Add risc-v based Android compile target

Signed-off-by: Chen Guoyin <chenguoyin.cgy@linux.alibaba.com>
Signed-off-by: Mao Han <han_mao@linux.alibaba.com>

compiler/rustc_target/src/spec/mod.rs

@@ -873,6 +873,7 @@ supported_targets! {
     ("armv7-linux-androideabi", armv7_linux_androideabi),
     ("thumbv7neon-linux-androideabi", thumbv7neon_linux_androideabi),
     ("aarch64-linux-android", aarch64_linux_android),
+    ("riscv64gc-linux-android", riscv64gc_linux_android),
 
     ("x86_64-unknown-none-linuxkernel", x86_64_unknown_none_linuxkernel),
 

compiler/rustc_target/src/spec/riscv64gc_linux_android.rs

@@ -0,0 +1,19 @@
+use crate::spec::{CodeModel, SanitizerSet, Target, TargetOptions};
+
+pub fn target() -> Target {
+    Target {
+        llvm_target: "riscv64-linux-android".into(),
+        pointer_width: 64,
+        data_layout: "e-m:e-p:64:64-i64:64-i128:128-n64-S128".into(),
+        arch: "riscv64".into(),
+        options: TargetOptions {
+            code_model: Some(CodeModel::Medium),
+            cpu: "generic-rv64".into(),
+            features: "+m,+a,+f,+d,+c".into(),
+            llvm_abiname: "lp64d".into(),
+            supported_sanitizers: SanitizerSet::ADDRESS,
+            max_atomic_width: Some(64),
+            ..super::android_base::opts()
+        },
+    }
+}

library/std/src/os/android/raw.rs

@@ -155,6 +155,74 @@ mod arch {
     }
 }
 
+#[cfg(target_arch = "riscv64")]
+mod arch {
+    use crate::os::raw::{c_uchar, c_ulong};
+    use crate::os::unix::raw::{gid_t, uid_t};
+
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub type dev_t = u64;
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub type mode_t = u32;
+
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub type blkcnt_t = u64;
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub type blksize_t = u64;
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub type ino_t = u64;
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub type nlink_t = u64;
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub type off_t = u64;
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub type time_t = i64;
+
+    #[repr(C)]
+    #[derive(Clone)]
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub struct stat {
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_dev: dev_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub __pad0: [c_uchar; 4],
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub __st_ino: ino_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_mode: mode_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_nlink: nlink_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_uid: uid_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_gid: gid_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_rdev: dev_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub __pad3: [c_uchar; 4],
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_size: off_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_blksize: blksize_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_blocks: blkcnt_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_atime: time_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_atime_nsec: c_ulong,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_mtime: time_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_mtime_nsec: c_ulong,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_ctime: time_t,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_ctime_nsec: c_ulong,
+        #[stable(feature = "raw_ext", since = "1.1.0")]
+        pub st_ino: ino_t,
+    }
+}
+
 #[cfg(target_arch = "x86_64")]
 mod arch {
     use crate::os::raw::{c_long, c_uint, c_ulong};

src/doc/rustc/src/platform-support.md

@@ -157,6 +157,7 @@ target | std | notes
 `riscv32i-unknown-none-elf` | * | Bare RISC-V (RV32I ISA)
 `riscv32imac-unknown-none-elf` | * | Bare RISC-V (RV32IMAC ISA)
 `riscv32imc-unknown-none-elf` | * | Bare RISC-V (RV32IMC ISA)
+`riscv64gc-linux-android` | ✓ | 64-bit RISC-V Android
 `riscv64gc-unknown-none-elf` | * | Bare RISC-V (RV64IMAFDC ISA)
 `riscv64imac-unknown-none-elf` | * | Bare RISC-V (RV64IMAC ISA)
 `sparc64-unknown-linux-gnu` | ✓ | SPARC Linux (kernel 4.4, glibc 2.23)

src/doc/rustc/src/platform-support/riscv64gc_linux_android.md

@@ -0,0 +1,52 @@
+# riscv64gc-linux-android
+
+**Tier: 3**
+
+Android target similar to "x86_64-linux-android" and "aarch64-linux-android".
+
+## Target maintainers
+
+- [@Mao Han](https://github.com/MaoHan001)
+
+## Requirements
+
+The requirements for android rust toolchian can be downloaded with:
+repo init -u https://android.googlesource.com/platform/manifest -b rust-toolchain
+
+## Building the target
+
+The target can be built by enabling it for a `rustc` build.
+
+```toml
+[build]
+target = ["riscv64gc-linux-android"]
+```
+
+Make sure your C compiler is included in `$PATH`, then add it to the `config.toml`:
+
+```toml
+[target.riscv64gc-linux-android]
+cc="clang-riscv64-linux-android"
+ar="llvm-ar"
+```
+
+## Building Rust programs
+
+Rust does not yet ship pre-compiled artifacts for this target. To compile for
+this target, you will either need to build Rust with the target enabled (see
+"Building the target" above), or build your own copy of `core` by using
+`build-std` or similar.
+
+## Testing
+Check adb can list the attached device
+$ adb devices
+List of devices attached
+emulator-5580   device
+
+Test assembly with stage 3 compiler
+$ ./x.py test src/test/assembly --stage 3 --target riscv64gc-linux-android
+
+## Cross-compilation toolchains and C code
+
+Compatible C code can be built with Clang's `riscv64-linux-android` targets as long as LLVM based C toolchains are used.
+- [clang-riscv64](https://github.com/riscv-android-src/platform-prebuilts-clang-host-linux-x86/tree/riscv64-android-12.0.0_dev)