[polly] r261474 - [FIX] Compare SCEVs not values during SCEV expansion

[Tobias Grosser via llvm-commits]

On 02/21/2016 07:16 PM, Johannes Doerfert wrote:
>> On 02/21/2016 05:36 PM, Johannes Doerfert via llvm-commits wrote:
>>> Author: jdoerfert
>>> Date: Sun Feb 21 10:36:00 2016
>>> New Revision: 261474
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=261474&view=rev
>>> Log:
>>> [FIX] Compare SCEVs not values during SCEV expansion
>>>
>>>    This fixes a compile time bug in SPEC2006 403.gcc, namely an endless
>>>    recursion in the ScopExpander::visitUnknown function.
>>
>> A test case would be good. Was there  a specific reason you could not add a
>> test case?
> I tried but could not generate one. Only when I run it with clang I
> triggered the problem. Tried to extract the module as Polly sees it but
> it didn't help.

How did you extract the code from clang?

The following commands should be equivalent to 'clang -O3 -mllvm -polly':

	clang -O3 -mllvm -disable-llvm-optzns -S -emit-llvm -o out.ll
	opt -O3 -polly

Not that extracting test cases with 'clang -O0 -S -emit-llvm' does not 
give the same results. When -O0 is specified clang e.g. does not emit
type based alias analysis metadata which could prevent Polly from 
optimizing code that it would have optimized otherwise.

Best,
Tobias