[WIP] rustbuild: Build jemalloc and libbacktrace only once

src/bootstrap/lib.rs

@@ -478,7 +478,8 @@ impl Build {
         //
         // These variables are primarily all read by
         // src/bootstrap/bin/{rustc.rs,rustdoc.rs}
-        cargo.env("RUSTC", self.out.join("bootstrap/debug/rustc"))
+        cargo.env("RUSTBUILD_NATIVE_DIR", self.native_dir(compiler.host))
+             .env("RUSTC", self.out.join("bootstrap/debug/rustc"))
              .env("RUSTC_REAL", self.compiler_path(compiler))
              .env("RUSTC_STAGE", stage.to_string())
              .env("RUSTC_DEBUGINFO", self.config.rust_debuginfo.to_string())
@@ -736,10 +737,15 @@ impl Build {
         }
     }
 
+    /// Directory for libraries built from C/C++ code and shared between stages.
+    fn native_dir(&self, target: &str) -> PathBuf {
+        self.out.join(target).join("native")
+    }
+
     /// Root output directory for rust_test_helpers library compiled for
     /// `target`
     fn test_helpers_out(&self, target: &str) -> PathBuf {
-        self.out.join(target).join("rust-test-helpers")
+        self.native_dir(target).join("rust-test-helpers")
     }
 
     /// Adds the compiler's directory of dynamic libraries to `cmd`'s dynamic

src/liballoc_jemalloc/build.rs

@@ -14,6 +14,7 @@ extern crate build_helper;
 extern crate gcc;
 
 use std::env;
+use std::fs;
 use std::path::PathBuf;
 use std::process::Command;
 use build_helper::run;
@@ -24,8 +25,9 @@ fn main() {
 
     let target = env::var("TARGET").expect("TARGET was not set");
     let host = env::var("HOST").expect("HOST was not set");
-    let build_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
     let src_dir = env::current_dir().unwrap();
+    let build_dir = PathBuf::from(env::var_os("RUSTBUILD_NATIVE_DIR").unwrap()).join("jemalloc");
+    let _ = fs::create_dir_all(&build_dir);
 
     // FIXME: This is a hack to support building targets that don't
     // support jemalloc alongside hosts that do. The jemalloc build is
@@ -81,6 +83,7 @@ fn main() {
         }
     }
 
+    if !build_dir.join("Makefile").metadata().is_ok() {
         let mut cmd = Command::new("sh");
         cmd.arg(src_dir.join("../jemalloc/configure")
                     .to_str()
@@ -152,6 +155,8 @@ fn main() {
         cmd.arg(format!("--build={}", build_helper::gnu_target(&host)));
 
         run(&mut cmd);
+    }
+
     let mut make = Command::new(build_helper::make(&host));
     make.current_dir(&build_dir)
         .arg("build_lib_static");

src/libstd/build.rs

@@ -14,6 +14,7 @@ extern crate gcc;
 extern crate build_helper;
 
 use std::env;
+use std::fs;
 use std::path::PathBuf;
 use std::process::Command;
 
@@ -67,7 +68,9 @@ fn main() {
 
 fn build_libbacktrace(host: &str, target: &str) {
     let src_dir = env::current_dir().unwrap().join("../libbacktrace");
-    let build_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    let build_dir =
+        PathBuf::from(env::var_os("RUSTBUILD_NATIVE_DIR").unwrap()).join("libbacktrace");
+    let _ = fs::create_dir_all(&build_dir);
 
     println!("cargo:rustc-link-lib=static=backtrace");
     println!("cargo:rustc-link-search=native={}/.libs", build_dir.display());
@@ -89,6 +92,7 @@ fn build_libbacktrace(host: &str, target: &str) {
     let ar = build_helper::cc2ar(compiler.path(), target).unwrap();
     let cflags = compiler.args().iter().map(|s| s.to_str().unwrap())
                          .collect::<Vec<_>>().join(" ");
+    if !build_dir.join("Makefile").metadata().is_ok() {
         run(Command::new("sh")
                     .current_dir(&build_dir)
                     .arg(src_dir.join("configure").to_str().unwrap()
@@ -104,6 +108,7 @@ fn build_libbacktrace(host: &str, target: &str) {
                     .env("AR", &ar)
                     .env("RANLIB", format!("{} s", ar.display()))
                     .env("CFLAGS", cflags));
+    }
     run(Command::new(build_helper::make(host))
                 .current_dir(&build_dir)
                 .arg(format!("INCDIR={}", src_dir.display()))