Auto merge of #50423 - hberntsen:armv5te_unknown_linux_musl, r=alexcrichton

Add armv5te-unknown-linux-musl target

This PR adds the armv5te-unknown-linux-musl target. The following steps should let you produce a fully statically linked binary now:
1. Running `./src/ci/docker/run.sh dist-armv5te-linux-musl`
2. Changing the run.sh script to start bash instead of the build process and running the container
3.
   ```sh
   export USER=root
   export PATH=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin:/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin:$PATH
   ```
4. Configuring Cargo
   ```yaml
   [target.armv5te-unknown-linux-musl]
   linker = "arm-linux-gnueabi-gcc"
   ```
5. Building a project
   ```sh
   cargo new --bin hello
   cd hello
   cargo build --target=armv5te-unknown-linux-musl --release
   ```

src/bootstrap/configure.py

@@ -120,6 +120,8 @@ v("musl-root-arm", "target.arm-unknown-linux-musleabi.musl-root",
   "arm-unknown-linux-musleabi install directory")
 v("musl-root-armhf", "target.arm-unknown-linux-musleabihf.musl-root",
   "arm-unknown-linux-musleabihf install directory")
+v("musl-root-armv5te", "target.armv5te-unknown-linux-musleabi.musl-root",
+  "armv5te-unknown-linux-musleabi 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",

src/ci/docker/dist-various-1/Dockerfile

@@ -43,6 +43,10 @@ ENV STAGING_DIR=/tmp
 
 COPY scripts/musl.sh /build
 RUN env \
+    CC=arm-linux-gnueabi-gcc CFLAGS="-march=armv5te -marm -mfloat-abi=soft" \
+    CXX=arm-linux-gnueabi-g++ CXXFLAGS="-march=armv5te -marm -mfloat-abi=soft" \
+    bash musl.sh armv5te && \
+    env \
     CC=arm-linux-gnueabi-gcc CFLAGS="-march=armv6 -marm" \
     CXX=arm-linux-gnueabi-g++ CXXFLAGS="-march=armv6 -marm" \
     bash musl.sh arm && \
@@ -84,6 +88,7 @@ ENV TARGETS=$TARGETS,mipsel-unknown-linux-musl
 ENV TARGETS=$TARGETS,arm-unknown-linux-musleabi
 ENV TARGETS=$TARGETS,arm-unknown-linux-musleabihf
 ENV TARGETS=$TARGETS,armv5te-unknown-linux-gnueabi
+ENV TARGETS=$TARGETS,armv5te-unknown-linux-musleabi
 ENV TARGETS=$TARGETS,armv7-unknown-linux-musleabihf
 ENV TARGETS=$TARGETS,aarch64-unknown-linux-musl
 ENV TARGETS=$TARGETS,sparc64-unknown-linux-gnu
@@ -100,9 +105,12 @@ ENV CC_mipsel_unknown_linux_musl=mipsel-openwrt-linux-gcc \
     CC_sparc64_unknown_linux_gnu=sparc64-linux-gnu-gcc \
     CC_x86_64_unknown_redox=x86_64-unknown-redox-gcc \
     CC_armv5te_unknown_linux_gnueabi=arm-linux-gnueabi-gcc \
-    CFLAGS_armv5te_unknown_linux_gnueabi="-march=armv5te -marm -mfloat-abi=soft"
+    CFLAGS_armv5te_unknown_linux_gnueabi="-march=armv5te -marm -mfloat-abi=soft" \
+    CC_armv5te_unknown_linux_musleabi=arm-linux-gnueabi-gcc \
+    CFLAGS_armv5te_unknown_linux_musleabi="-march=armv5te -marm -mfloat-abi=soft"
 
 ENV RUST_CONFIGURE_ARGS \
+      --musl-root-armv5te=/musl-armv5te \
       --musl-root-arm=/musl-arm \
       --musl-root-armhf=/musl-armhf \
       --musl-root-armv7=/musl-armv7 \

src/librustc_target/spec/armv5te_unknown_linux_musleabi.rs

@@ -0,0 +1,38 @@
+// 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.
+
+use spec::{LinkerFlavor, Target, TargetOptions, TargetResult};
+
+pub fn target() -> TargetResult {
+    let base = super::linux_musl_base::opts();
+    Ok(Target {
+        // It's important we use "gnueabihf" and not "musleabihf" here. LLVM
+        // uses it to determine the calling convention and float ABI, and LLVM
+        // doesn't support the "musleabihf" value.
+        llvm_target: "armv5te-unknown-linux-gnueabi".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "32".to_string(),
+        target_c_int_width: "32".to_string(),
+        data_layout: "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
+        arch: "arm".to_string(),
+        target_os: "linux".to_string(),
+        target_env: "musl".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+
+        options: TargetOptions {
+            features: "+soft-float,+strict-align".to_string(),
+            // Atomic operations provided by compiler-builtins
+            max_atomic_width: Some(32),
+            abi_blacklist: super::arm_base::abi_blacklist(),
+            .. base
+        }
+    })
+}

src/librustc_target/spec/mod.rs

@@ -283,6 +283,7 @@ supported_targets! {
     ("arm-unknown-linux-musleabihf", arm_unknown_linux_musleabihf),
     ("armv4t-unknown-linux-gnueabi", armv4t_unknown_linux_gnueabi),
     ("armv5te-unknown-linux-gnueabi", armv5te_unknown_linux_gnueabi),
+    ("armv5te-unknown-linux-musleabi", armv5te_unknown_linux_musleabi),
     ("armv7-unknown-linux-gnueabihf", armv7_unknown_linux_gnueabihf),
     ("armv7-unknown-linux-musleabihf", armv7_unknown_linux_musleabihf),
     ("aarch64-unknown-linux-gnu", aarch64_unknown_linux_gnu),

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

@@ -57,6 +57,7 @@ static TARGETS: &'static [&'static str] = &[
     "arm-unknown-linux-musleabi",
     "arm-unknown-linux-musleabihf",
     "armv5te-unknown-linux-gnueabi",
+    "armv5te-unknown-linux-musleabi",
     "armv7-apple-ios",
     "armv7-linux-androideabi",
     "armv7-unknown-cloudabi-eabihf",