Revert "Make the `c` feature for `compiler-builtins` opt-in instead of inferred"

[rust.git] / src / bootstrap / compile.rs

diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index e02a10b81640811b88770e6d95d9c378e32604d1..18e780a108d5a5420f677c2706786111766967d9 100644 (file)
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -299,7 +299,9 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
 
     // Determine if we're going to compile in optimized C intrinsics to
     // the `compiler-builtins` crate. These intrinsics live in LLVM's
-    // `compiler-rt` repository.
+    // `compiler-rt` repository, but our `src/llvm-project` submodule isn't
+    // always checked out, so we need to conditionally look for this. (e.g. if
+    // an external LLVM is used we skip the LLVM submodule checkout).
     //
     // Note that this shouldn't affect the correctness of `compiler-builtins`,
     // but only its speed. Some intrinsics in C haven't been translated to Rust
@@ -310,15 +312,8 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
     // If `compiler-rt` is available ensure that the `c` feature of the
     // `compiler-builtins` crate is enabled and it's configured to learn where
     // `compiler-rt` is located.
-    let compiler_builtins_c_feature = if builder.config.optimized_compiler_builtins {
-        if !builder.is_rust_llvm(target) {
-            panic!(
-                "need a managed LLVM submodule for optimized intrinsics support; unset `llvm-config` or `optimized-compiler-builtins`"
-            );
-        }
-
-        builder.update_submodule(&Path::new("src").join("llvm-project"));
-        let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
+    let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
+    let compiler_builtins_c_feature = if compiler_builtins_root.exists() {
         // Note that `libprofiler_builtins/build.rs` also computes this so if
         // you're changing something here please also change that.
         cargo.env("RUST_COMPILER_RT_ROOT", &compiler_builtins_root);