add codegen test for rust-lang#68667

Author: tesuji

tests/codegen/issues/issue-68667-unwrap-combinators.rs

@@ -0,0 +1,17 @@
+#![crate_type = "lib"]
+
+//@ compile-flags: -O
+
+// MIR inlining now optimizes this code.
+
+// CHECK-LABEL: @unwrap_combinators
+// CHECK: icmp
+// CHECK-NEXT: icmp
+// CHECK-NEXT: select i1
+// CHECK-NEXT: ret i1
+#[no_mangle]
+pub fn unwrap_combinators(a: Option<i32>, b: i32) -> bool {
+    a.map(|t| t >= b)
+     .unwrap_or(false)
+}
+