Allow using external builds of the compiler-rt profile lib

This changes the bootstrap config `target.*.profiler` from a plain bool
to also allow a string, which will be used as a path to the pre-built
profiling runtime for that target. Then `profiler_builtins/build.rs`
reads that in a `LLVM_PROFILER_RT_LIB` environment variable.

1 files changed, 6 insertions, 0 deletions

diff --git a/library/profiler_builtins/build.rs b/library/profiler_builtins/build.rs
index 1b1f11798d7..d14d0b82229 100644
--- a/library/profiler_builtins/build.rs
+++ b/library/profiler_builtins/build.rs
@@ -6,6 +6,12 @@ use std::env;
 use std::path::Path;
 
 fn main() {
+    println!("cargo:rerun-if-env-changed=LLVM_PROFILER_RT_LIB");
+    if let Ok(rt) = env::var("LLVM_PROFILER_RT_LIB") {
+        println!("cargo:rustc-link-lib=static:+verbatim={rt}");
+        return;
+    }
+
     let target = env::var("TARGET").expect("TARGET was not set");
     let cfg = &mut cc::Build::new();