i64 [ 0, %entry ], [ %0, %for.inc ]
>>>>
>>>> So the IR in the test case itself is already incorrect.
>>>
>>> Sorry for the stupid mistake. I have attached a new patch file!
>>
>> Great. This one looks correct.
>>
>>> Also, I am a little unhappy with the fact that we need to run
>>>
>>>> -polly-opt-isl to reproduce this bug. I would very much prefer to find a
>>>> test case that only runs 'opt %loadPolly -polly-codegen  < %s'. This ensures
>>>> that changes in -polly-opt-isl can not accidentally stop this test case
>>>> from testing the code path you fixed in this patch.
>>>
>>> Yes, you are right. But it seems difficult to construct a testcase that will show this bug using only "opt %loadPolly -polly-codegen".
>>> Our testcase fails with the following command:
>>> $ opt %loadPolly -basicaa -polly-opt-isl -polly-codegen test.ll
>>>
>>> but it works well with the following commands:
>>> $ opt %loadPolly -basicaa -polly-opt-isl -S -o test_1.ll test.ll
>>> $ opt %loadPolly -basicaa -polly-codegen test_1.ll
>>>
>>> The key of producing the bug is to construct a stmt_guard statment, so it will call codegen((clast_guard *)). Preliminary investigation shows that the  'stmt_guard' occurs only if we run opt-isl before codegen.  Sorry I have not found such a testcase by now.
>>
>> I just looked into this and I could also not find a trivial test case
>> that yields a guard statement. However, you can use
>>
>> opt -polly-opt-isl -polly-export-jscop
>>
>> to get a jscop file and the use opt -polly-import-jscop to read in this
>> jscop file instead of running polly-opt-isl. This at least removes the
>> dependency on the isl scheduler.
>>
>> test/Cloog/CodeGen/simple_vec_stride_one.ll
>>
>> The above test case should give an example how to use the import/export
>> of jscops.
>
> Thank you so much for your very helpful suggestion.  Yes, Jscop is a very help tool~
> I have attached a new patch file that reads Jscop file to avoid dependence to polly-opt-isl.

Great. This one looks perfect. I committed it in r189764.

Please feel free to close the related bug reports.

Cheers,
Tobias