[VPlan] Exit earlier when trying to widen with scalar VFs.

This simplifies the code a bit, suggested in D124718.

Reviewed By: Ayal

Differential Revision: https://reviews.llvm.org/D125029

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index cc9e742..22993f2 100644 (file)
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -8137,8 +8137,6 @@ VPRecipeBase *VPRecipeBuilder::tryToWidenMemory(Instruction *I,
          "Must be called with either a load or store");
 
   auto willWiden = [&](ElementCount VF) -> bool {
-    if (VF.isScalar())
-      return false;
     LoopVectorizationCostModel::InstWidening Decision =
         CM.getWideningDecision(I, VF);
     assert(Decision != LoopVectorizationCostModel::CM_Unknown &&
@@ -8335,8 +8333,6 @@ VPWidenCallRecipe *VPRecipeBuilder::tryToWidenCall(CallInst *CI,
     return nullptr;
 
   auto willWiden = [&](ElementCount VF) -> bool {
-    if (VF.isScalar())
-       return false;
     Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
     // The following case may be scalarized depending on the VF.
     // The flag shows whether we use Intrinsic or a usual Call for vectorized
@@ -8550,14 +8546,8 @@ VPRecipeOrVPValueTy
 VPRecipeBuilder::tryToCreateWidenRecipe(Instruction *Instr,
                                         ArrayRef<VPValue *> Operands,
                                         VFRange &Range, VPlanPtr &Plan) {
-  // First, check for specific widening recipes that deal with calls, memory
-  // operations, inductions and Phi nodes.
-  if (auto *CI = dyn_cast<CallInst>(Instr))
-    return toVPRecipeResult(tryToWidenCall(CI, Operands, Range));
-
-  if (isa<LoadInst>(Instr) || isa<StoreInst>(Instr))
-    return toVPRecipeResult(tryToWidenMemory(Instr, Operands, Range, Plan));
-
+  // First, check for specific widening recipes that deal with inductions, Phi
+  // nodes, calls and memory operations.
   VPRecipeBase *Recipe;
   if (auto Phi = dyn_cast<PHINode>(Instr)) {
     if (Phi->getParent() != OrigLoop->getHeader())
@@ -8595,6 +8585,17 @@ VPRecipeBuilder::tryToCreateWidenRecipe(Instruction *Instr,
                                                Range, *Plan)))
     return toVPRecipeResult(Recipe);
 
+  // All widen recipes below deal only with VF > 1.
+  if (LoopVectorizationPlanner::getDecisionAndClampRange(
+          [&](ElementCount VF) { return VF.isScalar(); }, Range))
+    return nullptr;
+
+  if (auto *CI = dyn_cast<CallInst>(Instr))
+    return toVPRecipeResult(tryToWidenCall(CI, Operands, Range));
+
+  if (isa<LoadInst>(Instr) || isa<StoreInst>(Instr))
+    return toVPRecipeResult(tryToWidenMemory(Instr, Operands, Range, Plan));
+
   if (!shouldWiden(Instr, Range))
     return nullptr;