Rollup merge of rust-lang#76048 - alistair23:alistair/rv32-linux, r=Amanieu

Initial support for riscv32gc_unknown_linux_gnu

Now that RISC-V 32-bit (RV32) support is in upstream glibc let's add support for userspace Rust.

Author: Dylan-DPC

compiler/rustc_target/src/spec/mod.rs

@@ -654,6 +654,7 @@ supported_targets! {
     ("riscv32i-unknown-none-elf", riscv32i_unknown_none_elf),
     ("riscv32imc-unknown-none-elf", riscv32imc_unknown_none_elf),
     ("riscv32imac-unknown-none-elf", riscv32imac_unknown_none_elf),
+    ("riscv32gc-unknown-linux-gnu", riscv32gc_unknown_linux_gnu),
     ("riscv64imac-unknown-none-elf", riscv64imac_unknown_none_elf),
     ("riscv64gc-unknown-none-elf", riscv64gc_unknown_none_elf),
     ("riscv64gc-unknown-linux-gnu", riscv64gc_unknown_linux_gnu),

compiler/rustc_target/src/spec/riscv32gc_unknown_linux_gnu.rs

@@ -0,0 +1,25 @@
+use crate::spec::{CodeModel, LinkerFlavor, Target, TargetOptions, TargetResult};
+
+pub fn target() -> TargetResult {
+    Ok(Target {
+        llvm_target: "riscv32-unknown-linux-gnu".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "32".to_string(),
+        target_c_int_width: "32".to_string(),
+        target_env: "gnu".to_string(),
+        data_layout: "e-m:e-p:32:32-i64:64-n32-S128".to_string(),
+        arch: "riscv32".to_string(),
+        target_os: "linux".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: TargetOptions {
+            unsupported_abis: super::riscv_base::unsupported_abis(),
+            code_model: Some(CodeModel::Medium),
+            cpu: "generic-rv32".to_string(),
+            features: "+m,+a,+f,+d,+c".to_string(),
+            llvm_abiname: "ilp32d".to_string(),
+            max_atomic_width: Some(32),
+            ..super::linux_base::opts()
+        },
+    })
+}

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

@@ -195,6 +195,7 @@ target | std | host | notes
 `powerpc64-unknown-linux-musl` | ? |  |
 `powerpc64-wrs-vxworks` | ? |  |
 `powerpc64le-unknown-linux-musl` | ? |  |
+`riscv32gc-unknown-linux-gnu` |   |   | RISC-V Linux (kernel 5.4, glibc 2.33)
 `sparc-unknown-linux-gnu` | ✓ |  | 32-bit SPARC Linux
 `sparc64-unknown-netbsd` | ✓ | ✓ | NetBSD/sparc64
 `sparc64-unknown-openbsd` | ? |  |