add (shimmed) std support for armv7a-vex-v5

Author: max-niederman

library/std/Cargo.toml

@@ -90,6 +90,9 @@ wasi = { version = "0.11.0", features = [
 r-efi = { version = "4.5.0", features = ['rustc-dep-of-std'] }
 r-efi-alloc = { version = "1.0.0", features = ['rustc-dep-of-std'] }
 
+[target.'cfg(target_os = "vexos")'.dependencies]
+vex-sdk = { version = "0.16.1", features = ['rustc-dep-of-std'] }
+
 [features]
 backtrace = [
     'addr2line/rustc-dep-of-std',

library/std/build.rs

@@ -56,6 +56,7 @@ fn main() {
         || target_os == "zkvm"
         || target_os == "rtems"
         || target_os == "nuttx"
+        || target_os == "vexos"
 
         // See src/bootstrap/src/core/build_steps/synthetic_targets.rs
         || env::var("RUSTC_BOOTSTRAP_SYNTHETIC_TARGET").is_ok()

library/std/src/sys/pal/mod.rs

@@ -61,6 +61,9 @@ cfg_if::cfg_if! {
     } else if #[cfg(target_os = "zkvm")] {
         mod zkvm;
         pub use self::zkvm::*;
+    } else if #[cfg(target_os = "vexos")] {
+        mod vexos;
+        pub use self::vexos::*;
     } else {
         mod unsupported;
         pub use self::unsupported::*;

library/std/src/sys/pal/vexos/mod.rs

@@ -0,0 +1,31 @@
+#[path = "../unsupported/alloc.rs"]
+pub mod alloc;
+#[path = "../unsupported/args.rs"]
+pub mod args;
+#[path = "../unsupported/env.rs"]
+pub mod env;
+#[path = "../unsupported/fs.rs"]
+pub mod fs;
+#[path = "../unsupported/io.rs"]
+pub mod io;
+#[path = "../unsupported/net.rs"]
+pub mod net;
+#[path = "../unsupported/os.rs"]
+pub mod os;
+#[path = "../unsupported/pipe.rs"]
+pub mod pipe;
+#[path = "../unsupported/process.rs"]
+pub mod process;
+#[path = "../unsupported/stdio.rs"]
+pub mod stdio;
+#[path = "../unsupported/thread.rs"]
+pub mod thread;
+#[path = "../unsupported/thread_local_key.rs"]
+pub mod thread_local_key;
+#[path = "../unsupported/time.rs"]
+pub mod time;
+
+#[path = "../unsupported/common.rs"]
+#[deny(unsafe_op_in_unsafe_fn)]
+mod common;
+pub use common::*;

src/bootstrap/src/core/sanity.rs

@@ -33,6 +33,7 @@ pub struct Finder {
 //
 // Targets can be removed from this list once they are present in the stage0 compiler (usually by updating the beta compiler of the bootstrap).
 const STAGE0_MISSING_TARGETS: &[&str] = &[
+    "armv7a-vex-v5",
     // just a dummy comment so the list doesn't get onelined
     "armv7-rtems-eabihf",
     "riscv32e-unknown-none-elf",

src/bootstrap/src/lib.rs

@@ -665,7 +665,7 @@ impl Build {
         }
         // Generate memcpy, etc.  FIXME: Remove this once compiler-builtins
         // automatically detects this target.
-        if target.contains("zkvm") {
+        if target.contains("zkvm") || target.contains("vex") {
             features.insert("compiler-builtins-mem");
         }