simplify LLVM submodule handling

Keep the LLVM submodule logic in single function to make it clear when it's called.

Signed-off-by: onur-ozkan <[email protected]>

src/bootstrap/src/core/build_steps/llvm.rs

@@ -88,9 +88,6 @@ impl LdFlags {
 /// This will return the llvm-config if it can get it (but it will not build it
 /// if not).
 pub fn prebuilt_llvm_config(builder: &Builder<'_>, target: TargetSelection) -> LlvmBuildStatus {
-    // If we have llvm submodule initialized already, sync it.
-    builder.update_existing_submodule("src/llvm-project");
-
     builder.config.maybe_download_ci_llvm();
 
     // If we're using a custom LLVM bail out here, but we can only use a
@@ -109,10 +106,6 @@ pub fn prebuilt_llvm_config(builder: &Builder<'_>, target: TargetSelection) -> L
         }
     }
 
-    // Initialize the llvm submodule if not initialized already.
-    // If submodules are disabled, this does nothing.
-    builder.config.update_submodule("src/llvm-project");
-
     let root = "src/llvm-project/llvm";
     let out_dir = builder.llvm_out(target);
 

src/bootstrap/src/core/config/config.rs

@@ -2737,6 +2737,12 @@ impl Config {
     ) -> bool {
         let download_ci_llvm = download_ci_llvm.unwrap_or(StringOrBool::Bool(true));
 
+        let update_llvm_submodule = || {
+            // Fetching the LLVM submodule is unnecessary for self-tests.
+            #[cfg(not(feature = "bootstrap-self-test"))]
+            self.update_submodule("src/llvm-project");
+        };
+
         let if_unchanged = || {
             if self.rust_info.is_from_tarball() {
                 // Git is needed for running "if-unchanged" logic.
@@ -2746,9 +2752,7 @@ impl Config {
                 return false;
             }
 
-            // Fetching the LLVM submodule is unnecessary for self-tests.
-            #[cfg(not(feature = "bootstrap-self-test"))]
-            self.update_submodule("src/llvm-project");
+            update_llvm_submodule();
 
             // Check for untracked changes in `src/llvm-project`.
             let has_changes = self
@@ -2761,10 +2765,14 @@ impl Config {
 
         match download_ci_llvm {
             StringOrBool::Bool(b) => {
-                if !b && self.download_rustc_commit.is_some() {
-                    panic!(
-                        "`llvm.download-ci-llvm` cannot be set to `false` if `rust.download-rustc` is set to `true` or `if-unchanged`."
-                    );
+                if !b {
+                    if self.download_rustc_commit.is_some() {
+                        panic!(
+                            "`llvm.download-ci-llvm` cannot be set to `false` if `rust.download-rustc` is set to `true` or `if-unchanged`."
+                        );
+                    }
+
+                    update_llvm_submodule();
                 }
 
                 // If download-ci-llvm=true we also want to check that CI llvm is available