MIPS: add r6 support

MIPS r6 is quite different with the previous version.
It use some new target triples:
  mipsisa32r6-unknown-linux-gnu
  mipsisa32r6el-unknown-linux-gnu
  mipsisa64r6-unknown-linux-gnuabi64
  mipsisa64r6el-unknown-linux-gnuabi64

This patch has been tested with Debian Port for mips64r6el,
and the support of these triples also is included in llvm:
  https://reviews.llvm.org/rGe58c45a695f39004710b6ce940d489fee800dbd3

Author: wzssyqa

src/librustc_target/spec/mipsisa32r6_unknown_linux_gnu.rs

@@ -0,0 +1,23 @@
+use crate::spec::{LinkerFlavor, Target, TargetOptions, TargetResult};
+
+pub fn target() -> TargetResult {
+    Ok(Target {
+        llvm_target: "mipsisa32r6-unknown-linux-gnu".to_string(),
+        target_endian: "big".to_string(),
+        target_pointer_width: "32".to_string(),
+        target_c_int_width: "32".to_string(),
+        data_layout: "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
+        arch: "mips".to_string(),
+        target_os: "linux".to_string(),
+        target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: TargetOptions {
+            cpu: "mips32r6".to_string(),
+            features: "+mips32r6".to_string(),
+            max_atomic_width: Some(32),
+
+            ..super::linux_base::opts()
+        },
+    })
+}

src/librustc_target/spec/mipsisa32r6el_unknown_linux_gnu.rs

@@ -0,0 +1,24 @@
+use crate::spec::{LinkerFlavor, Target, TargetOptions, TargetResult};
+
+pub fn target() -> TargetResult {
+    Ok(Target {
+        llvm_target: "mipsisa32r6el-unknown-linux-gnu".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "32".to_string(),
+        target_c_int_width: "32".to_string(),
+        data_layout: "e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".to_string(),
+        arch: "mips".to_string(),
+        target_os: "linux".to_string(),
+        target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+
+        options: TargetOptions {
+            cpu: "mips32r6".to_string(),
+            features: "+mips32r6".to_string(),
+            max_atomic_width: Some(32),
+
+            ..super::linux_base::opts()
+        },
+    })
+}

src/librustc_target/spec/mipsisa64r6_unknown_linux_gnuabi64.rs

@@ -0,0 +1,24 @@
+use crate::spec::{LinkerFlavor, Target, TargetOptions, TargetResult};
+
+pub fn target() -> TargetResult {
+    Ok(Target {
+        llvm_target: "mipsisa64r6-unknown-linux-gnuabi64".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-i8:8:32-i16:16:32-i64:64-n32:64-S128".to_string(),
+        arch: "mips64".to_string(),
+        target_os: "linux".to_string(),
+        target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: TargetOptions {
+            // NOTE(mips64r6) matches C toolchain
+            cpu: "mips64r6".to_string(),
+            features: "+mips64r6".to_string(),
+            max_atomic_width: Some(64),
+
+            ..super::linux_base::opts()
+        },
+    })
+}

src/librustc_target/spec/mipsisa64r6el_unknown_linux_gnuabi64.rs

@@ -0,0 +1,24 @@
+use crate::spec::{LinkerFlavor, Target, TargetOptions, TargetResult};
+
+pub fn target() -> TargetResult {
+    Ok(Target {
+        llvm_target: "mipsisa64r6el-unknown-linux-gnuabi64".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-n32:64-S128".to_string(),
+        arch: "mips64".to_string(),
+        target_os: "linux".to_string(),
+        target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: TargetOptions {
+            // NOTE(mips64r6) matches C toolchain
+            cpu: "mips64r6".to_string(),
+            features: "+mips64r6".to_string(),
+            max_atomic_width: Some(64),
+
+            ..super::linux_base::opts()
+        },
+    })
+}

src/librustc_target/spec/mod.rs

@@ -335,6 +335,10 @@ supported_targets! {
     ("mips-unknown-linux-gnu", mips_unknown_linux_gnu),
     ("mips64-unknown-linux-gnuabi64", mips64_unknown_linux_gnuabi64),
     ("mips64el-unknown-linux-gnuabi64", mips64el_unknown_linux_gnuabi64),
+    ("mipsisa32r6-unknown-linux-gnu", mipsisa32r6_unknown_linux_gnu),
+    ("mipsisa32r6el-unknown-linux-gnu", mipsisa32r6el_unknown_linux_gnu),
+    ("mipsisa64r6-unknown-linux-gnuabi64", mipsisa64r6_unknown_linux_gnuabi64),
+    ("mipsisa64r6el-unknown-linux-gnuabi64", mipsisa64r6el_unknown_linux_gnuabi64),
     ("mipsel-unknown-linux-gnu", mipsel_unknown_linux_gnu),
     ("powerpc-unknown-linux-gnu", powerpc_unknown_linux_gnu),
     ("powerpc-unknown-linux-gnuspe", powerpc_unknown_linux_gnuspe),

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

@@ -23,6 +23,10 @@ static HOSTS: &'static [&'static str] = &[
     "mips64-unknown-linux-gnuabi64",
     "mips64el-unknown-linux-gnuabi64",
     "mipsel-unknown-linux-gnu",
+    "mipsisa32r6-unknown-linux-gnu",
+    "mipsisa32r6el-unknown-linux-gnu",
+    "mipsisa64r6-unknown-linux-gnuabi64",
+    "mipsisa64r6el-unknown-linux-gnuabi64",
     "powerpc-unknown-linux-gnu",
     "powerpc64-unknown-linux-gnu",
     "powerpc64le-unknown-linux-gnu",
@@ -77,6 +81,10 @@ static TARGETS: &'static [&'static str] = &[
     "mips-unknown-linux-musl",
     "mips64-unknown-linux-gnuabi64",
     "mips64el-unknown-linux-gnuabi64",
+    "mipsisa32r6-unknown-linux-gnu",
+    "mipsisa32r6el-unknown-linux-gnu",
+    "mipsisa64r6-unknown-linux-gnuabi64",
+    "mipsisa64r6el-unknown-linux-gnuabi64",
     "mipsel-unknown-linux-gnu",
     "mipsel-unknown-linux-musl",
     "nvptx64-nvidia-cuda",

src/tools/compiletest/src/util.rs

@@ -49,7 +49,15 @@ const ARCH_TABLE: &'static [(&'static str, &'static str)] = &[
     ("mips", "mips"),
     ("mips64", "mips64"),
     ("mips64el", "mips64"),
+    ("mipsisa32r6", "mips"),
+    ("mipsisa32r6el", "mips"),
+    ("mipsisa64r6", "mips64"),
+    ("mipsisa64r6el", "mips64"),
     ("mipsel", "mips"),
+    ("mipsisa32r6", "mips"),
+    ("mipsisa32r6el", "mips"),
+    ("mipsisa64r6", "mips64"),
+    ("mipsisa64r6el", "mips64"),
     ("msp430", "msp430"),
     ("powerpc", "powerpc"),
     ("powerpc64", "powerpc64"),