[llvm-commits] [llvm] r158537 - /llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp

[Chandler Carruth]

On Fri, Jun 15, 2012 at 1:07 PM, Andrew Trick <atrick at apple.com> wrote:

> Author: atrick
> Date: Fri Jun 15 15:07:29 2012
> New Revision: 158537
>
> URL: http://llvm.org/viewvc/llvm-project?rev=158537&view=rev
> Log:
> LSR: fix expansion of scaled reg in non-address type formulae.
>
> For non-address users, Base and Scaled registers are not specially
> associated to fit an address mode, so SCEVExpander should apply normal
> expansion rules. Otherwise we may sink computation into inner loops
> that have already been optimized.
>

Test case possible?


>
> Modified:
>    llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
>
> Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=158537&r1=158536&r2=158537&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Fri Jun 15
> 15:07:29 2012
> @@ -4268,13 +4268,6 @@
>     Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, 0, IP)));
>   }
>
> -  // Flush the operand list to suppress SCEVExpander hoisting.
> -  if (!Ops.empty()) {
> -    Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);
> -    Ops.clear();
> -    Ops.push_back(SE.getUnknown(FullV));
> -  }
> -
>   // Expand the ScaledReg portion.
>   Value *ICmpScaledV = 0;
>   if (F.AM.Scale != 0) {
> @@ -4296,23 +4289,34 @@
>     } else {
>       // Otherwise just expand the scaled register and an explicit scale,
>       // which is expected to be matched as part of the address.
> +
> +      // Flush the operand list to suppress SCEVExpander hoisting address
> modes.
> +      if (!Ops.empty() && LU.Kind == LSRUse::Address) {
> +        Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);
> +        Ops.clear();
> +        Ops.push_back(SE.getUnknown(FullV));
> +      }
>       ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, 0, IP));
>       ScaledS = SE.getMulExpr(ScaledS,
>                               SE.getConstant(ScaledS->getType(),
> F.AM.Scale));
>       Ops.push_back(ScaledS);
> -
> -      // Flush the operand list to suppress SCEVExpander hoisting.
> -      Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);
> -      Ops.clear();
> -      Ops.push_back(SE.getUnknown(FullV));
>     }
>   }
>
>   // Expand the GV portion.
>   if (F.AM.BaseGV) {
> +    // Flush the operand list to suppress SCEVExpander hoisting.
> +    if (!Ops.empty()) {
> +      Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);
> +      Ops.clear();
> +      Ops.push_back(SE.getUnknown(FullV));
> +    }
>     Ops.push_back(SE.getUnknown(F.AM.BaseGV));
> +  }
>
> -    // Flush the operand list to suppress SCEVExpander hoisting.
> +  // Flush the operand list to suppress SCEVExpander hoisting of both
> folded and
> +  // unfolded offsets. LSR assumes they both live next to their uses.
> +  if (!Ops.empty()) {
>     Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);
>     Ops.clear();
>     Ops.push_back(SE.getUnknown(FullV));
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20120615/50949415/attachment.html>