[llvm-commits] [llvm] r60393 - /llvm/trunk/lib/Transforms/Scalar/GVN.cpp

[Chris Lattner]

On Dec 1, 2008, at 8:09 PM, Owen Anderson wrote:

> Author: resistor
> Date: Mon Dec  1 22:09:22 2008
> New Revision: 60393
>
> URL: http://llvm.org/viewvc/llvm-project?rev=60393&view=rev
> Log:
> Fix an issue that Chris noticed, where local PRE was not properly  
> instantiating
> a new value numbering set after splitting a critical edge.  This  
> increases
> the number of instances of PRE on 403.gcc from ~60 to ~570.

Thanks Owen, but testcase please!  We don't have enough feature tests  
for GVN, please help fix!

-Chris

>
>
> Modified:
>    llvm/trunk/lib/Transforms/Scalar/GVN.cpp
>
> Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=60393&r1=60392&r2=60393&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Mon Dec  1 22:09:22 2008
> @@ -1299,6 +1299,7 @@
>
>       if (isCriticalEdge(PREPred->getTerminator(), succNum)) {
>         toSplit.push_back(std::make_pair(PREPred->getTerminator(),  
> succNum));
> +        Changed = true;
>         continue;
>       }
>
> @@ -1361,10 +1362,14 @@
>   }
>
>   for (SmallVector<std::pair<TerminatorInst*, unsigned>, 4>::iterator
> -       I = toSplit.begin(), E = toSplit.end(); I != E; ++I)
> +       I = toSplit.begin(), E = toSplit.end(); I != E; ++I) {
>     SplitCriticalEdge(I->first, I->second, this);
> +    BasicBlock* NewBlock = I->first->getSuccessor(I->second);
> +    localAvail[NewBlock] =
> +             new ValueNumberScope(localAvail[I->first->getParent()]);
> +  }
>
> -  return Changed || toSplit.size();
> +  return Changed;
> }
>
> // iterateOnFunction - Executes one iteration of GVN
>
>
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