From fd92015fe669fb21d656303dba99e50c90f87a5b Mon Sep 17 00:00:00 2001
From: nils <48135649+Nilstrieb@users.noreply.github.com>
Date: Wed, 20 Jul 2022 17:19:29 +0200
Subject: [PATCH] [perf] Don't emit noalias for box when compiling rustc itself

This compiles rustc without noalias on box to evaluate the performance
impact of such a change on a large scale project like rustc. Most
importantly, this does NOT change the emitting of noalias when compiling
crates other than rustc, to avoid perf impacts from LLVM having to
process less attributes like in #98017.
---
 src/bootstrap/builder.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 575cbc3beb2e7..af4f0abc64b5a 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -1403,6 +1403,7 @@ impl<'a> Builder<'a> {
                 cargo.args(s.split_whitespace());
             }
             rustflags.env("RUSTFLAGS_NOT_BOOTSTRAP");
+            rustflags.arg("-Zbox-noalias=no");
         } else {
             if let Ok(s) = env::var("CARGOFLAGS_BOOTSTRAP") {
                 cargo.args(s.split_whitespace());