[polly] ICE with scev-codegen after removal of RegionSimplify

[Sebastian Pop]

Sebastian Pop wrote:
> Sebastian Pop wrote:
> > Let's focus on removing independent blocks, as it creates too many problems.
> 
> I quickly removed the independent blocks pass and it does fix the compilation of
> Isl/CodeGen/20110226-PHI-Node-removed.ll: the only fails that I see are
> 
> Failing Tests (2):
>     Polly :: Isl/CodeGen/20100713_2.ll
>     Polly :: Isl/CodeGen/20110226-Ignore-Dead-Code.ll
> 
> both of these fails are ICEing after codegen verification with:
> 
> Instruction does not dominate all uses!
>   %tmp25 = add i64 undef, 1
>   %exitcond26.old = icmp eq i64 undef, %tmp25
> 
> We most likely fail to copy the scalar dependences for %tmp25 that probably
> still points to the original scop or so.
> 

Both fails are due to codegen splitting the control flow to version the scop:
the definition is in one of the BBs of the original scop and the use is outside
the scop.  I think that we should get out of SSA in codegen for the scalars
defined in the scop and used outside the scop.

Another solution would be to not version the scop.

Sebastian
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