[SLP]Fix a crash for very long GEP chains

Need to check if the GEP bases are equal and return false early. Also,
need to return false if the lookup is too deep, considering bases equal
too. Fixes a crash in the assertion.

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -5355,11 +5355,10 @@ static bool clusterSortPtrAccesses(ArrayRef<Value *> VL,
     SmallPtrSet<Value *, 13> SecondPointers;
     Value *P1 = Ptr1;
     Value *P2 = Ptr2;
-    if (P1 == P2)
-      return false;
     unsigned Depth = 0;
-    while (!FirstPointers.contains(P2) && !SecondPointers.contains(P1) &&
-           Depth <= RecursionMaxDepth) {
+    while (!FirstPointers.contains(P2) && !SecondPointers.contains(P1)) {
+      if (P1 == P2 || Depth > RecursionMaxDepth)
+        return false;
       FirstPointers.insert(P1);
       SecondPointers.insert(P2);
       P1 = getUnderlyingObject(P1, /*MaxLookup=*/1);

llvm/test/Transforms/SLPVectorizer/RISCV/long-gep-chains.ll

@@ -0,0 +1,76 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S -passes=slp-vectorizer -mtriple=riscv64-unknown-linux -mattr=+v < %s |  FileCheck %s
+
+define i64 @test(ptr %arg, i32 %arg1, i64 %i) {
+; CHECK-LABEL: define i64 @test(
+; CHECK-SAME: ptr [[ARG:%.*]], i32 [[ARG1:%.*]], i64 [[I:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT:  [[BB:.*:]]
+; CHECK-NEXT:    [[I2:%.*]] = getelementptr i8, ptr [[ARG]], i64 [[I]]
+; CHECK-NEXT:    [[I3:%.*]] = getelementptr i8, ptr [[I2]], i64 [[I]]
+; CHECK-NEXT:    [[I4:%.*]] = getelementptr i8, ptr [[I3]], i64 [[I]]
+; CHECK-NEXT:    [[I5:%.*]] = getelementptr i8, ptr [[I4]], i64 [[I]]
+; CHECK-NEXT:    [[I6:%.*]] = getelementptr i8, ptr [[I5]], i64 [[I]]
+; CHECK-NEXT:    [[I7:%.*]] = getelementptr i8, ptr [[I6]], i64 [[I]]
+; CHECK-NEXT:    [[I8:%.*]] = getelementptr i8, ptr [[I7]], i64 [[I]]
+; CHECK-NEXT:    [[I9:%.*]] = getelementptr i8, ptr [[I8]], i64 [[I]]
+; CHECK-NEXT:    [[I10:%.*]] = getelementptr i8, ptr [[I9]], i64 [[I]]
+; CHECK-NEXT:    [[I11:%.*]] = getelementptr i8, ptr [[I10]], i64 [[I]]
+; CHECK-NEXT:    [[I12:%.*]] = getelementptr i8, ptr [[I11]], i64 [[I]]
+; CHECK-NEXT:    [[I13:%.*]] = getelementptr i8, ptr [[I12]], i64 [[I]]
+; CHECK-NEXT:    [[I14:%.*]] = getelementptr i8, ptr [[I13]], i64 [[I]]
+; CHECK-NEXT:    [[I140:%.*]] = load i8, ptr [[I14]], align 1
+; CHECK-NEXT:    [[I1412:%.*]] = zext i8 [[I140]] to i32
+; CHECK-NEXT:    [[I142:%.*]] = mul i32 [[ARG1]], [[I1412]]
+; CHECK-NEXT:    [[I143:%.*]] = getelementptr i8, ptr [[I13]], i64 15
+; CHECK-NEXT:    [[I144:%.*]] = load i8, ptr [[I143]], align 1
+; CHECK-NEXT:    [[I1453:%.*]] = zext i8 [[I144]] to i32
+; CHECK-NEXT:    [[I146:%.*]] = mul i32 [[ARG1]], [[I1453]]
+; CHECK-NEXT:    [[I147:%.*]] = getelementptr i8, ptr [[I13]], i64 14
+; CHECK-NEXT:    [[I148:%.*]] = load i8, ptr [[I147]], align 1
+; CHECK-NEXT:    [[I1494:%.*]] = zext i8 [[I148]] to i32
+; CHECK-NEXT:    [[I150:%.*]] = mul i32 [[ARG1]], [[I1494]]
+; CHECK-NEXT:    [[I151:%.*]] = getelementptr i8, ptr [[I13]], i64 13
+; CHECK-NEXT:    [[I152:%.*]] = load i8, ptr [[I151]], align 1
+; CHECK-NEXT:    [[I1535:%.*]] = zext i8 [[I152]] to i32
+; CHECK-NEXT:    [[I154:%.*]] = mul i32 [[ARG1]], [[I1535]]
+; CHECK-NEXT:    [[I1311:%.*]] = or i32 [[I142]], [[I146]]
+; CHECK-NEXT:    [[I1312:%.*]] = or i32 [[I1311]], [[I150]]
+; CHECK-NEXT:    [[I1313:%.*]] = or i32 [[I1312]], [[I154]]
+; CHECK-NEXT:    [[I1536:%.*]] = zext i32 [[I1313]] to i64
+; CHECK-NEXT:    ret i64 [[I1536]]
+;
+bb:
+  %i2 = getelementptr i8, ptr %arg, i64 %i
+  %i3 = getelementptr i8, ptr %i2, i64 %i
+  %i4 = getelementptr i8, ptr %i3, i64 %i
+  %i5 = getelementptr i8, ptr %i4, i64 %i
+  %i6 = getelementptr i8, ptr %i5, i64 %i
+  %i7 = getelementptr i8, ptr %i6, i64 %i
+  %i8 = getelementptr i8, ptr %i7, i64 %i
+  %i9 = getelementptr i8, ptr %i8, i64 %i
+  %i10 = getelementptr i8, ptr %i9, i64 %i
+  %i11 = getelementptr i8, ptr %i10, i64 %i
+  %i12 = getelementptr i8, ptr %i11, i64 %i
+  %i13 = getelementptr i8, ptr %i12, i64 %i
+  %i14 = getelementptr i8, ptr %i13, i64 %i
+  %i140 = load i8, ptr %i14, align 1
+  %i1412 = zext i8 %i140 to i32
+  %i142 = mul i32 %arg1, %i1412
+  %i143 = getelementptr i8, ptr %i13, i64 15
+  %i144 = load i8, ptr %i143, align 1
+  %i1453 = zext i8 %i144 to i32
+  %i146 = mul i32 %arg1, %i1453
+  %i147 = getelementptr i8, ptr %i13, i64 14
+  %i148 = load i8, ptr %i147, align 1
+  %i1494 = zext i8 %i148 to i32
+  %i150 = mul i32 %arg1, %i1494
+  %i151 = getelementptr i8, ptr %i13, i64 13
+  %i152 = load i8, ptr %i151, align 1
+  %i1535 = zext i8 %i152 to i32
+  %i154 = mul i32 %arg1, %i1535
+  %i1311 = or i32 %i142, %i146
+  %i1312 = or i32 %i1311, %i150
+  %i1313 = or i32 %i1312, %i154
+  %i1536 = zext i32 %i1313 to i64
+  ret i64 %i1536
+}