[VPlan] Remove SCEVToExpansion mapping (NFC).

VPlan::SCEVToExpansion isn't needed any longer, as SCEV expansion
de-duplication is handled locally in expandSCEVs.

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -4166,11 +4166,6 @@ class VPlan {
   /// definitions are VPValues that hold a pointer to their underlying IR.
   SmallVector<VPValue *, 16> VPLiveIns;
 
-  /// Mapping from SCEVs to the VPValues representing their expansions.
-  /// NOTE: This mapping is temporary and will be removed once all users have
-  /// been modeled in VPlan directly.
-  DenseMap<const SCEV *, VPValue *> SCEVToExpansion;
-
   /// Blocks allocated and owned by the VPlan. They will be deleted once the
   /// VPlan is destroyed.
   SmallVector<VPBlockBase *> CreatedBlocks;
@@ -4427,15 +4422,6 @@ class VPlan {
   LLVM_DUMP_METHOD void dump() const;
 #endif
 
-  VPValue *getSCEVExpansion(const SCEV *S) const {
-    return SCEVToExpansion.lookup(S);
-  }
-
-  void addSCEVExpansion(const SCEV *S, VPValue *V) {
-    assert(!SCEVToExpansion.contains(S) && "SCEV already expanded");
-    SCEVToExpansion[S] = V;
-  }
-
   /// Clone the current VPlan, update all VPValues of the new VPlan and cloned
   /// recipes to refer to the clones, and return it.
   VPlan *duplicate();

llvm/lib/Transforms/Vectorize/VPlanUtils.cpp

@@ -32,8 +32,6 @@ bool vputils::onlyScalarValuesUsed(const VPValue *Def) {
 }
 
 VPValue *vputils::getOrCreateVPValueForSCEVExpr(VPlan &Plan, const SCEV *Expr) {
-  if (auto *Expanded = Plan.getSCEVExpansion(Expr))
-    return Expanded;
   VPValue *Expanded = nullptr;
   if (auto *E = dyn_cast<SCEVConstant>(Expr))
     Expanded = Plan.getOrAddLiveIn(E->getValue());
@@ -50,7 +48,6 @@ VPValue *vputils::getOrCreateVPValueForSCEVExpr(VPlan &Plan, const SCEV *Expr) {
       Plan.getEntry()->appendRecipe(Expanded->getDefiningRecipe());
     }
   }
-  Plan.addSCEVExpansion(Expr, Expanded);
   return Expanded;
 }