[SLP]Do correct signedness analysis for clustered nodes

Should get the signedness info from the original scalar instructions, if
possible, to correctly generate sext/zext instructions. Also, the
clustered node must be assigned a gather node user info to correctly
estimate its bitwidth/sign.

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -9185,12 +9185,13 @@ void BoUpSLP::transformNodes() {
         for (unsigned Cnt : Slices) {
           ArrayRef<Value *> Slice = VL.slice(Cnt, VF);
           // If any instruction is vectorized already - do not try again.
-          if (const TreeEntry *SE = getTreeEntry(Slice.front());
+          if (TreeEntry *SE = getTreeEntry(Slice.front());
               SE || getTreeEntry(Slice.back())) {
             if (!SE)
               continue;
             if (VF != SE->getVectorFactor() || !SE->isSame(Slice))
               continue;
+            SE->UserTreeIndices.emplace_back(&E, UINT_MAX);
             AddCombinedNode(SE->Idx, Cnt);
             continue;
           }
@@ -13446,7 +13447,12 @@ class BoUpSLP::ShuffleInstructionBuilder final : public BaseShuffleAnalysis {
         if (CommonMask[Idx] != PoisonMaskElem)
           CommonMask[Idx] = Idx;
       for (auto [E, Idx] : SubVectors) {
-        Value *V = castToScalarTyElem(E->VectorizedValue);
+        Value *V = E->VectorizedValue;
+        if (V->getType()->isIntOrIntVectorTy())
+          V = castToScalarTyElem(V, any_of(E->Scalars, [&](Value *V) {
+                                   return !isKnownNonNegative(
+                                       V, SimplifyQuery(*R.DL));
+                                 }));
         Vec = Builder.CreateInsertVector(Vec->getType(), Vec, V,
                                          Builder.getInt64(Idx));
         if (!CommonMask.empty()) {

llvm/test/Transforms/SLPVectorizer/X86/subvector-minbitwidth-unsigned-value.ll

@@ -14,7 +14,7 @@ define i1 @test(i64 %v1, ptr %v2, i32 %v3, i1 %v4) {
 ; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq <2 x i32> [[TMP5]], zeroinitializer
 ; CHECK-NEXT:    [[TMP7:%.*]] = insertelement <4 x i32> poison, i32 [[V3]], i32 0
 ; CHECK-NEXT:    [[TMP8:%.*]] = shufflevector <4 x i32> [[TMP7]], <4 x i32> poison, <4 x i32> <i32 poison, i32 poison, i32 0, i32 0>
-; CHECK-NEXT:    [[TMP9:%.*]] = sext <2 x i8> [[TMP4]] to <2 x i32>
+; CHECK-NEXT:    [[TMP9:%.*]] = zext <2 x i8> [[TMP4]] to <2 x i32>
 ; CHECK-NEXT:    [[TMP10:%.*]] = call <4 x i32> @llvm.vector.insert.v4i32.v2i32(<4 x i32> [[TMP8]], <2 x i32> [[TMP9]], i64 0)
 ; CHECK-NEXT:    [[TMP11:%.*]] = uitofp <4 x i32> [[TMP10]] to <4 x float>
 ; CHECK-NEXT:    [[TMP12:%.*]] = fdiv <4 x float> zeroinitializer, [[TMP11]]