[llvm-commits] [llvm] r49928 - /llvm/trunk/lib/Analysis/ScalarEvolution.cpp

[Nick Lewycky]

Hi Dale,

I don't think this is right. The correct fix is to replace 
getNegativeSCEV with getNotSCEV.

Nick

Dale Johannesen wrote:
> Author: johannes
> Date: Fri Apr 18 16:38:31 2008
> New Revision: 49928
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=49928&view=rev
> Log:
> Fix a scalar evolution bug.  Reversing everything
> does not work because of 0; 2>0 but -2U is also >0.
> 
> 
> Modified:
>     llvm/trunk/lib/Analysis/ScalarEvolution.cpp
> 
> Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=49928&r1=49927&r2=49928&view=diff
> 
> ==============================================================================
> --- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
> +++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Fri Apr 18 16:38:31 2008
> @@ -1980,8 +1980,7 @@
>      break;
>    }
>    case ICmpInst::ICMP_UGT: {
> -    SCEVHandle TC = HowManyLessThans(SE.getNegativeSCEV(LHS),
> -                                     SE.getNegativeSCEV(RHS), L, false);
> +    SCEVHandle TC = HowFarToZero(SE.getMinusSCEV(LHS, RHS), L);
>      if (!isa<SCEVCouldNotCompute>(TC)) return TC;
>      break;
>    }
> 
> 
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