[llvm] [SLP] Check for instruction before casting (PR #195635)

[Alexey Bataev via llvm-commits]

https://github.com/alexey-bataev created https://github.com/llvm/llvm-project/pull/195635

Values can be transformed during earlier attempts for vectorization, so
need to check if they are still instructions to avoid a compiler crash.

Fixes #195607


>From a9125637eda8ca48bb72393031dc17de66a3f7dc Mon Sep 17 00:00:00 2001
From: Alexey Bataev <a.bataev at outlook.com>
Date: Mon, 4 May 2026 04:20:54 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.7
---
 .../lib/Transforms/Vectorize/SLPVectorizer.cpp |  9 +++++----
 .../X86/post-stores-non-inst-ops.ll            | 18 ++++++++++++++++++
 2 files changed, 23 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/Transforms/SLPVectorizer/X86/post-stores-non-inst-ops.ll

diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index a18df9c0882ab..43faf44564c9d 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -31124,11 +31124,12 @@ bool SLPVectorizerPass::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
       Type *ScalarTy = getValueType(PostProcessStores.front());
       if (!::isValidElementType(ScalarTy))
         return Changed;
+      auto *IF =
+          dyn_cast<Instruction>(PostProcessStores.front()->getValueOperand());
+      auto *IB =
+          dyn_cast<Instruction>(PostProcessStores.back()->getValueOperand());
       if (!NonVectReductions && PostProcessStores.size() == 2 &&
-          cast<Instruction>(PostProcessStores.front()->getValueOperand())
-                  ->getOpcode() !=
-              cast<Instruction>(PostProcessStores.back()->getValueOperand())
-                  ->getOpcode())
+          (!IF || !IB || IF->getOpcode() != IB->getOpcode()))
         return Changed;
       ScalarTy =
           IntegerType::get(ScalarTy->getContext(),
diff --git a/llvm/test/Transforms/SLPVectorizer/X86/post-stores-non-inst-ops.ll b/llvm/test/Transforms/SLPVectorizer/X86/post-stores-non-inst-ops.ll
new file mode 100644
index 0000000000000..fb93770a7a28e
--- /dev/null
+++ b/llvm/test/Transforms/SLPVectorizer/X86/post-stores-non-inst-ops.ll
@@ -0,0 +1,18 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt --passes=slp-vectorizer -S -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
+
+define i32 @test() {
+; CHECK-LABEL: define i32 @test() {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, ptr null, align 1
+; CHECK-NEXT:    store i8 [[TMP0]], ptr null, align 1
+; CHECK-NEXT:    store i32 0, ptr null, align 4
+; CHECK-NEXT:    ret i32 0
+;
+entry:
+  %0 = load i8, ptr null, align 1
+  store i8 %0, ptr null, align 1
+  %and = and i32 0, 0
+  store i32 %and, ptr null, align 4
+  ret i32 %and
+}