Integrate jobserver support to parallel codegen

src/libcore/Cargo.toml

@@ -9,6 +9,9 @@ path = "lib.rs"
 test = false
 bench = false
 
+[dev-dependencies]
+rand = { path = "../librand" }
+
 [[test]]
 name = "coretests"
 path = "../libcore/tests/lib.rs"

src/librustc/Cargo.toml

@@ -12,6 +12,7 @@ crate-type = ["dylib"]
 arena = { path = "../libarena" }
 fmt_macros = { path = "../libfmt_macros" }
 graphviz = { path = "../libgraphviz" }
+jobserver = "0.1"
 log = "0.3"
 owning_ref = "0.3.3"
 rustc_back = { path = "../librustc_back" }

src/librustc/lib.rs

@@ -61,6 +61,7 @@ extern crate rustc_errors as errors;
 #[macro_use] extern crate syntax;
 extern crate syntax_pos;
 #[macro_use] #[no_link] extern crate rustc_bitflags;
+extern crate jobserver;
 
 extern crate serialize as rustc_serialize; // used by deriving
 

src/librustc/session/mod.rs

@@ -38,14 +38,16 @@ use syntax_pos::{Span, MultiSpan};
 use rustc_back::{LinkerFlavor, PanicStrategy};
 use rustc_back::target::Target;
 use rustc_data_structures::flock;
+use jobserver::Client;
 
-use std::path::{Path, PathBuf};
 use std::cell::{self, Cell, RefCell};
 use std::collections::HashMap;
 use std::env;
+use std::fmt;
 use std::io::Write;
+use std::path::{Path, PathBuf};
 use std::rc::Rc;
-use std::fmt;
+use std::sync::{Once, ONCE_INIT};
 use std::time::Duration;
 
 mod code_stats;
@@ -134,6 +136,10 @@ pub struct Session {
     pub print_fuel_crate: Option<String>,
     /// Always set to zero and incremented so that we can print fuel expended by a crate.
     pub print_fuel: Cell<u64>,
+
+    /// Loaded up early on in the initialization of this `Session` to avoid
+    /// false positives about a job server in our environment.
+    pub jobserver_from_env: Option<Client>,
 }
 
 pub struct PerfStats {
@@ -697,6 +703,24 @@ pub fn build_session_(sopts: config::Options,
         print_fuel_crate: print_fuel_crate,
         print_fuel: print_fuel,
         out_of_fuel: Cell::new(false),
+
+        // Note that this is unsafe because it may misinterpret file descriptors
+        // on Unix as jobserver file descriptors. We hopefully execute this near
+        // the beginning of the process though to ensure we don't get false
+        // positives, or in other words we try to execute this before we open
+        // any file descriptors ourselves.
+        //
+        // Also note that we stick this in a global because there could be
+        // multiple `Session` instances in this process, and the jobserver is
+        // per-process.
+        jobserver_from_env: unsafe {
+            static mut GLOBAL_JOBSERVER: *mut Option<Client> = 0 as *mut _;
+            static INIT: Once = ONCE_INIT;
+            INIT.call_once(|| {
+                GLOBAL_JOBSERVER = Box::into_raw(Box::new(Client::from_env()));
+            });
+            (*GLOBAL_JOBSERVER).clone()
+        },
     };
 
     sess

src/librustc_trans/Cargo.toml

@@ -10,7 +10,9 @@ crate-type = ["dylib"]
 test = false
 
 [dependencies]
+crossbeam = "0.2"
 flate2 = "0.2"
+jobserver = "0.1.5"
 log = "0.3"
 owning_ref = "0.3.3"
 rustc = { path = "../librustc" }

src/librustc_trans/back/link.rs

@@ -329,34 +329,38 @@ pub fn filename_for_input(sess: &Session,
 }
 
 pub fn each_linked_rlib(sess: &Session,
-                        f: &mut FnMut(CrateNum, &Path)) {
+                        f: &mut FnMut(CrateNum, &Path)) -> Result<(), String> {
     let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
     let fmts = sess.dependency_formats.borrow();
     let fmts = fmts.get(&config::CrateTypeExecutable)
                    .or_else(|| fmts.get(&config::CrateTypeStaticlib))
                    .or_else(|| fmts.get(&config::CrateTypeCdylib))
                    .or_else(|| fmts.get(&config::CrateTypeProcMacro));
-    let fmts = fmts.unwrap_or_else(|| {
-        bug!("could not find formats for rlibs");
-    });
+    let fmts = match fmts {
+        Some(f) => f,
+        None => return Err(format!("could not find formats for rlibs"))
+    };
     for (cnum, path) in crates {
-        match fmts[cnum.as_usize() - 1] {
-            Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
-            _ => {}
+        match fmts.get(cnum.as_usize() - 1) {
+            Some(&Linkage::NotLinked) |
+            Some(&Linkage::IncludedFromDylib) => continue,
+            Some(_) => {}
+            None => return Err(format!("could not find formats for rlibs"))
         }
         let name = sess.cstore.crate_name(cnum).clone();
         let path = match path {
             LibSource::Some(p) => p,
             LibSource::MetadataOnly => {
-                sess.fatal(&format!("could not find rlib for: `{}`, found rmeta (metadata) file",
-                                    name));
+                return Err(format!("could not find rlib for: `{}`, found rmeta (metadata) file",
+                                   name))
             }
             LibSource::None => {
-                sess.fatal(&format!("could not find rlib for: `{}`", name));
+                return Err(format!("could not find rlib for: `{}`", name))
             }
         };
         f(cnum, &path);
     }
+    Ok(())
 }
 
 fn out_filename(sess: &Session,
@@ -669,7 +673,7 @@ fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
     let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
     let mut all_native_libs = vec![];
 
-    each_linked_rlib(sess, &mut |cnum, path| {
+    let res = each_linked_rlib(sess, &mut |cnum, path| {
         let name = sess.cstore.crate_name(cnum);
         let native_libs = sess.cstore.native_libraries(cnum);
 
@@ -694,6 +698,9 @@ fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
 
         all_native_libs.extend(sess.cstore.native_libraries(cnum));
     });
+    if let Err(e) = res {
+        sess.fatal(&e);
+    }
 
     ab.update_symbols();
     ab.build();

src/librustc_trans/back/lto.rs

@@ -10,15 +10,16 @@
 
 use back::link;
 use back::write;
-use back::symbol_export::{self, ExportedSymbols};
-use rustc::session::{self, config};
+use back::symbol_export;
+use rustc::session::config;
+use errors::FatalError;
 use llvm;
 use llvm::archive_ro::ArchiveRO;
 use llvm::{ModuleRef, TargetMachineRef, True, False};
 use rustc::util::common::time;
 use rustc::util::common::path2cstr;
 use rustc::hir::def_id::LOCAL_CRATE;
-use back::write::{ModuleConfig, with_llvm_pmb};
+use back::write::{ModuleConfig, with_llvm_pmb, CodegenContext};
 
 use libc;
 use flate2::read::ZlibDecoder;
@@ -39,30 +40,31 @@ pub fn crate_type_allows_lto(crate_type: config::CrateType) -> bool {
     }
 }
 
-pub fn run(sess: &session::Session,
+pub fn run(cgcx: &CodegenContext,
            llmod: ModuleRef,
            tm: TargetMachineRef,
-           exported_symbols: &ExportedSymbols,
            config: &ModuleConfig,
-           temp_no_opt_bc_filename: &Path) {
-    if sess.opts.cg.prefer_dynamic {
-        sess.struct_err("cannot prefer dynamic linking when performing LTO")
+           temp_no_opt_bc_filename: &Path) -> Result<(), FatalError> {
+    let handler = cgcx.handler;
+    if cgcx.opts.cg.prefer_dynamic {
+        handler.struct_err("cannot prefer dynamic linking when performing LTO")
             .note("only 'staticlib', 'bin', and 'cdylib' outputs are \
                    supported with LTO")
             .emit();
-        sess.abort_if_errors();
+        return Err(FatalError)
     }
 
     // Make sure we actually can run LTO
-    for crate_type in sess.crate_types.borrow().iter() {
+    for crate_type in cgcx.crate_types.iter() {
         if !crate_type_allows_lto(*crate_type) {
-            sess.fatal("lto can only be run for executables, cdylibs and \
-                            static library outputs");
+            let e = handler.fatal("lto can only be run for executables, cdylibs and \
+                                   static library outputs");
+            return Err(e)
         }
     }
 
     let export_threshold =
-        symbol_export::crates_export_threshold(&sess.crate_types.borrow());
+        symbol_export::crates_export_threshold(&cgcx.crate_types);
 
     let symbol_filter = &|&(ref name, level): &(String, _)| {
         if symbol_export::is_below_threshold(level, export_threshold) {
@@ -74,7 +76,7 @@ pub fn run(sess: &session::Session,
         }
     };
 
-    let mut symbol_white_list: Vec<CString> = exported_symbols
+    let mut symbol_white_list: Vec<CString> = cgcx.exported_symbols
         .exported_symbols(LOCAL_CRATE)
         .iter()
         .filter_map(symbol_filter)
@@ -83,16 +85,11 @@ pub fn run(sess: &session::Session,
     // For each of our upstream dependencies, find the corresponding rlib and
     // load the bitcode from the archive. Then merge it into the current LLVM
     // module that we've got.
-    link::each_linked_rlib(sess, &mut |cnum, path| {
-        // `#![no_builtins]` crates don't participate in LTO.
-        if sess.cstore.is_no_builtins(cnum) {
-            return;
-        }
-
+    for &(cnum, ref path) in cgcx.each_linked_rlib_for_lto.iter() {
         symbol_white_list.extend(
-            exported_symbols.exported_symbols(cnum)
-                            .iter()
-                            .filter_map(symbol_filter));
+            cgcx.exported_symbols.exported_symbols(cnum)
+                                 .iter()
+                                 .filter_map(symbol_filter));
 
         let archive = ArchiveRO::open(&path).expect("wanted an rlib");
         let bytecodes = archive.iter().filter_map(|child| {
@@ -102,7 +99,7 @@ pub fn run(sess: &session::Session,
             let bc_encoded = data.data();
 
             let bc_decoded = if is_versioned_bytecode_format(bc_encoded) {
-                time(sess.time_passes(), &format!("decode {}", name), || {
+                time(cgcx.time_passes, &format!("decode {}", name), || {
                     // Read the version
                     let version = extract_bytecode_format_version(bc_encoded);
 
@@ -117,44 +114,49 @@ pub fn run(sess: &session::Session,
                         let res = ZlibDecoder::new(compressed_data)
                             .read_to_end(&mut inflated);
                         if res.is_err() {
-                            sess.fatal(&format!("failed to decompress bc of `{}`",
-                                               name))
+                            let msg = format!("failed to decompress bc of `{}`",
+                                              name);
+                            Err(handler.fatal(&msg))
+                        } else {
+                            Ok(inflated)
                         }
-                        inflated
                     } else {
-                        sess.fatal(&format!("Unsupported bytecode format version {}",
-                                           version))
+                        Err(handler.fatal(&format!("Unsupported bytecode format version {}",
+                                                   version)))
                     }
-                })
+                })?
             } else {
-                time(sess.time_passes(), &format!("decode {}", name), || {
+                time(cgcx.time_passes, &format!("decode {}", name), || {
                     // the object must be in the old, pre-versioning format, so
                     // simply inflate everything and let LLVM decide if it can
                     // make sense of it
                     let mut inflated = Vec::new();
                     let res = ZlibDecoder::new(bc_encoded)
                         .read_to_end(&mut inflated);
                     if res.is_err() {
-                        sess.fatal(&format!("failed to decompress bc of `{}`",
-                                           name))
+                        let msg = format!("failed to decompress bc of `{}`",
+                                          name);
+                        Err(handler.fatal(&msg))
+                    } else {
+                        Ok(inflated)
                     }
-                    inflated
-                })
+                })?
             };
 
             let ptr = bc_decoded.as_ptr();
             debug!("linking {}", name);
-            time(sess.time_passes(), &format!("ll link {}", name), || unsafe {
-                if !llvm::LLVMRustLinkInExternalBitcode(llmod,
-                                                        ptr as *const libc::c_char,
-                                                        bc_decoded.len() as libc::size_t) {
-                    write::llvm_err(sess.diagnostic(),
-                                    format!("failed to load bc of `{}`",
-                                            name));
+            time(cgcx.time_passes, &format!("ll link {}", name), || unsafe {
+                if llvm::LLVMRustLinkInExternalBitcode(llmod,
+                                                       ptr as *const libc::c_char,
+                                                       bc_decoded.len() as libc::size_t) {
+                    Ok(())
+                } else {
+                    let msg = format!("failed to load bc of `{}`", name);
+                    Err(write::llvm_err(handler, msg))
                 }
-            });
+            })?;
         }
-    });
+    }
 
     // Internalize everything but the exported symbols of the current module
     let arr: Vec<*const libc::c_char> = symbol_white_list.iter()
@@ -167,13 +169,13 @@ pub fn run(sess: &session::Session,
                                          arr.len() as libc::size_t);
     }
 
-    if sess.no_landing_pads() {
+    if cgcx.no_landing_pads {
         unsafe {
             llvm::LLVMRustMarkAllFunctionsNounwind(llmod);
         }
     }
 
-    if sess.opts.cg.save_temps {
+    if cgcx.opts.cg.save_temps {
         let cstr = path2cstr(temp_no_opt_bc_filename);
         unsafe {
             llvm::LLVMWriteBitcodeToFile(llmod, cstr.as_ptr());
@@ -203,12 +205,13 @@ pub fn run(sess: &session::Session,
         assert!(!pass.is_null());
         llvm::LLVMRustAddPass(pm, pass);
 
-        time(sess.time_passes(), "LTO passes", ||
+        time(cgcx.time_passes, "LTO passes", ||
              llvm::LLVMRunPassManager(pm, llmod));
 
         llvm::LLVMDisposePassManager(pm);
     }
     debug!("lto done");
+    Ok(())
 }
 
 fn is_versioned_bytecode_format(bc: &[u8]) -> bool {