[LV] Move logic to check if op is invariant to legacy cost model. (NFC)

This allows the function to be re-used in other places

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -1527,6 +1527,10 @@ class LoopVectorizationCostModel {
   getReductionPatternCost(Instruction *I, ElementCount VF, Type *VectorTy,
                           TTI::TargetCostKind CostKind) const;
 
+  /// Returns true if \p Op should be considered invariant and if it is
+  /// trivially hoistable.
+  bool shouldConsiderInvariant(Value *Op);
+
 private:
   unsigned NumPredStores = 0;
 
@@ -6382,6 +6386,17 @@ void LoopVectorizationCostModel::setVectorizedCallDecision(ElementCount VF) {
   }
 }
 
+bool LoopVectorizationCostModel::shouldConsiderInvariant(Value *Op) {
+  if (!Legal->isInvariant(Op))
+    return false;
+  // Consider Op invariant, if it or its operands aren't predicated
+  // instruction in the loop. In that case, it is not trivially hoistable.
+  return !isa<Instruction>(Op) || !TheLoop->contains(cast<Instruction>(Op)) ||
+         (!isPredicatedInst(cast<Instruction>(Op)) &&
+          all_of(cast<Instruction>(Op)->operands(),
+                 [this](Value *Op) { return shouldConsiderInvariant(Op); }));
+}
+
 InstructionCost
 LoopVectorizationCostModel::getInstructionCost(Instruction *I,
                                                ElementCount VF) {
@@ -6621,19 +6636,8 @@ LoopVectorizationCostModel::getInstructionCost(Instruction *I,
       Op2 = cast<SCEVConstant>(PSE.getSCEV(Op2))->getValue();
     }
     auto Op2Info = TTI.getOperandInfo(Op2);
-    std::function<bool(Value *)> IsInvariant =
-        [this, &IsInvariant](Value *Op) -> bool {
-      if (!Legal->isInvariant(Op))
-        return false;
-      // Consider Op2invariant, if it or its operands aren't predicated
-      // instruction in the loop. In that case, it is not trivially hoistable.
-      return !isa<Instruction>(Op) ||
-             !TheLoop->contains(cast<Instruction>(Op)) ||
-             (!isPredicatedInst(cast<Instruction>(Op)) &&
-              all_of(cast<Instruction>(Op)->operands(),
-                     [&IsInvariant](Value *Op) { return IsInvariant(Op); }));
-    };
-    if (Op2Info.Kind == TargetTransformInfo::OK_AnyValue && IsInvariant(Op2))
+    if (Op2Info.Kind == TargetTransformInfo::OK_AnyValue &&
+        shouldConsiderInvariant(Op2))
       Op2Info.Kind = TargetTransformInfo::OK_UniformValue;
 
     SmallVector<const Value *, 4> Operands(I->operand_values());