[X86] Add test case for D58805. NFC

This demonstrates dead store elimination removing a store that may alias a gather that uses null as its base.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@355227 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Transforms/DeadStoreElimination/X86/gather-null-pointer.ll b/test/Transforms/DeadStoreElimination/X86/gather-null-pointer.ll
new file mode 100644 (file)
index 0000000..bd187c0
--- /dev/null
+++ b/test/Transforms/DeadStoreElimination/X86/gather-null-pointer.ll
@@ -0,0 +1,20 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -dse -S | FileCheck %s
+
+; Both stores should be emitted because we can't tell if the gather aliases.
+
+define <4 x i32> @bar(<4 x i32> %arg, i32* %arg1) {
+; CHECK-LABEL: @bar(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[TMP:%.*]] = tail call <4 x i32> @llvm.x86.avx2.gather.d.d(<4 x i32> zeroinitializer, i8* null, <4 x i32> [[ARG:%.*]], <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>, i8 1)
+; CHECK-NEXT:    store i32 10, i32* [[ARG1:%.*]]
+; CHECK-NEXT:    ret <4 x i32> [[TMP]]
+;
+bb:
+  store i32 5, i32* %arg1
+  %tmp = tail call <4 x i32> @llvm.x86.avx2.gather.d.d(<4 x i32> zeroinitializer, i8* null, <4 x i32> %arg, <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>, i8 1)
+  store i32 10, i32* %arg1
+  ret <4 x i32> %tmp
+}
+
+declare <4 x i32> @llvm.x86.avx2.gather.d.d(<4 x i32>, i8*, <4 x i32>, <4 x i32>, i8)