Add -Zcross-crate-inline-threshold=yes

tests/codegen/cross-crate-inlining/leaf-inlining.rs

@@ -0,0 +1,20 @@
+// compile-flags: -O -Zcross-crate-inline-threshold=yes
+// aux-build:leaf.rs
+
+#![crate_type = "lib"]
+
+extern crate leaf;
+
+// Check that we inline a leaf cross-crate call
+#[no_mangle]
+pub fn leaf_outer() -> String {
+    // CHECK-NOT: call {{.*}}leaf_fn
+    leaf::leaf_fn()
+}
+
+// Check that we do not inline a non-leaf cross-crate call
+#[no_mangle]
+pub fn stem_outer() -> String {
+    // CHECK: call {{.*}}stem_fn
+    leaf::stem_fn()
+}