[llvm] [VectorCombine] Fix crash in scalarizeVPIntrinsic (PR #72039)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Michael Maitland (michaelmaitland)

<details>
<summary>Changes</summary>

When getSplatOp returns nullptr, the intrinsic cannot be scalarized. This patch includes a test case that fixes a crash from trying to scalarize the VPIntrinsic when getSplatOp returns nullptr. This case can be scalarized in the future by improving getSplatOp, but the checks added in this patch should remain.

This fixes https://github.com/llvm/llvm-project/issues/72034.

---
Full diff: https://github.com/llvm/llvm-project/pull/72039.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Vectorize/VectorCombine.cpp (+2) 
- (added) llvm/test/Transforms/VectorCombine/RISCV/vpintrin-scalarization-shufflevector-splat.ll (+16) 


``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
index 9a91ce207bb04c9..6d79c9b13add067 100644
--- a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
+++ b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
@@ -843,6 +843,8 @@ bool VectorCombine::scalarizeVPIntrinsic(Instruction &I) {
 
   Value *ScalarOp0 = getSplatValue(Op0);
   Value *ScalarOp1 = getSplatValue(Op1);
+  if (!ScalarOp0 || !ScalarOp1)
+    return false;
   Value *ScalarVal =
       ScalarIntrID
           ? Builder.CreateIntrinsic(VecTy->getScalarType(), *ScalarIntrID,
diff --git a/llvm/test/Transforms/VectorCombine/RISCV/vpintrin-scalarization-shufflevector-splat.ll b/llvm/test/Transforms/VectorCombine/RISCV/vpintrin-scalarization-shufflevector-splat.ll
new file mode 100644
index 000000000000000..d3c477d180aa54f
--- /dev/null
+++ b/llvm/test/Transforms/VectorCombine/RISCV/vpintrin-scalarization-shufflevector-splat.ll
@@ -0,0 +1,16 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
+; RUN: opt -S -mtriple=riscv64 -mattr=+v %s -passes=vector-combine | FileCheck %s --check-prefix
+
+declare <4 x i64> @llvm.vp.add.v4i64(<4 x i64>, <4 x i64>, <4 x i1>, i32)
+
+define <4 x i64> @add_v4i64_allonesmask(<4 x i64> %x) {
+; CHECK-LABEL: define <4 x i64> @add_v4i64_allonesmask(
+; CHECK-SAME: <4 x i64> [[X:%.*]]) #[[ATTR1:[0-9]+]] {
+; CHECK-NEXT:    [[TMP1:%.*]] = shufflevector <4 x i64> [[X]], <4 x i64> zeroinitializer, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP2:%.*]] = call <4 x i64> @llvm.vp.add.v4i64(<4 x i64> [[TMP1]], <4 x i64> zeroinitializer, <4 x i1> <i1 true, i1 true, i1 true, i1 true>, i32 0)
+; CHECK-NEXT:    ret <4 x i64> [[TMP2]]
+;
+  %1 = shufflevector <4 x i64> %x, <4 x i64> zeroinitializer, <4 x i32> zeroinitializer
+  %2 = call <4 x i64> @llvm.vp.add.v4i64(<4 x i64> %1, <4 x i64> zeroinitializer, <4 x i1> <i1 true, i1 true, i1 true, i1 true>, i32 0)
+  ret <4 x i64> %2
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/72039