patch widen-cast in isSingleScalar

Author: Mel-Chen

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -1175,7 +1175,7 @@ static void narrowToSingleScalarRecipes(VPlan &Plan) {
            vp_depth_first_shallow(Plan.getVectorLoopRegion()->getEntry()))) {
     for (VPRecipeBase &R : make_early_inc_range(reverse(*VPBB))) {
       auto *RepR = dyn_cast<VPReplicateRecipe>(&R);
-      if (!RepR && !isa<VPWidenRecipe>(&R))
+      if (!RepR && !isa<VPWidenRecipe, VPWidenCastRecipe>(&R))
         continue;
       if (RepR && (RepR->isSingleScalar() || RepR->isPredicated()))
         continue;

llvm/lib/Transforms/Vectorize/VPlanUtils.h

@@ -75,6 +75,11 @@ inline bool isSingleScalar(const VPValue *VPV) {
     return PreservesUniformity(WidenR->getOpcode()) &&
            all_of(WidenR->operands(), isSingleScalar);
   }
+  if (auto *CastR = dyn_cast<VPWidenCastRecipe>(VPV)) {
+    return PreservesUniformity(CastR->getOpcode()) &&
+           all_of(CastR->operands(), isSingleScalar);
+  }
+
   if (auto *VPI = dyn_cast<VPInstruction>(VPV))
     return VPI->isSingleScalar() || VPI->isVectorToScalar() ||
            (PreservesUniformity(VPI->getOpcode()) &&

llvm/test/Transforms/LoopVectorize/X86/cost-model.ll

@@ -378,8 +378,8 @@ define void @multi_exit(ptr %dst, ptr %src.1, ptr %src.2, i64 %A, i64 %B) #0 {
 ; CHECK-NEXT:    [[TMP15:%.*]] = icmp eq <2 x i64> [[BROADCAST_SPLAT]], zeroinitializer
 ; CHECK-NEXT:    [[TMP16:%.*]] = icmp ne <2 x i64> [[BROADCAST_SPLAT10]], zeroinitializer
 ; CHECK-NEXT:    [[TMP17:%.*]] = and <2 x i1> [[TMP16]], [[TMP15]]
-; CHECK-NEXT:    [[TMP18:%.*]] = zext <2 x i1> [[TMP17]] to <2 x i8>
-; CHECK-NEXT:    [[TMP19:%.*]] = extractelement <2 x i8> [[TMP18]], i32 1
+; CHECK-NEXT:    [[TMP18:%.*]] = extractelement <2 x i1> [[TMP17]], i32 0
+; CHECK-NEXT:    [[TMP19:%.*]] = zext i1 [[TMP18]] to i8
 ; CHECK-NEXT:    store i8 [[TMP19]], ptr [[DST]], align 1, !alias.scope [[META10:![0-9]+]], !noalias [[META12:![0-9]+]]
 ; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
 ; CHECK-NEXT:    [[TMP20:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]