[llvm] 958e37c - [VectorCombine] scalarizeBinopOrCmp - check for out of bounds element indices

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2024-11-09T16:00:03Z
New Revision: 958e37cd1feabf29fb1cc3fb5ac82051ad8d43eb

URL: https://github.com/llvm/llvm-project/commit/958e37cd1feabf29fb1cc3fb5ac82051ad8d43eb
DIFF: https://github.com/llvm/llvm-project/commit/958e37cd1feabf29fb1cc3fb5ac82051ad8d43eb.diff

LOG: [VectorCombine] scalarizeBinopOrCmp - check for out of bounds element indices

Fixes #115575

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/VectorCombine.cpp
    llvm/test/Transforms/VectorCombine/X86/pr115575.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
index 04ea12ef0f1221..b8754b03c2ebc6 100644
--- a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
+++ b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
@@ -952,6 +952,12 @@ bool VectorCombine::scalarizeBinopOrCmp(Instruction &I) {
   if (!IsConst0 && !IsConst1 && Index0 != Index1)
     return false;
 
+  auto *VecTy0 = cast<VectorType>(Ins0->getType());
+  auto *VecTy1 = cast<VectorType>(Ins1->getType());
+  if (VecTy0->getElementCount().getKnownMinValue() <= Index0 ||
+      VecTy1->getElementCount().getKnownMinValue() <= Index1)
+    return false;
+
   // Bail for single insertion if it is a load.
   // TODO: Handle this once getVectorInstrCost can cost for load/stores.
   auto *I0 = dyn_cast_or_null<Instruction>(V0);

diff  --git a/llvm/test/Transforms/VectorCombine/X86/pr115575.ll b/llvm/test/Transforms/VectorCombine/X86/pr115575.ll
index 8e8bb808324e12..dd8e27727dd3c0 100644
--- a/llvm/test/Transforms/VectorCombine/X86/pr115575.ll
+++ b/llvm/test/Transforms/VectorCombine/X86/pr115575.ll
@@ -4,8 +4,8 @@
 define <2 x i8> @PR115575(i8 %x) {
 ; CHECK-LABEL: define <2 x i8> @PR115575(
 ; CHECK-SAME: i8 [[X:%.*]]) {
-; CHECK-NEXT:    [[BO_SCALAR:%.*]] = sdiv i8 [[X]], poison
-; CHECK-NEXT:    [[BO:%.*]] = insertelement <2 x i8> poison, i8 [[BO_SCALAR]], i64 3
+; CHECK-NEXT:    [[INS:%.*]] = insertelement <2 x i8> poison, i8 [[X]], i32 3
+; CHECK-NEXT:    [[BO:%.*]] = sdiv <2 x i8> [[INS]], <i8 5, i8 2>
 ; CHECK-NEXT:    ret <2 x i8> [[BO]]
 ;
   %ins = insertelement <2 x i8> poison, i8 %x, i32 3