[AArch64] Add test for llvm#90936. NFC

Author: topperc

llvm/test/CodeGen/AArch64/pr90936.ll

@@ -0,0 +1,18 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+; RUN: llc < %s -mtriple=aarch64 | FileCheck %s
+
+define void @f(i16 %arg, ptr %arg1) {
+; CHECK-LABEL: f:
+; CHECK:       // %bb.0: // %bb
+; CHECK-NEXT:    strh w0, [x1]
+; CHECK-NEXT:    ret
+bb:
+  %i = trunc i16 %arg to i8
+  %i2 = trunc i16 %arg to i14
+  %i3 = lshr i14 %i2, 8
+  store i8 %i, ptr %arg1, align 1
+  %i4 = getelementptr i8, ptr %arg1, i64 1
+  %i5 = trunc i14 %i3 to i8
+  store i8 %i5, ptr %i4, align 1
+  ret void
+}