bootstrap: Link LLVM as a dylib with ThinLTO (take 2)

src/bootstrap/check.rs

@@ -38,7 +38,6 @@ impl Step for Std {
         builder.info(&format!("Checking std artifacts ({} -> {})", &compiler.host, target));
         run_cargo(builder,
                   &mut cargo,
-                  vec![],
                   &libstd_stamp(builder, compiler, target),
                   true);
 
@@ -85,7 +84,6 @@ impl Step for Rustc {
         builder.info(&format!("Checking compiler artifacts ({} -> {})", &compiler.host, target));
         run_cargo(builder,
                   &mut cargo,
-                  vec![],
                   &librustc_stamp(builder, compiler, target),
                   true);
 
@@ -136,7 +134,6 @@ impl Step for CodegenBackend {
         let _folder = builder.fold_output(|| format!("stage{}-rustc_codegen_llvm", compiler.stage));
         run_cargo(builder,
                   &mut cargo,
-                  vec![],
                   &codegen_backend_stamp(builder, compiler, target, backend),
                   true);
     }
@@ -174,7 +171,6 @@ impl Step for Test {
         builder.info(&format!("Checking test artifacts ({} -> {})", &compiler.host, target));
         run_cargo(builder,
                   &mut cargo,
-                  vec![],
                   &libtest_stamp(builder, compiler, target),
                   true);
 
@@ -222,7 +218,6 @@ impl Step for Rustdoc {
         println!("Checking rustdoc artifacts ({} -> {})", &compiler.host, target);
         run_cargo(builder,
                   &mut cargo,
-                  vec![],
                   &rustdoc_stamp(builder, compiler, target),
                   true);
 

src/bootstrap/compile.rs

@@ -19,6 +19,7 @@ use build_helper::{output, mtime, up_to_date};
 use filetime::FileTime;
 use serde_json;
 
+use crate::dist;
 use crate::util::{exe, libdir, is_dylib};
 use crate::{Compiler, Mode, GitRepo};
 use crate::native;
@@ -104,7 +105,6 @@ impl Step for Std {
                 &compiler.host, target));
         run_cargo(builder,
                   &mut cargo,
-                  vec![],
                   &libstd_stamp(builder, compiler, target),
                   false);
 
@@ -365,7 +365,6 @@ impl Step for Test {
                 &compiler.host, target));
         run_cargo(builder,
                   &mut cargo,
-                  vec![],
                   &libtest_stamp(builder, compiler, target),
                   false);
 
@@ -493,7 +492,6 @@ impl Step for Rustc {
                  compiler.stage, &compiler.host, target));
         run_cargo(builder,
                   &mut cargo,
-                  vec![],
                   &librustc_stamp(builder, compiler, target),
                   false);
 
@@ -636,47 +634,18 @@ impl Step for CodegenBackend {
 
         let out_dir = builder.cargo_out(compiler, Mode::Codegen, target);
 
-        let mut cargo = builder.cargo(compiler, Mode::Codegen, target, "rustc");
+        let mut cargo = builder.cargo(compiler, Mode::Codegen, target, "build");
         cargo.arg("--manifest-path")
             .arg(builder.src.join("src/librustc_codegen_llvm/Cargo.toml"));
         rustc_cargo_env(builder, &mut cargo);
 
         let features = build_codegen_backend(&builder, &mut cargo, &compiler, target, backend);
 
-        let mut cargo_tails_args = vec![];
-
-        if builder.config.llvm_thin_lto {
-            cargo_tails_args.push("--".to_string());
-
-            let num_jobs = builder.jobs();
-
-            if !target.contains("msvc") {
-                // Here we assume that the linker is clang. If it's not, there'll
-                // be linker errors.
-                cargo_tails_args.push("-Clink-arg=-fuse-ld=lld".to_string());
-                cargo_tails_args.push("-Clink-arg=-flto=thin".to_string());
-
-                if builder.config.llvm_optimize {
-                    cargo_tails_args.push("-Clink-arg=-O2".to_string());
-                }
-
-                // Let's make LLD respect the `-j` option.
-                let num_jobs_arg = format!("-Clink-arg=-Wl,--thinlto-jobs={}", num_jobs);
-                cargo_tails_args.push(num_jobs_arg);
-            } else {
-                // Here we assume that the linker is lld-link.exe. lld-link.exe
-                // does not need the extra arguments except for num_jobs
-                let num_jobs_arg = format!("-Clink-arg=/opt:lldltojobs={}", num_jobs);
-                cargo_tails_args.push(num_jobs_arg);
-            }
-        }
-
         let tmp_stamp = out_dir.join(".tmp.stamp");
 
         let _folder = builder.fold_output(|| format!("stage{}-rustc_codegen_llvm", compiler.stage));
         let files = run_cargo(builder,
                               cargo.arg("--features").arg(features),
-                              cargo_tails_args,
                               &tmp_stamp,
                               false);
         if builder.config.dry_run {
@@ -749,7 +718,9 @@ pub fn build_codegen_backend(builder: &Builder,
                                          "libstdc++.a");
                 cargo.env("LLVM_STATIC_STDCPP", file);
             }
-            if builder.config.llvm_link_shared {
+            if builder.config.llvm_link_shared ||
+                (builder.config.llvm_thin_lto && backend != "emscripten")
+            {
                 cargo.env("LLVM_LINK_SHARED", "1");
             }
         }
@@ -989,6 +960,8 @@ impl Step for Assemble {
             copy_lld_to_sysroot(builder, target_compiler, &lld_install);
         }
 
+        dist::maybe_install_llvm_dylib(builder, target_compiler.host, &sysroot);
+
         // Link the compiler binary itself into place
         let out_dir = builder.cargo_out(build_compiler, Mode::Rustc, host);
         let rustc = out_dir.join(exe("rustc_binary", &*host));
@@ -1015,7 +988,6 @@ pub fn add_to_sysroot(builder: &Builder, sysroot_dst: &Path, stamp: &Path) {
 
 pub fn run_cargo(builder: &Builder,
                  cargo: &mut Command,
-                 tail_args: Vec<String>,
                  stamp: &Path,
                  is_check: bool)
     -> Vec<PathBuf>
@@ -1038,7 +1010,7 @@ pub fn run_cargo(builder: &Builder,
     // files we need to probe for later.
     let mut deps = Vec::new();
     let mut toplevel = Vec::new();
-    let ok = stream_cargo(builder, cargo, tail_args, &mut |msg| {
+    let ok = stream_cargo(builder, cargo, &mut |msg| {
         let filenames = match msg {
             CargoMessage::CompilerArtifact { filenames, .. } => filenames,
             _ => return,
@@ -1163,7 +1135,6 @@ pub fn run_cargo(builder: &Builder,
 pub fn stream_cargo(
     builder: &Builder,
     cargo: &mut Command,
-    tail_args: Vec<String>,
     cb: &mut dyn FnMut(CargoMessage),
 ) -> bool {
     if builder.config.dry_run {
@@ -1174,10 +1145,6 @@ pub fn stream_cargo(
     cargo.arg("--message-format").arg("json")
          .stdout(Stdio::piped());
 
-    for arg in tail_args {
-        cargo.arg(arg);
-    }
-
     builder.verbose(&format!("running: {:?}", cargo));
     let mut child = match cargo.spawn() {
         Ok(child) => child,

src/bootstrap/dist.rs

@@ -671,10 +671,18 @@ impl Step for Std {
         let mut src = builder.sysroot_libdir(compiler, target).to_path_buf();
         src.pop(); // Remove the trailing /lib folder from the sysroot_libdir
         builder.cp_filtered(&src, &dst, &|path| {
-            let name = path.file_name().and_then(|s| s.to_str());
-            name != Some(builder.config.rust_codegen_backends_dir.as_str()) &&
-                name != Some("bin")
-
+            if let Some(name) = path.file_name().and_then(|s| s.to_str()) {
+                if name == builder.config.rust_codegen_backends_dir.as_str() {
+                    return false
+                }
+                if name == "bin" {
+                    return false
+                }
+                if name.contains("LLVM") {
+                    return false
+                }
+            }
+            true
         });
 
         let mut cmd = rust_installer(builder);
@@ -1877,13 +1885,13 @@ impl Step for HashSign {
 // LLVM tools are linked dynamically.
 // Note: This function does no yet support Windows but we also don't support
 //       linking LLVM tools dynamically on Windows yet.
-fn maybe_install_llvm_dylib(builder: &Builder,
-                            target: Interned<String>,
-                            image: &Path) {
+pub fn maybe_install_llvm_dylib(builder: &Builder,
+                                target: Interned<String>,
+                                sysroot: &Path) {
     let src_libdir = builder
         .llvm_out(target)
         .join("lib");
-    let dst_libdir = image.join("lib/rustlib").join(&*target).join("lib");
+    let dst_libdir = sysroot.join("lib/rustlib").join(&*target).join("lib");
     t!(fs::create_dir_all(&dst_libdir));
 
     if target.contains("apple-darwin") {

src/bootstrap/tool.rs

@@ -77,7 +77,7 @@ impl Step for ToolBuild {
         let _folder = builder.fold_output(|| format!("stage{}-{}", compiler.stage, tool));
         builder.info(&format!("Building stage{} tool {} ({})", compiler.stage, tool, target));
         let mut duplicates = Vec::new();
-        let is_expected = compile::stream_cargo(builder, &mut cargo, vec![], &mut |msg| {
+        let is_expected = compile::stream_cargo(builder, &mut cargo, &mut |msg| {
             // Only care about big things like the RLS/Cargo for now
             match tool {
                 | "rls"

src/librustc_driver/lib.rs

@@ -200,14 +200,7 @@ pub fn run<F>(run_compiler: F) -> isize
 }
 
 fn load_backend_from_dylib(path: &Path) -> fn() -> Box<dyn CodegenBackend> {
-    // Note that we're specifically using `open_global_now` here rather than
-    // `open`, namely we want the behavior on Unix of RTLD_GLOBAL and RTLD_NOW,
-    // where NOW means "bind everything right now" because we don't want
-    // surprises later on and RTLD_GLOBAL allows the symbols to be made
-    // available for future dynamic libraries opened. This is currently used by
-    // loading LLVM and then making its symbols available for other dynamic
-    // libraries.
-    let lib = DynamicLibrary::open_global_now(path).unwrap_or_else(|err| {
+    let lib = DynamicLibrary::open(Some(path)).unwrap_or_else(|err| {
         let err = format!("couldn't load codegen backend {:?}: {:?}", path, err);
         early_error(ErrorOutputType::default(), &err);
     });

src/librustc_llvm/build.rs

@@ -132,6 +132,10 @@ fn main() {
             continue;
         }
 
+        if flag.starts_with("-flto") {
+            continue;
+        }
+
         // -Wdate-time is not supported by the netbsd cross compiler
         if is_crossed && target.contains("netbsd") && flag.contains("date-time") {
             continue;