[SLP]Fix a crash when reorder masked gather nodes with reused scalars.

[ABataev]

Summary

If the masked gather nodes must be reordered, we can just reorder
scalars, just like for gather nodes. But if the node contains reused
scalars, it must be handled same way as a regular vectorizable node,
since need to reorder reused mask, not the scalars directly.

[vdmitrie]

Looks good. Thanks for the fix.

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

if (TreeEntry *TE = getVectorizedOperand(UserTE, I)) {
                  [UserTE](const EdgeInfo &EI) { return EI.UserTE != UserTE; }))
         return false;
       // Add the node to the list of the ordered nodes with the identity
       // order.
       Edges.emplace_back(I, TE);
       // Add ScatterVectorize nodes to the list of operands, where just
       // reordering of the scalars is required. Similar to the gathers, so
       // simply add to the list of gathered ops.
-      if (TE->State != TreeEntry::Vectorize)
+      // If there are reused scalars, process this node as a regular vectorize
+      // node, just reorder reuses mask.
+      if (TE->State != TreeEntry::Vectorize && TE->ReuseShuffleIndices.empty())
         GatherOps.push_back(TE);
       continue;
     }
     ArrayRef<Value *> VL = UserTE->getOperand(I);
     TreeEntry *Gather = nullptr;
     if (count_if(ReorderableGathers,
                  [VL, &Gather](TreeEntry *TE) {
                    assert(TE->State != TreeEntry::Vectorize &&

llvm/test/Transforms/SLPVectorizer/X86/reorder-reused-masked-gather.ll

+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -slp-vectorizer -mattr=+avx512f -mtriple=x86_64 -S < %s | FileCheck %s
+
+define void @test(float* noalias %0, float* %p) {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <8 x float*> poison, float* [[P:%.*]], i32 0
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <8 x float*> [[TMP2]], <8 x float*> poison, <8 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr float, <8 x float*> [[SHUFFLE]], <8 x i64> <i64 15, i64 4, i64 5, i64 0, i64 2, i64 6, i64 7, i64 8>
+; CHECK-NEXT:    [[TMP4:%.*]] = getelementptr inbounds float, float* [[TMP0:%.*]], i64 2
+; CHECK-NEXT:    [[TMP5:%.*]] = call <8 x float> @llvm.masked.gather.v8f32.v8p0f32(<8 x float*> [[TMP3]], i32 4, <8 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true>, <8 x float> undef)
+; CHECK-NEXT:    [[SHUFFLE1:%.*]] = shufflevector <8 x float> [[TMP5]], <8 x float> poison, <16 x i32> <i32 4, i32 3, i32 0, i32 1, i32 2, i32 0, i32 1, i32 2, i32 0, i32 2, i32 5, i32 6, i32 7, i32 5, i32 6, i32 7>
+; CHECK-NEXT:    [[TMP6:%.*]] = shufflevector <16 x float> <float poison, float poison, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00>, <16 x float> [[SHUFFLE1]], <16 x i32> <i32 18, i32 19, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
+; CHECK-NEXT:    [[TMP7:%.*]] = fadd reassoc nsz arcp contract afn <16 x float> [[SHUFFLE1]], [[TMP6]]
+; CHECK-NEXT:    [[SHUFFLE2:%.*]] = shufflevector <16 x float> [[TMP7]], <16 x float> poison, <16 x i32> <i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 9, i32 0, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
+; CHECK-NEXT:    [[TMP8:%.*]] = bitcast float* [[TMP4]] to <16 x float>*
+; CHECK-NEXT:    store <16 x float> [[SHUFFLE2]], <16 x float>* [[TMP8]], align 4
+; CHECK-NEXT:    ret void
+;
+  %2 = getelementptr inbounds float, float* %p, i64 2
+  %3 = getelementptr inbounds float, float* %p, i64 4
+  %4 = load float, float* %3, align 4
+  %5 = getelementptr inbounds float, float* %p, i64 5
+  %6 = load float, float* %5, align 16
+  %7 = getelementptr inbounds float, float* %p, i64 15
+  %8 = load float, float* %7, align 4
+  %9 = fadd reassoc nsz arcp contract afn float %8, 0.000000e+00
+  %10 = getelementptr inbounds float, float* %0, i64 2
+  store float %9, float* %10, align 4
+  %11 = fadd reassoc nsz arcp contract afn float %4, 0.000000e+00
+  %12 = getelementptr inbounds float, float* %0, i64 3
+  store float %11, float* %12, align 4
+  %13 = fadd reassoc nsz arcp contract afn float %6, 0.000000e+00
+  %14 = getelementptr inbounds float, float* %0, i64 4
+  store float %13, float* %14, align 4
+  %15 = fadd reassoc nsz arcp contract afn float %8, 0.000000e+00
+  %16 = getelementptr inbounds float, float* %0, i64 5
+  store float %15, float* %16, align 4
+  %17 = fadd reassoc nsz arcp contract afn float %4, 0.000000e+00
+  %18 = load float, float* %p, align 16
+  %19 = getelementptr inbounds float, float* %0, i64 6
+  store float %17, float* %19, align 4
+  %20 = fadd reassoc nsz arcp contract afn float %6, 0.000000e+00
+  %21 = getelementptr inbounds float, float* %0, i64 7
+  store float %20, float* %21, align 4
+  %22 = fadd reassoc nsz arcp contract afn float %8, 0.000000e+00
+  %23 = load float, float* %2, align 8
+  %24 = getelementptr inbounds float, float* %0, i64 8
+  store float %22, float* %24, align 4
+  %25 = fadd reassoc nsz arcp contract afn float %4, %18
+  %26 = getelementptr inbounds float, float* %0, i64 9
+  store float %25, float* %26, align 4
+  %27 = fadd reassoc nsz arcp contract afn float %6, 0.000000e+00
+  %28 = getelementptr inbounds float, float* %0, i64 10
+  store float %27, float* %28, align 4
+  %29 = fadd reassoc nsz arcp contract afn float %8, %23
+  %30 = getelementptr inbounds float, float* %0, i64 11
+  store float %29, float* %30, align 4
+  %31 = getelementptr inbounds float, float* %p, i64 6
+  %32 = load float, float* %31, align 4
+  %33 = fadd reassoc nsz arcp contract afn float %32, 0.000000e+00
+  %34 = getelementptr inbounds float, float* %0, i64 12
+  store float %33, float* %34, align 4
+  %35 = getelementptr inbounds float, float* %p, i64 7
+  %36 = load float, float* %35, align 8
+  %37 = fadd reassoc nsz arcp contract afn float %36, 0.000000e+00
+  %38 = getelementptr inbounds float, float* %0, i64 13
+  store float %37, float* %38, align 4
+  %39 = getelementptr inbounds float, float* %p, i64 8
+  %40 = load float, float* %39, align 4
+  %41 = fadd reassoc nsz arcp contract afn float %40, 0.000000e+00
+  %42 = getelementptr inbounds float, float* %0, i64 14
+  store float %41, float* %42, align 4
+  %43 = fadd reassoc nsz arcp contract afn float %32, 0.000000e+00
+  %44 = getelementptr inbounds float, float* %0, i64 15
+  store float %43, float* %44, align 4
+  %45 = fadd reassoc nsz arcp contract afn float %36, 0.000000e+00
+  %46 = getelementptr inbounds float, float* %0, i64 16
+  store float %45, float* %46, align 4
+  %47 = fadd reassoc nsz arcp contract afn float %40, 0.000000e+00
+  %48 = getelementptr inbounds float, float* %0, i64 17
+  store float %47, float* %48, align 4
+  ret void
+}