Add test showing bug

Author: ostannard

llvm/test/CodeGen/ARM/big-endian-vector-trunc.ll

@@ -0,0 +1,16 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=armebv7-unknown-none-eabihf -mattr=+neon < %s | FileCheck %s
+
+define i32 @test(i64 %arg1) "target-features"="+neon" {
+; CHECK-LABEL: test:
+; CHECK:       @ %bb.0: @ %entry
+; CHECK-NEXT:    mov r0, #0
+; CHECK-NEXT:    bx lr
+entry:
+  %insert_zero = insertelement <8 x i64> poison, i64 %arg1, i64 0
+  %splat_zero = shufflevector <8 x i64> %insert_zero, <8 x i64> poison, <8 x i32> zeroinitializer
+  %cmp_vec = icmp ule <8 x i64> <i64 0, i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7>, %splat_zero
+  %first_cmp = extractelement <8 x i1> %cmp_vec, i32 0
+  %ext = zext i1 %first_cmp to i32
+  ret i32 %ext
+}