Add new Tier-3 target: loongarch64-unknown-linux-musl

MCP: rust-lang/compiler-team#518
(cherry picked from commit d756375)

compiler/rustc_target/src/spec/loongarch64_unknown_linux_musl.rs

@@ -0,0 +1,18 @@
+use crate::spec::{Target, TargetOptions};
+
+pub fn target() -> Target {
+    Target {
+        llvm_target: "loongarch64-unknown-linux-musl".into(),
+        pointer_width: 64,
+        data_layout: "e-m:e-p:64:64-i64:64-i128:128-n64-S128".into(),
+        arch: "loongarch64".into(),
+        options: TargetOptions {
+            cpu: "generic".into(),
+            features: "+f,+d".into(),
+            llvm_abiname: "lp64d".into(),
+            max_atomic_width: Some(64),
+            crt_static_default: false,
+            ..super::linux_musl_base::opts()
+        },
+    }
+}

compiler/rustc_target/src/spec/mod.rs

@@ -1242,6 +1242,7 @@ supported_targets! {
     ("i686-unknown-linux-gnu", i686_unknown_linux_gnu),
     ("i586-unknown-linux-gnu", i586_unknown_linux_gnu),
     ("loongarch64-unknown-linux-gnu", loongarch64_unknown_linux_gnu),
+    ("loongarch64-unknown-linux-musl", loongarch64_unknown_linux_musl),
     ("m68k-unknown-linux-gnu", m68k_unknown_linux_gnu),
     ("mips-unknown-linux-gnu", mips_unknown_linux_gnu),
     ("mips64-unknown-linux-gnuabi64", mips64_unknown_linux_gnuabi64),

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

@@ -155,6 +155,7 @@ target | std | notes
 `i686-unknown-freebsd` | ✓ | 32-bit FreeBSD
 `i686-unknown-linux-musl` | ✓ | 32-bit Linux with MUSL
 [`i686-unknown-uefi`](platform-support/unknown-uefi.md) | * | 32-bit UEFI
+[`loongarch64-unknown-linux-musl`](platform-support/loongarch-linux.md) | ? |  | LoongArch64 Linux (LP64D ABI)
 `mips-unknown-linux-musl` | ✓ | MIPS Linux with MUSL
 `mips64-unknown-linux-muslabi64` | ✓ | MIPS64 Linux, n64 ABI, MUSL
 `mips64el-unknown-linux-muslabi64` | ✓ | MIPS64 (LE) Linux, n64 ABI, MUSL