[llvm-commits] [llvm] r164636 - /llvm/trunk/lib/Transforms/Scalar/SROA.cpp

[Chandler Carruth]

On Tue, Sep 25, 2012 at 2:50 PM, Nick Lewycky <nicholas at mxc.ca> wrote:

> Author: nicholas
> Date: Tue Sep 25 16:50:37 2012
> New Revision: 164636
>
> URL: http://llvm.org/viewvc/llvm-project?rev=164636&view=rev
> Log:
> Revert the business end of r164634, and replace it with a different fix.
> The
> reason we were getting two of the same alloca is because of a
> memmove/memcpy
> which had the same alloca in both the src and dest. Now we detect that case
> directly. This has the same testcase as before, but fixes a clang test
> CodeGenObjC/exceptions.m which runs clang -O2.
>
> Modified:
>     llvm/trunk/lib/Transforms/Scalar/SROA.cpp
>
> Modified: llvm/trunk/lib/Transforms/Scalar/SROA.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SROA.cpp?rev=164636&r1=164635&r2=164636&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/SROA.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/SROA.cpp Tue Sep 25 16:50:37 2012
> @@ -2228,7 +2228,10 @@
>      // alloca that should be re-examined after rewriting this instruction.
>      if (AllocaInst *AI
>            = dyn_cast<AllocaInst>(OtherPtr->stripInBoundsOffsets()))
> -      Pass.Worklist.insert(AI);
> +      // Don't revisit the alloca if both sides of the memory transfer are
> +      // referring to the same alloca.
> +      if (AI != &NewAI)
> +        Pass.Worklist.insert(AI);
>

Also, this doesn't make a lot of sense to me. Worklist is a SetVector, and
we insert NewAI into it anyways... Were you trying to do something else
here? I don't want to misunderstand the intent of the patch.


>
>      if (EmitMemCpy) {
>        Value *OurPtr
> @@ -3108,12 +3111,6 @@
>    if (PromotableAllocas.empty())
>      return false;
>
> -  // Ensure that the list is unique.
> -  std::sort(PromotableAllocas.begin(), PromotableAllocas.end());
> -  PromotableAllocas.erase(std::unique(PromotableAllocas.begin(),
> -                                      PromotableAllocas.end()),
> -                          PromotableAllocas.end());
> -
>    NumPromoted += PromotableAllocas.size();
>
>    if (DT && !ForceSSAUpdater) {
>
>
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