[llvm] 1160994 - [SLP]Fix a crash for very long GEP chains

[Alexey Bataev via llvm-commits]

Author: Alexey Bataev
Date: 2025-01-08T06:47:41-08:00
New Revision: 1160994602b90890efd4df4e134e46cc3ad34bc8

URL: https://github.com/llvm/llvm-project/commit/1160994602b90890efd4df4e134e46cc3ad34bc8
DIFF: https://github.com/llvm/llvm-project/commit/1160994602b90890efd4df4e134e46cc3ad34bc8.diff

LOG: [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.

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

Modified: 
    llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index c4582df89213d8..894dc68b6146d3 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/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);

diff  --git a/llvm/test/Transforms/SLPVectorizer/RISCV/long-gep-chains.ll b/llvm/test/Transforms/SLPVectorizer/RISCV/long-gep-chains.ll
new file mode 100644
index 00000000000000..cf1ed54149b8b5
--- /dev/null
+++ b/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
+}