Add some groundwork for cross-language LTO.

src/bootstrap/test.rs

@@ -832,7 +832,7 @@ test!(RunFailFullDepsPretty {
     host: true
 });
 
-default_test!(RunMake {
+host_test!(RunMake {
     path: "src/test/run-make",
     mode: "run-make",
     suite: "run-make"
@@ -1019,7 +1019,7 @@ impl Step for Compiletest {
 
             // Only pass correct values for these flags for the `run-make` suite as it
             // requires that a C++ compiler was configured which isn't always the case.
-            if !builder.config.dry_run && suite == "run-make-fulldeps" {
+            if !builder.config.dry_run && mode == "run-make" {
                 let llvm_components = output(Command::new(&llvm_config).arg("--components"));
                 let llvm_cxxflags = output(Command::new(&llvm_config).arg("--cxxflags"));
                 cmd.arg("--cc").arg(builder.cc(target))
@@ -1032,13 +1032,13 @@ impl Step for Compiletest {
                 }
             }
         }
-        if suite == "run-make-fulldeps" && !builder.config.llvm_enabled {
+        if mode == "run-make" && !builder.config.llvm_enabled {
             builder.info(
                 &format!("Ignoring run-make test suite as they generally don't work without LLVM"));
             return;
         }
 
-        if suite != "run-make-fulldeps" {
+        if mode != "run-make" {
             cmd.arg("--cc").arg("")
                .arg("--cxx").arg("")
                .arg("--cflags").arg("")

src/bootstrap/tool.rs

@@ -10,6 +10,7 @@
 
 use std::fs;
 use std::env;
+use std::iter;
 use std::path::PathBuf;
 use std::process::{Command, exit};
 
@@ -593,7 +594,7 @@ impl<'a> Builder<'a> {
     /// right location to run `compiler`.
     fn prepare_tool_cmd(&self, compiler: Compiler, cmd: &mut Command) {
         let host = &compiler.host;
-        let mut paths: Vec<PathBuf> = vec![
+        let mut lib_paths: Vec<PathBuf> = vec![
             PathBuf::from(&self.sysroot_libdir(compiler, compiler.host)),
             self.cargo_out(compiler, Mode::Tool, *host).join("deps"),
         ];
@@ -610,11 +611,46 @@ impl<'a> Builder<'a> {
                 }
                 for path in env::split_paths(v) {
                     if !curpaths.contains(&path) {
-                        paths.push(path);
+                        lib_paths.push(path);
                     }
                 }
             }
         }
-        add_lib_path(paths, cmd);
+
+        // Add the llvm/bin directory to PATH since it contains lots of
+        // useful, platform-independent tools
+        if let Some(llvm_bin_path) = self.llvm_bin_path() {
+            if host.contains("windows") {
+                // On Windows, PATH and the dynamic library path are the same,
+                // so we just add the LLVM bin path to lib_path
+                lib_paths.push(llvm_bin_path);
+            } else {
+                let old_path = env::var_os("PATH").unwrap_or_default();
+                let new_path = env::join_paths(iter::once(llvm_bin_path)
+                        .chain(env::split_paths(&old_path)))
+                    .expect("Could not add LLVM bin path to PATH");
+                cmd.env("PATH", new_path);
+            }
+        }
+
+        add_lib_path(lib_paths, cmd);
+    }
+
+    fn llvm_bin_path(&self) -> Option<PathBuf> {
+        if self.config.llvm_enabled && !self.config.dry_run {
+            let llvm_config = self.ensure(native::Llvm {
+                target: self.config.build,
+                emscripten: false,
+            });
+
+            // Add the llvm/bin directory to PATH since it contains lots of
+            // useful, platform-independent tools
+            let llvm_bin_path = llvm_config.parent()
+                .expect("Expected llvm-config to be contained in directory");
+            assert!(llvm_bin_path.is_dir());
+            Some(llvm_bin_path.to_path_buf())
+        } else {
+            None
+        }
     }
 }

src/librustc/session/config.rs

@@ -1293,6 +1293,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "make the current crate share its generic instantiations"),
     chalk: bool = (false, parse_bool, [TRACKED],
           "enable the experimental Chalk-based trait solving engine"),
+    cross_lang_lto: bool = (false, parse_bool, [TRACKED],
+          "generate build artifacts that are compatible with linker-based LTO."),
 }
 
 pub fn default_lib_output() -> CrateType {

src/librustc_trans/back/write.rs

@@ -293,7 +293,8 @@ impl ModuleConfig {
         self.inline_threshold = sess.opts.cg.inline_threshold;
         self.obj_is_bitcode = sess.target.target.options.obj_is_bitcode;
         let embed_bitcode = sess.target.target.options.embed_bitcode ||
-            sess.opts.debugging_opts.embed_bitcode;
+                            sess.opts.debugging_opts.embed_bitcode ||
+                            sess.opts.debugging_opts.cross_lang_lto;
         if embed_bitcode {
             match sess.opts.optimize {
                 config::OptLevel::No |
@@ -841,13 +842,18 @@ unsafe fn embed_bitcode(cgcx: &CodegenContext,
         "rustc.embedded.module\0".as_ptr() as *const _,
     );
     llvm::LLVMSetInitializer(llglobal, llconst);
-    let section = if cgcx.opts.target_triple.triple().contains("-ios") {
+
+    let is_apple = cgcx.opts.target_triple.triple().contains("-ios") ||
+                   cgcx.opts.target_triple.triple().contains("-darwin");
+
+    let section = if is_apple {
         "__LLVM,__bitcode\0"
     } else {
         ".llvmbc\0"
     };
     llvm::LLVMSetSection(llglobal, section.as_ptr() as *const _);
     llvm::LLVMRustSetLinkage(llglobal, llvm::Linkage::PrivateLinkage);
+    llvm::LLVMSetGlobalConstant(llglobal, llvm::True);
 
     let llconst = C_bytes_in_context(llcx, &[]);
     let llglobal = llvm::LLVMAddGlobal(
@@ -856,7 +862,7 @@ unsafe fn embed_bitcode(cgcx: &CodegenContext,
         "rustc.embedded.cmdline\0".as_ptr() as *const _,
     );
     llvm::LLVMSetInitializer(llglobal, llconst);
-    let section = if cgcx.opts.target_triple.triple().contains("-ios") {
+    let section = if  is_apple {
         "__LLVM,__cmdline\0"
     } else {
         ".llvmcmd\0"
@@ -1350,6 +1356,10 @@ fn execute_work_item(cgcx: &CodegenContext,
             // settings.
             let needs_lto = needs_lto && mtrans.kind != ModuleKind::Metadata;
 
+            // Don't run LTO passes when cross-lang LTO is enabled. The linker
+            // will do that for us in this case.
+            let needs_lto = needs_lto && !cgcx.opts.debugging_opts.cross_lang_lto;
+
             if needs_lto {
                 Ok(WorkItemResult::NeedsLTO(mtrans))
             } else {

src/test/run-make/cross-lang-lto/Makefile

@@ -0,0 +1,53 @@
+
+# min-llvm-version 4.0
+# ignore-mingw
+
+-include ../../run-make-fulldeps/tools.mk
+
+# This test makes sure that the expected .llvmbc sections for use by
+# linker-based LTO are available in object files when compiling with
+# -Z cross-lang-lto
+
+LLVMBC_SECTION_NAME=\\.llvmbc
+
+ifeq ($(UNAME),Darwin)
+	LLVMBC_SECTION_NAME=__bitcode
+endif
+
+
+OBJDUMP=llvm-objdump
+SECTION_HEADERS=$(OBJDUMP) -section-headers
+
+BUILD_LIB=$(RUSTC) lib.rs -Copt-level=2 -Z cross-lang-lto -Ccodegen-units=1
+
+BUILD_EXE=$(RUSTC) main.rs -Copt-level=2 -Z cross-lang-lto -Ccodegen-units=1 --emit=obj
+
+all: staticlib staticlib-fat-lto staticlib-thin-lto rlib exe cdylib rdylib
+
+staticlib: lib.rs
+	$(BUILD_LIB) --crate-type=staticlib -o $(TMPDIR)/liblib.a
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/liblib.a | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+staticlib-fat-lto: lib.rs
+	$(BUILD_LIB) --crate-type=staticlib -o $(TMPDIR)/liblib-fat-lto.a -Clto=fat
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/liblib-fat-lto.a | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+staticlib-thin-lto: lib.rs
+	$(BUILD_LIB) --crate-type=staticlib -o $(TMPDIR)/liblib-thin-lto.a -Clto=thin
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/liblib-thin-lto.a | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+rlib: lib.rs
+	$(BUILD_LIB) --crate-type=rlib -o $(TMPDIR)/liblib.rlib
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/liblib.rlib | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+cdylib: lib.rs
+	$(BUILD_LIB) --crate-type=cdylib --emit=obj -o $(TMPDIR)/cdylib.o
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/cdylib.o | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+rdylib: lib.rs
+	$(BUILD_LIB) --crate-type=dylib --emit=obj -o $(TMPDIR)/rdylib.o
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/rdylib.o | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+exe: lib.rs
+	$(BUILD_EXE) -o $(TMPDIR)/exe.o
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/exe.o | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]

src/test/run-make/cross-lang-lto/lib.rs

@@ -0,0 +1,14 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[no_mangle]
+pub extern "C" fn foo() {
+    println!("abc");
+}

src/test/run-make/cross-lang-lto/main.rs

@@ -0,0 +1,13 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    println!("Hello World");
+}

src/tools/compiletest/src/header.rs

@@ -419,6 +419,15 @@ fn iter_header(testfile: &Path, cfg: Option<&str>, it: &mut FnMut(&str)) {
     if testfile.is_dir() {
         return;
     }
+
+    let comment = if testfile.to_string_lossy().ends_with(".rs") {
+        "//"
+    } else {
+        "#"
+    };
+
+    let comment_with_brace = comment.to_string() + "[";
+
     let rdr = BufReader::new(File::open(testfile).unwrap());
     for ln in rdr.lines() {
         // Assume that any directives will be found before the first
@@ -428,10 +437,11 @@ fn iter_header(testfile: &Path, cfg: Option<&str>, it: &mut FnMut(&str)) {
         let ln = ln.trim();
         if ln.starts_with("fn") || ln.starts_with("mod") {
             return;
-        } else if ln.starts_with("//[") {
+        } else if ln.starts_with(&comment_with_brace) {
             // A comment like `//[foo]` is specific to revision `foo`
             if let Some(close_brace) = ln.find(']') {
-                let lncfg = &ln[3..close_brace];
+                let open_brace = ln.find('[').unwrap();
+                let lncfg = &ln[open_brace + 1 .. close_brace];
                 let matches = match cfg {
                     Some(s) => s == &lncfg[..],
                     None => false,
@@ -440,11 +450,11 @@ fn iter_header(testfile: &Path, cfg: Option<&str>, it: &mut FnMut(&str)) {
                     it(ln[(close_brace + 1) ..].trim_left());
                 }
             } else {
-                panic!("malformed condition directive: expected `//[foo]`, found `{}`",
-                       ln)
+                panic!("malformed condition directive: expected `{}foo]`, found `{}`",
+                        comment_with_brace, ln)
             }
-        } else if ln.starts_with("//") {
-            it(ln[2..].trim_left());
+        } else if ln.starts_with(comment) {
+            it(ln[comment.len() ..].trim_left());
         }
     }
     return;

src/tools/compiletest/src/main.rs

@@ -610,7 +610,12 @@ pub fn is_test(file_name: &OsString) -> bool {
 }
 
 pub fn make_test(config: &Config, testpaths: &TestPaths) -> test::TestDescAndFn {
-    let early_props = EarlyProps::from_file(config, &testpaths.file);
+
+    let early_props = if config.mode == Mode::RunMake {
+        EarlyProps::from_file(config, &testpaths.file.join("Makefile"))
+    } else {
+        EarlyProps::from_file(config, &testpaths.file)
+    };
 
     // The `should-fail` annotation doesn't apply to pretty tests,
     // since we run the pretty printer across all tests by default.