Rollup merge of rust-lang#52861 - ColinFinck:master, r=alexcrichton

Add targets for HermitCore (https://hermitcore.org) to the Rust compiler and port libstd to it.

As a start, the port uses the simplest possible configuration (no jemalloc, abort on panic) and makes use of existing Unix-specific code wherever possible.
It adds targets for x86_64 (current main HermitCore platform) and aarch64 (HermitCore platform under development).

Together with the patches to "liblibc" (rust-lang/libc#1048) and llvm (rust-lang/llvm#122), this enables HermitCore applications to be written in Rust.

Author: Mark-Simulacrum

src/liballoc_system/lib.rs

@@ -174,7 +174,10 @@ mod platform {
         }
     }
 
-    #[cfg(any(target_os = "android", target_os = "redox", target_os = "solaris"))]
+    #[cfg(any(target_os = "android",
+              target_os = "hermit",
+              target_os = "redox",
+              target_os = "solaris"))]
     #[inline]
     unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
         // On android we currently target API level 9 which unfortunately
@@ -197,7 +200,10 @@ mod platform {
         libc::memalign(layout.align(), layout.size()) as *mut u8
     }
 
-    #[cfg(not(any(target_os = "android", target_os = "redox", target_os = "solaris")))]
+    #[cfg(not(any(target_os = "android",
+                  target_os = "hermit",
+                  target_os = "redox",
+                  target_os = "solaris")))]
     #[inline]
     unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
         let mut out = ptr::null_mut();

src/librustc_target/spec/aarch64_unknown_hermit.rs

@@ -0,0 +1,32 @@
+// Copyright 2016 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, TargetResult};
+
+pub fn target() -> TargetResult {
+    let mut base = super::hermit_base::opts();
+    base.max_atomic_width = Some(128);
+    base.abi_blacklist = super::arm_base::abi_blacklist();
+    base.linker = Some("aarch64-hermit-gcc".to_string());
+
+    Ok(Target {
+        llvm_target: "aarch64-unknown-hermit".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "64".to_string(),
+        target_c_int_width: "32".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: "hermit".to_string(),
+        target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: base,
+    })
+}

src/librustc_target/spec/hermit_base.rs

@@ -0,0 +1,37 @@
+// Copyright 2014 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::{LinkArgs, LinkerFlavor, PanicStrategy, TargetOptions};
+use std::default::Default;
+
+pub fn opts() -> TargetOptions {
+    let mut args = LinkArgs::new();
+    args.insert(LinkerFlavor::Gcc, vec![
+        "-Wl,-Bstatic".to_string(),
+        "-Wl,--no-dynamic-linker".to_string(),
+        "-Wl,--gc-sections".to_string(),
+        "-Wl,--as-needed".to_string(),
+    ]);
+
+    TargetOptions {
+        exe_allocation_crate: None,
+        executables: true,
+        has_elf_tls: true,
+        linker_is_gnu: true,
+        no_default_libraries: false,
+        panic_strategy: PanicStrategy::Abort,
+        position_independent_executables: false,
+        pre_link_args: args,
+        relocation_model: "static".to_string(),
+        target_family: Some("unix".to_string()),
+        tls_model: "local-exec".to_string(),
+        .. Default::default()
+    }
+}

src/librustc_target/spec/mod.rs

@@ -62,6 +62,7 @@ mod cloudabi_base;
 mod dragonfly_base;
 mod freebsd_base;
 mod haiku_base;
+mod hermit_base;
 mod linux_base;
 mod linux_musl_base;
 mod openbsd_base;
@@ -373,6 +374,9 @@ supported_targets! {
     ("armv7-unknown-cloudabi-eabihf", armv7_unknown_cloudabi_eabihf),
     ("i686-unknown-cloudabi", i686_unknown_cloudabi),
     ("x86_64-unknown-cloudabi", x86_64_unknown_cloudabi),
+
+    ("aarch64-unknown-hermit", aarch64_unknown_hermit),
+    ("x86_64-unknown-hermit", x86_64_unknown_hermit),
 }
 
 /// Everything `rustc` knows about how to compile for a specific target.

src/librustc_target/spec/x86_64_unknown_hermit.rs

@@ -0,0 +1,33 @@
+// Copyright 2016 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, TargetResult};
+
+pub fn target() -> TargetResult {
+    let mut base = super::hermit_base::opts();
+    base.cpu = "x86-64".to_string();
+    base.pre_link_args.get_mut(&LinkerFlavor::Gcc).unwrap().push("-m64".to_string());
+    base.linker = Some("x86_64-hermit-gcc".to_string());
+    base.max_atomic_width = Some(64);
+
+    Ok(Target {
+        llvm_target: "x86_64-unknown-hermit".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "64".to_string(),
+        target_c_int_width: "32".to_string(),
+        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        arch: "x86_64".to_string(),
+        target_os: "hermit".to_string(),
+        target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: base,
+    })
+}