Revert "[SLP]Use the size of gathered scalars when evaluating slice size"

This reverts commit e78aa8f to fix
crashes reported in https://lab.llvm.org/buildbot/#/builders/140/builds/16047.

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -15094,7 +15094,7 @@ ResTy BoUpSLP::processBuildVector(const TreeEntry *E, Type *ScalarTy,
       }
     }
     if (!GatherShuffles.empty()) {
-      unsigned SliceSize = getPartNumElems(GatheredScalars.size(), NumParts);
+      unsigned SliceSize = getPartNumElems(E->Scalars.size(), NumParts);
       SmallVector<int> VecMask(Mask.size(), PoisonMaskElem);
       for (const auto [I, TEs] : enumerate(Entries)) {
         if (TEs.empty()) {

llvm/test/Transforms/SLPVectorizer/X86/gathered-shuffle-resized.ll

@@ -18,9 +18,9 @@ define ptr @test(ptr %0, ptr %args_gep) {
 ; CHECK-NEXT:    [[TMP8:%.*]] = load i32, ptr [[TMP7]], align 4, !noalias [[META0:![0-9]+]]
 ; CHECK-NEXT:    [[TMP9:%.*]] = load <2 x i32>, ptr [[TMP6]], align 8, !noalias [[META0]]
 ; CHECK-NEXT:    [[TMP10:%.*]] = shufflevector <2 x i32> [[TMP1]], <2 x i32> poison, <4 x i32> <i32 0, i32 1, i32 poison, i32 poison>
-; CHECK-NEXT:    [[TMP11:%.*]] = shufflevector <2 x i32> [[TMP9]], <2 x i32> poison, <16 x i32> <i32 poison, i32 poison, i32 0, i32 1, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
+; CHECK-NEXT:    [[TMP11:%.*]] = shufflevector <2 x i32> [[TMP9]], <2 x i32> poison, <16 x i32> poison
 ; CHECK-NEXT:    [[TMP12:%.*]] = shufflevector <4 x i32> [[TMP10]], <4 x i32> poison, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
-; CHECK-NEXT:    [[TMP13:%.*]] = shufflevector <2 x i32> [[TMP1]], <2 x i32> [[TMP9]], <16 x i32> <i32 0, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 3, i32 3, i32 3>
+; CHECK-NEXT:    [[TMP13:%.*]] = shufflevector <2 x i32> [[TMP1]], <2 x i32> [[TMP9]], <16 x i32> <i32 0, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
 ; CHECK-NEXT:    [[TMP14:%.*]] = icmp eq <16 x i32> [[TMP13]], zeroinitializer
 ; CHECK-NEXT:    [[TMP15:%.*]] = zext <16 x i1> [[TMP14]] to <16 x i8>
 ; CHECK-NEXT:    store <16 x i8> [[TMP15]], ptr [[TMP5]], align 1