Rollup merge of #51619 - mksully22:ppc64le_rust, r=alexcrichton

rust: add initial changes to support powerpc64le musl

Initial changes to support rustc building on ppc64le with musl. A PR was also submitted to libc component https://github.com/rust-lang/libc/pull/1023 to add changes to libc musl definitions.

A PR was submitted on Alpine https://github.com/alpinelinux/aports/pull/4549 with equivalent temporary patches for building on Alpine for now.

As a verification test a github project was put together to build ppc64le versions of rustc, rust-stdlib, and cargo on Alpine, https://github.com/mksully22/ppc64le_alpine_rust_1.26.2

src/bootstrap/native.rs

@@ -631,6 +631,7 @@ impl Step for Openssl {
             "powerpc-unknown-netbsd" => "BSD-generic32",
             "powerpc64-unknown-linux-gnu" => "linux-ppc64",
             "powerpc64le-unknown-linux-gnu" => "linux-ppc64le",
+            "powerpc64le-unknown-linux-musl" => "linux-ppc64le",
             "s390x-unknown-linux-gnu" => "linux64-s390x",
             "sparc-unknown-linux-gnu" => "linux-sparcv9",
             "sparc64-unknown-linux-gnu" => "linux64-sparcv9",

src/librustc_target/spec/mod.rs

@@ -274,6 +274,7 @@ supported_targets! {
     ("powerpc-unknown-linux-gnuspe", powerpc_unknown_linux_gnuspe),
     ("powerpc64-unknown-linux-gnu", powerpc64_unknown_linux_gnu),
     ("powerpc64le-unknown-linux-gnu", powerpc64le_unknown_linux_gnu),
+    ("powerpc64le-unknown-linux-musl", powerpc64le_unknown_linux_musl),
     ("s390x-unknown-linux-gnu", s390x_unknown_linux_gnu),
     ("sparc-unknown-linux-gnu", sparc_unknown_linux_gnu),
     ("sparc64-unknown-linux-gnu", sparc64_unknown_linux_gnu),

src/librustc_target/spec/powerpc64le_unknown_linux_musl.rs

@@ -0,0 +1,35 @@
+// 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, TargetResult};
+
+pub fn target() -> TargetResult {
+    let mut base = super::linux_musl_base::opts();
+    base.cpu = "ppc64le".to_string();
+    base.pre_link_args.get_mut(&LinkerFlavor::Gcc).unwrap().push("-m64".to_string());
+    base.max_atomic_width = Some(64);
+
+    // see #36994
+    base.exe_allocation_crate = None;
+
+    Ok(Target {
+        llvm_target: "powerpc64le-unknown-linux-musl".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-n32:64".to_string(),
+        arch: "powerpc64".to_string(),
+        target_os: "linux".to_string(),
+        target_env: "musl".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: base,
+    })
+}

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

@@ -88,6 +88,7 @@ static TARGETS: &'static [&'static str] = &[
     "powerpc-unknown-linux-gnuspe",
     "powerpc64-unknown-linux-gnu",
     "powerpc64le-unknown-linux-gnu",
+    "powerpc64le-unknown-linux-musl",
     "s390x-unknown-linux-gnu",
     "sparc-unknown-linux-gnu",
     "sparc64-unknown-linux-gnu",