Auto merge of #44779 - tjkirch:master, r=alexcrichton

Add aarch64-unknown-linux-musl target

This adds support for the aarch64-unknown-linux-musl target in the build and CI systems.

This addresses half of issue #42520.

The new file `aarch64_unknown_linux_musl.rs` is a copy of `aarch64_unknown_linux_gnu.rs` with "gnu" replaced by "musl", and the added logic in `build-arm-musl.sh` is similarly a near-copy of the arches around it, so overall the changes were straightforward.

Testing:

```
$ sudo ./src/ci/docker/run.sh cross
...
Dist std stage2 (x86_64-unknown-linux-gnu -> aarch64-unknown-linux-musl)
Building stage2 test artifacts (x86_64-unknown-linux-gnu -> aarch64-unknown-linux-musl)
   Compiling getopts v0.2.14
   Compiling term v0.0.0 (file:///checkout/src/libterm)
   Compiling test v0.0.0 (file:///checkout/src/libtest)
    Finished release [optimized] target(s) in 16.91 secs
Copying stage2 test from stage2 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / aarch64-unknown-linux-musl)
...
Build completed successfully in 0:55:22
```

```
$ rustup toolchain link local obj/build/x86_64-unknown-linux-gnu/stage2
$ rustup default local
```

After setting the local toolchain as default, and adding this in ~/.cargo/config:

```
[target.aarch64-unknown-linux-musl]
linker = "aarch64-linux-musl-gcc"
```

...then the toolchain was able to build a working ripgrep as a test:

```
$ readelf -a target/aarch64-unknown-linux-musl/debug/rg | grep -i interpreter
$ readelf -a target/aarch64-unknown-linux-musl/debug/rg | grep NEEDED
$ file target/aarch64-unknown-linux-musl/debug/rg
target/aarch64-unknown-linux-musl/debug/rg: ELF 64-bit LSB executable, ARM aarch64, version 1 (GNU/Linux), statically linked, BuildID[sha1]=be11036b0988fac5dccc9f6487eb780b05186582, not stripped
```

Author: bors

src/bootstrap/configure.py

@@ -109,6 +109,8 @@ def v(*args):
   "arm-unknown-linux-musleabihf install directory")
 v("musl-root-armv7", "target.armv7-unknown-linux-musleabihf.musl-root",
   "armv7-unknown-linux-musleabihf install directory")
+v("musl-root-aarch64", "target.aarch64-unknown-linux-musl.musl-root",
+  "aarch64-unknown-linux-musl install directory")
 v("qemu-armhf-rootfs", "target.arm-unknown-linux-gnueabihf.qemu-rootfs",
   "rootfs in qemu testing, you probably don't want to use this")
 v("qemu-aarch64-rootfs", "target.aarch64-unknown-linux-gnu.qemu-rootfs",

src/bootstrap/native.rs

@@ -399,6 +399,7 @@ impl Step for Openssl {
         let os = match &*target {
             "aarch64-linux-android" => "linux-aarch64",
             "aarch64-unknown-linux-gnu" => "linux-aarch64",
+            "aarch64-unknown-linux-musl" => "linux-aarch64",
             "arm-linux-androideabi" => "android",
             "arm-unknown-linux-gnueabi" => "linux-armv4",
             "arm-unknown-linux-gnueabihf" => "linux-armv4",

src/ci/docker/cross/Dockerfile

@@ -14,6 +14,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   zlib1g-dev \
   g++-arm-linux-gnueabi \
   g++-arm-linux-gnueabihf \
+  g++-aarch64-linux-gnu \
   gcc-sparc64-linux-gnu \
   libc6-dev-sparc64-cross \
   bzip2 \
@@ -46,6 +47,7 @@ ENV TARGETS=$TARGETS,mipsel-unknown-linux-musl
 ENV TARGETS=$TARGETS,arm-unknown-linux-musleabi
 ENV TARGETS=$TARGETS,arm-unknown-linux-musleabihf
 ENV TARGETS=$TARGETS,armv7-unknown-linux-musleabihf
+ENV TARGETS=$TARGETS,aarch64-unknown-linux-musl
 ENV TARGETS=$TARGETS,sparc64-unknown-linux-gnu
 ENV TARGETS=$TARGETS,x86_64-unknown-redox
 
@@ -62,7 +64,8 @@ ENV RUST_CONFIGURE_ARGS \
       --target=$TARGETS \
       --musl-root-arm=/usr/local/arm-linux-musleabi \
       --musl-root-armhf=/usr/local/arm-linux-musleabihf \
-      --musl-root-armv7=/usr/local/armv7-linux-musleabihf
+      --musl-root-armv7=/usr/local/armv7-linux-musleabihf \
+      --musl-root-aarch64=/usr/local/aarch64-linux-musl
 ENV SCRIPT python2.7 ../x.py dist --target $TARGETS
 
 # sccache

src/ci/docker/cross/build-arm-musl.sh

@@ -65,11 +65,24 @@ CFLAGS="-march=armv7-a" \
 hide_output make -j$(nproc)
 hide_output make install
 cd ..
+rm -rf musl-$MUSL
+
+tar xf musl-$MUSL.tar.gz
+cd musl-$MUSL
+CC=aarch64-linux-gnu-gcc \
+CFLAGS="" \
+    hide_output ./configure \
+        --prefix=/usr/local/aarch64-linux-musl \
+        --enable-wrapper=gcc
+hide_output make -j$(nproc)
+hide_output make install
+cd ..
 rm -rf musl-$MUSL*
 
 ln -nsf ../arm-linux-musleabi/bin/musl-gcc /usr/local/bin/arm-linux-musleabi-gcc
 ln -nsf ../arm-linux-musleabihf/bin/musl-gcc /usr/local/bin/arm-linux-musleabihf-gcc
 ln -nsf ../armv7-linux-musleabihf/bin/musl-gcc /usr/local/bin/armv7-linux-musleabihf-gcc
+ln -nsf ../aarch64-linux-musl/bin/musl-gcc /usr/local/bin/aarch64-unknown-linux-musl-gcc
 
 curl -L https://github.com/llvm-mirror/llvm/archive/release_39.tar.gz | tar xzf -
 curl -L https://github.com/llvm-mirror/libunwind/archive/release_39.tar.gz | tar xzf -
@@ -116,5 +129,19 @@ cp lib/libunwind.a /usr/local/armv7-linux-musleabihf/lib
 cd ..
 rm -rf libunwind-build
 
+mkdir libunwind-build
+cd libunwind-build
+cmake ../libunwind-release_39 \
+          -DLLVM_PATH=/tmp/llvm-release_39 \
+          -DLIBUNWIND_ENABLE_SHARED=0 \
+          -DCMAKE_C_COMPILER=aarch64-linux-gnu-gcc \
+          -DCMAKE_CXX_COMPILER=aarch64-linux-gnu-g++ \
+          -DCMAKE_C_FLAGS="" \
+          -DCMAKE_CXX_FLAGS=""
+make -j$(nproc)
+cp lib/libunwind.a /usr/local/aarch64-linux-musl/lib
+cd ..
+rm -rf libunwind-build
+
 rm -rf libunwind-release_39
 rm -rf llvm-release_39

src/librustc_back/target/aarch64_unknown_linux_musl.rs

@@ -0,0 +1,36 @@
+// Copyright 2017 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.
+
+use LinkerFlavor;
+use target::{Target, TargetOptions, TargetResult};
+
+pub fn target() -> TargetResult {
+    let mut base = super::linux_musl_base::opts();
+    base.max_atomic_width = Some(128);
+
+    // see #36994
+    base.exe_allocation_crate = None;
+
+    Ok(Target {
+        llvm_target: "aarch64-unknown-linux-musl".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "64".to_string(),
+        target_env: "musl".to_string(),
+        data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
+        arch: "aarch64".to_string(),
+        target_os: "linux".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: TargetOptions {
+            abi_blacklist: super::arm_base::abi_blacklist(),
+            .. base
+        },
+    })
+}

src/librustc_back/target/mod.rs

@@ -153,6 +153,7 @@ supported_targets! {
     ("armv7-unknown-linux-gnueabihf", armv7_unknown_linux_gnueabihf),
     ("armv7-unknown-linux-musleabihf", armv7_unknown_linux_musleabihf),
     ("aarch64-unknown-linux-gnu", aarch64_unknown_linux_gnu),
+    ("aarch64-unknown-linux-musl", aarch64_unknown_linux_musl),
     ("x86_64-unknown-linux-musl", x86_64_unknown_linux_musl),
     ("i686-unknown-linux-musl", i686_unknown_linux_musl),
     ("mips-unknown-linux-musl", mips_unknown_linux_musl),

src/tools/build-manifest/src/main.rs

@@ -50,6 +50,7 @@ static TARGETS: &'static [&'static str] = &[
     "aarch64-unknown-fuchsia",
     "aarch64-linux-android",
     "aarch64-unknown-linux-gnu",
+    "aarch64-unknown-linux-musl",
     "arm-linux-androideabi",
     "arm-unknown-linux-gnueabi",
     "arm-unknown-linux-gnueabihf",