[VPlan] Improve getOrCreateVPValueForSCEVExpr (NFC) (llvm#165699)

Use early exit in getOrCreateVPValueForSCEVExpr.

Author: artagnon

llvm/lib/Transforms/Vectorize/VPlanUtils.cpp

@@ -32,22 +32,17 @@ bool vputils::onlyScalarValuesUsed(const VPValue *Def) {
 }
 
 VPValue *vputils::getOrCreateVPValueForSCEVExpr(VPlan &Plan, const SCEV *Expr) {
-  VPValue *Expanded = nullptr;
   if (auto *E = dyn_cast<SCEVConstant>(Expr))
-    Expanded = Plan.getOrAddLiveIn(E->getValue());
-  else {
-    auto *U = dyn_cast<SCEVUnknown>(Expr);
-    // Skip SCEV expansion if Expr is a SCEVUnknown wrapping a non-instruction
-    // value. Otherwise the value may be defined in a loop and using it directly
-    // will break LCSSA form. The SCEV expansion takes care of preserving LCSSA
-    // form.
-    if (U && !isa<Instruction>(U->getValue())) {
-      Expanded = Plan.getOrAddLiveIn(U->getValue());
-    } else {
-      Expanded = new VPExpandSCEVRecipe(Expr);
-      Plan.getEntry()->appendRecipe(Expanded->getDefiningRecipe());
-    }
-  }
+    return Plan.getOrAddLiveIn(E->getValue());
+  // Skip SCEV expansion if Expr is a SCEVUnknown wrapping a non-instruction
+  // value. Otherwise the value may be defined in a loop and using it directly
+  // will break LCSSA form. The SCEV expansion takes care of preserving LCSSA
+  // form.
+  auto *U = dyn_cast<SCEVUnknown>(Expr);
+  if (U && !isa<Instruction>(U->getValue()))
+    return Plan.getOrAddLiveIn(U->getValue());
+  auto *Expanded = new VPExpandSCEVRecipe(Expr);
+  Plan.getEntry()->appendRecipe(Expanded);
   return Expanded;
 }