Rollup merge of rust-lang#55562 - smaeul:powerpc-linux-musl, r=alexcrichton

Add powerpc- and powerpc64-unknown-linux-musl targets

Add targets for musl on 32-bit and 64-bit powerpc. This requires some ABI fixes, as musl [uses the ELFv2 ABI on regardless of endianness](http://git.musl-libc.org/cgit/musl/tree/configure?id=8084d6ab57cdb0b8f328d3cdbad3b9d09eaaee04#n638). At the moment, powerpc64 support requires [an LLVM patch](https://reviews.llvm.org/D52013) to select the correct ABI; or I can add [a patch to Rust's LLVM backend](smaeul@e8eaa2a) to always choose the right ABI.

Both architectures are able to run an extended bootstrap, and with some test fixes (e.g. rust-lang#55561), there are no architecture-dependent test failures on powerpc64 (most failures in `src/test` are existing musl-host-related issues).

Author: pietroalbini

src/librustc_target/abi/call/powerpc64.rs

@@ -14,11 +14,12 @@
 
 use abi::call::{FnType, ArgType, Reg, RegKind, Uniform};
 use abi::{Align, Endian, HasDataLayout, LayoutOf, TyLayout, TyLayoutMethods};
+use spec::HasTargetSpec;
 
 #[derive(Debug, Clone, Copy, PartialEq)]
 enum ABI {
     ELFv1, // original ABI used for powerpc64 (big-endian)
-    ELFv2, // newer ABI used for powerpc64le
+    ELFv2, // newer ABI used for powerpc64le and musl (both endians)
 }
 use self::ABI::*;
 
@@ -75,7 +76,9 @@ fn classify_ret_ty<'a, Ty, C>(cx: &C, ret: &mut ArgType<'a, Ty>, abi: ABI)
     let size = ret.layout.size;
     let bits = size.bits();
     if bits <= 128 {
-        let unit = if bits <= 8 {
+        let unit = if cx.data_layout().endian == Endian::Big {
+            Reg { kind: RegKind::Integer, size }
+        } else if bits <= 8 {
             Reg::i8()
         } else if bits <= 16 {
             Reg::i16()
@@ -110,22 +113,15 @@ fn classify_arg_ty<'a, Ty, C>(cx: &C, arg: &mut ArgType<'a, Ty>, abi: ABI)
     }
 
     let size = arg.layout.size;
-    let (unit, total) = match abi {
-        ELFv1 => {
-            // In ELFv1, aggregates smaller than a doubleword should appear in
-            // the least-significant bits of the parameter doubleword.  The rest
-            // should be padded at their tail to fill out multiple doublewords.
-            if size.bits() <= 64 {
-                (Reg { kind: RegKind::Integer, size }, size)
-            } else {
-                let align = Align::from_bits(64, 64).unwrap();
-                (Reg::i64(), size.abi_align(align))
-            }
-        },
-        ELFv2 => {
-            // In ELFv2, we can just cast directly.
-            (Reg::i64(), size)
-        },
+    let (unit, total) = if size.bits() <= 64 {
+        // Aggregates smaller than a doubleword should appear in
+        // the least-significant bits of the parameter doubleword.
+        (Reg { kind: RegKind::Integer, size }, size)
+    } else {
+        // Aggregates larger than a doubleword should be padded
+        // at the tail to fill out a whole number of doublewords.
+        let align = Align::from_bits(64, 64).unwrap();
+        (Reg::i64(), size.abi_align(align))
     };
 
     arg.cast_to(Uniform {
@@ -136,11 +132,15 @@ fn classify_arg_ty<'a, Ty, C>(cx: &C, arg: &mut ArgType<'a, Ty>, abi: ABI)
 
 pub fn compute_abi_info<'a, Ty, C>(cx: &C, fty: &mut FnType<'a, Ty>)
     where Ty: TyLayoutMethods<'a, C> + Copy,
-          C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>> + HasDataLayout
+          C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>> + HasDataLayout + HasTargetSpec
 {
-    let abi = match cx.data_layout().endian {
-        Endian::Big => ELFv1,
-        Endian::Little => ELFv2,
+    let abi = if cx.target_spec().target_env == "musl" {
+        ELFv2
+    } else {
+        match cx.data_layout().endian {
+            Endian::Big => ELFv1,
+            Endian::Little => ELFv2
+        }
     };
 
     if !fty.ret.is_ignore() {

src/librustc_target/abi/mod.rs

@@ -229,7 +229,7 @@ impl HasDataLayout for TargetDataLayout {
 }
 
 /// Endianness of the target, which must match cfg(target-endian).
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, PartialEq)]
 pub enum Endian {
     Little,
     Big

src/librustc_target/spec/mod.rs

@@ -297,7 +297,9 @@ supported_targets! {
     ("mipsel-unknown-linux-gnu", mipsel_unknown_linux_gnu),
     ("powerpc-unknown-linux-gnu", powerpc_unknown_linux_gnu),
     ("powerpc-unknown-linux-gnuspe", powerpc_unknown_linux_gnuspe),
+    ("powerpc-unknown-linux-musl", powerpc_unknown_linux_musl),
     ("powerpc64-unknown-linux-gnu", powerpc64_unknown_linux_gnu),
+    ("powerpc64-unknown-linux-musl", powerpc64_unknown_linux_musl),
     ("powerpc64le-unknown-linux-gnu", powerpc64le_unknown_linux_gnu),
     ("powerpc64le-unknown-linux-musl", powerpc64le_unknown_linux_musl),
     ("s390x-unknown-linux-gnu", s390x_unknown_linux_gnu),

src/librustc_target/spec/powerpc64_unknown_linux_musl.rs

@@ -0,0 +1,32 @@
+// 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 = "ppc64".to_string();
+    base.pre_link_args.get_mut(&LinkerFlavor::Gcc).unwrap().push("-m64".to_string());
+    base.max_atomic_width = Some(64);
+
+    Ok(Target {
+        llvm_target: "powerpc64-unknown-linux-musl".to_string(),
+        target_endian: "big".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/librustc_target/spec/powerpc_unknown_linux_musl.rs

@@ -0,0 +1,31 @@
+// 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.pre_link_args.get_mut(&LinkerFlavor::Gcc).unwrap().push("-m32".to_string());
+    base.max_atomic_width = Some(32);
+
+    Ok(Target {
+        llvm_target: "powerpc-unknown-linux-musl".to_string(),
+        target_endian: "big".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-n32".to_string(),
+        arch: "powerpc".to_string(),
+        target_os: "linux".to_string(),
+        target_env: "musl".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: base,
+    })
+}