Auto merge of #36339 - brson:emscripten-new, r=alexcrichton

Working asmjs and wasm targets

This patch set results in a working standard library for the asmjs-unknown-emscripten and wasm32-unknown-emscripten targets. It is based on the work of @badboy and @rschulman.

It does a few things:

- Updates LLVM with the emscripten [fastcomp](https://github.com/rust-lang/llvm/pull/50) patches, which include the pnacl IR legalizer and the asm.js backend. This patch is thought not to have any significant effect on existing targets.
- Teaches rustbuild to correctly link C code with emscripten
- Updates gcc-rs to work correctly with emscripten
- Teaches rustbuild to run crate tests for emscripten with node
- Modifies Thread::new to return an error on emscripten, to facilitate debugging a common failure mode
- Modifies libtest to run in single-threaded mode for emscripten
- Ignores a host of tests that don't work yet, mostly dealing with threads and I/O
- Updates libc with wasm32 definitions (presently the same as asmjs)
- Adds a wasm32-unknown-emscripten target that feeds the output of LLVM's asmjs backend through emcc to generate wasm

Notes and caveats:

- This is only known to work with `--enable-rustbuild`.
- The wasm32 target can't be tested correctly yet because of issues in compiletest and limitations in node https://github.com/kripken/emscripten/issues/4542, but hello.rs does seem to work when run on node via the binaryen interpreter
- This requires an up to date installation of the emscripten sdk from its incoming branch
- Unwinding is very broken
- When enabling the emscripten targets jemalloc is disabled for all targets, which results in test failures for the host

Next steps are to fix the jemalloc issue, start building the two emscripten targets on the auto builders, then start producing nightlies.

https://github.com/rust-lang/rust/issues/36317 tracks work on this.

Fixes https://github.com/rust-lang/rust/issues/36515
Fixes https://github.com/rust-lang/rust/issues/36515
Fixes https://github.com/rust-lang/rust/issues/36356

5 files changed, 22 insertions, 7 deletions

diff --git a/src/libstd/sys/common/io.rs b/src/libstd/sys/common/io.rs
index 3cd70eddb85..47cec4ef5c2 100644
--- a/src/libstd/sys/common/io.rs
+++ b/src/libstd/sys/common/io.rs
@@ -50,7 +50,7 @@ pub unsafe fn read_to_end_uninitialized(r: &mut Read, buf: &mut Vec<u8>) -> io::
     }
 }
 
-#[cfg(test)]
+#[cfg(all(test, not(target_os = "emscripten")))]
 pub mod test {
     use path::{Path, PathBuf};
     use env;
@@ -165,6 +165,7 @@ mod tests {
     }
 
     #[bench]
+    #[cfg_attr(target_os = "emscripten", ignore)]
     fn bench_uninitialized(b: &mut ::test::Bencher) {
         b.iter(|| {
             let mut lr = repeat(1).take(10000000);
diff --git a/src/libstd/sys/common/remutex.rs b/src/libstd/sys/common/remutex.rs
index cbdeaad7f6b..4d0407ccf6c 100644
--- a/src/libstd/sys/common/remutex.rs
+++ b/src/libstd/sys/common/remutex.rs
@@ -156,7 +156,7 @@ impl<'a, T> Drop for ReentrantMutexGuard<'a, T> {
 }
 
 
-#[cfg(test)]
+#[cfg(all(test, not(target_os = "emscripten")))]
 mod tests {
     use sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard};
     use cell::RefCell;
diff --git a/src/libstd/sys/unix/ext/net.rs b/src/libstd/sys/unix/ext/net.rs
index 3f93fce1935..40fe24cf10e 100644
--- a/src/libstd/sys/unix/ext/net.rs
+++ b/src/libstd/sys/unix/ext/net.rs
@@ -786,7 +786,7 @@ impl IntoRawFd for UnixDatagram {
     }
 }
 
-#[cfg(test)]
+#[cfg(all(test, not(target_os = "emscripten")))]
 mod test {
     use thread;
     use io;
diff --git a/src/libstd/sys/unix/process.rs b/src/libstd/sys/unix/process.rs
index 50014f51f6c..dafc11d9cc8 100644
--- a/src/libstd/sys/unix/process.rs
+++ b/src/libstd/sys/unix/process.rs
@@ -369,7 +369,7 @@ impl Command {
         }
 
         // NaCl has no signal support.
-        if cfg!(not(target_os = "nacl")) {
+        if cfg!(not(any(target_os = "nacl", target_os = "emscripten"))) {
             // Reset signal handling so the child process starts in a
             // standardized state. libstd ignores SIGPIPE, and signal-handling
             // libraries often set a mask. Child processes inherit ignored
@@ -589,7 +589,7 @@ impl Process {
     }
 }
 
-#[cfg(test)]
+#[cfg(all(test, not(target_os = "emscripten")))]
 mod tests {
     use super::*;
 
diff --git a/src/libstd/sys/unix/thread.rs b/src/libstd/sys/unix/thread.rs
index 980ef01f549..1e879117f73 100644
--- a/src/libstd/sys/unix/thread.rs
+++ b/src/libstd/sys/unix/thread.rs
@@ -29,6 +29,20 @@ pub struct Thread {
 unsafe impl Send for Thread {}
 unsafe impl Sync for Thread {}
 
+// The pthread_attr_setstacksize symbol doesn't exist in the emscripten libc,
+// so we have to not link to it to satisfy emcc's ERROR_ON_UNDEFINED_SYMBOLS.
+#[cfg(not(target_os = "emscripten"))]
+unsafe fn pthread_attr_setstacksize(attr: *mut libc::pthread_attr_t,
+                                    stack_size: libc::size_t) -> libc::c_int {
+    libc::pthread_attr_setstacksize(attr, stack_size)
+}
+
+#[cfg(target_os = "emscripten")]
+unsafe fn pthread_attr_setstacksize(_attr: *mut libc::pthread_attr_t,
+                                    _stack_size: libc::size_t) -> libc::c_int {
+    panic!()
+}
+
 impl Thread {
     pub unsafe fn new<'a>(stack: usize, p: Box<FnBox() + 'a>)
                           -> io::Result<Thread> {
@@ -38,8 +52,8 @@ impl Thread {
         assert_eq!(libc::pthread_attr_init(&mut attr), 0);
 
         let stack_size = cmp::max(stack, min_stack_size(&attr));
-        match libc::pthread_attr_setstacksize(&mut attr,
-                                              stack_size as libc::size_t) {
+        match pthread_attr_setstacksize(&mut attr,
+                                        stack_size as libc::size_t) {
             0 => {}
             n => {
                 assert_eq!(n, libc::EINVAL);