Add a sparc-unknown-none-elf target.

Tested with the Gaisler bcc2 toolchain (both gcc and clang) and the Leon3 simulator.

compiler/rustc_target/src/spec/mod.rs

@@ -1433,6 +1433,8 @@ fn $module() {
     ("riscv64gc-unknown-linux-gnu", riscv64gc_unknown_linux_gnu),
     ("riscv64gc-unknown-linux-musl", riscv64gc_unknown_linux_musl),
 
+    ("sparc-unknown-none-elf", sparc_unknown_none_elf),
+
     ("loongarch64-unknown-none", loongarch64_unknown_none),
     ("loongarch64-unknown-none-softfloat", loongarch64_unknown_none_softfloat),
 

compiler/rustc_target/src/spec/sparc_unknown_none_elf.rs

+use crate::abi::Endian;
+use crate::spec::{Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, Target, TargetOptions};
+
+pub fn target() -> Target {
+    let options = TargetOptions {
+        linker_flavor: LinkerFlavor::Gnu(Cc::Yes, Lld::No),
+        linker: Some("sparc-elf-gcc".into()),
+        endian: Endian::Big,
+        cpu: "v7".into(),
+        abi: "elf".into(),
+        max_atomic_width: Some(32),
+        atomic_cas: true,
+        panic_strategy: PanicStrategy::Abort,
+        relocation_model: RelocModel::Static,
+        no_default_libraries: false,
+        emit_debug_gdb_scripts: false,
+        eh_frame_header: false,
+        ..Default::default()
+    };
+    Target {
+        data_layout: "E-m:e-p:32:32-i64:64-f128:64-n32-S64".into(),
+        llvm_target: "sparc-unknown-none-elf".into(),
+        pointer_width: 32,
+        arch: "sparc".into(),
+        options,
+    }
+}

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

@@ -176,6 +176,7 @@ target | std | notes
 `thumbv8m.base-none-eabi` | * | Bare ARMv8-M Baseline
 `thumbv8m.main-none-eabi` | * | Bare ARMv8-M Mainline
 `thumbv8m.main-none-eabihf` | * | Bare ARMv8-M Mainline, hardfloat
+`sparc-unknown-none-elf` | * | Bare 32-bit SPARC V7+
 `wasm32-unknown-emscripten` | ✓ | WebAssembly via Emscripten
 `wasm32-unknown-unknown` | ✓ | WebAssembly
 `wasm32-wasi` | ✓ | WebAssembly with WASI

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

@@ -127,6 +127,7 @@
     "s390x-unknown-linux-gnu",
     "sparc64-unknown-linux-gnu",
     "sparcv9-sun-solaris",
+    "sparc-unknown-none-elf",
     "thumbv6m-none-eabi",
     "thumbv7em-none-eabi",
     "thumbv7em-none-eabihf",