[llvm] [SystemZ] SLP reductions: cost functions of reductions and scalarization (PR #112491)

[Jonas Paulsson via llvm-commits]

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@@ -780,24 +780,28 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
   InstructionCost getScalarizationOverhead(VectorType *InTy,
                                            const APInt &DemandedElts,
                                            bool Insert, bool Extract,
-                                           TTI::TargetCostKind CostKind) {
+                                           TTI::TargetCostKind CostKind,
+                                           ArrayRef<Value *> VL = {}) {
     /// FIXME: a bitfield is not a reasonable abstraction for talking about
     /// which elements are needed from a scalable vector
     if (isa<ScalableVectorType>(InTy))
       return InstructionCost::getInvalid();
     auto *Ty = cast<FixedVectorType>(InTy);
 
     assert(DemandedElts.getBitWidth() == Ty->getNumElements() &&
+           (VL.empty() || VL.size() == Ty->getNumElements()) &&
            "Vector size mismatch");
 
     InstructionCost Cost = 0;
 
     for (int i = 0, e = Ty->getNumElements(); i < e; ++i) {
       if (!DemandedElts[i])
         continue;
-      if (Insert)
+      if (Insert) {
+        Value *InsertedVal = VL.size() ? VL[i] : nullptr;
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JonPsson1 wrote:

ok, I wonder if this is part of the coding guidelines somewhere? It should be equivalent, right?

https://github.com/llvm/llvm-project/pull/112491