Support compiling rustc without LLVM

src/bootstrap/config.rs

@@ -53,6 +53,7 @@ pub struct Config {
     pub profiler: bool,
 
     // llvm codegen options
+    pub llvm_enabled: bool,
     pub llvm_assertions: bool,
     pub llvm_optimize: bool,
     pub llvm_release_debuginfo: bool,
@@ -182,6 +183,7 @@ struct Install {
 /// TOML representation of how the LLVM build is configured.
 #[derive(RustcDecodable, Default)]
 struct Llvm {
+    enabled: Option<bool>,
     ccache: Option<StringOrBool>,
     ninja: Option<bool>,
     assertions: Option<bool>,
@@ -252,6 +254,7 @@ struct TomlTarget {
 impl Config {
     pub fn parse(build: &str, file: Option<PathBuf>) -> Config {
         let mut config = Config::default();
+        config.llvm_enabled = true;
         config.llvm_optimize = true;
         config.use_jemalloc = true;
         config.backtrace = true;
@@ -345,6 +348,7 @@ impl Config {
                 Some(StringOrBool::Bool(false)) | None => {}
             }
             set(&mut config.ninja, llvm.ninja);
+            set(&mut config.llvm_enabled, llvm.enabled);
             set(&mut config.llvm_assertions, llvm.assertions);
             set(&mut config.llvm_optimize, llvm.optimize);
             set(&mut config.llvm_release_debuginfo, llvm.release_debuginfo);

src/bootstrap/config.toml.example

@@ -14,6 +14,9 @@
 # =============================================================================
 [llvm]
 
+# Indicates whether rustc will support compilation with LLVM (currently broken)
+#enabled = true
+
 # Indicates whether the LLVM build is a Release or Debug build
 #optimize = true
 

src/bootstrap/lib.rs

@@ -583,6 +583,9 @@ impl Build {
         if self.config.use_jemalloc {
             features.push_str(" jemalloc");
         }
+        if self.config.llvm_enabled {
+            features.push_str(" llvm");
+        }
         return features
     }
 

src/bootstrap/native.rs

@@ -35,6 +35,11 @@ use build_helper::up_to_date;
 
 /// Compile LLVM for `target`.
 pub fn llvm(build: &Build, target: &str) {
+    // If we're not compiling for LLVM bail out here.
+    if !build.config.llvm_enabled {
+        return;
+    }
+
     // If we're using a custom LLVM bail out here, but we can only use a
     // custom LLVM for the build triple.
     if let Some(config) = build.config.target_config.get(target) {

src/librustc_driver/Cargo.toml

@@ -29,9 +29,12 @@ rustc_plugin = { path = "../librustc_plugin" }
 rustc_privacy = { path = "../librustc_privacy" }
 rustc_resolve = { path = "../librustc_resolve" }
 rustc_save_analysis = { path = "../librustc_save_analysis" }
-rustc_trans = { path = "../librustc_trans" }
+rustc_trans = { path = "../librustc_trans", optional=true }
 rustc_typeck = { path = "../librustc_typeck" }
 serialize = { path = "../libserialize" }
 syntax = { path = "../libsyntax" }
 syntax_ext = { path = "../libsyntax_ext" }
 syntax_pos = { path = "../libsyntax_pos" }
+
+[features]
+llvm = ["rustc_trans"]

src/librustc_driver/driver.rs

@@ -31,7 +31,11 @@ use rustc_incremental::{self, IncrementalHashesMap};
 use rustc_resolve::{MakeGlobMap, Resolver};
 use rustc_metadata::creader::CrateLoader;
 use rustc_metadata::cstore::{self, CStore};
+#[cfg(feature="llvm")]
 use rustc_trans::back::{link, write};
+#[cfg(not(feature="llvm"))]
+use ::link;
+#[cfg(feature="llvm")]
 use rustc_trans as trans;
 use rustc_typeck as typeck;
 use rustc_privacy;
@@ -111,7 +115,7 @@ pub fn compile_input(sess: &Session,
         };
 
         let outputs = build_output_filenames(input, outdir, output, &krate.attrs, sess);
-        let crate_name = link::find_crate_name(Some(sess), &krate.attrs, input);
+        let crate_name: String = link::find_crate_name(Some(sess), &krate.attrs, input);
         let ExpansionResult { expanded_crate, defs, analysis, resolutions, mut hir_forest } = {
             phase_2_configure_and_expand(
                 sess, &cstore, krate, registry, &crate_name, addl_plugins, control.make_glob_map,
@@ -204,55 +208,71 @@ pub fn compile_input(sess: &Session,
                 println!("Pre-trans");
                 tcx.print_debug_stats();
             }
-            let trans = phase_4_translate_to_llvm(tcx, analysis, &incremental_hashes_map,
-                                                  &outputs);
 
-            if log_enabled!(::log::LogLevel::Info) {
-                println!("Post-trans");
-                tcx.print_debug_stats();
-            }
+            #[cfg(feature="llvm")]
+            {
+                let trans = phase_4_translate_to_llvm(tcx, analysis, &incremental_hashes_map,
+                                                    &outputs);
+
+                if log_enabled!(::log::LogLevel::Info) {
+                    println!("Post-trans");
+                    tcx.print_debug_stats();
+                }
 
-            if tcx.sess.opts.output_types.contains_key(&OutputType::Mir) {
-                if let Err(e) = mir::transform::dump_mir::emit_mir(tcx, &outputs) {
-                    sess.err(&format!("could not emit MIR: {}", e));
-                    sess.abort_if_errors();
+                if tcx.sess.opts.output_types.contains_key(&OutputType::Mir) {
+                    if let Err(e) = mir::transform::dump_mir::emit_mir(tcx, &outputs) {
+                        sess.err(&format!("could not emit MIR: {}", e));
+                        sess.abort_if_errors();
+                    }
                 }
+
+                return Ok((outputs, trans))
             }
 
-            Ok((outputs, trans))
+            #[cfg(not(feature="llvm"))]
+            panic!("Unreachable")
         })??
     };
 
     if sess.opts.debugging_opts.print_type_sizes {
         sess.code_stats.borrow().print_type_sizes();
     }
 
-    let phase5_result = phase_5_run_llvm_passes(sess, &trans, &outputs);
+    #[cfg(feature="llvm")]
+    {
+        let phase5_result = phase_5_run_llvm_passes(sess, &trans, &outputs);
 
-    controller_entry_point!(after_llvm,
-                            sess,
-                            CompileState::state_after_llvm(input, sess, outdir, output, &trans),
-                            phase5_result);
-    phase5_result?;
+        controller_entry_point!(after_llvm,
+                                sess,
+                                CompileState::state_after_llvm(input, sess, outdir, output, &trans),
+                                phase5_result);
+        phase5_result?;
 
-    write::cleanup_llvm(&trans);
+        write::cleanup_llvm(&trans);
 
-    phase_6_link_output(sess, &trans, &outputs);
+        phase_6_link_output(sess, &trans, &outputs);
 
-    // Now that we won't touch anything in the incremental compilation directory
-    // any more, we can finalize it (which involves renaming it)
-    rustc_incremental::finalize_session_directory(sess, trans.link.crate_hash);
+        // Now that we won't touch anything in the incremental compilation directory
+        // any more, we can finalize it (which involves renaming it)
+        rustc_incremental::finalize_session_directory(sess, trans.link.crate_hash);
 
-    if sess.opts.debugging_opts.perf_stats {
-        sess.print_perf_stats();
-    }
+        if sess.opts.debugging_opts.perf_stats {
+            sess.print_perf_stats();
+        }
+
+        controller_entry_point!(compilation_done,
+                                sess,
+                                CompileState::state_when_compilation_done(input,
+                                                                          sess,
+                                                                          outdir,
+                                                                          output),
+                                Ok(()));
 
-    controller_entry_point!(compilation_done,
-                            sess,
-                            CompileState::state_when_compilation_done(input, sess, outdir, output),
-                            Ok(()));
+        return Ok(())
+    }
 
-    Ok(())
+    #[cfg(not(feature="llvm"))]
+    panic!("Unreachable")
 }
 
 fn keep_hygiene_data(sess: &Session) -> bool {
@@ -355,6 +375,7 @@ pub struct CompileState<'a, 'tcx: 'a> {
     pub resolutions: Option<&'a Resolutions>,
     pub analysis: Option<&'a ty::CrateAnalysis>,
     pub tcx: Option<TyCtxt<'a, 'tcx, 'tcx>>,
+    #[cfg(feature="llvm")]
     pub trans: Option<&'a trans::CrateTranslation>,
 }
 
@@ -381,6 +402,7 @@ impl<'a, 'tcx> CompileState<'a, 'tcx> {
             resolutions: None,
             analysis: None,
             tcx: None,
+            #[cfg(feature="llvm")]
             trans: None,
         }
     }
@@ -470,6 +492,7 @@ impl<'a, 'tcx> CompileState<'a, 'tcx> {
     }
 
 
+    #[cfg(feature="llvm")]
     fn state_after_llvm(input: &'a Input,
                         session: &'tcx Session,
                         out_dir: &'a Option<PathBuf>,
@@ -893,6 +916,7 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
     mir::provide(&mut local_providers);
     reachable::provide(&mut local_providers);
     rustc_privacy::provide(&mut local_providers);
+    #[cfg(feature="llvm")]
     trans::provide(&mut local_providers);
     typeck::provide(&mut local_providers);
     ty::provide(&mut local_providers);
@@ -904,6 +928,7 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
 
     let mut extern_providers = ty::maps::Providers::default();
     cstore::provide(&mut extern_providers);
+    #[cfg(feature="llvm")]
     trans::provide(&mut extern_providers);
     ty::provide_extern(&mut extern_providers);
     traits::provide_extern(&mut extern_providers);
@@ -1045,6 +1070,7 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
 
 /// Run the translation phase to LLVM, after which the AST and analysis can
 /// be discarded.
+#[cfg(feature="llvm")]
 pub fn phase_4_translate_to_llvm<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                            analysis: ty::CrateAnalysis,
                                            incremental_hashes_map: &IncrementalHashesMap,
@@ -1076,6 +1102,7 @@ pub fn phase_4_translate_to_llvm<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 
 /// Run LLVM itself, producing a bitcode file, assembly file or object file
 /// as a side effect.
+#[cfg(feature="llvm")]
 pub fn phase_5_run_llvm_passes(sess: &Session,
                                trans: &trans::CrateTranslation,
                                outputs: &OutputFilenames) -> CompileResult {
@@ -1124,6 +1151,7 @@ pub fn phase_5_run_llvm_passes(sess: &Session,
 
 /// Run the linker on any artifacts that resulted from the LLVM run.
 /// This should produce either a finished executable or library.
+#[cfg(feature="llvm")]
 pub fn phase_6_link_output(sess: &Session,
                            trans: &trans::CrateTranslation,
                            outputs: &OutputFilenames) {