Add test for issue rust-lang#85872

This has been fixed by the LLVM 15 upgrade, add a codegen test.

Fixes rust-lang#85872.

Author: nikic

src/test/codegen/issue-85872-multiple-reverse.rs

@@ -0,0 +1,20 @@
+// min-llvm-version: 15.0.0
+// compile-flags: -O
+
+#![crate_type = "lib"]
+
+#[no_mangle]
+pub fn u16_be_to_arch(mut data: [u8; 2]) -> [u8; 2] {
+    // CHECK-LABEL: @u16_be_to_arch
+    // CHECK: @llvm.bswap.i16
+    data.reverse();
+    data
+}
+
+#[no_mangle]
+pub fn u32_be_to_arch(mut data: [u8; 4]) -> [u8; 4] {
+    // CHECK-LABEL: @u32_be_to_arch
+    // CHECK: @llvm.bswap.i32
+    data.reverse();
+    data
+}