Allow plugins to register LLVM passes

src/librustc/plugin/registry.rs

@@ -22,6 +22,7 @@ use syntax::ptr::P;
 use syntax::ast;
 
 use std::collections::HashMap;
+use std::borrow::ToOwned;
 
 /// Structure used to register plugins.
 ///
@@ -50,6 +51,9 @@ pub struct Registry<'a> {
 
     #[doc(hidden)]
     pub lint_groups: HashMap<&'static str, Vec<LintId>>,
+
+    #[doc(hidden)]
+    pub llvm_passes: Vec<String>,
 }
 
 impl<'a> Registry<'a> {
@@ -62,6 +66,7 @@ impl<'a> Registry<'a> {
             syntax_exts: vec!(),
             lint_passes: vec!(),
             lint_groups: HashMap::new(),
+            llvm_passes: vec!(),
         }
     }
 
@@ -116,4 +121,13 @@ impl<'a> Registry<'a> {
     pub fn register_lint_group(&mut self, name: &'static str, to: Vec<&'static Lint>) {
         self.lint_groups.insert(name, to.into_iter().map(|x| LintId::of(x)).collect());
     }
+
+    /// Register an LLVM pass.
+    ///
+    /// Registration with LLVM itself is handled through static C++ objects with
+    /// constructors. This method simply adds a name to the list of passes to
+    /// execute.
+    pub fn register_llvm_pass(&mut self, name: &str) {
+        self.llvm_passes.push(name.to_owned());
+    }
 }

src/librustc/session/mod.rs

@@ -52,6 +52,7 @@ pub struct Session {
     pub working_dir: PathBuf,
     pub lint_store: RefCell<lint::LintStore>,
     pub lints: RefCell<NodeMap<Vec<(lint::LintId, codemap::Span, String)>>>,
+    pub plugin_llvm_passes: RefCell<Vec<String>>,
     pub crate_types: RefCell<Vec<config::CrateType>>,
     pub crate_metadata: RefCell<Vec<String>>,
     pub features: RefCell<feature_gate::Features>,
@@ -391,6 +392,7 @@ pub fn build_session_(sopts: config::Options,
         working_dir: env::current_dir().unwrap(),
         lint_store: RefCell::new(lint::LintStore::new()),
         lints: RefCell::new(NodeMap()),
+        plugin_llvm_passes: RefCell::new(Vec::new()),
         crate_types: RefCell::new(Vec::new()),
         crate_metadata: RefCell::new(Vec::new()),
         features: RefCell::new(feature_gate::Features::new()),