Add codegen test

Author: AnthonyMikh

src/test/codegen/slice-windows-no-bounds-check.rs

@@ -0,0 +1,35 @@
+#![crate_type = "lib"]
+
+// compile-flags: -O
+
+use std::slice::Windows;
+
+// CHECK-LABEL: @naive_string_search
+#[no_mangle]
+pub fn naive_string_search(haystack: &str, needle: &str) -> Option<usize> {
+    if needle.is_empty() {
+        return Some(0);
+    }
+    // CHECK-NOT: panic
+    // CHECK-NOT: fail
+    haystack
+        .as_bytes()
+        .windows(needle.len())
+        .position(|sub| sub == needle.as_bytes())
+}
+
+// CHECK-LABEL: @next
+#[no_mangle]
+pub fn next<'a>(w: &mut Windows<'a, u32>) -> Option<&'a [u32]> {
+    // CHECK-NOT: panic
+    // CHECK-NOT: fail
+    w.next()
+}
+
+// CHECK-LABEL: @next_back
+#[no_mangle]
+pub fn next_back<'a>(w: &mut Windows<'a, u32>) -> Option<&'a [u32]> {
+    // CHECK-NOT: panic
+    // CHECK-NOT: fail
+    w.next_back()
+}