[llvm-commits] [llvm] r85634 - /llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp

[Evan Cheng]

Hi Dan,

This is breaking consumer-typeset (and other tests). I've reverted it  
for now.

Evan

On Oct 30, 2009, at 4:15 PM, Dan Gohman wrote:

> Author: djg
> Date: Fri Oct 30 18:15:21 2009
> New Revision: 85634
>
> URL: http://llvm.org/viewvc/llvm-project?rev=85634&view=rev
> Log:
> Optimize around the fact that pred_iterator is slow: instead of  
> sorting
> PHI operands by the predecessor order, sort them by the order used  
> by the
> first PHI in the block. This is still suffucient to expose duplicates.
>
> Modified:
>    llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
>
> Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=85634&r1=85633&r2=85634&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp  
> (original)
> +++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Fri  
> Oct 30 18:15:21 2009
> @@ -10981,22 +10981,24 @@
>     }
>   }
>
> -  // Sort the PHI node operands to match the pred iterator order.  
> This will
> -  // help identical PHIs be eliminated by other passes. Other  
> passes shouldn't
> -  // depend on this for correctness however.
> -  unsigned i = 0;
> -  for (pred_iterator PI = pred_begin(PN.getParent()),
> -       PE = pred_end(PN.getParent()); PI != PE; ++PI, ++i)
> -    if (PN.getIncomingBlock(i) != *PI) {
> -      unsigned j = PN.getBasicBlockIndex(*PI);
> -      Value *VA = PN.getIncomingValue(i);
> +  // If there are multiple PHIs, sort their operands so that they  
> all list
> +  // the blocks in the same order. This will help identical PHIs be  
> eliminated
> +  // by other passes. Other passes shouldn't depend on this for  
> correctness
> +  // however.
> +  PHINode *FirstPN = cast<PHINode>(PN.getParent()->begin());
> +  if (&PN != FirstPN)
> +    for (unsigned i = 0, e = FirstPN->getNumIncomingValues(); i !=  
> e; ++i) {
>       BasicBlock *BBA = PN.getIncomingBlock(i);
> -      Value *VB = PN.getIncomingValue(j);
> -      BasicBlock *BBB = PN.getIncomingBlock(j);
> -      PN.setIncomingBlock(i, BBB);
> -      PN.setIncomingValue(i, VB);
> -      PN.setIncomingBlock(j, BBA);
> -      PN.setIncomingValue(j, VA);
> +      BasicBlock *BBB = FirstPN->getIncomingBlock(i);
> +      if (BBA != BBB) {
> +        Value *VA = PN.getIncomingValue(i);
> +        unsigned j = FirstPN->getBasicBlockIndex(BBA);
> +        Value *VB = PN.getIncomingValue(j);
> +        PN.setIncomingBlock(i, BBB);
> +        PN.setIncomingValue(i, VB);
> +        PN.setIncomingBlock(j, BBA);
> +        PN.setIncomingValue(j, VA);
> +      }
>     }
>
>   return 0;
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits