[SLP][X86] Add test coverage for #111126

This needs to be expanded to a wider range of tests but for now just focus on #111126

Author: RKSimon

llvm/test/Transforms/SLPVectorizer/X86/store-constant.ll

@@ -0,0 +1,32 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -S -mtriple=x86_64-- -passes=slp-vectorizer -mcpu=x86-64    | FileCheck %s --check-prefixes=SSE
+; RUN: opt < %s -S -mtriple=x86_64-- -passes=slp-vectorizer -mcpu=x86-64-v2 | FileCheck %s --check-prefixes=SSE
+; RUN: opt < %s -S -mtriple=x86_64-- -passes=slp-vectorizer -mcpu=x86-64-v3 | FileCheck %s --check-prefixes=AVX
+; RUN: opt < %s -S -mtriple=x86_64-- -passes=slp-vectorizer -mcpu=x86-64-v4 | FileCheck %s --check-prefixes=AVX
+
+@arr = global [20 x i64] zeroinitializer, align 16
+
+define void @PR111126() {
+; SSE-LABEL: @PR111126(
+; SSE-NEXT:    store i64 1, ptr @arr, align 16
+; SSE-NEXT:    store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 8), align 8
+; SSE-NEXT:    store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 16), align 16
+; SSE-NEXT:    store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 24), align 8
+; SSE-NEXT:    store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 32), align 16
+; SSE-NEXT:    store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 40), align 8
+; SSE-NEXT:    ret void
+;
+; AVX-LABEL: @PR111126(
+; AVX-NEXT:    store <4 x i64> splat (i64 1), ptr @arr, align 16
+; AVX-NEXT:    store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 32), align 16
+; AVX-NEXT:    store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 40), align 8
+; AVX-NEXT:    ret void
+;
+  store i64 1, ptr @arr, align 16
+  store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 8), align 8
+  store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 16), align 16
+  store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 24), align 8
+  store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 32), align 16
+  store i64 1, ptr getelementptr inbounds (i8, ptr @arr, i64 40), align 8
+  ret void
+}