[llvm] r174932 - Cost model: Add check for reverse shuffles to CostModel analysis

[Arnold Schwaighofer]

Author: arnolds
Date: Mon Feb 11 20:40:37 2013
New Revision: 174932

URL: http://llvm.org/viewvc/llvm-project?rev=174932&view=rev
Log:
Cost model: Add check for reverse shuffles to CostModel analysis

Check for reverse shuffles in the CostModel analysis pass and query
TargetTransform info accordingly. This allows us we can write test cases for
reverse shuffles.

radar://13171406

Modified:
    llvm/trunk/lib/Analysis/CostModel.cpp

Modified: llvm/trunk/lib/Analysis/CostModel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/CostModel.cpp?rev=174932&r1=174931&r2=174932&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/CostModel.cpp (original)
+++ llvm/trunk/lib/Analysis/CostModel.cpp Mon Feb 11 20:40:37 2013
@@ -80,6 +80,13 @@ CostModelAnalysis::runOnFunction(Functio
  return false;
 }
 
+static bool isReverseVectorMask(SmallVector<int, 16> &Mask) {
+  for (unsigned i = 0, MaskSize = Mask.size(); i < MaskSize; ++i)
+    if (Mask[i] > 0 && Mask[i] != (int)(MaskSize - 1 - i))
+      return false;
+  return true;
+}
+
 unsigned CostModelAnalysis::getInstructionCost(const Instruction *I) const {
   if (!TTI)
     return -1;
@@ -171,6 +178,17 @@ unsigned CostModelAnalysis::getInstructi
       return TTI->getVectorInstrCost(I->getOpcode(),
                                      IE->getType(), Idx);
     }
+  case Instruction::ShuffleVector: {
+    const ShuffleVectorInst *Shuffle = cast<ShuffleVectorInst>(I);
+    Type *VecTypOp0 = Shuffle->getOperand(0)->getType();
+    unsigned NumVecElems = VecTypOp0->getVectorNumElements();
+    SmallVector<int, 16> Mask = Shuffle->getShuffleMask();
+
+    if (NumVecElems == Mask.size() && isReverseVectorMask(Mask))
+      return TTI->getShuffleCost(TargetTransformInfo::SK_Reverse, VecTypOp0, 0,
+                                 0);
+    return -1;
+  }
   default:
     // We don't have any information on this instruction.
     return -1;