Enable relocations for BOLT

Author: Kobzol

src/bootstrap/bin/rustc.rs

@@ -217,6 +217,12 @@ fn main() {
         eprintln!("{prefix} libdir: {libdir:?}");
     }
 
+    if env::var_os("RUSTC_BOLT_LINK_FLAGS").is_some() {
+        if let Some("rustc_driver") = crate_name {
+            cmd.arg("-Clink-args=-Wl,-q");
+        }
+    }
+
     let start = Instant::now();
     let (child, status) = {
         let errmsg = format!("\nFailed to run:\n{cmd:?}\n-------------");

src/bootstrap/compile.rs

@@ -906,6 +906,11 @@ impl Step for Rustc {
             cargo.arg("-p").arg(krate);
         }
 
+        if compiler.stage == 1 {
+            // Relocations are required for BOLT to work.k
+            cargo.env("RUSTC_BOLT_LINK_FLAGS", "1");
+        }
+
         let _guard = builder.msg_sysroot_tool(
             Kind::Build,
             compiler.stage,