[llvm-commits] [llvm] r126452 - in /llvm/trunk: lib/Transforms/Utils/SimplifyCFG.cpp test/Transforms/SimplifyCFG/select-gep.ll

[Chris Lattner]

On Feb 24, 2011, at 3:26 PM, Benjamin Kramer wrote:

> +++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Thu Feb 24 17:26:09 2011
> @@ -247,11 +247,13 @@
>     if (PBB->getFirstNonPHIOrDbg() != I)
>       return false;
>     break;
> -  case Instruction::GetElementPtr:
> -    // GEPs are cheap if all indices are constant.
> -    if (!cast<GetElementPtrInst>(I)->hasAllConstantIndices())
> +  case Instruction::GetElementPtr: {
> +    // GEPs are cheap if all indices are constant or if there's only one index.
> +    GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
> +    if (!GEP->hasAllConstantIndices() && GEP->getNumIndices() > 1)
>       return false;
>     break;
> +  }

FYI getNumIndices() will return 2 for "gep x, 0, i".  I tend to agree with Dan that we should only allow a variable index if the scale is 1.

-Chris