[SLP]Check if user node is same as other node and check operand order

Need to check if the user node is same as other node and check operand
order to prevent a compiler crash when trying to find matching gather
node with user nodes, having the same last instruction.

Fixes #131195

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -14081,6 +14081,17 @@ BoUpSLP::isGatherShuffledSingleRegisterEntry(
     }
     return true;
   };
+  auto CheckParentNodes = [&](const TreeEntry *User1, const TreeEntry *User2,
+                              unsigned EdgeIdx) {
+    const TreeEntry *Ptr1 = User1;
+    while (Ptr1) {
+      unsigned Idx = Ptr1->UserTreeIndex.EdgeIdx;
+      Ptr1 = Ptr1->UserTreeIndex.UserTE;
+      if (Ptr1 == User2)
+        return Idx < EdgeIdx;
+    }
+    return false;
+  };
   for (Value *V : VL) {
     if (isConstant(V) || !VisitedValue.insert(V).second)
       continue;
@@ -14121,6 +14132,9 @@ BoUpSLP::isGatherShuffledSingleRegisterEntry(
             (TEUseEI.UserTE->Idx < UseEI.UserTE->Idx ||
              HasGatherUser(TEUseEI.UserTE)))
           continue;
+        // If the user node is the operand of the other user node - skip.
+        if (CheckParentNodes(TEUseEI.UserTE, UseEI.UserTE, UseEI.EdgeIdx))
+          continue;
       }
 
       // Check if the user node of the TE comes after user node of TEPtr,

llvm/test/Transforms/SLPVectorizer/X86/user-node-with-same-last-instr.ll

@@ -0,0 +1,49 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S --passes=slp-vectorizer -mtriple=x86_64-unknown-linux-gnu -slp-threshold=-99999 < %s | FileCheck %s
+
+define void @wombat(i32 %arg) {
+; CHECK-LABEL: define void @wombat(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT:  [[BB:.*:]]
+; CHECK-NEXT:    br label %[[BB1:.*]]
+; CHECK:       [[BB1]]:
+; CHECK-NEXT:    br i1 false, label %[[BB2:.*]], label %[[BB5:.*]]
+; CHECK:       [[BB2]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = phi <2 x i32> [ [[TMP4:%.*]], %[[BB4:.*]] ], [ zeroinitializer, %[[BB1]] ]
+; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <2 x i32> <i32 poison, i32 1>, i32 [[ARG]], i32 0
+; CHECK-NEXT:    [[TMP2:%.*]] = sub <2 x i32> [[TMP0]], [[TMP1]]
+; CHECK-NEXT:    [[TMP3:%.*]] = or <2 x i32> [[TMP0]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4]] = shufflevector <2 x i32> [[TMP2]], <2 x i32> [[TMP3]], <2 x i32> <i32 0, i32 3>
+; CHECK-NEXT:    [[TMP5:%.*]] = insertelement <2 x i32> <i32 poison, i32 0>, i32 [[ARG]], i32 0
+; CHECK-NEXT:    [[TMP6:%.*]] = sub <2 x i32> [[TMP0]], [[TMP5]]
+; CHECK-NEXT:    [[TMP7:%.*]] = and <2 x i32> [[TMP0]], [[TMP5]]
+; CHECK-NEXT:    [[TMP8:%.*]] = shufflevector <2 x i32> [[TMP6]], <2 x i32> [[TMP7]], <2 x i32> <i32 0, i32 3>
+; CHECK-NEXT:    br label %[[BB4]]
+; CHECK:       [[BB4]]:
+; CHECK-NEXT:    br i1 false, label %[[BB2]], label %[[BB5]]
+; CHECK:       [[BB5]]:
+; CHECK-NEXT:    [[TMP9:%.*]] = phi <2 x i32> [ zeroinitializer, %[[BB1]] ], [ [[TMP8]], %[[BB4]] ]
+; CHECK-NEXT:    ret void
+;
+bb:
+  br label %bb1
+
+bb1:
+  br i1 false, label %bb2, label %bb5
+
+bb2:
+  %phi = phi i32 [ %or, %bb4 ], [ 0, %bb1 ]
+  %phi3 = phi i32 [ %sub, %bb4 ], [ 0, %bb1 ]
+  %or = or i32 %phi, 1
+  %and = and i32 0, %phi
+  %sub = sub i32 %phi3, %arg
+  br label %bb4
+
+bb4:
+  br i1 false, label %bb2, label %bb5
+
+bb5:
+  %phi6 = phi i32 [ 0, %bb1 ], [ %and, %bb4 ]
+  %phi7 = phi i32 [ 0, %bb1 ], [ %sub, %bb4 ]
+  ret void
+}