[LLVMdev] [Polly] Assert in Scope construction

[Tobias Grosser]

On 07/04/2013 07:20 PM, Hongbin Zheng wrote:
> Hi Sergei,
>
>
> On Thu, Jul 4, 2013 at 1:36 AM, Sergei Larin <slarin at codeaurora.org> wrote:
>
>> Should have changed the subject line...
>>
>> ---
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted
>> by
>> The Linux Foundation
>>
>>
>>> -----Original Message-----
>>> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
>>> On Behalf Of Sergei Larin
>>> Sent: Wednesday, July 03, 2013 12:29 PM
>>> To: 'Tobias Grosser'
>>> Cc: 'llvmdev'
>>> Subject: Re: [LLVMdev] [LNT] Question about results reliability in LNT
>>> infrustructure
>>>
>>>
>>> Tobias,
>>>
>>>    I seem to trigger an assert in Polly lib/Analysis/TempScopInfo.cpp
>>>
>>> void TempScopInfo::buildAffineCondition(Value &V, bool inverted,
>>>                                          Comparison **Comp) const { ...
>>>    ICmpInst *ICmp = dyn_cast<ICmpInst>(&V);
>>>    assert(ICmp && "Only ICmpInst of constant as condition supported!");
>> ...
>>>
>>>    The code it chokes on looks like this (see below). The problem is this
>> OR-ed
>>> compare result:
>>>
>>>    %cmp3 = icmp sgt i32 %j.0, 2
>>>    %cmp5 = icmp eq i32 %j.0, 1
>>>    %or.cond13 = or i1 %cmp3, %cmp5
>>> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< ==
>>> Value V
>>>
>>>
>>> My question - is this a bug or a (missing) feature?
>
> I think it is a bug.
>
>
>>   ...and how it should
>> be
>>> handled in theory?
>>
> Such condition should be filtered out by ScopDetection (line 188 of
> ScopDetection.cpp).

Hongbin is right. Running your test case gives:

$ polly-opt -polly-detect -analyze /tmp/test.ll -debug-only=polly-detect
Checking region: entry => <Function Return>
	Top level region is invalid
Checking region: for.cond2 => for.end8
	Condition in BB 'for.cond2' neither constant nor an icmp
         instruction

Did you try this test case on the open source version of Polly? In case 
you want to support this code in the open source version of Polly, the 
way to go is pretty simple. You first enhance -polly-detect to allow 
boolean operations like 'and' and 'or'. You then change TempScop and 
ScopInfo to support those. The changes are pretty straightforward. You 
just need to keep track of a list of conditions and then and/or the 
conditions with isl when generating the iteration space.

Cheers,
Tobias