Add testcase that should have been added to 56b7b08.

The test is testing the handling of vector registers and is thus
restricted to x86_64.

rdar://problem/27891980
(cherry picked from commit 4a85b83)

Author: adrian-prantl

test/DebugInfo/liverange-extension-vector.swift

@@ -0,0 +1,15 @@
+// RUN: %target-swift-frontend %s -g -emit-ir -o - | %FileCheck %s
+// REQUIRES: objc_interop, CPU=x86_64
+import simd
+
+func use<T>(_ x: T) {}
+
+func getInt32() -> Int32 { return -1 }
+
+public func rangeExtension(x: Int32, y: Int32) {
+  let p = int2(x, y)
+  // CHECK: define {{.*}}rangeExtension
+  // CHECK: llvm.dbg.value(metadata <2 x i32> %[[P:.*]], i64 0, metadata
+  use(p)
+  // CHECK: asm sideeffect "", "r"{{.*}}[[P]]
+}