Multiple bounds checking elision failures

rust-lang · samueltardieu · Jun 17, 2025 · Jun 17, 2025 · Jun 18, 2025 · Jun 25, 2025
commit 19c6815a212d86c389ef54c3ddb02697ffc45f93
diff --git a/tests/codegen-llvm/bounds-check-elision-slice-min.rs b/tests/codegen-llvm/bounds-check-elision-slice-min.rs
@@ -0,0 +1,19 @@
+//! Regression test for #<https://github.com/rust-lang/rust/issues/120433>:
+//! Multiple bounds checking elision failures
+//! (ensures bounds checks are properly elided,
+//! with no calls to panic_bounds_check in the LLVM IR).
+
+//@ compile-flags: -C opt-level=3
+
+#![crate_type = "lib"]
+
+// CHECK-LABEL: @foo
+// CHECK-NOT: panic_bounds_check
+#[no_mangle]
+pub fn foo(buf: &[u8], alloced_size: usize) -> &[u8] {
+    if alloced_size.checked_add(1).map(|total| buf.len() < total).unwrap_or(true) {
+        return &[];
+    }
+    let size = buf[0];
+    &buf[1..1 + usize::min(alloced_size, usize::from(size))]
+}