[AArch64] Add test for constant shrinking with multiple users (NFC).

Test to avoid regression fixed by rL350684.

llvm-svn: 350762

llvm/test/CodeGen/AArch64/shrink-constant-multiple-users.ll

@@ -0,0 +1,18 @@
+; RUN: llc -mtriple arm64-ios- %s -o - | FileCheck %s
+
+; Check the -8 constant is shrunk if there are multiple users of the AND instruction.
+
+; CHECK-LABEL:  _test:
+; CHECK:          and x0, x0, #0xfffffff8
+; CHECK-NEXT:     add x19, x0, #10
+; CHECK-NEXT:     bl  _user
+
+define i64 @test(i32 %a) {
+  %ext = zext i32 %a to i64
+  %v1 = and i64 %ext, -8
+  %v2 = add i64 %v1, 10
+  call void @user(i64 %v1)
+  ret i64 %v2
+}
+
+declare void @user(i64)