From c9d04c2b238dc5ab51bd8a92c41ba17bb5b00ed7 Mon Sep 17 00:00:00 2001
From: Giacomo Stevanato <giaco.stevanato@gmail.com>
Date: Sun, 24 Jan 2021 21:07:25 +0100
Subject: [PATCH] Add codegen test checking binary_search allows eliding bound
 checks

---
 .../binary-search-index-no-bound-check.rs     | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 src/test/codegen/binary-search-index-no-bound-check.rs

diff --git a/src/test/codegen/binary-search-index-no-bound-check.rs b/src/test/codegen/binary-search-index-no-bound-check.rs
new file mode 100644
index 000000000000..110d1d55626f
--- /dev/null
+++ b/src/test/codegen/binary-search-index-no-bound-check.rs
@@ -0,0 +1,19 @@
+// min-llvm-version: 11.0.0
+// compile-flags: -O
+// ignore-debug: the debug assertions get in the way
+#![crate_type = "lib"]
+
+// Make sure no bounds checks are emitted when slicing or indexing
+// with an index from `binary_search`.
+
+// CHECK-LABEL: @binary_search_index_no_bounds_check
+#[no_mangle]
+pub fn binary_search_index_no_bounds_check(s: &[u8]) -> u8 {
+    // CHECK-NOT: panic
+    // CHECK-NOT: slice_index_len_fail
+    if let Ok(idx) = s.binary_search(&b'\\') {
+        s[idx]
+    } else {
+        42
+    }
+}