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

[Tobias Grosser]

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.


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.


> The assert fail is caused by those LoopInfo updates added in r181987.
> Note that the LoopInfo of MergeBlock has been updated in the function "SplitBlock", so it should not be updated again in CodeGen.
>
>
> @Tobias or @Sebastian, could you do me a favor to commit the patch file?
Cheers,
Tobias